- Carbon and hydrogen isotopic evidence for the origin of combustible gases in water-supply wells in north-central Pennsylvania
From abstract: The origin of the combustible gases in groundwater from glacial-outwash and fractured-bedrock aquifers was investigated in northern Tioga County, Pennsylvania. Thermogenic methane (CH4) and ethane (C2H6) and microbial CH4 were found. Microbial CH4 is from natural in situ processes in the shale bedrock and occurs chiefly in the bedrock aquifer... see full abstract
- Thermal maturity map of Devonian shale in the Illinois, Michigan, and Appalachian basins of North America: U.S. Geological Survey Scientific Investigations Map 3214
Much of the oil and gas in the Illinois, Michigan, and Appalachian basins of eastern North America is thought to be derived from Devonian shale that is within these basins (for example, Milici and others, 2003; Swezey, 2002, 2008, 2009; Swezey and others, 2005, 2007). As the Devonian strata were buried by younger sediments, the Devonian shale was subjected to great temperature and pressure, and in some areas the shale crossed a thermal maturity threshold and began to generate oil. With increasing burial (increasing temperature and pressure), some of this oil-generating shale crossed another thermal maturity threshold and began to generate natural gas. Knowledge of the thermal maturity of the Devonian shale is therefore useful for predicting the occurrence and the spatial distribution of oil and gas within these three basins.
This publication presents a thermal maturity map of Devonian shale in the Illinois, Michigan, and Appalachian basins. The map shows outlines of the three basins (dashed black lines) and an outline of Devonian shale (solid black lines). The basin outlines are compiled from Thomas and others (1989) and Swezey (2008, 2009). The outline of Devonian shale is a compilation from Freeman (1978), Thomas and others (1989), de Witt and others (1993), Dart (1995), Nicholson and others (2004), Dicken and others (2005a,b), and Stoeser and others (2005).
- Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources: Progress Report
This report describes 18 research projects underway to answer research questions and presents each project’s progress as of September 2012. Information presented in this report should not be used to draw conclusions about potential impacts to drinking water resources from hydraulic fracturing. The research projects are organized according to the following categories: analysis of existing data, scenario evaluations, laboratory studies, toxicity assessments, and case studies. Note that this a final draft report is expected to be released for public comment and peer review in 2014.
- Hydraulic fractures: How far can they go?
Abstract: The maximum reported height of an upward propagating hydraulic fracture from several thousand fracturing operations in the Marcellus, Barnett, Woodford, Eagle Ford and Niobrara shale (USA) is ∼588 m. Of the 1170 natural hydraulic fracture pipes imaged with three-dimensional seismic data offshore of West Africa and mid-Norway it is ∼1106 m. Based on these empirical data, the probability of a stimulated and natural hydraulic fracture extending vertically >350 m is ∼1% and ∼33% respectively. Constraining the probability of stimulating unusually tall hydraulic fractures in sedimentary rocks is extremely important as an evidence base for decisions on the safe vertical separation between the depth of stimulation and rock strata not intended for penetration.
- The effects of a natural gas boom on employment and income in Colorado, Texas, and Wyoming
From abstract: Improvements in technology have made it profitable to tap unconventional gas reservoirs in relatively impermeable shale and sandstone deposits, which are spread throughout the U.S., mostly in rural areas. Proponents of gas drilling point to the activity's local economic benefits yet no empirical studies have systematically documented the magnitude or distribution of economic gains. I estimate these gains for counties in Colorado, Texas, and Wyoming, three states where natural gas production expanded substantially since the late 1990s. I find that a large increase in the value of gas production caused modest increases in employment, wage and salary income, and median household income. The results suggest that each million dollars in gas production created 2.35 jobs in the county of production, which led to an annualized increase in employment that was 1.5% of the preboom level for the average gas boom county. Comparisons show that ex-ante estimates of the number of jobs created by developing the Fayetteville and Marcellus shale gas formations may have been too large...... See abstract
- Underground injection and moderately saline groundwater in the Uinta Basin, Utah
From Abstract: The base of the moderately saline water (BMSW) in the Uinta Basin was first mapped in 1987 and re-mapped in this study using similar methods. Oil and gas operators in the Uinta Basin seeking underground disposal are generally required to inject waste production water below the BMSW or in waters greater than 10,000 mg/L total dissolved solids (TDS). Approximately 8000 new wells have been drilled in the basin since the 1987 study, providing new data for refining the previous mapping... see full abstract.
- Greenwashing gas: Might a 'transition fuel' label legitimize carbon-intensive natural gas development?
From the abstract: Natural gas is widely considered to be the crucial “bridging fuel” in the transition to the low-carbon energy systems necessary to mitigate climate change. This paper develops a case study of the shale gas industry in British Columbia (BC), Canada to evaluate this assumption. We find that the transition fuel argument for gas development in BC is unsubstantiated by the best available evidence. Emissions factors for shale gas and LNG remain poorly characterized and contested in the academic literature, and context-specific factors have significant impacts on the lifecycle emissions of shale gas but have not been evaluated. Moreover, while the province has attempted to frame natural gas development within its ambitious climate change policy, this framing misrepresents substantive policy on gas production. The “transition fuel” and “climate solution” labels applied to development by the BC provincial government risk legitimizing carbon-intensive gas development. We argue that policy makers in BC and beyond should abandon the “transition fuel” characterization of natural gas..... see full abstract.
- Geochemical evidence for possible natural migration of Marcellus Formation brine to shallow aquifers in Pennsylvania
From the abstract: The debate surrounding the safety of shale gas development in the Appalachian Basin has generated increased awareness of drinking water quality in rural communities. Concerns include the potential for migration of stray gas, metal-rich formation brines, and hydraulic fracturing and/or flowback fluids to drinking water aquifers. A critical question common to these environmental risks is the hydraulic connectivity between the shale gas formations and the overlying shallow drinking water aquifers. We present geochemical evidence from northeastern Pennsylvania showing that pathways, unrelated to recent drilling activities, exist in some locations between deep underlying formations and shallow drinking water aquifers. Integration of chemical data (Br, Cl, Na, Ba, Sr, and Li) and isotopic ratios (87Sr/86Sr, 2H/H, 18O/16O, and 228Ra/226Ra) from this and previous studies in 426 shallow groundwater samples and 83 northern Appalachian brine samples suggest that mixing relationships between shallow ground water and a deep formation brine causes groundwater salinization in some locations.... see abstract
- Bacterial communities associated with hydraulic fracturing fluids in thermogenic natural gas wells in North Central Texas, USA
From Abstract: Hydraulic fracturing is used to increase the permeability of shale gas formations and involves pumping large volumes of fluids into these formations. A portion of the frac fluid remains in the formation after the fracturing process is complete, which could potentially contribute to deleterious microbially induced processes in natural gas wells. Here, we report on the geochemical and microbiological properties of frac and flowback waters from two newly drilled natural gas wells in the Barnett Shale in North Central Texas. Most probable number studies showed that biocide treatments did not kill all the bacteria in the fracturing fluids... see full abstract.
- Characterization of gas shale pore systems by porosimetry, pycnometry, surface area, and field emission scanning electron microscopy/transmission electron microscopy image analyses: Examples from the Barnett, Woodford, Haynesville, Marcellus, and Doig units
The nanometer-scaled pore systems of gas shale reservoirs were investigated from the Barnett, Marcellus, Woodford, and Haynesville gas shales in the United States and the Doig Formation of northeastern British Columbia, Canada. The purpose of this article is to provide awareness of the nature and variability in pore structures within gas shales and not to provide a representative evaluation on the previously mentioned North American reservoirs. To understand the pore system of these rocks, the total porosity, pore-size distribution, surface area, organic geochemistry, mineralogy, and image analyses by electron microscopy were performed. Total porosity from helium pycnometry ranges between 2.5 and 6.6%. Total organic carbon content ranges between 0.7 and 6.8 wt. %, and vitrinite reflectance measured between 1.45 and 2.37%. The gas shales in the United States are clay and quartz rich, with the Doig Formation samples being quartz and carbonate rich and clay poor. Higher porosity samples have higher values because of a greater abundance of mesopores compared with lower porosity samples. With decreasing total porosity, micropore volumes relatively increase whereas the sum of mesopores and macropore volumes decrease. Focused ion beam milling, field emission scanning electron microscopy, and transmission electron microscopy provide high-resolution (∼5 nm) images of pore distribution and geometries. Image analysis provides a visual appreciation of pore systems in gas shale reservoirs but is not a statistically valid method to evaluate gas shale reservoirs. Macropores and mesopores are observed as either intergranular porosity or are confined to kerogen-rich aggregates and show no preferred orientation or align parallel with the laminae of the shale. Networks of mesopores are observed to connect with the larger macropores within the kerogen-rich aggregates.
- Bacterial Survival in Fractured Shale-Gas Wells of the Horn River Basin
From the summary: Traditional ideology on the upper temperature limits of life suggest that extreme temperatures such as those observed in the Horn River Basin shale-gas formation (i.e., up to 175°C) should alleviate microbiologically influenced corrosion and souring concerns associated with hydraulic-fracturing procedures. The present case history investigates the accuracy of this theory. Horn River basin wells currently in the flowback or production stage and the source water used to fracture these wells were studied for the presence and identity of viable bacteria. The effectiveness of two biocides (one glutaraldehyde-based and the other cocodiamine-based) in eradicating these bacteria in both the field and the laboratory was also studied. The results show that source ponds are highly contaminated with bacteria. Furthermore, the high-temperature, high-pressure downhole conditions in this region are not sufficient for eradicating bacteria introduced during the fracturing process. These bacteria survive and establish viable, proliferating communities. See full summary
- Atomic-Force Microscopy: A New Tool for Gas-Shale Characterization
From the summary: An atomic-force microscope (AFM), a relatively new tool for studying surface characterization, can generate image features down to atomic resolution. Not only can the AFM obtain topographic images of surfaces, but it also can simultaneously identify different materials on a surface at high resolution. Since its invention in the 1980s, AFM has been used in material science and medical research, although it has not received the attention that it probably deserves in reservoir engineering. The emergence of unconventional shale-gas reservoirs, however, has opened new research frontiers for the AFM in the field of reservoir engineering. The unique capabilities of the AFM make it ideal for studying nanopores, organic materials (kerogen), minerals, and diagenetic fractures in shales.... See full summary
- Role of Alternative Energy Sources: Natural Gas Power Technology Assessment
A broad, comprehensive overview of the natural gas power sector, including discussion of power plant performance and efficiency, environmental life cycle analysis (LCA), and cost analysis. The increasing share of shale gas (growth from 14 to 24 percent of the overall U.S. natural gas supply from 2009 to 2010) is also discussed. Important environmental considerations mentioned include greenhouse gas emissions and water withdrawals.
- Light volatile liquid and gas shale reservoir potential of the Cretaceous Shaftesbury Formation in northeastern British Columbia
The geologic controls on reservoir properties and potential hydrocarbon (volatile, low-molecular-weight liquid and gas) resources of the Cretaceous Shaftesbury Formation in northeastern British Columbia have been investigated. Maturity varies from the oil to dry gas window (Tmax = 429–486°C), with increasing maturity and depth of burial toward the south. TheTmax, in degrees Celsius, is the oven temperature at the peak generation of S2 during pyrolysis. Total organic carbon (TOC) content ranges between 0.64 and 8.0 wt. %, with an average of 2.2 wt. %. The TOC content distribution mirrors the trends in maturity, with lower TOC content in areas of high maturity. Kerogen is characterized as either type II-III or type III. The quartz content ranges between 33 and 66%, with higher quartz content in areas with lower TOC content and greater maturities. Porosity ranges between 4.5 and 14.6%, with higher porosities observed within shallower wells, low quartz content, or maturities, or a combination of all three. The porosity is reduced in high-maturity samples by mechanical compaction and silica cementation. Total gas capacities range between 4.5 and 24.8 cm3/g, and gas-in-place (GIP) estimates are between 0.98 and 3.39 bcf/(section × meter). The calculated hydrocarbon generation is less than 3.6 bcf/(section × meter), with light liquid generation between 3.7 and 516.2 MMBO.
Present-day depths and organic maturity have strong influences on the hydrocarbon capacity more so than TOC content. Deeper, higher maturity samples in the south have the largest total gas capacity and GIP estimates (0.98–3.39 bcf/[section × meter]). Maturity is within the dry gas window in the southern one-third of the study area. Highest volumes of light liquid hydrocarbons are found within the less mature northern part of the study area.
- Definitive Indicators of Hydrocarbon Production Character in Horizontal Shale Exploration
From Abstract: ... This study demonstrates an analytical use of DQMS [direct quadrupole mass spectrometry]-derived component ratios. In this study, the component ratio application is used to predict the production character of horizontal shale wells. When performed on DQMS-derived data, scores for component ratios are shown to confidently differentiate shale wells that will produce significant liquids...see full abstract.
- Early trends in landcover change and forest fragmentation due to shale-gas development in Pennsylvania: A potential outcome for the Northcentral Appalachians
Worldwide shale-gas development has the potential to cause substantial landscape disturbance. The northeastern U.S., specifically the Allegheny Plateau in Pennsylvania, West Virginia, Ohio, and Kentucky, is experiencing rapid exploration. Using Pennsylvania as a proxy for regional development across the Plateau, we examine land cover change due to shale-gas exploration, with emphasis on forest fragmentation. Pennsylvania’s shale-gas development is greatest on private land, and is dominated by pads with 1–2 wells; less than 10 % of pads have five wells or more. Approximately 45–62 % of pads occur on agricultural land and 38–54 % in forest land (many in core forest on private land). Development of permits granted as of June 3, 2011, would convert at least 644–1072 ha of agricultural land and 536–894 ha of forest land. Agricultural land conversion suggests that drilling is somewhat competing with food production… see full abstract.
- The Utility of Enhanced Mudlogging Methodologies for Improving Geosteering of Horizontal Wells
From Abstract: The analysis of rock materials cut by drill bits and transported to the surface in the drilling fluid is commonly known as mud logging. Data from such analysis are most valuable to the geologist responsible for operational decisions on the well if the analytical processes utilized to derive the data are scientifically robust and done in a highly standardized and timely manner. In practice, complex methodologies and procedures are difficult to rigorously quality control in the field... see full abstract.
- A Depositional and Diagenetic History of the Barnett Shale (Mississippian) in the Oil Window, Northern Ft Worth Basin, Cooke County, Texas
From Abstract: The Barnett Shale (Mississippian) in the Fort Worth basin is one of the most prolific unconventional gas plays in North America. Successful economic wells in this low-permeability reservoir result from application of innovative drilling and completion techniques such as horizontal drilling and hydraulic fracturing. Until recently production has been mainly from areas of the basin that yield only dry gas. Declining gas prices have caused operators to shift exploration to areas of the basin that produce condensate, natural gas liquids and oil in addition to gas. The organic-rich shale serves as the source, reservoir, and seal for the hydrocarbons... see full abstract.
- HCl/Formic In-Situ-Gelled Acids as Diverting Agents for Carbonate Acidizing
In highly heterogeneous carbonate reservoirs, several acid systems have been used to enhance acid diversion during matrix acidizing such as surfactant-based acids and in-situ-gelled acids. In-situ-gelled acids are also used to reduce leakoff rate in acid fracturing. The main acid used in this system is hydrochloric acid (HCl). However, high reaction rates and severity of corrosion problems, especially for wells completed with Cr-based tubulars, limit the use of HCl at high temperatures. On the other hand, mixing organic acids with HCl either increases the acid penetration or reduces the necessary strength of HCl and the necessary load of the corrosion inhibitors. A few studies addressed the systems that use both advantages.
- Regional Flow Simulation in Fractured Aquifers Using Stress-Dependent Parameters
A model function relating effective stress to fracture permeability is developed from Hooke's law, implemented in the tensorial form of Darcy's law, and used to evaluate discharge rates and pressure distributions at regional scales. The model takes into account elastic and statistical fracture parameters, and is able to simulate real stress-dependent permeabilities from laboratory to field studies. This modeling approach gains in phenomenology in comparison to the classical ones because the permeability tensors may vary in both strength and principal directions according to effective stresses. Moreover this method allows evaluation of the fracture porosity changes, which are then translated into consolidation of the medium.
- Understanding the Marcellus Shale Supply Chain: Katz Graduate School of Business Working Paper
Abstract: Understanding the Marcellus Shale Supply Chain examines the overall supply chain as it currently exists for the Marcellus Shale development, principally located in and around Pennsylvania. This study seeks to fill a critical information gap on the nature of the supply chain, derived from the drilling and extraction of natural gas from Marcellus Shale geologic deposits. The study first looks at the macroeconomics of the natural gas market, the major components of the supply chain, and an analysis of supplier characteristics, resources, and best practices. Our analysis is based on extensive field research and interviews, as well as information gathering from a number of publicly available sources.
- Environmental Impacts During Marcellus Shale Gas Drilling: Causes, Impacts, and Remedies
From Executive Summary: This study provides a detailed analysis of notices of violations (NOVs) from the Pennsylvania Department of Environmental Protection (PA DEP) from January 2008 through August 2011, categorizing each violation...The number of these environmental violations, however, is a misleading metric because an individual event may be associated with multiple environmental violations. As such, the 845 unique environmental events considered in this study were associated with 1,144 NOVs. To produce an accurate accounting of the environmental impacts of these 845 unique events, this study defines major and non-major environmental events through a detailed examination of NOV records... see Full Text
- Geochemical Controls on Shale Microstructural Evolution
From Abstract: The complex chemical and structural properties of shale source rocks, primarily a reflection of the intimate association of organic matter with mineral grains and their combined maturation history, regulate the physiochemical speciation and transport of petroleum during generation, migration, and production stages. In order to better understand the fundamental relationship between these constituents and pore network characteristics, we analyzed the variation in rock matrix microstructural properties with organic and mineral composition, distribution, and maturity in core samples... see full abstract.
- Maximum Flooding Surfaces -- The Key to Successful Laterals in Shale Wells
From Abstract: Eagle Ford, Austin and Taylor Formations in South Texas are recognized by the highest occurrence of Calcareous Nannofossils and Foraminifers and log signatures. Their age ranges from the Cenomanian, Turonian, and Coniacian to Santonian and are correlated to Upper Cretaceous sequence stratigraphic cycle chart after Gradstein, 2010. Marker species and abundance peaks are correlated to the high gamma and low resistivity on well logs and continuous reflectors on seismic. This interval is the maximum flooding surface condensed section and its seismic expression is the maximum flooding surface... see full abstract.
- Can Rare-Earth Elements be Useful Geochemical Tracers for Gaining an Insight into a Hydraulic Fracturing Event?
From Abstract: To determine whether or not analyses of rare-earth elements in fluids related to hydraulic fracturing of low permeability hydrocarbon-bearing formations could provide valuable information concerning a hydraulic fracturing event, an investigation was made of both pre-frac injection fluid and flow-back fluids, collected over a span of nine days from a well that was drilled into the Devonian Woodford Shale in the western Arkoma Basin in Coal County, Oklahoma. While the total REE content of the pre-frac injection fluid was about 6.29 ppb, the contents of the flow-back fluids ranged from about 4.46 ppb to about 3.80 ppb... see full abstract.
- Evaluating the Impact of Natural Fractures, In-Situ Stress and Mineralogy on Hydraulically-Induced Fracture System Geometry in Horizontal Shale Wells
From Abstract: The objective of this study is to better understand the impact of mineralogy, in-situ stress and natural fractures on hydraulically-induced fracture system geometry within horizontal organic shale wells. Vertical heterogeneity within organic shales occurs at a much smaller scale than that in the lateral direction. Previous studies involving borehole image analyses suggest that the lateral variability observed in most horizontal shale wells is the result of the wellbore traversing multiple layers of different rock properties... see full abstract.
- Water as a Driver for Building Adaptive Capacity and Resilience in Oil and Gas Resource Plays: Geosciences is a Transformative Agent for the Public Good
From Abstract: Water management in regions of the country and world where shale oil and gas plays have become active is undergoing significant change. Water needs for well stimulation are significant (3 to 7 millions of gallons per well), but typically not overwhelming, depending on the geology of the reservoir, rock properties, well depth, regional hydrology and climate. As a boom develops, there is little time for planning by water managers, if they even exist. Water management has become a critical issue for communities and oil and gas operators... see full abstract.
- Pore Structure Inhibits Gas Diffusion in the Barnett Shale
From Abstract: The Barnett Shale is a profitable gas field, but at current recovery rates only 10-15% of the estimated gas-in-place will be extracted. Gas recovery in this tight formation is limited by diffusive transport from the matrix storage to the stimulated fracture network. But despite the central role of diffusion, there are no systematic studies examining the measurements and effects of pore structure on diffusion of the Barnett Shale. We present results of a study of pore structure (pore connectivity, tortuosity, pore-size distribution) in the Barnett Shale... see full abstract.
- Sweet Spots in Shale Gas and Liquids Fairways: Understanding Petroleum Composition and Reservoir Pressure
From Abstract: rediction of fluid composition and reservoir pressure is critical for assessing value in shale gas and liquids plays. The most profitable parts of a fairway can sometimes be defined by the intersection of high reservoir pressure with the right gas-oil ratio. This study used regional basin modeling and an in-house source rock kinetic model in the Eagle Ford Shale to: (1) predict fluid compositions and viscosity; (2) evaluate the relative effects on pore pressure caused by disequilibrium compaction and petroleum generation... see full abstract.
- Proppant Diagenesis-Integrated Analyses Provide New Insights Into Origin, Occurrence, and Implications for Proppant Performance
In the application of hydraulic fracturing of oil and gas reservoirs, the objective is to create a conductive pathway for hydrocarbons to flow into the wellbore. This is accomplished by placing a proppant into the created fracture that will prevent fracture closure and maintain a high conductivity for an extended time period. A number of mechanisms have been identified that can degrade the fracture conductivity, including mechanical failure of the proppant grains, liberation of formation fines, proppant embedment, formation spalling, damage from the fracturing fluid, stress cycling, asphaltene deposition, proppant dissolution, and others. These factors in combination can reduce the effective conductivity by orders of magnitude as compared with the typically published conductivity data measured under reference conditions.
- Microseismic Monitoring of Hydraulic Fracture Treatments: Geology Matters - Acquisition, Processing and Interpretation Examples
From Abstract: ... Using various treatment and monitoring configurations, we demonstrate that ignoring the geology (e.g., lithology, stress contrast, natural fracturing, structural or depositional dip, faulting) and the associated rock properties (e.g., noise, slowness, anisotropy, attenuation) can potentially lead to poor stimulation and well placement, inadequate monitoring configurations, inconsistent processing approaches, and misleading interpretations. Thus, geology matters for validation of the exploration and production effort... see full abstract.
- A New Correlation of Acid-Fracture Conductivity Subject to Closure Stress
The conductivity of an acid-etched fracture depends strongly on void spaces and channels along the fracture resulting from uneven acid etching of the fracture walls. In this study, we modeled the deformation of the rough fracture surfaces acidized in heterogeneous formations based on the synthetic permeability distributions and developed a new correlation to calculate the acid-etched fracture conductivity.
- Case Study of Unconventional Gas-Well Fracturing in Hungary
Well Ba-E-1 was drilled in the Tompa prospect (now the Ba-IX Mining Plot) in Hungary targeting the Miocene and Cretaceous formations between 2600 and 3500 mTVD. These are tight sandstones, and the expected permeabilities were in the range of 0.001 to 0.5 md. Two hydraulic-fracture treatments were performed. The first fracture treatment was in the lower part, and the second treatment was in the upper part of the deepest interval. With no previous propped-fracturing experience in this field, the first treatment was designed as a conventional crosslinked-gel treatment to minimize the risk of a premature screenout. Following the analysis of the data from the first zone, it became clear that the average permeability was closer to the minimum expectation of 0.001 md. Because of lower-than-expected stimulation effectiveness of the first fracture, and the confirmation of the low permeability, the second fracture treatment was changed to a water-fracture design. This formation clearly falls into the unconventional category, and consequently was a good candidate for a water fracture.
- EPA's Reduced Emission Completion Rule. New Regulation on Hydraulic Fracturing
From Abstract: On August 23, 2011, the Environmental Protection Agency proposed an unprecedented rule aimed at establishing new emission standards to reduce volatile organic compounds (VOCs) and sulfur dioxide emissions from certain newly-constructed equipment. The rule covers a number of sources in oil and gas production... see full abstract.
- Natural Fracture Stratigraphy of Gas Shales in the Horn River Basin, NEBC, Canada: Relation to Lithostratigraphy and Implications for Hydraulic Fracture Growth
From Abstract: The Horn River Basin contains a 170-190m section of gas shales in the Muskwa, Otter Park and Evie Formations. One of the key decisions to be made in development of the resource is the optimal placement of horizontal wells within the stratigraphy to adequately stimulate and drain reserves from the entire section. Understanding the geomechanical properties of the reservoir is one of the keys to informing this decision. Construction of a calibrated in-situ stress vertical profile from elastic properties shows the section can be divided into two mechanical/reservoir packages... see full abstract.
- Source Rock Evaluation Technique: A Probabilistic Approach for Determining Hydrocarbon Generation Potential and In-Place Volume for Shale Plays
From Abstract: The hydrocarbon generation potential of a source rock is a calculated volume that utilizes multiple rock properties including gross rock volume, total organic carbon, kerogen type, and pyrolysis parameters. Here we detail a probabilistic workflow to the generation potential calculation, using Monte Carlo simulation of the modified Schmoker, 1994, equation with a distribution of values for each input parameter. This methodology can be an important component in identifying prospective shale plays for oil and gas production, and can be compared against traditionally calculated hydrocarbons-in-place as a screening tool for ranking prospects... see full abstract.
- How Do Fractures, Stress, and Rock Fabric Influence Velocity of the Marcellus Shale?
From Abstract: A systematic petrophysical investigation of sonic logs from multiple wells with Marcellus Shale core was undertaken to determine the relative importance of fractures, stress, and rock fabric on influencing sonic velocity. The shale is typically well laminated throughout the entire core, with numerous sub-vertical, calcite-filled veins. Some veins are propped open by bridging cements that maintain porosity in the subsurface... see full abstract.
- Molybdenum, Uranium, and Chloride Abundances in the Marcellus Shale -- Significance to Basin Hydrography and Organic Matter Preservation
From Abstract: Trace element and metals abundances have proven useful to elucidating the hydrography and water mass chemistry of shale basins. Our analysis of several Marcellus Shale cores by use of handheld XRF technology has yielded a robust dataset that sheds light on the nature and evolution of the water column of the Marcellus basin. Regional covariance trends of molybdenum and uranium and their respective enrichment factors define a uniform Mo/U molar ratio of ≈ 2 - 3 times that of seawater... see full abstract.
- Distribution and Character of Complex Micropore Systems in the Eagle Ford Formation of South Texas
From Abstract: Detailed plane light and milled surface SEM petrographic studies of the Eagle Ford indicate that reservoir quality is controlled by complex micropore systems that reflect mineralogy, depositional fabric, grain type, organic content, and diagenesis. Cyclic interbedding of contrasting marl, limestone, and shale lithologies created strongly layered, heterogeneous reservoirs with poor recovery efficiency... see full abstract.
- Unconventional Shale Resources Exploration in Kuwait -- Opportunities, Challenges and Way Forward
From Abstract: The state of Kuwait is endowed with both conventional and unconventional hydrocarbon resources occurring over a wide range of stratigraphic spectrum spanning from Paleozoic to Cenozoic. Unconventional resources of Kuwait mainly include heavy oil, tight gas, shale gas, shale oil, etc. The exploration for heavy oil and tight gas in the country has kept pace with the global efforts; while the shale gas and shale oil are yet to find a place in the country’s energy basket. The study, initiated to fill the knowledge gap, has brought out the shale resource potential of Kuwait... see abstract.
- Geomechanical Interpretation of a 'Zipper Frac' in Barnett Shale Wells
From Abstract: As lateral wells’ reaches extend and more wells gets drilled from the same pad, various stimulation patterns and techniques are being tested in search of the optimum approach to hydraulic fracture treatment. ‘Zipper frac’ is a process where two horizontal wells are alternately stimulated with large hydraulic fracture treatments... see full abstract.
- Could Gas Hydrate in Fine Grained Sediments be a Precursor for Some Shale Gas Deposits?
From Abstract: ...A means of sequestering gas produced early in the diagenetic history of the shale involves the formation of solid, mechanically strong gas hydrate grains, nodules, or veins in the still highly porous, muddy shales. Hydrate concentrates gas by compressing it by a factor of about 164 into its crystalline lattice. A great deal of natural gas is sequestered in gas hydrate... see full abstract.
- Fracture Mechanics Interpreted from Stress Inversion Analysis on Microseismic Event Source Mechanisms in the Marcellus Shale
From Abstract: A multiple inverse stress analysis technique was applied to source mechanisms from microseismic events detected during a stimulation treatment of a horizontal well in the Marcellus Formation in order to determine the stress state(s) responsible for rock failure during the treatment. The microseismicity was mapped with a monitoring array of geophones located on the surface above the well and during the stimulation treatment, their locations formed two well-defined trends... see full abstract.
- Lessons Learned from the Floyd Shale Play
From Abstract: ...To determine what is limiting the deliverability of gas from the Floyd Shale, the source rock and reservoir properties were characterized. With respect to kerogen type, organic matter content, thermal maturity, bulk mineralogy, porosity, and permeability, the Floyd compares favorably with successful shale gas plays. Analysis of core and cuttings samples indicates... see full abstract.
- Testing the Gas Plume Hypothesis Using Fracture Distribution above Marcellus
From Abstract: Joints in the Middle and Upper Devonian formations of the Appalachian Basin, the Catskill Delta Complex, are common, particularly in the silt- and sandstone layers. The planar surface and cyclic plumose morphology indicate these joints are gas driven. Generally two sets of joints can be seen: J1 and J2 (Engelder et al. 2009). The strike of J1 joints range from 060o to 085o, while those of J2 joints range from 320o to 010o. J1 is present in organic rich shales and rapidly disappears above these source rocks, while J2 appears in coarser clastic rocks of the delta complex as much as 2000 m above the Marcellus... see full abstract.
- Extending Shale Gas Well Life with Low Grade Geothermal Power -- Haynesville Case
From Abstract: The hydraulic fracture network of a shale gas well, after its production rate has dropped below the economic limit, can be used for low grade geothermal heat extraction. Conceptually, the stimulated reservoir volume (SRV) for the shale gas well consists of multiple parallel transverse fractures created along one horizontal well. The idea investigated is to connect the created hydraulic fractures with horizontal wells... see full abstract.
- A Geomechanics Approach to Evaluate Gas Shale Fracability: A Case Study with the Woodford Shale
From Abstract: In addition to the TOC, the brittleness of the shale formation has recently been used as a deciding factor for identifying prospect intervals for fracturing stimulation. This paper provides a geomechanics approach to quantify gas shale fracability taking into account the transversely isotropic nature of shales. In addition, geomechanics explanations are given for the field observations that hydraulic fracturing in clay-rich and finely laminated intervals produce less microseism than in quartz-rich and coarsely laminated intervals... see full abstract.
- Regional Interpretation of the Late Ordovician Utica Shale Play in the Appalachian Basin
From Abstract: ...While the number of producing Utica wells is still low, there is sufficient data by which to construct a regional framework. Facies determinations from a regional data set of well logs helps identify the platform, slope, and trough facies. A regional sequence stratigraphic interpretation of the Late Ordovician succession allows for correlation between the carbonate platforms and through the trough... see full abstract.
- C-wave Spectral Broadening to Match P-wavelengths for Improved Fracture/Lithology Characterization
From Abstract: The Marcellus shale has become an active area for gas exploration, and has fracture and lithology characteristics that make it a good candidate for multicomponent data. It is well established that similar vertical wavelength ranges must be preserved in multicomponent data and that wavelengths of P- and S-waves must match in order to sample reflectivity in an equivalent manner. Although registration functions align corresponding stratigraphic events of the P-wave and P- to S-wave (C-wave) reflections, they distort the seismic wavelet...see full abstract.
- Natural Gas Development in the Marcellus Shale: Environmental Footprints and Mitigations
From Abstract: The process of gas development is intensive and involves risk to the environment. Statistics confirm that 0.5-1% of wells drilled result in a blowout. Causes of these exploration risks are identified as; (a) Violations (b) Operational Pollution (accidental spills and leaks (c) Operators policy. In addressing this concern, a risk assessment methodology was employed to evaluate all violations by operators in Pennsylvania from January 2008 to November 2010, using Statistical Analysis Software (SAS)... see full abstract.
- Integrated Evaluation of Alleged Natural Gas Contamination of the Trinity Aquifer by Horizontal Gas Wells Completed in the Barnett Formation, Southern Parker County, Texas
From Abstract: During 2010, the Texas Railroad Commission and the US Environmental Protection Agency (EPA) responded to complaints by a landowner that his residential water well near Weatherford, Texas was contaminated with natural gas caused by production from two nearby horizontal gas wells (Butler #1H and Teal #1H) operated by Range Production Company. We used geological, geochemical, and petroleum engineering data obtained from those gas wells and from 26 nearby water wells to determine that gas dissolved in the Twin Mountains (Trinity) aquifer is not related to Barnett gas production... see full abstract.
- Hydraulic Fracturing Implications: Forensic Ambiguity, Science and Rhetoric
From Abstract: ...In February, the EPA released a plan of seven case studies to assess the potential impacts of hydraulic fracturing on drinking water and groundwater. The case study sites were chosen where natural gas resources are geographically extensive. The chances of naturally occurring gas in domestic water wells is also highly probable in these locations. Information from the Raton Basin, one of the EPA retrospective case study locations, is presented to demonstrate some of the potential problems and limitations of the proposed EPA study... see full abstract.
- A Scanning Electron Microscope Study of Porosity in the Eagle Ford Shale of Texas
From Abstract: The Eagle Ford Shale accumulated in intra-shelf basins at relatively low latitudes on a southeast facing margin during early part of the late Cretaceous. A scanning electron microscope study on drill-core samples from LaSalle County was conducted to understand the development of petrographic features and porosity. Samples were argon ion-milled and examined with a field emission scanning electron microscope. Because organic matter is liable to develop additional pores due to heating by the argon beam, extensive testing was undertaken with variable beam intensities and sample-stage temperatures to identify potential milling artifacts... see full abstract.
- The Transformation of Hydrofracked Reservoirs to Thermal Energy Production
From Abstract: ...Individual [gas] wells, in most circumstances, do not have an extended economic lifetime as yields from these fracture-stimulated wells generally decline quickly and new wells must be drilled and fractured. The substantial investment in well design, installation and reservoir stimulation should not be abandon, however, as many of these wells can be converted into thermal mining wells, yielding geothermal energy on a sustainable basis for as long as the well casing and well integrity can be maintained... see full abstract.
- Quantification of Porosity, Permeability and Mineral Structure in Shales Using Nano- to Micron-scale X-ray Tomography
From Abstract: ...Understanding how the distribution and geometry of the macro, micro and nanoscale pore networks control natural and stimulated fracture formation, and gas release can only be achieved using a multi-scale characterisation and modelling approach. Given the scale of the pore spaces and fractures, X-ray imaging is demonstrated to be an effective tool to achieve this goal. An organic-rich Carboniferous shale was studied from a gas-charged sedimentary basin in the UK... see full abstract.
- Environmental Forensics in the Context of the Oil and Gas Industry
From Abstract: ...In the case of shale gas problems, one area where stable isotopes can play an immediate role is first distinguishing sources of microbial and thermogenic gas on the basis of the isotopic compositions. In addition gases from different sources and thermal maturity regimes can be differentiated through this approach. So in brief this presentation will provide a number of examples where stable isotopes have been used in the manner described above, including oil spills, groundwater contamination with a variety of products and environmental issues associated with shale gas development... see full abstract.
- Oil and Natural Gas Sector: New Source Performance Standards and National Emission Standards for Hazardous Air Pollutants Reviews
From Summary: This action finalizes the review of new source performance standards for the listed oil and natural gas source category. In this action the EPA revised the new source performance standards for volatile organic compounds from leaking components at onshore natural gas processing plants and new source performance standards for sulfur dioxide emissions from natural gas processing plants... See Full Summary
- Measurement, Modeling, and Diagnostics of Flowing Gas Composition Changes in Shale Gas Wells
From Abstract: Few attempts have been made to model shale gas reservoirs on a compositional basis. Multiple distinct micro-scale physical phenomena influence the transport and storage of reservoir fluids in shale, including differential desorption, preferential Knudsen diffusion, and capillary critical effects. Concerted, these phenomena cause a measureable compositional change in the produced gas over time. We developed a compositional numerical model capable of describing the coupled processes of diffusion and desorption in ultra-tight rocks as a function of pore size... see full abstract.
- High-Resolution Numerical Modeling of Complex and Irregular Fracture Patterns in Shale Gas and Tight Gas Reservoirs
From Abstract: Various models featuring horizontal wells with multiple fractures have been proposed to characterize flow behavior over time in tight and shale gas systems. Currently, only very little is known about the effects of nonideal fracture patterns and coupled primary-secondary fracture interactions on reservoir performance in unconventional gas reservoirs. We developed a 3D Voronoi mesh-maker that provides the flexibility to accurately represent various complex and irregular fracture patterns.. see full abstract.
- Using the SPE/WPC/AAPG/SPEE/SEG PRMS To Evaluate Unconventional Resources
From Summary: It is the intention of the SPE/World Petroleum Council (WPC)/American Association of Petroleum Geologists (AAPG)/ Society of Petroleum Evaluation Engineers (SPEE)/ Society of Exploration Geophysicists (SEG) Petroleum Resources Management System (PRMS) to provide a consistent approach to estimating petroleum quantities, evaluating development projects, and presenting results within a comprehensive classification framework. The reserves and resources definitions and application guidelines are designed to be applicable to both conventional and unconventional petroleum accumulations... see full summary.
- Eagle Ford Water Management Strategy, Piloncillo Ranch, Southwest Texas
From Abstract:... In the last few years [southwest Texas] has experienced an unprecedented activity boom related to the development of the Eagle Ford shale formation. Sustainable development is imperative given the scarcity of water in the area and the large volumes of water required for hydraulic fracturing. Shell has a multi-pronged approach to its water management strategy. Our goals are to minimize our impact on the Carrizo aquifer by using alternatives where available, treat/reuse water as possible and have disposal options that protect potable water... see full abstract.
- Intraformational Slip Surfaces in the Marcellus and Overlying Hamilton Group
From Abstract: Detachment is very common in the Penn State ABBSG core collection of Marcellus gas shale and greater Hamilton Group from south of the Allegheny Front. The Hamilton section is populated with a variety of bedding-parallel slip surfaces that range in thickness from individual bedding planes to cleavage duplexes up to a meter thick. The bedding-plane slip surfaces are decorated with a variety of structures that include mainly tails, streaks, fibers, and striations by Mean’s (1987) classification... see full abstract.
- Variability of Hydraulic Fractures in Shale or Tight Gas Reservoirs
From Abstract: ...We present a comparison of a number of hydraulic fracture monitoring programs in shale and tight gas reservoirs. Accounting for a representative dataset, there is a tremendous amount of variability in the fracture trends and distributions within the same formations. The prediction that fractures grow in two symmetric vertical wings away from the treatment zone is rarely observed... see full abstract.
- Proppant Free Fracturing Technique for Production Optimization in Tight Gas Reservoirs - An Overview
From Abstract: ...Applying proppant free fracturing technique to stimulate tight gas reservoirs is the newest technology. It has been recognized as shear dilation induced by elevated fluid pressure. This paper discusses the mechanism of proppant free fracturing technique, advantages, limitations and candidates for proppant free technique... see full abstract.
- Sensitivity Analysis of Hydraulic Fracturing Damage Factors: Reservoir Properties and Operation Variables
From Abstract: Although a stimulation technique, the hydraulic fracturing process can also cause damage to the reservoir in a variety of ways. These damage mechanisms cannot be completely eliminated, but by careful examination of their individual characteristics and effects on production, focus can be placed on minimizing the most critical factors. This paper presents the results of a sensitivity study of numerous reservoir properties and operational control variables on fracture effectiveness and production from a fractured gas well... see full abstract.
- Production Data Analysis in Eagle Ford Shale Gas Reservoir
From Abstract: Eagle Ford shale in South Texas is one of the recent shale play in US which the development began in late 2008. So far many horizontal wells have been drilled and put into production using hydraulic fracturing. Production behaviour in shale gas reservoirs unlike conventional reservoirs is different in various plays and there are no published reports for production data analysis in Eagle Ford shale. We have used the linear dual porosity type curve analysis technology to analyse the production behaviour and to estimate the essential parameters for this reservoir... see full abstract.
- New Hydraulic Fracturing Process Enables Far-Field Diversion in Unconventional Reservoirs
From Abstract: ...Technological advances and improved operational efficiency have made production from shale resources around the globe far more viable; however, while the wells being completed today are proving to be reasonably economical, the question that remains is if the operators are truly capitalizing on their full potential. In recent years, the industry has been in search of a better method to enable well operators to capitalize on the natural fractures commonly found in shale reservoirs. If properly developed, these natural fractures will create a network of connectivity... see full abstract.
- Visualizing Stress Trajectories around Hydraullicaly Pressurized Wellbores
From Abstract: A new approach, using stress functions, reveals how each component of the stress regime affects the stress pattern around the wellbore. The effect of tectonic far field stress on the stress trajectories in the host rock near a wellbore is visualized in a series of plots with the analytical stress trajectory solutions for a large range of net pressures on the wellbore... see full abstract.
- A New Approach to Biocide Application Offers Improved Efficiency in Fracturing Fluids
From Abstract: Hydraulic fracturing of oil and gas wells requires high volumes of water. Often these waters originate from rivers, lakes, ponds, and recovered water from previous fracturing treatments. These waters are often infested with aerobic and anaerobic bacteria that can cause multiple problems. These include degradation of fracturing chemicals, down-hole corrosion, biological-based H2S generation, and down-hole flow-impairment due to slime producing bacteria. Historically, these waters have been treated with biocides... see full abstract.
- Unconventional Shale Play Selective Fracturing Using Multilateral Technology
From Abstract: ...Using conventional equipment and techniques, a multilateral well (with any number of laterals) can accommodate any type of fracturing system and program with pressures up to 12,500 psi with complete isolation of the lateral junction(s). In this project, a plug-and-perf system was used to address ten plus intervals in each leg, with average stimulation pressures up to 9,000 psi... see full abstract.
- Novel Traceable Proppant Enables Propped Frac Height Measurement While Reducing the Environmental Impact
From Abstract: ...Fracture height is measured by the industry through the use of radioactive tracers which are blended into the proppant at the wellsite. Clearly this can present both a safety and environmental hazard. Furthermore, in some regions of the world operators are prohibited from using these hazardous materials altogether. This paper presents an innovative, environmentally responsible proppant detection technology and the associated logging techniques for propped height measurement and/or proppant placement. Its non-radioactive nature... see full abstract.
- Real-Time Downhole Monitoring Of Hydraulic Fracturing Treatments Using Fibre Optic Distributed Temperature And Acoustic Sensing
From Abstract: ... Fibre optic distributed sensing has the potential of providing key insights during both the hydraulic fracturing and initial flowback. The passive nature of fibre optic sensors allows intervention-free surveillance, which makes fibre-optic technology an effective platform for permanent sensing in producing wells. Until recently, the oil & gas industry fibre optic sensing technology has focused mainly on temperature (DTS) profiling along the wellbore... see full abstract.
- An Environmental Solution to Help Reduce Freshwater Demands and Minimize Chemical Use
From Abstract: ...Recent developments have allowed one operator to minimize freshwater usage through recycling of their flowback and produced water using electrocoagulation (EC) technology. EC is a water-treatment process that removes colloidal solids through methods of coagulation, electroflotation, and settling. Unlike conventional water-treatment practices, such as reverse osmosis or distillation, EC generates relatively small quantities of waste, while leaving dissolved solids in the water... see full abstract.
- Post-Frac Production Analysis of Horizontal Completions in CANA Woodford Shale
From Abstract: ...Recent horizontal development using multistage fracture stimulations of the CANA Woodford located in the Anadarko basin has resulted in high initial gas-flow rates, and substantial liquid production when in the gas-condensate window. Completion type and strategy have changed from methods used during the initial discovery phase in 2005 to the present development phase in 2011. This paper compares completion parameters... see full abstract.
- Cyclic Shut-in Eliminates Liquid-Loading in Gas Wells
From Abstract: This paper presents a method to eliminate production loss due to liquid-loading in tight gas wells. Cyclic shut-in control is a simple production strategy that particularly benefits lower-permeability stimulated wells, including but not limited to shale gas wells... see full abstract.
- European Shale Gas, Getting Buy-in From The Public and Stakeholders
From Abstract: ...This paper provides a discussion of a shale gas exploration program currently being conducted by Cuadrilla Resources in England. It examines the concerns of the local residents, and how these have affected media coverage, and support (or opposition) from politicians. It discusses the strategy and approach used by Cuadrilla for addressing questions and concerns from the local residents, various UK regulatory bodies, politicians and the media.... see full abstract.
- Overcoming Drilling Challenges in the Marcellus Unconventional Shale Play Using a New Steerable Motor with Optimized Design
From Abstract: Although drilling horizontal wells in US-land unconventional shale plays has increased exponentially in the last few years, maximizing well productivity and improving drilling efficiency remains a major challenge. Well placement in the sweet spot and extended laterals help maximize productivity. Drilling a curve with higher dogleg severity (DLS) reduces its verticalsection and maximizes the length of subsequent lateral section in the productive zone... see full abstract.
- Can We Achieve Acceptable Hydraulic Fracture Conductivity Using Waterfracs?
From Abstract: ..During the early 2000’s, the combination of long horizontals, and extreme multi-stage hydraulic fracturing (mostly using Waterfracs) turned the Barnett Shale into the launching pad of our present-day madhouse search for the next great shale play to chase. It is clear that long horizontal completions and WaterFrac stimulation methods have played an important role in opening the door to economic success in the numerous “resource plays” (i.e. shales). In this paper we will investigate if WaterFrac treatments are violating or upholding (?) one of our most significant fracturing beliefs: Fracture Conductivity should be optimized... see full abstract.
- Water Management and Microbial Control Programs in the Exploitation of Unconventional Hydrocarbons
From Abstract: ...New formulations of biocides and control programs aimed at the needs of the gas and oil industry have been developed, e.g. improved heat stability and the reduction in biocide levels to achieve the same level of microbial control. These newly developed microbial control technologies will be presented in this paper, and the related regulatory and product stewardship support will be shortly addressed... see full abstract.
- Exploring Shale Basins using Existing Wells
From Abstract: In the search for unconventional shale plays with commercial potential, many operators have properties in petroprovince basins containing wells through potentially productive shale zones. These shales were often encountered as part of exploration or development programs for deeper conventional targets. Often, the overlying shale is known to have had gas or oil shows reported during initial drilling, but little or no additional geological data was acquired at the time. This paper discusses the workflow and method to use the minimal information from these existing wells, and to quantitatively incorporate them into a basin exploration program... see full abstract.
- Shale Reservoir Properties from Digital Rock Physics
From Abstract: A majority of the whole core samples recovered in the US today come from shale reservoirs. A primary reason for so much shale coring is that shale well log analysis requires rigorous core calibration to provide reliable data for reservoir quality, hydrocarbon-in-place, and hydraulic fracturing potential. However, the uncertainty in interpreting shale well log data is sometimes matched or exceeded by the uncertainty observed in traditional methods of analyzing core samples... see full abstract.
- Using Microseismic Monitoring to Determine Influence of Cement-Filled Natural Fractures on Hydraulic Fracturing
From Abstract: Microseismic data was acquired with a shallowly buried monitoring array during a hydraulic fracture stimulation treatment of a deep, over-pressured shale gas reservoir. The locations of the microseismic events define parallel trends that formed during all of the stages of the stimulation treatment. Microseismic location trends with this type of geometry are generally interpreted to indicate the formation of new fractures parallel to the direction of maximum horizontal stress in the reservoir... see full abstract.
- Fracking and the Neoliberalization of the Hydro-Social Cycle in Pennsylvania's Marcellus Shale
From the abstract: Oil and gas firms are utilizing a controversial drilling technique, hydraulic fracturing, or fracking, to access unconventional natural gas reserves in Pennsylvania's Marcellus Shale. The potential impacts of fracking are creating sharp tensions between stakeholders over the costs and benefits of drilling within their communities. In particular, much contention has emerged over water resources as the process both uses and degrades billions of gallons of water. This paper takes a critical look at the way multi-scale neoliberal discourses obfuscate comprehensive understandings of fracking's effect on water resources. We turn to the neoliberal environments literature as a way to situate the economic logic that normalizes the impacts of fracking on resources, particularly in the absence of an effective regulatory framework. We argue that neoliberal pro-fracking arguments are (re)defining the relationship among people, the environment, and institutions, which in turn normalizes the impacts on communities and the resources on which they depend.
- Real Property Tax Base, Market Values, And Marcellus Shale: 2007 to 2009
From the introduction: Directly examining the impact of Marcellus activity on the local real property tax base and on aggregate
market values at the local level can provide another perspective on the local fiscal impacts of gas
development. If the local tax base is increasing due to gas development, local real property tax
collections will increase with no change in tax rates, giving local governments and school districts more
dollars to manage impacts of Marcellus shale development.
Data available from the Pennsylvania State Tax Equalization Board (STEB)2 allows looking at how
assessed and market values are changing in relation to Marcellus drilling activity at the county and
municipal level. This analysis is important because it helps understand overall what is occurring at these
jurisdictional levels, with implications for local tax collections and the overall real estate market. See full text
- Water Use for Shale-Gas Production in Texas
Shale-gas production using hydraulic fracturing of mostly horizontal wells has led to considerable controversy over water-resource and environmental impacts. The study objective was to quantify net water use for shale-gas production using data from Texas, which is the dominant producer of shale gas in the U.S. with a focus on three major plays: the Barnett Shale (15 000 wells, mid-2011), Texas-Haynesville Shale (390 wells), and Eagle Ford Shale (1040 wells). Past water use was estimated from well-completion data, and future water use was extrapolated from past water use constrained by shale-gas resources. Cumulative water use in the Barnett totaled 145 Mm3 (2000–mid-2011). Annual water use represents 9% of water use in Dallas (population 1.3 million). Water use in younger (2008–mid-2011) plays, although less (6.5 Mm3 Texas-Haynesville, 18 Mm3 Eagle Ford), is increasing rapidly. Water use for shale gas is <1% of statewide water withdrawals; however, local impacts vary with water availability and competing demands. Projections of cumulative net water use during the next 50 years in all shale plays total 4350 Mm3.... See full abstract
- Hydrocarbon emissions characterization in the Colorado Front Range: A pilot study
Emissions of methane and other hydrocarbon from land-based activities can be estimated using "bottom-up" or "top-down" approaches. This technical article discusses the latter approach, whereby atmospheric measurements (taken from automobile-based surveys) were employed to estimate hydrocarbon emissions. The researchers' findings suggest that conventional ground-based approaches of estimating hydrocarbon release may be greatly underestimating the actual rates.
- Metagenetic methane generation in gas shales I. Screening protocols using immature samples
The gas generative potential of organic matter is one key parameter for the calculation of total gas in place (GIP) when evaluating thermogenic shale gas plays. Having first demonstrated that late gas-forming structures are present in coals of anthracite rank (>2% R0) we go on to examine other rocks at the immature stage of maturity and report on how to recognise which might generate significant amounts of late dry gas at geologic temperatures well in excess of 200 °C in the zone of metagenesis (R0 > 2.0%), i.e. subsequent to primary and secondary gas generation by thermal cracking of kerogen or retained oil. Such a distinction could clearly be of major value when assessing risks and pinning down “sweet spots”. A large selection (51 samples) of source rocks, i.e. shales and coals, stemming from different depositional environments and containing various types of organic matter which contribute to the formation of petroleum in putative gas shales were investigated using open- and closed-system pyrolysis methods for the characterisation of kerogen type, molecular structure, and late gas generative behaviour.
- Marcellus Shale and Local Collection of State Taxes: What the 2011 Pennsylvania Tax Data Say
State tax collection information gathered by the Pennsylvania Department of Revenue can provide some insight into the short run economic and state tax implications of gas development in the Commonwealth. This document provides analysis of reported Pennsylvania tax information between the years of 2007-2011 and updates a similar analysis conducted using 2010 data (Costanzo and Kelsey, 2011). The data continue to show differences between counties with Marcellus Shale gas drilling and those without.
- Isotopic reversal (`rollover') in shale gases produced from the Mississippian Barnett and Fayetteville formations
From Abstract: Ethane, propane, and carbon dioxide show reversed carbon isotopic maturity trends in natural gas produced from the Barnett and Fayetteville Shales at thermal maturities greater than ∼1.5% VRE. At this high level of thermal maturity, the iso-butane to n-butane ratio also reverses, suggesting wet gas cracking has occurred, generating more gas molecules in the same volume resulting in overpressure, and increased stabilized production rates in the Barnett. Hydrothermal fluids... See Full Abstract
- Haynesville and Bossier mudrocks: A facies and sequence stratigraphic investigation, East Texas and Louisiana, USA
From Abstract: Upper Jurassic Haynesville and Bossier shale-gas plays of the northwestern Gulf of Mexico (GOM) Basin produce from organic-rich, marine transgressive to highstand mudrocks within mixed carbonate-clastic depositional systems. Modern wireline-log suites from ∼200 deep wells were used for detailed correlations, and 10 + cores throughout the upper Kimmeridgian to lower Tithonian basin were incorporated into detailed facies, stratigraphic, and lithologic analyses... See Full Abstract
- Transport properties of unconventional gas systems
From Abstract: An overview is given of the mechanisms and processes (viscous flow, diffusion, sorption, desorption) affecting transport in unconventional reservoir rocks. Processes are described, terms and definitions are given, and selected literature data are presented to document the state of knowledge and the data situation on gas, water and two-phase flow in low-permeable lithotypes... See Full Abstract
- How the technical differences between shale gas and conventional gas projects lead to a new business model being required to be successful
From Abstract: This paper will make the case that the unconventional natural gas business is not the same as the conventional natural gas business. The skills involved in finding, developing and producing discreet pools of oil and gas are not identical to those for shale gas projects. However... See Full Abstract
- UK shale gas: The story so far
From Abstract: The UK’s first well to encounter shale gas was drilled into the Upper Jurassic Kimmeridge Clay in 1875, but its significance was not realised at the time. 25 years ago research at Imperial College applied the US shale gas paradigm to evaluate the UK’s shale gas potential. Shale sequences with potential for gas production were identified in... See Full Abstract
- Comprehensive Petrophysical Shale Reservoir Evaluation ... the Foundation for Shale Asset Life Cycle Management
- Geosteering in Unconventional Shales: Current Practice and Developing Methodologies
From Abstract: ... This paper reviews the current common practices used in geosteering in shales, for both gas- and oil-producing reservoirs. A brief history of strategy development is outlined, with comments about its perceived effectiveness and value. Examples of successes and failures are examined to attempt to determine the viability of a particular strategy. Finally, alternative approaches and methodologies are reviewed and examined, with comments about the potential application, benefits, and value... see full abstract.
- Water Management -- An Increasing Trend in the Oil and Gas Industry
From Abstract: Water plays an essential role in the recovery of oil and gas. Managing subsurface water conformance can maximize hydrocarbon production and reduce operating costs. However, unchecked water can decrease hydrocarbon production, reduce oil and gas recovery, increase costs substantially, and lead to possible well abandonment... see full abstract.
- A Practical Guide to Interpreting Microseismic Measurements
From Abstract: Thousands of hydraulic fracture treatments have been monitored in the past ten years using microseismic mapping, providing a wealth of measurements that show a surprising degree of diversity in event patterns. Interpreting the microseismic data to determine the geometry and complexity of hydraulic fractures continues to be focused on visualization of the event patterns and qualitative estimates of the “stimulated volume”, which has led to wide variations and inconsistencies in interpretations... see full abstract.
- A Technical and Economic Study of Completion Techniques in Five Emerging US Gas Shales: A Woodford Shale Example
From Abstract: ... There are very few papers in the petroleum literature that provide a logical method to select completion techniques for given shale-gas-reservoir conditions. There are papers discussing successful completion techniques that seem to work for a specific shale. We have used many of these SPE papers to help define "best practices" in completing shale-gas reservoirs. We then developed logic to determine the best practice in completing shale-gas reservoirs as a function of reservoir conditions. In this paper, we will specifically cover the logic we have developed for choosing completion techniques in shale-gas reservoirs... see full abstract.
- Improving Completion And Stimulation Effectiveness In Unconventional Reservoirs- Field Results In The Eagle Ford Shale Of North America
From Abstract: ...This paper focuses on several areas that are critical in a successful completion such as: casing size and pressure rating, wellhead selection, treatment design, spacing of the perforations and stages, linear verses cross-linked fluid, and the impact of proppant selection. With over 1800 wells completed and stimulated so far, a comparison of successful treatments and the cause of unsuccessful treatments will be provided. A review of actual field applications will be presented where possible, and a method for identifying best completion practices will be discussed... see full abstract.
- Novel Water Based Mud for Shale Gas Part II: Mud Formulation and Performance
From Abstract: Shale-gas plays and other unconventional resources have gained significant importance worldwide. Historically, synthetic based drilling fluids (SBM) are used in these plays when no environmental concerns are in place and are preferred when wellbore stability is necessary. In this paper, we study the use of an improved water based drilling fluid (WBM) that is simple in formulation and maintenance that shows excellent rheological properties, maintains wellbore stability, and a good environmental profile... see full abstract.
- Unconventional Reservoirs: Basic Petrophysical Concepts for Shale Gas
From Abstract: Unconventional reservoirs have burst with considerable force in oil and gas production worldwide. Shale Gas is one of them, with intense activity taking place in regions like North America. To achieve commercial production, these reservoirs should be stimulated through massive hydraulic fracturing and, frequently, through horizontal wells as a mean to enhance productivity... see full abstract.
- Shale Gas-in-Place Calculations Part I: New Pore-Scale Considerations
From Summary: Using focused-ion-beam (FIB)/scanning-electron-microscope (SEM) imaging technology, a series of 2D and 3D submicroscale investigations revealed a finely dispersed porous organic (kerogen) material embedded within an inorganic matrix. The organic material has pores and capillaries having characteristic lengths typically less than 100 nm. A significant portion of total gas in place appears to be associated with interconnected large nanopores within the organic material... see full summary.
- Production Optimization and Forecasting of Shale Gas Wells Using Simulation Models and Decline Curve Analysis
From Abstract: This paper involves the use of simulation models and the decline curve analysis (DCA) as a production optimization and forecasting tools. Production data from three neighboring counties (with high, medium and low cumulative gas productions) of the Eagle Ford shale, an analogue to the Shublik shale of Alaska, was analyzed using the DCA to correlate production performance with completion (horizontal leg/stages of fracture) and length of horizontal leg... see full abstract.
- Maximize the placement of wells and production in unconventional reservoirs: Part 2
From Abstract: ...Modeling, simulating and predicting well productivity requires integrated exploratory, predictive and forecasting capabilities underpinned by advanced analytical models to unlock the true potential of each wellbore. Without the critical insight enabled by integrated analysis to pair productivity analysis with economic feasibility, companies face significant risk and uncertainty when developing new wells or optimizing production of extant wellbores.This paper walks through a case study implemented in the Barnett asset in the United States, exemplifying data mining workflows that successfully improved hydrocarbon production... see full abstract.
- Analysis of production data in shale gas reservoirs: Rigorous corrections for fluid and flow properties
From Abstract: ...The purpose of the current work is to evaluate the current methods for analyzing linear flow in shale gas reservoirs, and establish which method is the most accurate for reservoir characterization. First, recent studies addressing linear flow under constant flowing pressure and constant gas rate production are briefly reviewed. Then, a comparison among the above-mentioned methods for calculating fracture half-length or contacted matrix surface area is made... see full abstract.
- Identifying Fault Activation in Unconventional Reservoirs in Real Time Using Microseismic Monitoring
From Abstract: Identification of fault related microseismicity in hydraulic fracture treatments is crucial to understanding how treatments are stimulating a reservoir. Evaluating b values in combination with event source mechanism provides a reliable and intuitive method for separating fault related microseismic events from standard fracture related events... see full abstract.
- Impacts of the Number of Perforation Clusters and Cluster Spacing on Production Performance of Horizontal Shale-Gas Wells
From Abstract: Multistage hydraulic fracturing has become the key technology to complete horizontal wells in shale-gas reservoirs. In each stage, multiple perforation clusters are used to create multiple transverse fractures. How these clusters are placed significantly affects both the short-term and long-term production performance of horizontal shale-gas wells... see full abstract.
- Hydraulic Fracturing 101: What Every Representative, Environmentalist, Regulator, Reporter, Investor, University Researcher, Neighbor and Engineer Should Know About Estimating Frac Risk and Improving Frac Performance in Unconventional Gas and Oil Wells
From Abstract: ...To enable more transparency on the oil and gas side, both to assist in the understanding of oil and gas activities and to set a foundation for rational discussion of fracturing risks, a detailed explanation of well development activities is offered in this paper, from well construction to production, written at a level of general public understanding, along with an initial estimation of frac risk and alternatives to reduce the risk, documented by literature and case histories. This discussion is a starting point for the well development descriptions and risk evaluation discussions, not an ending point... see full abstract.
- Gas Shale Hydraulic Fracturing: A Numerical Evaluation of the Effect of Geomechanical Parameters
From Abstract:... In this paper, we present the results of a detailed parametric evaluation of the shear failure (and, by analogy, the microseismicity) due to the creation of a hydraulic fracture as a function of fracture length within two different fracture networks (DFNs) using the 2D Distinct Element Model (DEM), UDEC. Simulations were conducted as a function of... see full abstract.
- Fact-Based Regulation for Environmental Protection in Shale Gas Development
From Preface: The discovery of large reserves of natural gas in shale formations – shale gas – has been a major positive development for the energy picture of the US and the world. Yet a number of controversies over shale gas development have emerged that must be resolved in order for the full potential of this valuable resource to be realized. The Energy Institute has launched a series of initiatives to help deal with these issues and ensure responsible development of shale gas. This report... See Full Text
- Estimate of Impacts of EPA Proposals to Reduce Air Emissions from Hydraulic Fracturing Operations
- Life-Cycle Greenhouse Gas Emissions of Shale Gas, Natural Gas, Coal, and Petroleum
From abstract: The technologies and practices that have enabled the recent boom in shale gas production have also brought attention to the environmental impacts of its use. It has been debated whether the fugitive methane emissions during natural gas production and transmission outweigh the lower carbon dioxide emissions during combustion when compared to coal and petroleum. Using the current state of knowledge of methane emissions from shale gas, conventional natural gas, coal, and petroleum, we estimated up-to-date life-cycle greenhouse gas emissions... see full abstract
- Empirical Methods for Detecting Regional Trends and Other Spatial Expressions in Antrim Shale Gas Productivity, with Implications for Improving Resource Projections Using Local Nonparametric Estimation Techniques
The primary objectives of this research were to (1) investigate empirical methods for establishing regional trends in unconventional gas resources as exhibited by historical production data and (2) determine whether or not incorporating additional knowledge of a regional trend in a suite of previously established local nonparametric resource prediction algorithms influences assessment results. Three different trend detection methods were applied to publicly available production data (well EUR aggregated to 80-acre cells) from the Devonian Antrim Shale gas play in the Michigan Basin. This effort led to the identification of a southeast-northwest trend in cell EUR values across the play that, in a very general sense, conforms to the primary fracture and structural orientations of the province.
- Well Completion for Effective Deliquification of Natural Gas Wells
Liquid loading has been a problem in natural gas wells for several decades. With gas fields becoming mature and gas production rates dropping below the critical rate, deliquification becomes more and more critical for continuous productivity and profitability of gas wells. Current methods for solving liquid loading in the wellbore include plunger lift, velocity string, surfactant, foam, well cycling, pumps, compression, swabbing, and gas lift. All these methods are to optimize the lifting of liquid up to surface, which increases the operating cost, onshore, and offshore. However, the near-wellbore liquid loading is critical but not well understood. Through numerical reservoir simulation studies, effect of liquid loading on gas productivity and recovery has been quantified in two aspects: backup pressure and near-wellbore liquid blocking by considering variable reservoir permeability, reservoir pressure, formation thickness, liquid production rate, and geology. Based on the new knowledge, we have developed well completion methods for effective deliquifications. These lead to better field operations and increased ultimate gas recovery.
- Hydraulic-Fracture-Height Growth: Real Data
From Abstract: Much public discourse has taken place regarding hydraulic-fracture growth in unconventional reservoirs and whether fractures could potentially grow up to the surface and create communication pathways for frac fluids or produced hydrocarbons to pollute groundwater supplies. Real fracture-growth data mapped during thousands of fracturing treatments in unconventional reservoirs are presented along with the reported aquifer depths in the vicinity of the fractured wells... see full abstract.
- Public perception of the natural gas industry: Data from the Barnett Shale, Energy Sources
See abstract link
- Toward strategic management of shale gas development: Regional, collective impacts on water resources
From Abstract: ...Specifically, we examine hypothetical water withdrawals for hydraulic fracturing and the subsequent treatment of wastewater that could be returned or produced from future active shale gas wells in the currently undeveloped Susquehanna River Basin region of New York. Our results indicate that proposed water withdrawal management strategies may not provide greater environmental protection than simpler approaches. We suggest a strategy that maximizes protectiveness while reducing regulatory complexity... see full text.
- Geochemical and Strontium Isotope Characterization of Produced Waters from Marcellus Shale Natural Gas Extraction
From abstract: Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters... see full abstract
- Overview of Rock Property Relationships and Charicterization methods for Selected Oil and Gas Shales in North America
From Abstract:...This paper is an overview of five shale plays, including the Bakken, Marcellus, Barnett, Haynesville, and Woodford Shale. A brief geologic background for each is provided along with potential methods for multi-faceted geophysical characterization. Data examples are provided where available. These five shales exhibit some similarity amongst themselves in terms of composition and/ or fracturing... see full text.
- Maximize the placement of wells and production in unconventional reservoirs:Part 1
From Abstract: Over the past decade significant supplies of natural gas have been discovered in shale. While the development of new technologies has driven down the cost of gas extraction, pursuing natural gas in shale continues to be risky and capital intensive. Producers seek the most productive zones in their shale basins, as well as continued improvement in hydraulic fracturing processes... see full abstract.
- Economic Impacts of Marcellus Shale in Bradford County: Employment and Income in 2010: Pennsylvania College of Technology and Penn State Extension Marcellus Shale Education & Training Center report
From the introduction: How much of the economic benefit of gas drilling actually stays local is important to know, because the communities where drilling is occurring are most directly bearing the costs of that development. For residents living in those communities, the impacts statewide are less relevant than what is occurring within their community itself. Gas development does create some social, environmental and economic challenges for host communities, in part due to the influx of new workers, increase in truck and other traffic, increasing demands for services, and large use of water and other natural resources. Identifying local impacts is critical to understanding the implications of natural gas development for communities where drilling is occurring.... see full text
- Isotope Fractionation of Methane during Natural Gas Flow with Coupled Diffusion and Adsorption/Desorption
From Abstract: Fractionation of carbon isotopes of methane in natural gas due to mass transport is evaluated based on statistical thermodynamics, microkinetics and fluid dynamics analysis. A continuum flow model with coupled adsorption/desorption and diffusion is defined and calibrated to describe isotope fractionation of natural gas due to flux in low permeability rocks. Isotopic fractionations due to post-generation mass transport are evaluated with analytical and numerical solutions under different conditions... see full abstract.
- Lithofacies and sequence stratigraphy of the Barnett Shale in east-central Fort Worth Basin, Texas
From Abstract: Ten Barnett Shale lithofacies have been recognized in a 223-ft (68-m)-long core from Johnson County, Texas. Eight of these lithofacies match those previously identified in the main producing area of the Newark East (Barnett Shale) field in the northern part of the Fort Worth Basin, but two new lithofacies have been identified in this core, resedimented spiculitic mudstone lithofacies and lag deposits, both of which are indicative of a relatively higher energy environment and downslope resedimentation of shallower water deposits... see full abstract.
- Empirical Methods for Detecting Regional Trends and Other Spatial Expressions in Antrim Shale Gas Productivity, with Implications for Improving Resource Projections Using Local Nonparametric Estimation Techniques
The primary objectives of this research were to (1) investigate empirical methods for establishing regional trends in unconventional gas resources as exhibited by historical production data and (2) determine whether or not incorporating additional knowledge of a regional trend in a suite of previously established local nonparametric resource prediction algorithms influences assessment results. Three different trend detection methods were applied to publicly available production data (well EUR aggregated to 80-acre cells) from the Devonian Antrim Shale gas play in the Michigan Basin. This effort led to the identification of a southeast–northwest trend in cell EUR values across the play that, in a very general sense, conforms to the primary fracture and structural orientations of the province. However, including this trend in the resource prediction algorithms did not lead to improved results. Further analysis indicated the existence of clustering among cell EUR values that likely dampens the contribution of the regional trend. The reason for the clustering, a somewhat unexpected result, is not completely understood, although the geological literature provides some possible explanations. With appropriate data, a better understanding of this clustering phenomenon may lead to important information about the factors and their interactions that control Antrim Shale gas production, which may, in turn, help establish a more general protocol for better estimating resources in this and other shale gas plays.
- The Economic Value of Shale Natural Gas in Ohio: The Ohio State University Swank Program in Rural-Urban Policy Summary and Report
From the Executive Summary: Increased production of US natural gas in recent years has helped to meet the growing demands of American customers and has reduced natural gas imports. Natural gas is also a cleaner burning fuel when compared to its most realistic substitute, coal. This substantial increase in production has been attributed in large part due to the development of shale gas through a process called hydraulic fracturing. Hydraulic fractur-ing has enabled the expansion of natural gas extraction into new undeveloped areas. The Marcellus shale in Pennsylvania has experienced impressive growth in its natural gas industry and neighboring Ohio is beginning down the same path. Proponents argue that among the many purported advantages, natural gas production is associated with significant amounts of new economic activity.... See full text
- The Economic and Employment Contributions of Shale Gas in the United States
From Executive Summary: This study presents the economic contribution of the shale gas industry - today and in the future. It does so in terms of jobs, economic value, and government revenues. The research demonstrates how the development of new sources of natural gas from shale formations has changed the US energy outlook and the economy... See Full Text
- Draft Investigation of Ground Water Contamination near Pavillion, Wyoming
This draft report appears to present the first well-documented cases of groundwater contamination directly related to hydraulic fracturing. The geology of the gas field is quite different than the Marcellus Shale. The targeted Wind River and Fort Union Formations are relatively shallow, somewhat discontinuous sandstones that exhibit vertical and lateral stratigraphic variations over short distances. These units tend not to have effective low permeability cap rocks above them. The study concludes that several inorganic and organic constituents in groundwater are best explained as the result of contamination related to hydraulic fracturing. The study found very elevated pH (11.2-12), elevated K and Cl, synthetic organic compounds, petroleum hydrocarbons, breakdown products of organic compounds at shallow depths, sporadic bonding of well casings suggesting poor casing, hydraulic fracturing into thin discontinuous sandstone units, carbon isotopes suggesting thermogenic rather than boigenic origin of hydrocarbons, elevated methane near production wells, some shallow surface casing, and citizens' complaints that were consistent with technical observations. Surface impoundments likely contaminated shallower groundwater in wells for watering livestock.
- Unconventional natural gas resources in Pennsylvania: The backstory of the modern Marcellus Shale play
Pennsylvania is not only the birthplace of the modern petroleum industry but also the focus of the modern Marcellus Shale gas play. For more than 150 yr, Pennsylvania has experienced a rich history of oil and gas exploration and production, witnessed the advent of modern petroleum regulations, and now sits deep in the heart of the largest domestic shale gas play the United States has ever seen. Although a known source rock for decades, the Marcellus Shale was not considered a viable gas reservoir until Range Resources Corporation (Range) discovered the play with its completion of the Renz No. 1 well in Washington County in October 2004. Using horizontal drilling and hydraulic fracturing techniques used by operators working the Barnett Shale gas play, Range has gone on to complete hundreds of horizontal shale gas wells in Washington County alone. Other operators have followed suit in counties from one corner of the state to the other, and as of June 2011, the Commonwealth has issued nearly 6500 Marcellus Shale gas well permits. Based on publicly reported well completion and production data, an average Marcellus Shale gas well requires 2.9 million gal of water during the hydraulic fracturing process and produces 1.3 mmcf gas/day. Furthermore, the U.S. Energy Information Administration has estimated that as of mid-2011, daily Marcellus Shale gas production in Pennsylvania exceeds 2.8 bcf. Because of the level of drilling activity and production associated with the Marcellus play, Pennsylvania has become the nexus of shale gas production and water management issues.
- Establishment of an Evaluation and Approval Process for the Use of Abandoned Mine Drainage (AMD) for Industrial Uses Including Natural Gas Extraction: A PADEP White Paper
In November, DEP announced an interim procedure for how the department would process requests by the oil and gas industry to use water impacted by active or abandoned mines for the development of gas wells particularly in the Marcellus Shale regions of the state. The process was outlined in a draft “white paper” that was developed by a team of DEP staff. The department is following the process outlined in the draft white paper to guide staff in granting approvals for the use of AMD in fracking. Following the public input sessions, DEP will update the process, and publish a final “white paper” in the spring.
- World Energy Outlook 2011: Are We Entering a Golden Age of Gas?: International Energy Agency and Organization for Economic Cooperation and Development report
Discussion of a scenario entitled "Golden Age of Gas" in which natural gas will play a greater role in satisfying world energy demand. This report examines factors driving natural gas demand and the implications of the rise of gas both for the energy economy as well as the environment.
- Final Report on Unconventional Gas in Europe
From Introduction: The main purpose of the Study is to analyse how the relevant applicable European legal framework, including environmental law, is applied to the licensing/authorisation and operational permitting for prospection, exploration and production/exploitation of shale gas based on a sample of four Member States, i.e. Poland, France, Germany and Sweden. It is, however, not purpose of the study to assess whether Member State legislation based on EU legislation has been properly transposed... See Full Text
- Rapid expansion of natural gas development poses a threat to surface waters
Natural gas development is likely to increase ecological impacts to the surrounding forests and waterways.This review article includes data on wells from the Fayetteville (AR, OK) and Marcellus (NY, PA, OH, WV, VA, KY) shale formations, and specifically addresses the issue of well proximity to water resources. The article discusses environmental threats to surface water (such as streams and rivers) from road construction, water withdrawals, sediment runoff, contaminant intrusion and improper wastewater disposal. Impacts on organisms and biological communities are also discussed.
- Geomechanical Study of Bowland Shale Seismicity
This technical source addresses detection of seismic events related to or induced by hydraulic fracturing.
- Elastic and resistivity anisotropy of shale during compaction and diagenesis: Joint effective medium modeling and field observations
Shales are anisotropic materials which have been observed to have both electrical and elastic anisotropy. Shales also comprise most of the sedimentary column in clastic basins, and thus, the ability to model shale response to electrical and seismic fields may improve our ability to better resolve anisotropy by using different measurements. Compacting shale-effective media modeling, which captures the geological process of porosity reduction and geochemical compaction, was formulated in this research in microstructural parameters associated with particle alignment and pore-shape deformation. The state of compaction, captured by the porosity of the soft sediment, governs the pore aspect ratio and the amount of particle alignment. Diagenetic processes are captured using temperature-dependent mineral elasticity and conductivity
- Induced and Natural Fractures in Shales - A Geomechanical Perspective
From Abstract: hales can serve as pressure barriers in basins, as top seals, and as reservoirs in shale gas plays. This paper emphasises the role of geomechanics in governing shale fracturing. In many basins, the fluid pressure of the aqueous system becomes significantly elevated, leading to the formation of a hydrofracture, and fluid bleed-off. Natural hydrofracture is an unlikely process in the circumstances that exist in most basins... see full abstract.
- Characteristics Of High Quality Frac Sand, And Where To Find It In The Upper Midwest
From Abstract: Geologists define sand as any sediment particle from 1/16th millimeter to 2 millimeters in size. However, there is a narrower definition of sand that would be ideal for use as a “proppant” in hydraulic fracturing operations and a host of other characteristics that relate to the economic value of a frac-sand deposit. Hydraulic fracturing involves injecting water, proppant, and chemicals into bedrock formations under pressures great enough to induce fractures. The sand grains “prop” open the fractures so that hydraulic conductivity is maintained... See full abstract.
- Derisking of Unconventional Gas Opportunities: Application of Basin Modelling
From Abstract: ...Basin modeling is a well known technique and has been successfully applied to basins in the exploration for conventional petroleum systems. It has to be the main goal of modern basin modeling to help in identifying the areas of highest resource density and to account for the highly variable character of gas shales around the world. This in turn will help to de-risk potential unconventional gas opportunities... see full abstract.
- Gas Generation at High Maturities (> Ro = 2%) in Gas Shales
From Abstract: Shale gas is most often of thermal origin. The secondary cracking of unexpelled oil at temperatures exceeding 150° C over geological time is usually viewed as the major pathway for generating the gas, corresponding to Ro = 1.5%, and kinetic models of secondary gas generation are used as part of GIP estimations to predict the extent of secondary cracking in time and space. Here we present new findings concerning a second later gas charge that is generated from some types of organic-rich shale at high maturity... see full abstract.
- Designing Tight-Shale Production Strategies Using Diamondoid Nanotechnology
From Abstract: The determination of diamondoid concentrations in tight shale core and cutting samples provides the first direct indication of natural oil cracking and also provides the first means of calculating the percentage of liquid within the shale which has been converted to gas. Diamondoids are hydrogen-terminated nanodiamonds that are present in all oils and rock extracts. Like larger diamond, they have high thermal stability that makes them ideal natural internal standards for studying oil cracking... see full abstract.
- Overview of Natural Gas Engineering Technology and the Energize Appalachian Ohio Project
- Petrophysics of Triple-Porosity Tight Gas Reservoirs With a Link to Gas Productivity
Petrographic work on thin sections from rock samples collected in tight gas sandstones of the western Canada sedimentary basin (WCSB) shows that the sandstones are composed of intergranular, microfracture and slot, and isolated noneffective porosities. The petrographic observations of these triple-porosity rocks have led to a petrophysical interpretation with the use of a triple-porosity model.
- Shale Natural Gas - Water Use Management
- Marcellus Natural Gas Development's Effect On Housing In Pennsylvania
From the Executive Summary: Commissioned by the Pennsylvania Housing Finance Agency (PHFA), the Center for the Study of Community and the Economy (CSCE) at Lycoming College researched the effects that the Marcellus Shale natural gas industry, broadly defined, is having on housing, also broadly defined, across the Commonwealth of Pennsylvania. CSCE conducted interviews with over 70 stakeholders in six counties (Bradford, Greene, Lycoming, Sullivan, Washington and Westmoreland) including local elected officials, county and municipal planners, housing authority officials, social service agency representatives, landlords, developers, realtors, gas company representatives and new residents on four broad issues: 1) rental housing, 2) owner-occupied housing, 3) housing affordability and availability, and 4) the capacity of the development community to meet demand for housing.
Several broad themes emerged from the interviews. First, the severity of the housing problem attributable to Marcellus Shale development depends on the nature and scale of the growth of the natural gas industry in a given county or community and on the existing pre-Marcellus capacity of that county or community to absorb the increased demand for housing. See full text
- Strategy for Assessment of European Gas Shales
From Abstract: In cooperation with European geoscience organizations, the United States Geological Survey (USGS) has begun an assessment of potential additions to reserves from continuous-type gas and oil accumulations in fine-grained rocks of Europe. Development of continuous-type accumulations has transformed the energy outlook of Canada and the United States and the degree to which such accumulations can be developed outside North America may determine the future of European and global energy markets... see full abstract.
- Outcrop Characteristics for the Woodford Shale
From Abstract: The Woodford Shale is the foremost hydrocarbon source rock and unconventional reservoir in Oklahoma. Depending on current depth of burial and thermal maturity, it produces natural gas and/or oil. In the most active play areas, the Woodford varies in thickness from about 100 to 300 ft; limited production from intervals as thin as ~25 ft thick also occurs... see full abstract.
- Shale Assets: Applying the Right Technology for Improving Results
From Abstract: The current practice commonly used in shale gas and oil wells is to use very simple tools to position and evaluate wells. This practice follows a statistical approach that accepts a considerable amount of variation in results. With competitive natural-gas pricing, every effort is made to keep costs under control, which precludes applying a more rigorous approach to realizing the value of these assets. Several alternative approaches have been proposed by interested parties to improve individual well results... see full abstract.
- OGIP Evaluation of Shale Gas and CBM with Basin Modeling and Gas Isotopes Interpretation
From Abstract: Shale gas and coal-bed methane (CBM) are retained gas in source rocks. The application of basin modeling and gas isotopes will forecast OGIP, but the procedure is different from conventional gas. Using advanced chemistry of basin modeling, the distribution of expelled oil/gas, adsorbed gas, and free gas can be simulated.. see full abstract.
- Shale Gas in Europe
From Abstract: Test drilling for shale gas (oil) is underway in Europe. While the geological setting is fundamentally different to that of the USA, complexity being the rule rather than the exception, opportunities appear abundant. In Poland it is mainly the Silurian, in England the Namurian and Wealden, in France the Jurassic, in Sweden the Cambrian and in Germany the Carboniferous, Jurassic and Wealden that are in focus... see full abstract.
- Geological Characterization of the Upper Mississippian Fayetteville Shale in Northern and Eastern Arkoma Basin, and Mississippi Embayment Regions, Arkansas
From Abstract: ... As of February 2010, the cumulative production of the Fayetteville Shale totaled approximately 900 Bcf. However, there is little to no commercial gas production from the Fayetteville Shale in the west-central portion of the Arkoma Basin (Li et al., 2010). The purpose of this study is to establish a correlation between surface data obtained in outcrops of Upper and Lower Fayetteville Formation in Searcy and Stone counties in northern Arkansas, with subsurface data obtained from wells located in the Embayment, and to differentiate the geological and geochemical settings that cause unequal gas production in this region...see full abstract.
- Geologic analysis of the Upper Jurassic Haynesville Shale in east Texas and west Louisiana
From Abstract: The Upper Jurassic Haynesville Shale is currently regarded as one of the most prolific emerging shale-gas plays in the continental United States. It has estimated play resources of several hundred trillion cubic feet and per-well reserves estimated as much as 7.5 bcf. The reservoir spans more than 16 counties along the boundary of eastern Texas and western Louisiana... see full abstract.
- The Effect of Mechanical Properties Anisotropy in the Generation of Hydraulic Fractures in Organic Shales
From Abstract: ... A series of sonic logs have been run in organic shales and the stress profile generated from these logs has been estimated, accounting for the difference in mechanical properties in the vertical and horizontal directions. This stress profile has been calibrated to measured closure stresses acquired in-situ via micro-fracturing of multiple intervals in vertical, openhole environments. The results show that ignoring the impact of mechanical property anisotropy can lead to significant errors in the estimation of hydraulic fracture height... see full abstract.
- Heat Transfer Applications for the Stimulated Reservoir Volume (SRV)
From Abstract: Multistage hydraulic fracturing of horizontal wells enables creation of a Stimulated Reservoir Volume (SRV). An idealization of the SRV for shale gas production is a rectangle of length equal to horizontal well length and width equal to twice the half length of the created hydraulic fractures. This paper discusses the use of an analogous SRV design for two novel thermal applications... see full abstract.
- A spatial investigation of metal and mineral associations in the Marcellus Shale
Fortson et al. use Mass Spectrometry to determine the composition of elements, particularly metals uranium and chromium, as well as oxygen, hydrogen and carbon, in six Marcellus Shale samples from western New York and Pennsylvania.
- Boron and strontium isotopes as sensitive tracers for indicating potential shallow groundwater contamination from Marcellus formation brines
- The Impact of Marcellus Gas Drilling on Rural Drinking Water Supplies
This report explains key findings from a research study that took place in 2010 to 2011 using data collected from over 200 privately owned water wells. Three key findings are: 1) 40% of rural water wells already exceed at least one EPA drinking water standard (e.g., for coliform bacteria or turbidity) before drilling begins; 2) drilling does not appear to have a statistically significant impact on dissolved methane content in tested wells; 3) bromide may represent a novel contaminant of interest, although post-drilling levels increased in only one well. The authors also believe more intensive and longer-term research is needed. This report is sponsored by the Center for Rural Pennsylvania, a bipartisan legislative agency within the PA General Assembly that seeks to sustain Pennsylvania's rural communities and provide a resource for rural policy.
- Dissolved gas geochemistry of shallow groundwater systems in Pennsylvania and New York, associated with natural gas extraction
- Reservoir characterization of the Devonian Shale formations in the Applachian basin and the impact on current gas development
- Stable isotope fingerprinting of co-produced waters associated with Marcellus Shale natural gas extraction
- Coupling lead isotope ratios and element concentrations to track processes involved in resource extraction from the Marcellus Shale
- Structural and topographic assessment of shallow bedrock permeability variations throughout Susquehanna County, PA: A focus area of Marcellus Shale gas development
- Economic Incentives and Regulatory Framework for Shale Gas Well Site Reclamation in Pennsylvania
From the abstract: Improperly abandoned gas wells threaten human health and safety as well as pollute the air and water. In the next 20 years, tens of thousands of new gas wells will be drilled into the Marcellus, Utica, and Upper Devonian shale formations of Pennsylvania. Pennsylvania currently requires production companies to post a bond to ensure environmental reclamation of abandoned well sites, but the size of the bond covers only a small fraction of the site reclamation costs. The economics of shale gas development favor transfer of assets... see full abstract.
- Tight gas: From pore-scale to well decline curve analysis
- Marcellus Shale: A Citizens View
Pennsylvanians believe that gas drilling in the Marcellus Shale has moved too quickly and that public officials need to do a better job protecting their communities and the environment, according to the final report of the Citizens Marcellus Shale Commission.
- The successful development of shale gas resources in the United States
- Geochemical and strontium isotope study of sequentially extracted metals from Marcellus Shale drill core
The authors analyze produced waters from hydrofracking associated with the Marcellus shale formation in Tioga County, NY. They employ four extraction methods on drill core samples and use strontium (Sr) isotope analyses in order to gather data on the probable source of total dissolved solids (TDS) in produced waters from hydrofracking. Their results are found to be consistent with a mainly water-soluble source for the total dissolved solids.
- Risk Of Contamination Of Aquatic Resources From Energy Development In The Williston Basin Based On A Spatial, Chemical, And Geophysical Assessment
From Abstract:The Williston Basin of Montana, North Dakota, and South Dakota has been a leading domestic oil producing region for over half a century, with extensive new development associated with the Bakken Formation. Overlapping the Williston Basin is the Prairie Pothole Region (PPR), an area of abundant wetlands that provide critical habitats for breeding and migrating waterfowl and other wildlife. Energy exploration, development, and production can result in the release of saline and toxic co-produced waters... See full Abstract
- Integrated Diagenetic Study Of The Mississippian Barnett Shale, Fort Worth Basin, Texas
From Abstract: An integrated diagenetic study using paleomagnetic, geochemical, and petrographic data from cores was conducted to better understand the nature and timing of diagenetic events in the Mississippian Barnett Shale, a source rock and the major unconventional gas reservoir in the Fort Worth Basin, Texas. Paleomagnetic analysis indicates the unit contains chemical remanent magnetizations (CRMs) with shallow inclinations and streaked southeasterly to southerly declinations. The streak could represent a mixing trend... see full Abstract
- Original Gas-in-Place Evaluation for Non-American Gas Shale: The Petroleum System Modelling Supported Approach
From Abstract: In the major american Gas Shale basins the Gas in Place volume evaluation can be approached by simply extrapolating the well experimental data (Geochemistry and Logs) due to the intense drilling activity that allows to have available hundreds or more wells. On the other hand in the first phases of a gas shale project evaluation the well data resolution is so low that the normal approach (quantification of well data only) is not enough to describe properly the properties distribution... see full abstract.
- Fabric of Shales Relating to Sedimentary Processes and Gas Shale Characteristics
From Abstract: The fabric of shales revealed by x-radiographic, petrographic, and scanning electron microscopic analysis provides clues to shale sedimentary processes and properties of potential gas shales. Presented here are examples of fabric signatures useful in recognizing the following shale forming processes... see full abstract.
- Geological Features and Exploration for Tight Sand Gas, Shale Gas and Other Unconventional Oil/Gas Resources in China
From Abstract: Petroleum exploration and development in China has extended rapidly from the conventional oil/gas resource to the unconventional oil/gas resource, which has large exploration potential. In China, there are various types of unconventional oil/gas resources, covering a large area. Especially, the exploration domains of shale gas and tight sand gas are very broad... see full abstract.
- Impact of Syndepositional Faulting on the Distribution of Organic-Rich Utica Shale, New York State
From Abstract: The Utica Shale is a potential drilling target in eastern North America and Canada. Total thickness of the organic-rich strata ranges from zero in the west to as much as 1300 feet in the east with common TOC values of up 3.5%. The Utica Shale was deposited during the Late Ordovician Taconic Orogeny... see full abstract.
- A Tale of Two Shales: Time-Series Geochemistry of the Devonian Marcellus and New Albany Shale Formations
From Abstract: Time-series carbon, nitrogen, and sulfur elemental and isotopic analyses of the Middle Devonian Marcellus Shale and Late Devonian New Albany Shale reveal strong stratigraphic variations related to changes in physical and chemical depositional environments. In the Marcellus Shale, collected from outcrop near Kistler, PA, peak abundances of carbon (up to 8 wt.%), nitrogen, and sulfur are recorded at the maximum flooding surface near the base of the ~120 meter thick unit, suggesting a target horizon for horizontal drilling... see full abstract.
- Effective Fracture Treatment Determination in Unconventional Reservoirs
From Abstract: ...Recent work with dipole sonic logs has demonstrated the ability of the log to resolve rock mechanical properties in the traditional vertical direction along with these same properties in the horizontal dimension. This vertical and horizontal resolution is acquired in a pilot hole and used for landing horizon definition. The same data is used to establish expectations of fracture treatment behavior from the initiation in a horizontal wellbore... see full abstract.
- The Role of Matrix and Fractures on Appalachian Basin Upper Devonian Gas Production
From Abstract: ...The Upper Devonian Shales are composed of several black shale intervals that have been exploited for hydrocarbons for over 100 years, including the Dunkirk and Rhinestreet shales. Gas storage efficiency and movement of gas through these shales needs to be viewed in three different time frames and conditions: geologic via hydrocarbon migration, formation connectivity via natural wellbore production, long-term production via artificial fractures connecting a larger area... see full abstract.
- A USANS/GP-SANS Study of the Accessibility of Pores in Gas Shale to Methane, Water, and Brine
From Abstract: ...In a pilot study of the accessibility of methane in wet shale, we have studied the penetrability of methane, water, and brine solution into Mississippian Barnett Shale samples using the ultra-high-resolution small-angle neutron scattering (USANS) diffractometer at the National Institute of Standards and Technology and the General Purpose Small-Angle Neutron Scattering Diffractometer (GP-SANS) at Oak Ridge National Laboratory. Neutron scattering techniques are useful in this regard... see full abstract.
- Seismic Signatures of Faults in the Appalachian Basin of NYS, and the Effect of These Faults on Devonian Black Shales: An Update
From Abstract: In 2002 the Appalachian Basin in NYS was proposed to be riddled by literally hundreds of faults, based primarily on EarthSat’s (1997) Landsat lineaments integrated with gravity and magnetics and in western NYS, surface geology and soil gas. This report summarizes advances the UB Rock Fracture Group and associated partners have made in fault understanding since 2002, based principally on extensive 3D seismic, as well as integration with field studies of fracture systems in the black shales... see full abstract.
- Biomarkers in the Upper Devonian Lower Huron Shale as Indicators of Biological Source of Organic Matter, Depositional Environment, and Thermal Maturity
From Abstract: The Lower Huron Shale (Upper Devonian) is considered the largest shale gas reservoir in the Big Sandy Field in Kentucky and West Virginia. The potential for gas shales, such as the Lower Huron, to produce natural gas is a function of type, amount, and thermal maturation of their organic matter. Twenty-one Lower Huron Shale samples from eight wells located in eastern Kentucky and southern West Virginia were analyzed for biomarker content to interpret biological source of organic matter, depositional environment conditions, and thermal maturity...see full abstract.
- North Carolina Shale Gas: Dan River Basin ¿ Stokes and Rockingham Counties
From Abstract: The Dan River Basin is an approximately 93-mile-long, northeast-trending half-graben Triassic rift basin with a steeply dipping western border fault in north-central North Carolina (NC) and Virginia. The basin is filled with ~6,600 feet of Triassic strata that dip at about 30 degrees west toward the border fault. The Triassic is divided into the following three formations in descending stratigraphic order: (1) Stoneville Formation (red and gray siltstone and shale); (2) Cow Branch Formation (black shale, with some beds of gray shale, sandstone and very thin coal); and (3) Pine Hall Formation (gray sandstone and shale)... see full abstract.
- Chemostratigraphic trends of the Middle Devonian Marcellus Shale, Appalachian Basin; Preliminary Observations
From Abstract: Trace element and metals abundances have been used to elucidate the hydrography of silled basins as well as watermass chemistry and deep-water residence times. The database of our preliminary study of the Middle Devonian Marcellus Shale comprises chemostratigraphic (X-ray fluorescence) elemental concentrations determined from cores recovered from eastern New York, southwest Pennsylvania, and northern West Virginia... see full abstract.
- Shale Gas Sweet Spot Identification Using Play Fairway Analysis and Shale Gas Reservoir Simulation
From Abstract: ...The objectives of this study were to: (1) geologically identify sweet spots [in the NY Utica Shale], (2) apply a Shale Gas Production Model (SGPM) that calculates the production reserves and rates for both vertical and horizontal wells, (3) vary the input distribution to the SGPM by Monte Carlo techniques such that multiple realizations were performed, and (4) create P10, P50, and P90 maps of cumulative methane production... see full abstract.
- Examination of the Shale Gas Potential of Devonian Shales in the Broadtop Synclinorium, Appalachian Basin (Virginia, West Virginia, Maryland, and Southern Pennsylvania)
From Abstract: ...Outcrops within the 16-county study area that occupies the Broadtop Synclinorium in northern West Virginia, northwestern Virginia, western Maryland and the southern tier of counties in Pennsylvania were examined, described, sampled, and analyzed for total organic carbon (TOC) content, thermal stress levels (vitrinite reflectance, VR), and mineralogical content. One hundred and nine samples were analyzed for TOC and VR; 106 of these samples were examined for mineralogical content using x-ray diffraction. Of the 109 samples examined for TOC and VR, the Marcellus shale samples have a TOC range of 0.17% to 7.22% (n=92) and a VR range of 0.74% to 3.43% (n=95)... see full abstract.
- A New 3D Structural Modeling Technique Unravels Complex Structures within the Marcellus Shale: Utilizing Borehole Image Logs
From Abstract: ...In many instances within the Marcellus Shale, wells are drilled out of zone and the problems can be attributed to complex structural settings. Such structural complexities can often be understood using seismic data. In this case the horizontal well indeed encountered a complex structure, however, the available seismic at the time of drilling the well was poor and therefore no definite interpretation could be made. In an attempt to better understand the structure, high resolution borehole image logs were acquired within both the pilot and horizontal wellbores... see full abstract.
- Composite geochemical database for coalbed methane produced water quality in the Rocky Mountain region
Identifying potential water quality contamination from natural gas hydraulic fracturing is a critical concern complicated by the existence of coalbed methane (CBM), also known as coalbed natural gas. Highly saline CBM produced water is commonly reinjected into the subsurface for disposal, presenting the possibility of contamination. This article looks at water quality parameters in a specific coal deposit region of the United States, in the Rocky Mountains. The authors found values in exceedance of standards for drinking, livestock, and irrigation water applications for the following constituents: total dissolved solids (TDS), sodium adsorption ratio (SAR), temperature, iron, and fluoride.
- Revised Draft of the Supplemental Generic Environmental Impact Statement On The Oil, Gas and Solution Mining Regulatory Program - Well Permit Issuance for Horizontal Drilling and High-Volume Hydraulic Fracturing to Develop the Marcellus Shale and Other Low-Permeability Gas Reservoirs: Executive Summary
This document broadly addresses the permitting of oil and gas exploration and production in the state of New York and has been revised several times, including July of 2011. This document, the September 2011 revision ("Revised Draft"), issued by the NY Department of Environmental Conservation, represents the most recent draft to date. Its main area of concern is to document potential impacts from new technologies for shale gas development such as hydraulic fracturing and horizontal drilling. A technicality is that the SGEIS is not itself regulation, though it refers to regulations.
- USGS Assessment of In-Place, Oil-Shale Resources of the Upper Devonian Antrim Shale in the Michigan Basin, Eastern United States
From Abstract: The U.S. Geological Survey is assessing in-place, oil-shale resources in the immature Upper Devonian Antrim Shale in the Michigan Basin. The Antrim Shale is a black, organic-rich shale that was deposited during the Late Devonian Period in a large epeiric, low-energy, marine environment that covered Michigan, northern Indiana, northwestern Ohio, and parts of Lake Michigan and Lake Huron; it was also part of the Devonian sea that covered a large area of the eastern United States. In the western part of the Michigan Basin, the Antrim Shale grades into the contemporaneous Ellsworth Shale, a low-organic content, gray shale... see full abstract.
- Testing Depositional Models and Basin Geometry for the Utica Shale, Mohawk Valley, New York State
From Abstract: The Ordovician Utica Shale is a natural gas producing black shale that crops out in the Mohawk Valley of eastern New York State. The environment of deposition has traditionally been interpreted to be deep water anoxia in the tectonically enclosed Taconic foreland basin where accommodation space growth is thought to have initially greatly exceeded sediment supply. Smith et al. recently suggested an alternative model, however, in which the Utica was deposited on the western limb of the Taconic foreland in relatively shallow water... see full abstract.
- Assessment of Spatial Variability in the Marcellus Shale from High Resolution Sedimentology and Stratigraphy, Finger Lakes Region, NY
From Abstract: ...In this study we intend to establish the variations in lithofacies within the Marcellus Shale in the Finger Lakes region of New York and use these as criteria with which to understand the environmental conditions under which the Marcellus Shale was deposited. A second component of our study is to recognize key surfaces that may be indicative of basin wide base-level changes that can be tied to the geophysical log signals. We intend to place the rock property variations in a sequence stratigraphic framework. Ultimately, we will estimate the magnitude and variability of those rock properties... see full abstract.
- Examination of Inferred Third-Order Structural Features of the Marcellus Shale Using Wireline Logs in the Broadtop Synclinorium, Virginia and West Virginia
From Abstract: ...During recent field work within the Valley and Ridge Province, we observed intraformational deformation in the Marcellus Shale. In an attempt to determine if this outcrop-scale deformation is discernible in the subsurface, we examined conventional gamma-ray and density logs from nine wells in a 30-mile by 30-mile (50-km by 50-km) area in eastern West Virginia and western Virginia... see full abstract.
- Nanometer-scale Authigenic Quartz Associated with Algal Bituminite and Intraorganic Nanoporosity in the Devonian Marcellus Shale: Observations and Hypotheses
From Abstract: ...Organic-richness and formation brittleness are two principal components of reservoir quality assessment, as the former is indicative of the amount of hydrocarbons present, and the latter is indicative of hydrocarbon accessibililty via hydraulic fracturing. Interestingly, organic matter is associated with authigenic quartz, a primary brittle component within mudstone; therefore the nature of the organic-quartz association is critical to better understanding shale gas reservoirs... see full abstract.
- Natural Fracture Characterization in Shale-Gas Reservoirs: Spatial Organization and Fracture Sealing
From Abstract: Natural fracture systems are important for production in shale-gas reservoirs in two ways. They may reactivate during hydraulic fracture treatments or they may be partly open, contributing to permeability without reactivation. Degree of openness and fracture plane strength are related in part to the specific structural-diagenetic history of each fracture set and shale host rock. Several possible mechanisms control fracture formation... see full abstract.
- Geochemical and Isotopic Variations in Waters of an Area of Accelerating Shale Gas
From Abstract: The main concern associated with Marcellus shale gas development is that water quality of surface waters and fresh water aquifers can be compromised during gas well drilling, stimulation and improper disposal practices. However, in shale development areas of West Virginia, the frac flowback waters can have similar chemical constituents found in some saline formations and coal mine waters originating from several thousand acres of abandoned coal mines in this region. Therefore, to better assess any detrimental effect on water quality there is need to understand the natural temporal and spatial variations in the geochemical parameters of the surface waters and groundwaters in the area... see full abstract.
- Revising the 2006 USGS Assessment of In-Place Oil Shale Resources of Devonian - Mississippian Black Shales in the Eastern United States
From Abstract: The U.S. Geological Survey (USGS) is revising the 2006 assessment of 189 billion barrels of surface-mineable oil-in-place in the Devonian Mississippian black shales in the eastern United States, which was published as part of a study on world oil-shale deposits (Dyni, 2006). The 2006 USGS assessment was based on earlier work by Matthews and others (1980) who estimated the area, average thickness, and average oil yield for the most organic-rich shales in each of six states... see full abstract.
- Empirical Evaluation of Procedures to Detect Spatial Anomalies in the Devonian Antrim Shale (Michigan Basin), and Potential Effects on Resource Assessment
From Abstract: ...The primary objective of this study is to investigate empirical methods for establishing regional trends in unconventional gas resources as exhibited by historical production data and to determine whether or not the inclusion of such trends influences localized assessment results. To this end, the following two important questions are posited: (1) Can results of past drilling (i.e., well productivity) be used to confirm trends that might be inferred from available geological evidence, particularly with regard to naturally-occurring fractures? (2) Can information about such trends be used to inform the estimates of recoverable gas at undrilled sites as well as the aggregate assessments of remaining recoverable gas?... see full abstract.
- Major and Minor Element and Radium Geochemistry of Produced Water Samples from the Marcellus Shale in New York, Pennsylvania, and West Virginia
From Abstract: The inorganic geochemistry of produced water from the Marcellus Shale has been compared with analyses of waters produced from adjacent Devonian strata, including sandstone in the overlying Bradford Group, and the underlying Onondaga Limestone and Oriskany Sandstone using published data combined with a limited number of new analyses. Total dissolved solids values in waters produced from the Marcellus are similar to those produced from adjacent formations... see full abstract.
- Zero Discharge Water Management for Horizontal Shale Gas Well Developmen
From Abstract: ...A West Virginia University (WVU) research team is looking at methods for managing frac water withdrawals and returns from large gas wells in the Marcellus Formation by converting the briny waste into a suitable, partial replacement of the fresh water that is currently used as the fracturing fluid of choice. The objective of this two-year, two-phase project is to develop and demonstrate a process for treating return frac water (RFW) from Marcellus horizontal well development that will allow an increased recycle rate while decreasing make-up water and disposal requirements... see full abstract.
- The Horton Bluff Formation Gas Shale, Frontier Shale Play Fairway Analysis, Nova Scotia, Canada
From Abstract: The Horton Bluff Formation gas shale’s are within the Carboniferous lacustrine and marginal marine Horton Group of the Maritimes Basin. Gas in place (GIP) estimates are > 69 TCF and leading indicators of a prospective shale gas play such as TOC at >5.5 %, Maturity (Ro) of 1.6, thickness of >500 meters and estimates of 100 Bcf per section across an area of > 2 million acres, have generated an increased interest in the Horton Bluff Formation within this frontier basin... see full abstract.
- A Regional Perspective of the Devonian Shale and Ordovician Utica Shale Total Petroleum Systems of the Appalachian Basin
From Abstract: The Devonian Shale-Middle and Upper Paleozoic and the Utica-Lower Paleozoic Total Petroleum Systems (TPS) are the prominent Appalachian basin TPSs defined by the USGS. They have known petroleum volumes (cumulative production + proved reserves), through 2008, of about 2.6 BBO/59.1 TCFG and 0.9 BBO/10.7 TCFG, respectively. A mean recoverable undiscovered gas resource of 61.3 TCFG (USGS 2002 assessment) from tight sandstone and black shale in both TPSs is conservative... see full abstract.
- Vertical and Lateral Extent and TOC Content of Middle and Upper Devonian Organic-Rich Shales, New York State
From Abstract: While most of the focus is on the Middle Devonian Marcellus Shale, there are numerous other organic-rich shales in the Middle and Upper Devonian strata of New York State that might also produce gas or liquids. The purpose of this presentation is to show in-house TOC and calcite content data, maps and cross sections of Middle and Upper Devonian black shales in New York... see full abstract.
- Marcellus Flowback Waters: Examination of Water and Solute Sources
From Abstract: Hydraulic fracturing of the Marcellus Shale and other shale gas units can produce large quantities of fluids during flowback and hydrocarbon extraction. Because of the high total dissolved solid (TDS) content of Appalachian Basin formation waters (up to 402,000 mg/L) relative to that of water used as the primary solvent for the fracturing fluid, a 2-4 order of magnitude increase in salt load is observed in produced waters during flowback. However, the characteristics and sources of the flowback water and solutes have received relatively little attention... see full abstract.
- Sequence Stratigraphy, Reservoir Properties and Preservation of Organic Carbon in the Middle Devonian Marcellus Shale
From Abstract: ...This study is intended to investigate the influencing geologic parameters under which the Marcellus Shale accumulated over a portion of the Appalachian basin, specifically, northern West Virginia and southwestern Pennsylvania. The study incorporates characterization of the sedimentology of the cored Hamilton Group sections including pyrite framboid size and distribution, sedimentary structures, and microfossil assemblages. This is accompanied by geochemical analysis... see full abstract.
- North American Shale Gas Reservoirs -- Similar, Yet So Different
From Abstract: Recent estimates of recoverable gas from unconventional shale reservoirs in the US exceed .5 qcf (quadrillion cubic feet) (USGS 2009) with potential for another .1 qcf in Canada (NEB). While broadly distributed, North American shale gas basins generally follow a trend of thrust belts and a Mississippian/Devonian shale fairway from Western Canada and into the Western, Southern, and Eastern United States... see full abstract.
- An Overview of Marcellus and Other Devonian Shale Production in West Virginia
From Abstract: The Middle Devonian Marcellus Shale Play has put the Appalachian Basin at the center of a national debate concerning America’s future energy supply. Although it has been received in the region with mixed reviews, this highly organic shale formation has secured itself as a major contributor to the natural gas supply of West Virginia and other states in the Basin. As production continues throughout West Virginia, areas of high production continue to emerge... see full abstract.
- Hydraulic Re-Fracturing
This paper provides a discussion and review of re-fracturing of both vertical and horizontal wells. Discussion of basic fundamentals of hydraulic fracturing, reasons to re-frac, candidate selection, operational considerations, and case histories... see full presentation.
- Depositional Model of the Marcellus Shale in West Virginia Based on Facies Analysis
From Abstract: A lithologic analysis of well exposed Marcellus outcrops has identified six different facies in West Virginia and neighboring states: (1) light gray calcareous shale, (2) fossiliferous limestone, (3) black calcareous shale, (4) black noncalcareous shale, (5) dark gray noncalcareous shale, and (6) K-bentonite. Close interbedding of these rock types attests to a complex, ever-changing environment on the eastern foreland ramp of the Appalachian Basin... see full abstract.
- Understanding the Regional Haynesville and Bossier Shale Depositional Systems in East Texas and Northern Louisiana: An Integrated Structural/Stratigraphic Approach
From Abstract: Recent discoveries in the Haynesville and Bossier shales have dramatically increased unconventional gas exploration activity in the mature petroleum provinces of East Texas and Northern Louisiana. Using a variety of subsurface data including 2D seismic, well logs, mud logs, core descriptions, and absolute age control based on multi-disciplinary biostratigraphy, detailed depositional models for the Haynesville and Bossier Shale depositional systems have been developed... see full abstract.
- Natural gas operations from a public health perspective
Summarizes potential health effects of products and chemicals used in natural gas operations. Toxicological categorization of the products and chemicals that are summarized in the article were acquired by obtaining the Material Safety Data Sheets, reports and environmental assessments from different sources, including states and industry.
- Radium content of oil- and gas-field produced waters in the northern Appalachian Basin (USA): Summary and discussion of data
- Hydraulic fracturing not responsible for methane migration
This article addresses the current debate of whether hydraulic fracturing contributes to methane contamination of shallow groundwater. In contrast to earlier studies, this author reports microseismic observations that appear not to support the methane migration phenomenon.
- Natural gas: Should fracking stop?
This short commentary offers three expert opinions on whether shale gas extraction is desirable. Natural gas extracted from shale comes at too great a cost to the environment, say Robert W. Howarth and Anthony Ingraffea. However, Terry Engelder says fracking is crucial to global economic stability and the economic benefits outweigh the environmental risks.
- Shale Gas Revolution
- Success and Failure in Shale Gas Exploration and Development: Attributes that Make the Difference
From Abstract: Unconventional shale-gas reservoirs are receiving increasing attention and have revitalized natural gas production in North America. Though costly and manpower intensive, they have less risk of a dry hole and can hold significant quantities of gas. With the current trend towards unconventional shale-gas plays, it is useful to examine the tools we use to explore for them. Attributes such as TOC, vitrinite reflectance, thickness, and mineralogy are touted as the path towards success... see full abstract.
- Generation and Modification of Natural Gases in the Marcellus Formation, Central Appalachian Basin, USA: Evidence from Stable Isotope Geochemistry
From Abstract: Exploration and production in the Marcellus Formation of the central Appalachian basin are focused in two core areas: southwestern Pennsylvania/ northern West Virginia and north central to northeastern Pennsylvania. Both associated gases and non-associated gases are produced in the southwestern core region. Only non-associated gases are produced in the northeastern core region. BTU values vary throughout the play... see full abstract.
- Economic Impacts of Marcellus Shale in Pennsylvania: Employment and Income in 2009: Pennsylvania College of Technology and Penn State Extension Marcellus Shale Education & Training Center report
This report was produced by the Marcellus Shale Education & Training Center (MSETC), a partnership of the Pennsylvania College of Technology and Penn State Extension. The authors attempt to determine where the income stemming from natural gas development, namely, leasing and royalties, eventually ends up, including Pennsylvania households, the state government, and non-residents of the Commonwealth. Data for the study came from surveys, data on industry spending, and land ownership data. The authors also relied on a computer modeling tool known as IMPLAN. The study findings suggest that the economic impact of Marcellus shale in Pennsylvania ranged between 23,385 and 23,884 jobs, and $3.1 and $3.2 billion in the year 2009. The study does not address environmental- or health-related costs arising from natural gas development.
- Identification of source carbon for microbial methane in unconventional gas reservoirs
A method is proposed for identifying the carbon source for methane generated by carbonate-reduction microbial methanogenesis using the isotopic and compositional mass balance of carbon in cogenerated carbon dioxide (CO2) and methane. Microbial methanogenesis from bitumen or petroleum generates more methane than CO2, so the carbon isotopic compositions of methane and CO2 are relatively heavy and similar to the carbon isotopic composition of thermogenic methane. Microbial methanogenesis that uses kerogen or recent organic matter as a carbon source generates relatively more CO2 than methane; therefore, methane and CO2 have the light carbon typical of shallow microbial methane.
- The Economic Impact of the Value Chain of a Marcellus Shale Well
- Methods for Enhancing Far-Field Complexity in Fracturing Operations
From Abstract: For decades the oil industry has struggled to overcome near-wellbore fracture complexity during fracturing treatments, particularly in low-permeability, naturally fractured hard-rock reservoirs. A number of techniques have been created to diagnose and remediate these conditions to enable extension of created fractures and successful placement of proppant deep in the reservoir. Microseismic fracture-mapping (MSFM) technology has revealed the creation of far-field complex fracture networks in hard-rock reservoirs during fracture extension... see full abstract.
- Fracking Under Pressure: The Environmental and Social Impacts and Risks of Shale Gas Development
From Executive Summary: Despite mounting evidence of climate change and the resulting need to shift toward a lower-carbon economy, the demand for fossil fuel continues to rise. Natural gas production and consumption are projected to continue to increase in both absolute terms and as a proportion of the fossil fuel mix. Meanwhile, reserves of conventional sources of oil and gas are dwindling and producers are increasingly focusing on unconventional sources, the development of which usually generates higher environmental and social risks... See Full Summary
- Life cycle greenhouse gas emissions of Marcellus shale gas
This article gives a rough estimate of greenhouse gas (GHG) emissions to develop a typical well in the Marcellus Shale: 5500 tons of carbon dioxide equivalent (CO2e) emissions, assuming conservative estimates of the production lifetime of such a well. The article situates this estimate in the context of other fossil fuels such as coal. "Life cycle assessment" refers to the totaled GHG emissions associated with a process from beginning to end. In this article, the life cycle GHG emissions of Marcellus shale natural gas are estimated to be 63 to 75 g CO2e/MJ of gas produced with an average of 68 g CO2e/MJ of gas produced, which is comparable to life cycle emissions associated with imported liquefied natural gas. Natural gas from the Marcellus Shale has generally lower life cycle GHG emissions than coal for production of electricity. The authors acknowledge significant uncertainty in their calculations due to variability in factors such as flaring, construction and transportation.
- Blind Rush: Shale Gas Boom Proceeds amid Human Health Questions
This article discusses some of the major environmental health concerns associated with the processes of hydraulic fracturing and horizontal drilling. It refers to data from health studies from many regions of the country, including not only Marcellus but Texas and Wyoming as well, stating that air and groundwater pollution are two main concerns. Water pollution is a main concern due to the quantity of water and and types of chemicals used in the process, as well as the produced water from after the process is complete, containing the same toxins as well as salt, heavy metals and other contaminants. Issues can also be seen related to residential drilling, as often the mineral rights associated with land are not owned by the homeowner. Further, there is still a lack of definitive research regarding the variety of potential human health effects related to shale gas drilling, so more definitive, long-term research is necessary before moving ahead.
- Eagle Ford Approach Optimizes Completion Design
From Introduction: Horizontal wells drilled in the northeast part of the Eagle Ford Shale play in the DeWitt County, Tx., region require a reservoirspecific completion strategy. Production in this part of the Eagle Ford has high liquid-to-gas ratios, and core analysis shows a low Young’s modulus (soft rock) and high clay content. These and other factors present different challenges to hydraulic fracturing... See Full Text
- Shale Gas Predictive Model (SGPM) -- An Alternate Approach To Model Shale Gas Production
From Abstract: ... For a project to be economically viable, under downward price pressures, large number of wells in multi-well drilling campaigns needs to produce commercial quantities of gas. Not surprisingly, numerous attempts are being made to type-cast mineralogy, organic contents, fracture design and completion optimization in order to reduce exploration and exploitation risks. Many uncertainties still remain, however. The proposed model (SGPM) is developed to mitigate some of these challenges... see full abstract.
- Backgrounds: Hydraulic Fracturing and Water Resources
This short piece provides background information on the effects of hydraulic fracturing on water resources. It includes helpful internet resources and summarizes information revealed at a Senate hearing in April 2011 (Committee on Environment and Public Works).
- Hydraulic Fracturing in Wyoming
- Drill, Maybe, Drill
- Wells or Woods: The Natural Gas Industry Meets the Pennsylvania Wilds
- Data Confirm Safety of Well Fracturing
From Introduction: North American oil and gas companies and energy services providers are following with a keen and vested interest the news coming out of Washington regarding the “Frac Act,” a congressional proposal to amend the Safe Drinking Water Act to remove a 2005 Energy Policy Act exemption on hydraulic fracturing and effectively give the U.S. Environmental Protection Agency the authority to regulate fracturing operations... See Full Text
- Hydrofracking: Uncertain Decision-Making in a Value-Laden Conflict
- Shale Gas and U.S. National Security: Rice University James A. Baker III Institute of Public Policy report
This study by the Baker Institute for Public Policy examines the implications of U.S. shale gas development on the nation's energy security, national security and foreign policy.
- Finger Lakes Region Gas Lease Mapping Report
This report provides a snapshot of the scale and impacts of potential gas drilling development for a rural, agricultural region in New York state. The report uses a geographic information system (GIS) mapping approach to examine publicly available information on land areas under gas leases in eight selected NY Finger Lakes counties (Cayuga, Chemung, Cortland, Livingston, Ontario, Schuyler, Seneca, and Steuben) with three additional counties mentioned in appendices to the report. The economic impacts of gas development are discussed. Some highlights from the report include these observations: over 600,000 acres in the specified region are under a gas lease filed between 2005 and 2010; of the eight counties, the county with the most absolute area under gas lease is Steuben County, with over 200,000 acres; the county with the highest percentage of land under gas lease is Cortland County, at 41%.
- Land Application of Hydrofracturing Fluids Damages a Deciduous Forest Stand in West Virginia
This study examined the effects of land application of about 300,000 liters of hydraulic fracturing fluid on the Fernow Experimental Forest site, West Virginia. Two years after fluid application, 56 percent of the trees in the fluid application area were dead, with American Beech trees suffering particularly high mortality. The study also looked at trends in sodium and chloride concentrations in the soil as well as changes in soil acidity over time. The author is affiliated with USDA Forest Service.
- Governor's Marcellus Shale Advisory Commission Report
From the Executive Summary: By assembling experts from within the environmental, conservation, state and local government, academic and natural gas industry communities, Governor Corbett has created the Marcellus Shale Advisory Commission and charged it to identify, prioritize and craft recommendations regarding the safe, efficient and environmentally
responsible extraction and use of unconventional natural gas reserves in Pennsylvania.
As outlined in Executive Order 2011-01, the Commission undertook a broad review of a multitude of issues related to Marcellus Shale natural gas development. The review included examining and recommending efforts to mitigate environmental impacts; fostering efforts to promote market development; developing a trained workforce; enhancing emergency response; identifying and mitigating uncompensated local and community impacts; providing for appropriate public health monitoring and analysis; and the responsible and efficient deployment of infrastructure.
- Parametric Study of Fracture Treatment Parameters for Ultra Tight Gas Reservoirs
Tight gas reservoirs are expected to contribute significantly to the gas and energy supply all over the world. However, the productivity of tight gas wells, especially in the ultra-tight formations, is often lower than expected. One of the needed improvements in reservoir stimulation technology is in the advancement of fracturing fluids and techniques that can help create long and highly conductive fractures and reduce phase trapping at the face of the fracture. Introduction of aqueous based fluids in ultralow permeability sands during hydraulic fracturing decreases the effective gas permeability and ultimate gas recovery. Unfortunately most fracture fluids currently deployed are aqueous based owing to their ease of preparation and low cost. This paper aims to investigate the effect of different fracture fluid systems and fracture treatment parameters and then determine one that achieves a balance of minimal fluid retention, optimal fracture geometry and low cost for ultra-tight gas reservoirs.
- Water management challenges associated with the production of shale gas by hydraulic fracturing
From Abstract: Development of unconventional, onshore natural gas resources in deep shales is rapidly expanding to meet global energy needs. Water management has emerged as a critical issue in the development of these inland gas reservoirs, where hydraulic fracturing is used to liberate the gas. Following hydraulic fracturing, large volumes of water containing very high concentrations of total dissolved solids (TDS) return to the surface... see full abstract.
- Resource Potential of the Woodford Shale in New Mexico
From Abstract: Shale resource plays are either shale-gas or shale-oil. Better evaluation procedures considering more number of parameters are needed to estimated resource potential. Successful shale-gas and shale-oil plays in the United States are variable in geological age, depositional sequence, organic richness, thermal maturity, kerogen type, and mineralogy among a few key parameters... see full abstract.
- The Woodford Shale in southeastern New Mexico: Distribution and source rock characteristics
From Abstract: The Woodford Shale (Upper Devonian) is 0 to 300 ft thick in southeastern New Mexico. Maximum thickness is in south-central Lea County where it lies at depths of 18,000 ft. The Woodford pinches out to the north and northwest in Roosevelt and Chaves counties, where it is present at depths of less than 7000 ft as it rises out of the Permian Basin... see full abstract.
- Changes and Considerations in the Natural Gas Marketplace
From Abstract: The Potential Gas Committee has reported the natural gas resource base in the United States has grown to over 2000 TCF in their last report. Some estimate that number may grow to over 2600 TCF in their next report. The advent of an increasing role for unconventional natural gas is dominating the prospect generations, lease acquisition, drilling and the merger and acquisition activity worldwide... see full abstract.
- Five Things I Wish a Geologist Had Taught Me -- Confessions of a Frac Engineer
From Abstract: Engineers are forced to use “simplified” models to describe reservoirs and propped fractures. It is generally anticipated that these models will give useful and approximately correct answers. Unfortunately, on many occasions the oversimplified tools have caused us to envision fractures incorrectly - resulting in poorly designed completions and missed opportunities. Frequently, we blame the underperformance of a well on “poor reservoir quality” instead of correctly recognizing the inadequacy of our created fractures... see full abstract.
- The Role of Expulsion Fracturing on the Redistribution of Reservoir Pressure in Niobrara Shale Reservoirs
From Abstract: The development and preservation of over pressured compartments in unconventional shale reservoirs requires low-permeability seals that inhibit fluid movement of generated hydrocarbons. The Niobrara is composed of interlaminated marl, silty marl and chalky marl with total organic matter (TOC) ranging from 2-8%. Geomechanical data indicates these laminae are relatively weak as compared to other mud rock formations with Young’s Modulus ranging from 2.0-2.5 mpsi... see full abstract.
- Citizen David Tames Gas Goliaths on the Marcellus Shale Stage: Citizen Action as a Form of Dispute Prevention in the Internet Age
This article reviews some general information on environmental and public health risks associated with hydraulic fracturing in the Marcellus shale and emphasizes the particular role of citizen action. The scope is broad and covers impacts and actions in multiple states. Includes a comprehensive bibliography. This journal is edited by third-year law students at the Cardozo School of Law.
- The Future of Natural Gas
This lengthy report was compiled by an interdisciplinary panel of scientists and academics primarily affiliated with the Massachusetts Institute of Technology (MIT) and the MIT Energy Initiative (MITEI). Basing its assessment on a "carbon-constrained" scenario in which greenhouse gas emissions are priced in the marketplace, the report discusses recommendations for U.S. policy regarding natural gas development. The report states that the environmental impacts of shale development, though large, can be successfully managed, especially with sound regulatory tools. The co-authors also recommend increased funding for research and development on natural gas and improvements to gas distribution (i.e., pipeline) safety programs.
- The Economic Opportunities of Shale Energy Development
An analysis that concludes that economic and environmental impacts of shale gas drilling in New York state are, by and large, beneficial. According to the authors, the economic benefit greatly outweighs the economic cost, in part because the environmental damage is believed to have a small probability of taking place, and to occur in a local rather than broad scope. Environmental impacts were analyzed by noting violations on land, water, and air resources reported by the Pennsylvania Department of Environmental Protection (DEP). The report discusses the types of problems reported, focusing on four of the eight violation categories that are considered most severe and harmful to human health: major spills; cement and casing violations; blowouts and venting; and stray gas. Any problems associated with hydraulic fracturing, according to this report, result more from a failure to use more stringent design standards for drilling and well casings, and from a greater need for vigilant regulatory oversight.
- Indirect Emissions of Carbon Dioxide from Marcellus Shale Gas Development
From Summary: In this report, we estimate the emissions of carbon dioxide associated with all fuel combustion associated with the shale gas life-cycle focusing on the Marcellus shale as a case study. We calculate all GHG emissions from land clearing, resource consumption, and diesel consumed in internal-combustion engines (mobile and stationary) during well development. Energy consumed once the gas well is brought into production (i.e. that consumed in production, processing, and transmission/distribution streams) are assumed to be similar to previously published estimates... See Full Text
- Waterless Fracturing Technology: Making the Most of your Reservoir
From Abstract: As the oil and gas industry tackles lower quality reservoirs and the need for more environmentally sustainable techniques grow, a new stimulation technology has been introduced to enhance well performance by eliminating the use of water in the stimulation process. The answer is using LPG or propane as the fracturing fluid. LPG is a nondamaging fluid, will not create water blocks, and has minimal surface tension making its post frac recovery approaching 100%... see full abstract.
- Restored State Automated Shale Analysis
From Abstract: A new laboratory technique was developed to measure the shale desorption isotherms (the gas in place) without the use of specialized field laboratory. Due to high industry activity the field laboratories are not always available. The samples are retrieved from the well, preserved on location and then shipped to the laboratory... see full abstract.
- The Shale Gas Shock: The Global Warming Policy Foundation Report
Excerpt from the cover: The Global Warming Policy Foundation is an all-party and non-party think tank and a registered educational charity which, while open-minded on the contested science of global
warming, is deeply concerned about the costs and other implications of many of the policies currently being advocated.
Our main focus is to analyse global warming policies and their economic and other implications. Our aim is to provide the most robust and reliable economic analysis and advice.
Excerpt from the summary: ....A surge in gas
production and use may prove to be both the cheapest and most effective way to hasten the
decarbonisation of the world economy, given the cost and land requirements of most
- The Unconventional Promise and Problems of Shale Gas Development in the US and China: A Comparative Study
From Introduction: On March 23, 2011, China successfully opened its first shale gas well in the Sichuan basin to the fanfare of its Central government and the international oil and gas industry. The Sichuan well is being lauded as a triumphant first step towards greater energy independence and cleaner air, as the country races to meet nationally-mandated gas use goals. Echoing the sentiment, Ming Sung of the American Clean Air Task Force stated "Shale gas is a game changer for the US and should do the same for China"... see full Introduction
- Parameterization of elastic stress sensitivity in shales
Stress dependency and anisotropy of dynamic elastic properties of shales is important for a number of geophysical applications, including seismic interpretation, fluid identification, and 4D seismic monitoring. Using Sayers-Kachanov formalism, we developed a new model for transversely isotropic (TI) media that describes stress sensitivity behavior of all five elastic coefficients using four physically meaningful parameters. The model is used to parameterize elastic properties of about 20 shales obtained from laboratory measurements and the literature. The four fitting parameters, namely, specific tangential compliance of a single crack, ratio of normal to tangential compliances, characteristic pressure, and crack orientation anisotropy parameter, show moderate to good correlations with the depth from which the shale was extracted.
- Marcellus Shale: The Science Beneath the Surface: a paper series sponsored by the National Science Foundation
This paper series, sponsored by the National Science Foundation, is dedicated to exploring Earth System Science issues related to Marcellus Shale drilling.
Paper titles include:
Introduction to the Marcellus Shale
Why the Geology Matters
and eight other titles.
- The Rush to Drill for Natural Gas: A Public Health Cautionary Tale
From Abstract: The Marcellus Shale, located in western New York, Pennsylvania, and Ohio, is estimated to contain enough natural gas to supply the United States for the next 45 years. New drilling technology-horizontal drilling and high-volume hydraulic fracturing of shale (fracking)-has made gas extraction much more economically feasible. However, this technique poses a threat to the environment and to the public's health... see full abstract.
- Marcellus Shale Water Management - An Operator's Viewpoint
- Optimizing Fracture Spacing and Sequencing in Horizontal-Well Fracturing
Horizontal wells with multiple fractures are now commonly used in unconventional (low-permeability) gas reservoirs. The spacing between perforations and the number and orientation of transverse fractures all have a major impact on well production.
The opening of propped fractures results in the redistribution of local Earth stresses. In this paper, the extent of stress reversal and reorientation has been calculated for fractured horizontal wells using a 3D numerical model of the stress interference induced by the creation of one or more propped fractures. The results have been analyzed for their impact on simultaneous and sequential fracturing of horizontal wells.
- Seismic Anisotropy of the Marcellus Shale: Feasibility Study for Fracture Characterization
From Summary: Recent interest in the Marcellus shale play in Pennsylvania, USA, is growing rapidly. An orthogonal set of fractures could play an important role to define optimal gas production. In this study we investigate the feasibility of measuring azimuthal anisotropy from a 3D-3C dataset. If the anisotropy exhibits an orthorhombic symmetry, fracture characterization of two principal crack densities, an infill fluid factor and isotropic background velocity is possible by inversion of NMO ellipses and zero-offset traveltimes of P-waves and the two split S-waves... see full text.
- Using Simulations and Virtual Worlds for Success in the Marcellus
From Abstract: The goal is to talk about the realities of how people learn and apply what they are learning to a complex, rapidly evolving field; namely, resource plays (and the Marcellus), where success depends on how rapidly and accurately continuous knowledge development and transfer can take place. ... see full abstract.
- Isotope reversals and rollovers: The last gasp of shale gas?
From Abstract: ...During studies of unconventional gas accumulations in strata of Silurian and Ordovician age in the northern Appalachian basin we have observed several types of reversals of stable isotopic compositions and rollover of the isotopic composition of ethane with decreasing wetness and with increasing depth. The gases were generated from organic carbon-rich mudrocks in the Ordovician Utica Formation, a potential shale gas reservoir. We developed a model... see full abstract.
- Methane Contamination of Drinking Water Accompanying Gas-well Drilling and Hydraulic Fracturing
This article investigates methane concentrations in well drinking water in the extent of the Marcellus Shale formation. It looks at whether increased methane concentrations are observed within 1 kilometer of a shale-gas well. Higher well water methane concentrations were found in these active gas extraction areas less than 1 km from one or more gas wells. The source of the methane was investigated. The presence of ethane and other higher-chain hydrocarbons as well as the δ13C-CH4 data and δ2H-CH4 data indicate a deeper thermogenic methane source (where the methane was formed by heat and pressure deep in the crust). The putative source comes from a rock formation aged Middle Devonian or older. The well water was tested for deep formation brine contamination but no signs of contamination were found. The authors call for more research and monitoring of water wells to be done to establish a data baseline for the region that will help with monitoring changes or contamination in the future.
- Will Natural Gas Fuel America in the 21st Century?
The author describes the US energy system and the percent of total energy produced by the various fossil fuels and renewable resources. He goes on to describe the main usage of each main energy source in the US. The Author remarks on the unpredictability of the natural gas market which he claims is due to the yearly 30% decline of gas production at each well. He shows the price fluctuations from the past 20 years as well as showing the average annual gas production per well versus the total number of producing wells and the total annual gas production versus the number of new wells drilled. Using these numbers the author claims that the EIA¿s forecast for gas production in the coming years is exaggerated and that it is unlikely to be able to consistently produce the amount of gas needed to replace coal with gas as the main source of electrical generation. The author compares gas versus coal for electrical generation and pushes to replace current coal plants with more efficient ones in addition to making sure that these fossil fuels are used where they will be most efficient and effective.
- Agriculture and Natural Gas
The author discusses the use of natural gas in the agriculture industry, remarking that most gas used in farming is consumed off-site to make nitrogen fertilizer. The use of nitrogen fertilizer in farming has increased in the past 50 years to increase grain production. Also, more nitrogen fertilizer is being imported as opposed to being produced in the United States, causing the environmental burden of drilling and refinement to fall on others. The author states that the use of nitrogen fertilizer depletes the natural nitrogen retention ability of soils, leading to more and continued dependency on fertilizer inputs. The article calls for a reduction in synthetic fertilizer use. While many state that reducing fertilizer use will lower grain production, possibly increasing the risk of mass starvation, the author points to studies that show reduced fertilizer use, in conjunction with more efficient farming techniques, could not only maintain current grain levels but could even increase grain production. This is a supplementary article to the Post Carbon Institute Hughes report, "Will Natural Gas Fuel America in the 21st Century?".
- Problems and Opportunities with Natural Gas as a Transportation Fuel
The authors discuss the issue of using natural gas as a transportation fuel, stating that the proposed plan of using liquefied natural gas (LNG) as an internal combustion fuel is the least energy efficient. They compare the efficiency of using LNG as a fuel source to the efficiency of an electric system powered by natural gas generated electricity. The combustion system has an efficiency of about 20 percent while the electric system has an efficiency of about 30-35 percent. They also comment that using natural gas to continue an internal combustion dependency will only hurt the economy in the long run. This is a supplementary article to the Post Carbon Institute Hughes report, "Will Natural Gas Fuel America in the 21st Century?".
- Public Health Concerns of Shale Gas Production
The authors highlight some of the practices and processes of shale gas drilling that might pose a health risk. Not enough research has been done on all aspects of shale gas drilling to know the exact health risks but the authors claim that enough is known to raise a high level of concern for individual and community health. The authors call for drilling to be slowed or stopped to allow adequate research to improve our understanding of the health implications of shale gas drilling. This is a supplementary article to the Post Carbon Institute Hughes report, "Will Natural Gas Fuel America in the 21st Century?".
- The economic impact of shale gas extraction: A review of existing studies
This review article on economic impacts from shale gas production examines three recently published reports resulting from joint academic institution and industry affiliation (Considine, 2009, Considine, 2010, and the Center for Business and Economic Research of the University of Arkansas, 2008) as well as a selection of recent non-academic-affiliated reports. The author expresses the need to provide critical peer review of these otherwise uncritiqued reports. This article also addresses the more general methodology of defining economic impact and raises the issue of whether or not to impose a severance tax on gas extraction.
- Chemical analysis of major constituents and trace contaminants of rock salt
From the Executive Summary: The main purpose of this study is to analyze various rock salt sources to determine the existing composition of rock salt. The results will then be compared to the chemical composition of the salt produced from Shale Gas Extraction Wastewater (SGEW) evaporation. Naturally occurring rock salt was formed from the evaporation of inland seas. Its primary constituents are sodium, chloride, calcium, magnesium, potassium, and sulfate. Rock salt generally contains between 90 to 98% sodium chloride. The salt content in SGEW may exceed 200,000 mg/l or approximately 7 times saltier than sea water.
- Experimental Gas Extraction by Rock Crushing: Evidence for Preservation of Methane in Core Samples from the Mudstones of the Eagle Ford Formation
From Abstract: Accurately determining oil-in-place (OIP) and gas-in-place (GIP) is critical for evaluating shale oil and gas plays. Methane is typically stored in nano-size pores in low permeability mudstones, but many of these hydrocarbon-saturated pores may isolate from surrounding mineral matrix. A rock crushing experiment has been devised to test for the presence of gas and condensate in isolated nanopores... see full abstract.
- Characterization of Gas Generated by Sequential Hydrous Pyrolysis of Potential Gas-Prone Source Rocks for Tight-Gas Reservoirs in the Rocky Mountain Area
From Abstract: The source of unconventional gas in tight-gas reservoirs of the Rocky Mountain area is uncertain, but possible Cretaceous gas-prone source rocks include the Cameo coal zone, Mowry, Mancos, and Baxter/Hilliard Shales. Hydrous pyrolysis experiments were conducted on immature samples of these source rocks to characterize their generated gases and evaluate their potential as sources for gas accumulations in the Green River and Piceance Basins... see full abstract.
- Mapping the Production Characteristics of the Haynesville Shale with a Well-Log Derived High-Density Stratigraphic Framework
From Abstract: Detailed stratigraphic correlations were made in the Upper Jurassic interval of Western Louisiana and East Texas on approximately 1000 digital logs from wells that penetrate the section. The primary geophysical log used for identification of bounding surfaces was the GammaRay. Other geophysical logs used to support the interpretations were the Deep-Induction and Spontaneous Potential... see full abstract.
- USGS Assessment of Undiscovered Shale Gas Resources in the Lower Cretaceous Pearsall Formation, Maverick Basin, South Texas
From Abstract: The U.S. Geological Survey (USGS) completed a geologic assessment of technically recoverable undiscovered shale gas resources in the Lower Cretaceous Pearsall Formation in the Maverick Basin, south Texas, following established USGS methodologies for the assessment of unconventional hydrocarbon accumulations. This work was part of a comprehensive assessment of undiscovered hydrocarbon resources in Mesozoic strata underlying the U.S. Gulf of Mexico Coastal Plain and State waters... see full abstract.
- Preparing for and Handling Common Complaints by Private Water Well Owners Related to Coal Bed Methane, Shale Gas and Other Unconventional Development Programs
From Abstract: A major public concern with unconventional oil and gas development occurring today is the potential impact to ground water or private well owners. When development occurs in a populated rural area, it’s not long before the operators and regulators are hit with complaints from private water well owners suspecting that their water well is impacted from nearby development activities. The current public fear about hydrofracturing practices is unwarranted and should be easily defended... see full abstract.
- USGS Definition of a Greater Gulf Basin Lower Cretaceous and Upper Cretaceous Lower Cenomanian Shale Gas Assessment Unit, Gulf Coastal Plain and State Waters, USA
From Abstract: An assessment unit (AU) for undiscovered continuous shale gas in Lower Cretaceous Aptian and Albian, and Upper Cretaceous lower Cenomanian fine-grained clastic rocks in the Gulf of Mexico coastal plain was recently defined by the U.S. Geological Survey (USGS). The AU is part of the Upper Jurassic-Cretaceous-Tertiary Composite Total Petroleum System (TPS) of the Gulf of Mexico Basin. This work was conducted as part of the USGS assessment of Jurassic and Cretaceous stratigraphic intervals in 2010... see full abstract.
- Examination of the Elvins Shale Gas Assessment Unit of the Reelfoot Rift for Undiscovered Oil and Gas Resources, Missouri and Arkansas, USA
From Abstract: The U. S. Geological Survey (USGS) recently concluded an assessment of the undiscovered, technically recoverable, oil and natural gas resources of Arkoma Basin Province and related geological areas. One of these areas is the Reelfoot Rift of southeastern Missouri and northeastern Arkansas. Within this rift zone is a thick section of Cambrian Elvins shale, which is defined by two northeast trending normal fault zones that expand the Cambrian section... see full abstract.
- Deciphering Depositional Controls on Shale - Gas Reservoir Distribution and Resource Density Using Detailed Sedimentology and Sequence Stratigraphy
From Abstract: Detailed examination of a wide range of physical, biogenic, and chemical attributes indicates that shale reservoirs such as the Barnett, Marcellus, Haynesville, Eagle Ford, Bakken, etc., accumulated discontinuously in intra-shelf basins in various depositional environments with significant changes in primary biogenic production, bottom-energy and oxygen levels, and sediment accumulation modes and rates. Rock properties that influence reservoir behavior vary in systematic ways that can be deciphered using an integrated sequence-stratigraphic approach... see full abstract.
- Tight Gas Sands and Natural Fractures in the Cretaceous Mesaverde Group, Greater Natural Buttes Field, Uinta Basin, Utah
From Abstract: Greater Natural Buttes field (GNB) in the Uinta Basin is the largest gas field in Utah. GNB lies in an area of gentle northwest dip on the southern flank of the basin. The field produces natural gas primarily from low-permeability sandstone in the Mesaverde Group and the Tertiary Wasatch Formation. GNB has produced over 2.1 TCF of gas from about 3,950 wells and continues to be the most active drilling area in Utah... see full abstract.
- Developing Water Budgets for Unconventional Oil and Gas Production: A Study in the Williston Basin, Montana and North Dakota
From Abstract: ...U.S. Geological Survey (USGS) scientists are developing water budget methods for oil and gas production on a regional scale. USGS oil and gas assessments provide estimates of technically recoverable resources and facilitate the determination of future hydrocarbon production scenarios. We extend these results to include volume estimates for the water involved. The Williston Basin in Montana and North Dakota is the area of our initial focus... see full abstract.
- Primary Depositional Controls on Shale Gas/Shale Oil Potential in the U.S.: A Global Sequence Stratigraphic Perspective
From Abstract:... An increasing focus for US unconventional hydrocarbon companies is to ascertain better well locations in the pre-drill phase, with the aim of reducing the number of low-value wells drilled, and increasing the commerciality of any campaign. This can only be achieved through improved understanding of the subsurface regional geology and stratigraphic context. The application of our biostratigraphically calibrated, global, 3rd-order sequence stratigraphic Earth Model to these shale gas/shale oil horizons... see full abstract.
- Petrographic Recognition of Artificially Induced Microfractures Versus Natural Microfractures in Oil/Gas Shales
From Abstract: Thin section observations of most open microfractures in organic-rich shales/limestones indicate they are artificially created by a variety of processes which are listed below along with their general morphology. Bit-created petal fractures are high angle, straight and slightly diffuse. Microfractures created during coring and gas expansion as the core is lifted to the surface are bedding parallel, occasionally discontinuous, branching and have even walls... see full abstract.
- Sequence Stratigraphic Control on Lateral Placement in the Marcellus Shale, Appalachian Basin
From Abstract: Placement of a lateral in the Marcellus shale necessitates consideration of two properties of the reservoir: location of the hydrocarbon within the reservoir, and pre- and post stimulation deliverability of the formation. Core calibrated petrophysical analysis of Marcellus logs is conducted to determine total organic carbon (TOC) content, gas-filled porosity, clay volume, and both free and adsorbed gasin-place volumes... see full abstract.
- Integrated Sedimentary, Geochemical, and Geomechanical Evaluation of the Mancos Shale, Uinta Basin, Utah
From Abstract: The Mancos Shale is a clastically-influenced shallow marine deposit that demonstrates potential for shale gas production in the Uinta Basin, Utah. A detailed understanding of vertical and lateral lithologic and geochemical heterogeneity and its predictability are lacking, yet are necessary for delineating prospective development targets. It has proved difficult to link prospective geologic characteristics to engineering success in many shale gas plays. Here, we have conducted an integrated sedimentary, geochemical and geomechanical study on one Mancos core in order to identify geologic predictors of geomechanical properties that are favorable from an engineering standpoint... see full abstract.
- Development of Mechanically Layered Haynesville-Bossier Shale-Gas Play
From Abstract: The Haynesville shale is characterized by high TOC, good porosity, high gas saturation, low clay content and nano Darcy permeabilities, all which makes for an exceptional shale gas reservoir. However, recent well IP's have been variable, and given the planned extensive development, it is necessary to de-risk some of the geologic variables to up-grade acreage and optimize well development plans. This was done through a two-part study covering the greater Sabine area... see full abstract.
- Hydrocarbon Phase Prediction in Unconventional Resource Plays Using Geochemical and PVT Data
From Abstract: The economic viability of an unconventional resource play can be very dependent on the hydrocarbon phase produced. For example, the lack of robust price support for gas plays in 2010 has made unconventional oil plays become more economically attractive. Various geochemical parameters from both sediments and fluids can be used to understand and even predict the hydrocarbon phase and associated production levels for any given play... see full abstract.
- The Future of Natural Gas
From Abstract: The history of global energy use through the 160 years of the western industrial revolution shows a progression of fuel substitution, with one resource being partly or largely displaced by a more efficient, versatile and generally cheaper source. If trends in carbon reduction and hydrogen increase continue, methane should constitute the dominant fuel in the global energy mix, representing a long-term bridge to a non-fossil, probably hydrogen economy. Is this likely? Probably, but not without the substantial uncertainties attendant to any major transition... see full abstract.
- Petroleum Potential of the Upper Three Forks Formation, Williston Basin, USA
From Abstract: The upper Three Forks is evolving into a significant resource play in the Williston Basin. Although Three Forks production was established in Antelope Field in 1953, the play has re-emerged because of the horizontal drilling and multi-stage fracturing technologies. The upper Three Forks can be subdivided into three main facies... see full abstract.
- The Economic Impact of Marcellus Shale Gas Drilling What Have We Learned? What are the Limitations?
The author points out the strengths and weaknesses of an input-output analysis model for quantifying economic impact from the Marcellus shale. The author reviews selected existing economic studies and discusses key assumptions that could contribute to model inaccuracies. According to the author, many important economic variables needed to complete an accurate model, such as drilling pace over time and locals' spending habits, have not been adequately researched. More information must be included to accurately characterize economic models. More research is needed on the economic trends and variables for the Marcellus shale.
- Analysis of Delaware River Basin Commission Proposed (Article 7) Natural Gas Development Regulations
From Introduction: The project review responsibilities of the Delaware River Basin Commission (DRBC) extend to projects having a substantial effect on the water resources of the Delaware River Basin (Basin). The recent proposed Article 7 regulations seek to expand the project review function of the Commission to include natural gas regulation. In order to better understand this expansion of regulatory authority, an independent review... See Full Text
- A Comparative Study of the Mississippian Barnett Shale, Fort Worth Basin, and Devonian Marcellus Shale, Appalachian Basin
From Executive Summary: This present study compares and contrasts critical geological characteristics of the Barnett and Marcellus Shales and successful engineering practices used in drilling and stimulation. Specific topics include stratigraphy,structure, and lithofacies; organic carbon content, thermal maturity, and reservoir characteristics; fracture stimulation, horizontal drilling, and well performance. With this knowledge, producers in both regions should better understand the controls on gas volumes and distribution, those reservoir properties that influence gas production, and how drilling and stimulation techniques can be more effective in the future... See full Summary
- Quantitative Assessment of Shale Gas Potential Based on Its Special Generation and Accumulation Processes
From Abstract: In our recent work a new mechanism of shale gas generation was recognized, that is a Fischer-Tropsch-type synthesis of hydrocarbon from CO2 and H2 resulting from the water-reforming of residual organic matter in shale... see full abstract.
- The Importance of Subcritical Index for Determining Fracture Spacing in the New Albany Shale, Illinois Basin
From Abstract: Production of gas from the New Albany Shale in southern Indiana and western Kentucky, where gas is mostly thermogenic, is partly dependent on understanding how the natural fracture system interacts with hydraulic fracture treatments. A key component of this interaction is natural fracture spacing, which includes the distance between individual fractures as well as the spacing between clusters or swarms of fractures. Static analysis of the stress field around opening-mode fractures suggests that fractures should be regularly spaced at an interval approximately equal to bed thickness... see full abstract.
- Recognition of Mudrock Types from Integration and Upscaling of Geologic, Petrophysical and Geochemical Data Examples from Haynesville, Woodford and Marcellus Shales
From Abstract: Integrated petrologic analyses are used to develop a proprietary gas shale classification that captures the textural and compositional variability of shales and provides a scheme to more precisely recognize shale types and their associated petrophysical parameters. The classification incorporates two components: 1) the lithology based on bulk composition as determined by X-ray diffraction (XRD) analyses, and 2) microfabrics recognized by thin section petrography... see full abstract.
- Estimation of Gas Volumes in Shales Gas: Kinetic and Isotope Modeling for Methane and Ethane Generation
From Abstract: The aim of the present study is to elaborate a compositional kinetic model predicting the different thermal cracking reactions occurring in source rock for methane and ethane generation. Then, these main reactions will be coupled to an isotope model to predict the 13C signature of methane and ethane in natural conditions with increasing thermal maturity from Ro at 0.5 to 4.0%... see full abstract.
- An Integrated Geochemistry and Basin Modeling Study of the Bakken Formation, Williston Basin, USA
From Abstract: ...The geochemistry of Bakken oils has been investigated to gain insight into processes controlling petroleum distribution within the Bakken petroleum system. Initial results indicate petroleum migration is a significant process. The oils being produced from the middle member of the Bakken are derived from the Bakken shale. From oil biomarker data, variable source rock facies are interpreted. Basin modeling was performed to constrain petroleum generation and migration timing... see full abstract.
- An Overview of Some Key Factors Controlling Well Productivity in Core Areas of the Appalachian Basin Marcellus Shale Play
From Abstract: ...Two major cores areas have developed in the 500-mi long, southwest-northeast trending Marcellus Shale play fairway. The two core areas display unique combinations of controlling geologic factors. Thickness, organic content, intra-organic matter porosity, overpressure, and maturity are some of the key Marcellus gas productivity factors... see full abstract.
- Potential Paleozoic Shale Gas Resources in Utah
From Abstract: Paleozoic shales in Utah have tremendous untapped gas potential. These include the Mississippian/Pennsylvanian Manning Canyon Shale and Pennsylvanian Paradox Formation of central and southeastern Utah, respectively. Shale beds within these formations are widespread, thick, buried deep enough to generate dry gas, and sufficiently rich in organic material and fractures to hold significant recoverable gas reserves... see full abstract.
- Are Rescaled Decline Curves a Solution for Shale Gas Assessment?
From Abstract: The intent of this study has been to find a reliable way to predict ultimate recoveries as soon as possible after the start of production in unconventional gas wells. In order to create single decline curves that combine many wells, our approach has been to rescale the data by using the logarithm of the cumulative production instead of the traditional production parameter (Mcf or Bcf)... see full abstract.
- A Global Perspective on LNG [Liquid Natural Gas]
From Abstract: The first commercial supply contracts over LNG supply were signed in the early 1960s between Algeria and the United Kingdom and France (Atlantic market). The United States started shipping LNG from Alaska to Japan in 1969, establishing the Pacific market. By the end of 1970s new liquefaction capacity was installed in... see full abstract.
- Sedimentological and Sequence Stratigraphic Analysis of the Marcellus Formation and Associated Strata
From Abstract: This study uses approximately 1000 wireline well logs from across Pennsylvania and 8 cores in Central PA to construct a depositional model of the Middle Devonian Marcellus Formation and associated strata. Although previous studies invoked tectonic forces to explain shifts in black shale deposition, we conclude that facies shifts in the proximal to medial portions of the basin are due to eustatic sea level fluctuations... see full abstract.
- A New, Systematic Approach to Achieve Effective Completions in Unconventional Reservoirs
From Abstract: Recent technical papers have highlighted the difficulty of achieving efficient completions in horizontal wells. Although every stage of a horizontal unconventional well was fracture treated, many of the clusters completed in these wells were unproductive, as demonstrated by production logs through these intervals. The economics of a well is negatively affected when a large number of stimulation clusters will not produce. Some data analysis that could preclude unnecessary or unproductive intervals would be useful... see full abstract.
- Observations of Low Frequency, Long Duration Events in a Microseismic Dataset Recorded in a Horizontal Shale Gas Well
From Abstract: We investigate two classes of unusual events of long duration and relatively low frequencies observed during hydraulic fracturing operations in a gas shale reservoir. Multiple stages of hydraulic fracturing operations in five sub-parallel wells were monitored with an array of seismometers deployed in the central horizontal well. When this well was fractured, the array was deployed in a vertical well... see full abstract.
- Primary Controls on Organic Carbon Content in UK Upper Mississippian Gas Shales
From Abstract: ...This study investigates the biological influences on the quality of mudstones as a source and reservoir of shale gas. In detail, the objectives are to: (1) interpret different lithofacies in terms of sedimentary processes and changing local environment; (2) investigate the distribution and abundance of organic matter in relation to lithofacies and determine their potential for gas generation; (3) link palaeoenvironments to larger scale climate change and carbon cycle events; and finally (4) develop a predictive model relating biological input to shale gas prospectivity... see full abstract.
- Power and Limitations of X-ray Fluorescence from Cuttings, a Test in the Utica and Lorraine Shales from Quebec
From Abstract: Shale gas exploration in the Quebec Lowlands is in full swing. The present main target is a roughly 200-m-thick Utica Shale (carbonate-rich); a potential target for the future is the overlying Lorraine Shale, which can exceed 2500 meters in thickness. Both shale units are laterally extensive. Whereas the stratigraphy of the Utica is well understood, log analyses of the Lorraine have failed to provide any stratigraphic framework, as the gamma ray is relatively featureless in every well... see full abstract.
- The Geochemistry of Montney and Lower Doig Tight Gas Reservoir, Northeastern British Columbia, Western Canada
From Abstract: Triassic Montney and Lower Doig strata in northeastern British Columbia and northwestern Alberta host substantial volumes of unconventional gas (est. 326.7 TCF). Despite the economic significance of these intervals the location and predictability of the best reservoir units remains conjectural: in large part because the lithologic variability, mineralogy, geochemistry and reservoir parameters of this succession has not been adequately characterized. This study aims to propose mechanisms of porosity / permeability development and preservation by establishing a petrogenetic framework for known reservoir intervals... see full abstract.
- Burial and Thermal History of the Haynesville Shale: Implications for Gas Generation, Overpressure, and Natural Hydrofracture
From Abstract: The Haynesville Shale is a thin organic rich sedimentary rock found in Northwest Louisiana, Eastern Texas, and Southwest Arkansas. It was deposited during the Late Jurassic in a shallow marine environment. The Haynesville Shale is typically found at depths of 3 km (10,000 ft) or more and is characterized by ultra low permeability. Nunn et al. (1984) showed that subsidence of the Northern Gulf Coast is consistent with crustal extension by a factor of 1.5 to 2 during Late Triassic to Early Jurassic... see full abstract.
- Natural Gas Resources, Reserves and Production: Unconventional, Less - Conventional and Conventional
From Abstract: The Natural Gas Year-In-Review 2009 (U.S. Energy Information Administration, July 2010) highlights six recent developments in the U.S. natural gas industry, several of which established all-time records:
Gas consumption fell 2% from 2008, to 62.6 Bcf/day;
Net imports recorded a 15-year low of 2,677 Bcf;
Natural gas storage reached 3,833 Bcf, the highest on record... see full abstract.
- Natural Gas Supply: Not as Great or as Inexpensive as Commonly Believed
From Abstract: It is widely believed that shale plays will provide an abundant and inexpensive supply of natural gas that can also be produced at a great profit to operators. While shale gas has added significantly to U.S. supply, the plays are marginally commercial at best, and the resources and reserves are considerably less than commonly believed. Shale plays will probably add 7-10 years of supply, but much of that will be non-commercial unless gas prices increase dramatically... see full abstract.
- Deformation in the Appalachian Foreland: Detachment Structures in the Basal Marcellus Shale, Central New York
From Abstract: Deformation in the basal Marcellus Subgroup (Union Springs, Cherry Valley and Oatka Creek Formations) is of interest to developers of gas resources in the Appalachian foreland of New York and Pennsylvania. Road cut and quarry exposures in a 180-km along-strike zone in the Marcellus outcrop belt document a recurrent pattern of north -directed overthrusting. These detachment structures are present in areas lacking subsurface Silurian salt... see full abstract.
- Fracture Permeability of Shale: Effects of Roughness, Fracture Offset, Proppant, and Confining Pressure
From Abstract: Domestic gas shale production is made economic through new completion practices which include horizontal wells and multiple hydraulic fractures. The performance of these fractures is improved through the injection of proppant. Success has largely been based on empiricism through field experiments. The attempt here to remove some uncertainty in this empiricism through a series of laboratory controlled experiments... see full abstract.
- Field Characterization and Analog Modeling of Natural Fractures in the Woodford Shale
From Abstract: Understanding the mechanisms under which shales deform is fundamental to improving exploration success in unconventional resource plays. Several outcrops of the Woodford Shale have been chosen to characterize fracture patterns at the outcrop level, and relate them to the structural regime of the study area and internal stratigraphy of the formation... see full abstract.
- My Source Rock Is Now My Shale-Gas Reservoir -- Characterization of Organic-Rich Rocks
From Abstract: Oil-prone source rocks comprise sediments that are rich in organic carbon and contain organic material sufficiently hydrogen rich to convert mainly to oil during thermal maturation. The organic materials that are generally the richest in hydrogen include marine plankton, freshwater algae, spores, pollen, leaf cuticle, tree resin, and anaerobic bacteria. All of these materials are initially oil prone and are classified as Type I or II kerogen... see full abstract.
- Pore Types in the Barnett and Woodford Gas Shales: Contribution to Understanding Gas Storage and Migration Pathways in Fine-Grained Rocks
From Abstract: The identification of “organoporosity” (microscale and nanoscale pores within organic matter in shales), its importance to storage and perhaps transfer of gas molecules through shales, and methods for gathering three-dimensional images of the pores, such as by argon-ion milling and/or field emission scanning electron microscopy, have all been well documented and discussed for unconventional gas shales. However, other types of pores exist within shales that can be important to storage and migration of gas (and oil), and other technologies are available for their identification and imaging. The different pore types found in the Barnett and Woodford shales are described and classified in this article... see full abstract.
- Gas Generation Reactions in Highly Mature Gas Shales
From Abstract: ...As part of the European GASH project (GAs SHales) coordinated by the GFZ-Potsdam, organic-rich calcareous mudstone samples from Northern Germany at varying stages of thermal maturation have been characterized using an original combination of compositional organic geochemistry and spectromicroscopy techniques, including synchrotron-based STXM (scanning transmission X-ray microscopy) allowing in situ imaging of organic-rich samples with a chemical based contrast at a 25-nm spatial resolution while providing spatially-resolved information of organic constituent speciation...see full abstract.
- Unconventional (Shale Oil or Gas) Petroleum Systems of the Eastern Canadian Paleozoic Sedimentary Basins: Effects of Organic Facies, Organic-Mineral Network, and Maturation
From Abstract: The unconventional (oil and gas shale) petroleum systems of the Eastern Canadian Paleozoic Sedimentary Basins includes the Devonian-Ordovician marine black shale sequences from Ontario; Lower/Upper Ordovician marine Green Point and Utica Group sediments from Newfoundland and Quebec, and the Mississippian (Tournaisian and Visean - lacustrine and marine) or Pennsylvanian (Bashkirian - fluviodeltaic and lacustrine) organic rich shales from the Maritimes Basin (Western Newfoundland, Nova Scotia, and New Brunswick... see full abstract.
- Future of Microseismic Analysis -- Integration of Monitoring and Reservoir Simulation
From Abstract: Monitoring of microseismic events induced by reservoir stimulation has become a key aspect in evaluation of hydraulic fractures and their optimization. Future developments of this technology are dependent on improvements in multiple discipline areas, two of which are discussed in this study: better quantification of event locations along with the velocity model, and improved understanding and calibration of the type of rock failure responsible for the seismic events... see full abstract.
- Compositional and Textural Variability of Shales as Hindrance to Understanding Shale Fracturing
From Abstract: ...Shale fracturing is poorly understood, largely because the term “shale” includes polymineralic rocks of different compositions and textures and whose major components (clays, quartz, carbonates, feldspars, and organic matter) have different mechanical properties. If one accepts the premise that each shale reservoir has unique mechanical facies, then it follows that use of the unqualified term “shale” hinders progress in understanding shale fracturing... see full abstract.
- Natural Fractures in Shales: Timing, Sealing, Mechanisms of Formation, and Relevance for Shale-Gas Reservoirs
From Abstract: Natural fracture systems are important for production in shale-gas reservoirs in two ways. They may reactivate during hydraulic fracture treatments or they may be partly open, contributing to permeability without reactivation. Degree of openness and fracture plane strength are related in part to the specific structural-diagenetic history of each fracture set and shale host rock. Several possible mechanisms control fracture formation... see full abstract.
- The Role of Strain in Controlling Orientation of Natural Hydraulic Fractures in Gas Shales
From abstract: Horizontal, bedding-parallel veins constitute the most common fracture type displayed in core and in borehole images from the Jurassic Haynesville gas shale of Louisiana. Vertical joints and veins are more common in both outcrops and core from the Middle Devonian Marcellus gas shale of the northern Appalachian Basin. Differences between the orientation of mesoscopic cracks populations in the Haynesville and Marcellus begs a hypothesis based on the premise that crack orientation is controlled by stress state... see full abstract.
- A Preliminary Diagenetic and Paleomagnetic Study of the Fayetteville Shale, Arkansas
From Abstract: We are undertaking an integrated diagenetic and paleomagnetic study of outcrops of the Fayetteville Shale in Arkansas to determine the timing of diagenetic events and assess how diagenesis has affected the lithological variability in the unit. Preliminary petrographic analysis indicates that the carbonate beds sampled in the upper Fayetteville Shale range from micrite to microspar (25-40 μm)... see full abstract.
- Appalachian Basin Database for Devonian Gas Shales
From Abstract: The U.S. Geological Survey (USGS) in cooperation with the State Geological Surveys of Virginia, West Virginia, Kentucky, Ohio, Pennsylvania, and New York has prepared an organic geochemistry database for the Devonian shales of the Appalachian basin. The database consists of previously published data and new data from samples submitted by the states for analyses. In general, the samples are analyzed for percentage of total organic carbon (TOC), vitrinite reflectance (Ro), and Rock Eval... see full abstract.
- Produced Gas Composition Variations and Its Relationship to Sequence Stratigraphy and Structural Complexity of the Marcellus Shale
From Abstract: Gas composition data is an inexpensive dataset that can give insight into the depositional, structural, and thermal maturity history of an organic-rich shale reservoir when integrated with well log interpretation and mapping. At a regional scale, gas composition changes of produced gas samples strongly reflect the thermal maturation history of the shale... see full abstract.
- Carbon and Hydrogen Isotope Systematics in Gases from Horizontal Bakken Shale Wells
From Abstract: We report here composition and isotope data from horizontal Bakken shale wells in North Dakota that penetrated different sections of different maturities and found that ethane carbon isotopes in oil-dissolved gases are excellent predictors of maturity of the organic matter of the source rock kerogens, thus opening opportunities for assessing migration of oils and gases... see full abstract.
- Characterization of Unconventional Shale Gas Reservoirs Using a Shale Gas Facies Expert System to Identify Lithofacies and Optimal Completion Intervals
From Abstract: ...A shale gas facies expert system was developed with the goal of helping operators identify optimal zones for designing selective completion strategies. This can potentially reduce fracturing expenses and optimize well productivity. The expert system first chemostratigraphically characterizes the reservoir into different lithofacies based on their geochemical makeup obtained from geochemical logging measurements... see full abstract.
- Facies and Lithostratigraphy of the Upper Cretaceous (Turonian-Cenomanian) Eagle Ford Formation, Central and South Texas
From Abstract: ...To characterize facies, depositional processes, and system geometry of the Eagle Ford, we investigated more than 50 cores from 30 counties for depositional texture, sedimentary structure, and fossil assemblages. These studies were supported by light and electron microscopy, analysis of elemental chemistry and mineralogy, and determination of organ carbon distribution and thermal maturity... see full abstract.
- Undiscovered Petroleum Resources for the Woodford Shale and Thirteen Finger Limestone- Atoka Shale, Anadarko Basin
From Abstract: In 2010 the U.S. Geological Survey assessed undiscovered oil and gas resources for the Anadarko Basin province of Colorado, Kansas, Oklahoma, and Texas. The assessment included two continuous (unconventional) assessment units (AU): the Devonian Woodford Shale Gas AU, and the Pennsylvanian Thirteen Finger Limestone-Atoka Shale AU of the lower Atoka Group. Both AUs are mature for gas generation within the deep basin of Oklahoma and Texas... see full abstract.
- Dating Diagenetic Events in the Barnett and Marcellus Shale: Evidence from Paleomagnetic, Petrographic, and Geochemical Analysis
From Abstract: The Mississippian Barnett and Devonian Marcellus Shale are the source and reservoir for hydrocarbons. To understand the nature and timing of diagenetic events in these prominent gas shales, integrated paleomagnetic and diagenetic studies have been undertaken. A key focus of these studies is to test if orogenic fluids from the Appalachian-Ouachitas entered and altered these units... see full abstract.
- Evaluating the Gas Shale Potential of the Hilliard/ Baxter Formation in the Green River Basin, Wyoming
From Abstract: Several Paleozoic and Mesozoic petroleum systems exist in the Green River Basin (GRB). However, the source(s) of the dry gas produced from Upper Cretaceous (Lance) tight gas sands at the Pinedale and Jonah fields is uncertain. If the marine shales in the underlying Upper Cretaceous Hilliard/Baxter Formation generated and expelled a significant amount of that gas, this deeper stratigraphic unit also may be a prospective gas-shale resource... see full abstract.
- Fractures, Veins, Fluid Migration and Hydrocarbon Generation in the Utica Shale, Northern Appalachian Basin, New York
From Introduction: The Upper Ordovician Utica Formation is a widespread hydrocarbon source rock in the Appalachian Basin, and development of the Utica as a gas shale reservoir in Quebec demonstrates the potential of this unit in New York and Pennsylvania. Successful well stimulation of gas shale reservoirs is best carried out with an understanding of the orientation and character of natural fractures in the shale... see full introduction.
- The Downside of Using GR to Determine TOC Content: An Example from the Marcellus Shale in SE West Virginia
From Abstract: Two “core holes” (wells drilled to collect geologic and engineering data) were drilled recently in southeast West Virginia by Bluescape Resources Company. The wells...were drilled to help characterize the gas potential of the Marcellus Shale in Bluescape’s extensive acreage position in the area; the wells are located 17 miles apart. In total, 15 whole cores were collected from the gray-shale interval adjacent to the Marcellus, the Marcellus itself, and the underlying Onondaga and Huntersville formations. An extensive suite of wireline logs were run in each of these wells... see full abstract.
- Multi-scale, Brittle-Ductile Couplets in Unconventional Gas Shales: Merging Sequence Stratigraphy and Geomechanics
From Abstract: The words “ductile” and “brittle” have emerged as two key descriptors for characterizing unconventional gas shales. The former is usually considered to be relatively organic (TOC)- and clay-mineral rich, while the latter is considered to be more enriched in “silica” (i.e., biogenic and/or detrital quartz)- and/or carbonate (calcite/dolomite) minerals. Our studies of some gas shales have shown that such ductile and brittle rocks occur as alternating „couplets¿ at a variety of scales... see full abstract.
- Algal Cysts in the Marcellus Shale (Middle Devonian), Appalachian Basin: The Impact of Algal Blooms on Gas Shale Reservoirs
From Abstract: To confirm the existence of algal blooms during deposition of Marcellus shale and its impact on gas shale reservoir properties, more than 40 Marcellus cores have been investigated over a large area of the Appalachian Basin in western Pennsylvania and West Virginia. Mineralized algal cysts (Tasmanites) are widespread throughout the Marcellus basin, and particularly abundant in the high gamma ray zone in the lower portion of the Union Springs Member... see full abstract.
- Integrated Reservoir Characterization of Barnett Shale Gas: Defining the Stratigraphic Influences on Production
From Abstract: Many factors related to completions and operations affect production from shale-gas reservoirs, and these parameters typically change from well to well. Similarly, shale property variations are observed at different scales: from basin to basin, within a basin, along a single wellbore or within a single core. Seldom are there attempts to correlate these stratigraphic variations to variations in gas production. We report here the results of analyses that show how variations in stratigraphic parameters (e.g., thickness and depositional facies) affect gas production from the Barnett Shale... see full abstract.
- A Petrophysical Model to Estimate Free Gas in Organic Shales
From Abstract: A method is presented whereby conventional open hole logs -density, neutron, Pe, GR, and resistivity - can be used to quantify the volume of free gas in organic shale. The calculations involve determining silt and clay mineral volumes in the shale fraction of the rock. Porosity associated with the clay minerals is subtracted from total porosity, and the difference remaining is silt porosity... see full abstract.
- Formation Evaluation of Barnett Shale by Kohonen Self Organizing Maps - An Example from North East Fort Worth Basin
From Abstract: Automatic seismic facies analysis aims to classify similar seismic traces based on amplitude, phase, frequency and other seismic attributes. This research shows how this technique helps in formation evaluation in the Barnett Shale... see full abstract.
- Fractures Interactions in Multistage Hydraulic Fracturing
From Abstract: Very low permeability of shale gas reservoirs has made multi-stage fracturing a promising solution for geologists to improve recovery factor and consequently production in the horizontal wells. Lacking a good understanding of the mechanisms involved in the multistage fracturing has left operators with trial and error approaches in designing fracture treatments. This research is mainly focused on understanding the mechanics of multi-stage fracturing... see full abstract.
- Microseismic Monitoring Reveals Natural Fracture Networks
From Abstract: Microseismic monitoring is used to visualize fracture growth during hydraulic fracture treatments. Naturally occurring fracture networks within the formation of interest, as well as direction of maximum horizontal stress, play significant roles in determining the way that these fractures propagate. Naturally occurring fracture networks may include large-scale faults... see full abstract.
- Chemostratigraphic Studies of the Marcellus Shale by Handheld X-ray Fluorescence (HHXRF) Analysis
From Abstract: Handheld X-ray fluorescence is a powerful tool for correlating rock geochemistry to stratigraphy. Chemostratigraphic techniques employ major, minor and trace element abundances and ratios to correlate elemental chemistry to mineralogy and rock properties. Trace metals (e.g. V, Cr, Ni, and Mo) have been shown to be proxies for total organic carbon (TOC) in mudrocks. A HHXRF equipped with a large area (25 mm2) silicon drift detector (SDD) was compared with independent laboratory results obtained by ICP-MS on 160 sedimentary rock samples of mixed lithology... see full abstract.
- Black Shale Diagenesis: Insights from Integrated High-Definition Analyses of Post-Mature Marcellus Formation Rocks, Northeastern Pennsylvania
From Abstract: Thermogenic shale-gas produced from the Marcellus Formation in northeastern Pennsylvania is post-mature. The reservoirs reached maximum burial temperatures characteristic of prehnite facies low-grade metamorphism. Although methane can be generated and remain stable under these conditions, this degree of burial diagenesis raises critical questions regarding metagenesis and reservoir quality... see full abstract.
- The Marcellus Shale Revealed with Full Azimuth 3D Multi-Component Seismic Data
From Summary: 3D seismic data will contribute significantly to the understanding of the Marcellus. Geophysical analysis/evaluation, although in the early stages, looks very promising for optimizing well locations... see full presentation.
- Predicting Hydraulically Induced Fractures Using Acoustic Impedance Inversion Volumes: A Barnett Shale Formation Example
From Abstract: Once considered only as source rocks and seals, shale formations are now also considered as tight-porosity and low-permeability unconventional gas reservoirs. The classification as a reservoir is mainly technology- and economics-driven. Major gas (and minor oil) production from these plays is facilitated by massive hydraulic fracturing treatments that increase permeability and help to reactivate natural fractures... see full abstract.
- Hydraulic Fracture and Natural Fracture Simulation for Improved Shale Gas Development
From Abstract: This paper describes a discrete fracture approach for assessment and exploitation of unconventional gas plays. The strategy depends on the evaluation of a localized, well trajectory specific tributary drainage volume, which considers the combined effect of hydraulic and natural fractures... see full abstract.
- Predicting Fracability in Shale Reservoirs
From Abstract: ...To address the behavior of shale reservoirs, we integrate qualitative and quantitative data. These data include core and thin section descriptions, penetrometer and MRH readings, description of present-day stress field, using a stress-strength equilibrium stress polygon approach, which includes estimates of overburden stress, maximum horizontal stress, minimum horizontal stress, and direction of maximum horizontal stress... see full abstract.
- Overpressure in Shale Gas -- When Geochemistry and Engineering Data Meet and Agree
From Abstract: A multidisciplinary study has shed a new light on the process of overpressure in shale gas reservoirs. The work consisted of the integration of a large geochemical data set with hydraulic frac and reservoir pressure data from the same wells. Results from this integrated approach suggest that distinct pressure domains exist and that their specific depths and attributes can be easily determined... see full abstract.
- Economic Determinants of the Global Natural Gas Balance
From Abstract: Over the past two decades natural gas has become increasingly important in meeting global energy needs. Projected demand growth, largely for power generation, in the U.S., China, and Europe has highlighted the need to expand long distance gas transport capabilities and develop new supplies. The former development has promoted rapid expansion of global trade in natural gas, while the latter has manifested in dramatic expansion of production from unconventional resources, such as shale gas... see full abstract.
- The US Natural Gas Revolution: Technology Transforms a Market
From Abstract: The North American natural gas market has transformed over the last decade owing to the extreme growth in shale gas production. Shale gas will continue to exert a significant impact on U.S. and international markets, reducing the need for Canadian and LNG imports in the coming decade. The Marcellus Shale has the greatest potential to create significant market disruptions since natural gas production from the Appalachian Basin could increase by two or three times in the next five years... see full abstract.
- Impact of Regulation on the Power Sector: Opportunities for Natural Gas
From Abstract: ...We review key policies and regulations having an impact on the power sector, namely electricity prices, investments in new generating capacity, and choice of fuels. The analysis of command-and-control policies versus market-based instruments will be presented, with a discussion on the inefficiencies in policies’ formulations. The impact of fuel prices and expectations about future policies will also be explored... see full abstract.
- Shale Gas Prospectivity in South Australia
From Abstract: Shale gas exploration in Australia is in its infancy compared to the United States. In the US, exploration and development of shale gas plays has accelerated over the past decade, and shale gas now provides in excess of 2 TCF gas per annum to the US domestic gas market. In Australia, explorers are in the early stages of identifying shale gas play fairways within prospective basins, and much of the basic data required to assess prospectivity has not yet been acquired... see full abstract.
- Future Water Needs of the Oil and Gas Industry in Texas
From Abstract: The Barnett Shale gas play, located in North Texas, has seen a quick growth in the past decade with the development of new “frac” technologies able to create pathways to produce gas from the very low permeability shales. More plays such as the Haynesville, Woodford, and Eagle Ford are coming online at a steeper rate than the Barnett did. A typical horizontal well completion consumes more than 3 millions gallons of fresh water in a very short time (days)... see full abstract.
- Shale-Gas Production and Sequence Stratigraphy: What Makes the Best Part of the Best Plays?
From Abstract: Stratigraphic and sedimentologic analyses of productive and non-productive “shale-gas” units (e.g., Haynesville/Bossier, Barnett, Eagle Ford, Marcellus, Woodford, Muskwa, Lewis, Mancos) demonstrate that the best gas production is from thermally mature, pelagic-rich strata that can be assigned to the transgressive systems tract and condensed section (TST/CS). These rocks are relatively enriched in marine organic matter and biogenic silica and/or carbonate... see full abstract.
- Regional Stratigraphic and Rock Characteristics of Eagle Ford Shale in Its Play Area: Maverick Basin to East Texas Basin
From Abstract: The potential play area of the Upper Cretaceous Eagle Ford Shale (EFS) extends for at least 400 mi from the Texas-Mexico border northeastward to the East Texas Basin. Observations of the variations in lithostratigraphy, thickness, and depth trends of the EFS in this area provide a first approximation of potential producing areas... see full abstract.
- Observations of Pores in the Cretaceous Eagle Ford Shale, South Texas, USA
From Abstract: The Upper Cretaceous Eagle Ford Shale is an organic-rich, calcareous mudstone found in the Maverick Basin and adjoining areas of south Texas. The unit serves as a source, seal, and reservoir for hydrocarbon production. More than 30 core samples from 9 wells were examined using a field-emission scanning electron microscope. Samples were prepared using Ar-ion milling, a technique that provides a flat surface free of artifacts...see full abstract.
- New Insights Regarding Aquifers in the Uinta Basin, Utah: Implications for Saline Water Disposal
From Abstract: As Uinta Basin petroleum production has increased – natural gas alone increased 60% in the last 10 years – so has saline water production, increasing the need for economic and environmentally responsible disposal plans. Current water disposal wells are near capacity and permitting for new wells is delayed because of insufficient technical data regarding potential disposal aquifers and questions concerning contamination of fresh water sources... see full abstract.
- Geologic Framework of the Southeastern Portion of the U. Jurassic Haynesville/Bossier Shale Gas Play, Northwest Louisiana
From Abstract: The Upper Jurassic (Early Kimmeridgian) Haynesville and Bossier formations are composed of organic-rich, argillaceous to calcareous silty mudstones that were deposited on a broad, sediment-starved shelf with an average water depth of about 150-300 feet. The Hayneville averages 120 - 150’ thick and is approximately equal parts terriginous clay (from deltas), biogenic carbonates (forams and other fossil fragments), and silt grains (possibly of windblown origin). Prodelta clay from southward-advancing deltas causes the Haynesville section to thicken northward... see abstract.
- Merging sequence stratigraphy and geomechanics for unconventional gas shales
From Abstract: The recent revelation of vast global quantities of potentially gas- (and oil-) productive shales has paved the way for rapid advancements in understanding their geological properties, many of which affect their geomechanical properties, and ultimately reservoir operations and performance. Because of shale's unique and very intricate geological, physical and mechanical properties at all scales... see full abstract.
- Methane and the greenhouse-gas footprint of natural gas from shale formations
The authors claim that methane leaks, or methane fugitive emissions, are higher in unconventional gas drilling, such as shale gas drilling, than in conventional vertical gas drilling. The main difference in fugitive emission levels comes from the flowback and plug drilling stages of horizontal hydraulic fracturing drilling, the type of drilling most used in the shale gas region. The authors state that the greenhouse effect from fugitive CH4 emissions prevents natural gas from being a true "energy bridge" fuel, i.e., a fossil fuel of lower greenhouse impact that extends the nation's traditional energy supplies during a transition to cleaner, renewable energy sources. Methane has a relatively short residence time in the atmosphere but, according to the authors, in a time span of twenty years, methane from natural gas production has a 20% to 200% larger greenhouse effect than coal. The authors call for more research on methane's effects as a greenhouse gas and on fugitive emissions from both conventional and unconventional gas drilling.
- Strontium isotopic composition of flowback waters associated with Marcellus Shale natural gas extraction, Bradford County, Pennsylvania
This research in progress investigates whether salinity in Marcellus Shale flowback waters originates from the fracturing fluids or from the formation waters. Flowback waters from five hydraulically fractured Marcellus Shale gas wells in Bradford County, PA were tested for strontium (Sr) isotope composition. Two of the samples represent initial flowback fluids, and three represent waters that had been recycled multiple times as fracturing fluids. Results showed a Sr concentration range of 2.0-5.2 x 1000 mg/L. The highest observed isotopic ratios are surmised to be associated with Marcellus (± adjacent units) solids and brines. Results suggest that Marcellus shale flowback water, brine from the Upper Devonian Venango Group sands, and mine drainage from Pennsylvanian Allegheny and Monongahela Group coal seams fall into isotopically distinct clusters.
- Understanding Geophysical Responses of Shale-Gas Plays
- Microseismic hydraulic fracture imaging: The path toward optimizing shale gas production
- Changing Perceptions of United States Natural-Gas Resources as Shown by Successive U.S. Department of the Interior Assessments
From Abstract:Trends in four successive estimates of United States technically recoverable natural gas resources are examined in this report. The effective dates of these assessments were January 1 of 1975, 1980, 1987, and 1994... See Full Text
- Evaluation of variable gas saturation on acoustic log data from the Haynesville Shale gas play, NW Louisiana, USA
- Rock physics of organic shales
- Inversion and attribute-assisted hydraulically induced microseismic fracture characterization in the North Texas Barnett Shale
- A Comprehensive Economic Impact Analysis Of Natural Gas Extraction In The Marcellus Shale
From Summary: Thousands of short and long-term jobs will be created as natural gas drilling and hydrofracturing takes place in the Marcellus Shale, presenting both employment opportunities and workforce development challenges. These jobs – found primarily on crews needed during the drilling and completion process – are not for everyone and require a diverse skill set and a rigorous work ethic. In Pennsylvania, the industry has thus far relied on “out-of-town” workers to fill many of these hard-to-fill roles, but over time will replace a portion of these workers with local employees if they are available... see full text.
- Reservoir Engineering for Unconventional Reservoirs: What Do We Have to Consider?
From Abstract: ...We propose a workflow for the optimization of UGR [unconventional gas resources] field development to guide discussion of the reservoir engineer’s role in the process. Critical issues related to reservoir sample and log analysis, rate-transient and production data analysis, hydraulic and reservoir modeling and economic analysis are raised. Further, we have provided illustrations of each step of the workflow using tight gas examples. Our intent is to provide some guidance for best practices... see full abstract.
- Eagle Ford Shale Reservoir Properties from Digital Rock Physics
From Introduction:This presentation describes an integrated Digital Rock Physics (DRP) process for analyzing rock properties of shales and other unconventional reservoirs at multiple scales. The process begins with whole core and progresses to smaller plug size samples, then ultimately to very high resolution 3D imaging of the pore space... See Full Text
- A Critical Evaluation of Unconventional Gas Recovery from the Marcellus Shale, Northeastern United States
This article discusses the challenges facing natural gas production from Marcellus tight gas shale within the northeastern United States. Those challenges include prospecting, access by drilling, stimulation, and recovery. Prospecting takes into account the viability of the reservoir. Drilling compromises 50% of the cost of the well; horizontal drilling leads to larger productive zones and fewer costs. Stimulation and recovery methods improve gas yields and attempt to reduce environmental impacts. The author discusses those challenges involved in the recovery of gas and the Marcellus in particular.
- The Role of Isotopes in Monitoring Water Quality Impacts Associated with Shale Gas Drilling
Methane can be found in drinking water both naturally and also because of human activities, like the drilling of gas wells. Monitoring techniques using stable isotopes of carbon and hydrogen exist to help protect water well owners from contamination. Extensive and coordinated monitoring can be used in conjunction with careful data interpretation to understand the potential for methane contamination of drinking water. This report discusses monitoring and analysis techniques used in New York State to diagnose shale gas drilling contamination, while also noting limitations, uncertainties, and possible confounding factors. The language of the report, suitable for non-specialists, is technical but not complex.
- Analysis of Data From the Barnett Shale Using Conventional Statistical and Virtual Intelligence Techniques
A Barnett shale water-production data set from approximately 11,000 completions was analyzed using conventional statistical techniques. Additionally, a water/hydrocarbon ratio and first-derivative diagnostic-plot technique developed elsewhere for conventional reservoirs was extended to analyze Barnett shale water-production mechanisms. To determine hidden structure in well and production data, self-organizing maps and the k-means algorithm were used to identify clusters in data. A competitive-learning-based network was used to predict the potential for continuous water production from a new well, and a feed-forward neural network was used to predict average water production for wells drilled in Denton and Parker Counties, Texas, of the Barnett shale.
- Effects of development of a natural gas well and associated pipeline on the natural and scientific resources of the Fernow Experimental Forest
The motivation for this report is to provide much-needed published data on the effects of natural gas development on eastern forests, including information on erosion rates, sediment loading, soil and water chemistry, and vegetation loss. This report specifically documents the impacts of natural gas development on a single 1,900-hectare study site, the Fernow Experimental Forest, situated in the Monongahela National Forest, West Virgnia. The time period considered is 2007 (when work was approved) through 2009 (when the pipeline was fully completed). According to this report, some environmental impacts from land clearing and well and pipeline construction were predictable, whereas other impacts were not predicted. For instance, increased presence and activity of white-tailed deer was noted in disturbed areas (e.g., where the pit fluids were land-applied and on the well site in the area of the buried drill pit).
- Geologic Overview and Activity Update for the Utica-Point Pleasant Shale Play in Ohio
From Abstract: ... [Well] Leasing activity reached a fevered pitch in Ohio in 2010, and the first horizontal exploration wells were drilled and completed in the Utica-Point Pleasant in early 2011. Analysis of source rock geochemistry indicates the Utica-Point Pleasant to contain sufficient hydrocarbons to sustain a major drilling play. Oil-source rock pairings indicate the Utica-Point Pleasant has been the primary source for numerous conventional reservoirs in the region...see full abstract.
- A Thematic Analysis of Local Respondent's Perceptions of Barnett Shale Energy Development
From abstract: Researchers have found that the economic, social, and environmental impacts of energy development vary with both the type and location of development. Previous studies have highlighted impacts associated with the conventional energy development that occurred in the western United States in the 1970s and 1980s... see full text.
- Natural Gas Landowner Coalitions in New York State: Emerging Benefits of Collective Natural Resource Management
From abstract: Thousands of rural landowners in New York State have joined together to form grassroots organizations aimed at collectively bargaining with natural gas companies. The leverage afforded by acting collectively allows these landowner coalitions to potentially influence the economic, environmental, and community impacts of gas development across hundreds of thousands of acres... see full abstract
- Explaining Residential Energy Consumption: a Focus on Location and Race Differences in Natural Gas Use
From the abstract: Researchers have long considered factors related to residential energy consumption. We contribute to this genre of work by exploring how residential location (rural-urban) and race are related to residential natural gas consumption. We also consider whether these relationships, if they exist, are functions of differences in housing characteristics, investment in energy efficiency, and weather conditions. Analyzing four waves of the Residential Energy Consumption Surveys, we find that natural gas consumption differs by residential location only to the extent that investment in energy efficiency and weather conditions are not taken into consideration. We also find race differences in natural gas consumption, with African-Americans consuming more per year than whites. African-Americans’ higher natural gas consumption persists even after the effects of housing characteristics, investment in energy efficiency, weather conditions, and other critical covariates of energy consumption are statistically held constant. More work, especially field research, is needed to understand why African-Americans consume more natural gas than other groups.
- Resource and Environmental Studies on the Marcellus Shale
- A Thematic Analysis of Local Respondents' Perceptions of Barnett Shale Energy Development
From the abstract: Researchers have found that the economic, social, and environmental impacts of energy development vary with both the type and location of development. Previous studies have highlighted impacts associated with the conventional energy development that occurred in the western United States in the 1970s and 1980s, and with offshore oil drilling in the Gulf of Mexico. Recently, however, unconventional natural gas development has become a more common type of energy development, the impacts of which are not yet well understood. To assess these impacts, as part of a larger quantitative study conducted within two Texas counties, survey respondents were invited to share “additional comments” as desired. I analyzed these comments using open coding and constant comparison to identify prominent themes for each county. Themes ranged from positive to negative, and reflected economic, social, and environmental impacts accompanying unconventional natural gas development. Findings may inform theory and be of interest to community leaders and others interested in the impacts of unconventional gas development.
- Introduction: Special Issue on Social Issues Associated with Unconventional Natural Gas Development
- Constraining the timing of microbial methane generation in an organic-rich shale using noble gases, Illinois Basin, USA
At least 20% of the world's natural gas originates from methanogens subsisting on organic-rich coals and shales; however in-situ microbial methane production rates are unknown. Methanogens in the Upper Devonian New Albany Shale in the Illinois Basin extract hydrogen from low salinity formation water to form economic quantities of natural gas. Because of this association, constraining the source and timing of groundwater recharge will enable estimation of minimum in-situ metabolic rates. Thirty-four formation water and gas samples were analyzed for stable isotopes (oxygen and hydrogen), chloride, tritium, 14C, and noble gases. Chloride and δ18O spatial patterns reveal a plume of water with low salinity (0.7 to 2154 mM) and δ18O values (− 0.14 to − 7.25‰) penetrating ~ 1 km depth into evapo-concentrated brines parallel to terminal moraines of the Laurentide Ice Sheet, suggesting glacial mediated recharge. However, isotopic mixing trends indicate that the recharge endmember (~− 7‰ δ18O) is higher than the assumed bulk ice sheet value (<−15‰ δ18O), and similar to modern local precipitation (− 7.5 to − 4.5‰ δ18O). Continental paleoprecipitation records reveal that throughout the Pleistocene, δ18O of precipitation in the region ranged from − 10 to − 5‰, suggesting that the dilute groundwater was primarily sourced from paleoprecipitation with minor contributions from glacial meltwater.
- Maturity and Impedance Analysis of Organic-Rich Shales
Organic-rich shales (ORSs) need to be studied in detail to understand the provenance and the generation of hydrocarbons from source rocks. In recent years, ORSs have gained importance as hydrocarbon resources as well. Successful exploration and production programs for ORSs need reliable identification of their kerogen content as well as maturity through indirect seismic methods. However, the properties of kerogen are poorly understood, so predictions about maturity and rock-kerogen systems remain a challenge. Assessment of maturity from indirect measurements can be greatly enhanced by establishing and exploiting correlations between physical properties, microstructure, and kerogen content.
- Practices for Mitigating Surface Impacts Associated with Hydraulic Fracturing
- The depositional setting of the Marcellus black shale
- Boomtowns, Resource Dependence and Socio-economic Well-being
The issue of socio-economic well-being in resource-dependent communities has been one of ongoing interest for geographers, rural sociologists and economists. While much research focuses on the impacts of industry downturn and closure on well-being, this paper is focused on the implications of large-scale resource development and rapid growth in boomtowns. In contrast to a long tradition of research in other parts of the developed world, relatively few studies explicitly examine the relationship between resource reliance and socio-economic well-being in Australia's resource-dependent regions. Within the context of a nationwide resources boom, this paper presents an analysis of resource dependence and socio-economic well-being in the remote mining towns of Kalgoorlie-Boulder, Port Hedland and Karratha-Dampier in Western Australia.
- Marcellus Shale Gas Extraction; Public Health Impacts and Visualizations of Environmental Threats
- Measuring low permeabilities of gas-sands and shales using a pressure transmission technique
Liquid and gas permeability measurements for tight gas-sand and shales were done using a pressure transmission technique in specially designed apparatus in which confining pressure, pore pressure, and temperature are independently controlled. Downstream pressure changes were measured after increasing and maintaining upstream pressure constant. The initial pressure difference changes only after the pressure pulse propagates across the sample. For low permeability samples, the downstream pressure increase is delayed but the measurement senses a greater sample volume. On the other hand, conventional pulse decay techniques provide a more rapid response but are sensitive to local sample permeability heterogeneity. Permeability measured for the rocks studied varies from 1.18×10−15 to 3.95×10−21 m2
- Gas Shale Potential of Cambay Formation, Cambay Basin, India
From Abstract: Cambay Basin is an intracratonic rift graben located in the state of Gujarat, India. The general basinal axis is NNW-SSE, but swings are noticed across major lineaments/faults. The entire basin is divisible into five tectonic blocks, based on transverse fault system, and the associated depocenters are governed by rifted basement... see full abstract.
- Residents' Perceptions of Community and Environmental Impacts from Development of Natural Gas in the Marcellus Shale: A Comparison of Pennsylvania and New York Cases
From Abstract: Communities experiencing rapid growth due to energy development (‘boomtowns’) have reported positive and negative impacts on community and individual well-being. The perceptions of impacts vary according to stage of energy development as well as experience with extractive industries. Development of the Marcellus Shale provides an opportunity to examine these impacts over time and across geographic and historical contexts. This paper describes case study research in Pennsylvania and New York to document preliminary impacts of development occurring there... see full abstract.
- Pore-to-regional-scale Integrated Characterization Workflow for Unconventional Gas Shales
From Abstract: Based on recent studies of Barnett and Woodford gas shales in Texas and Oklahoma, a systematic characterization workflow has been developed that incorporates lithostratigraphy and sequence stratigraphy, geochemistry, petrophysics, geomechanics, well log, and three-dimensional (3-D) seismic analysis. The workflow encompasses a variety of analytical techniques at a variety of geologic scales. It is designed as an aid in identifying the potentially best reservoir, source, and seal facies for targeted horizontal drilling... see full abstract.
- Impacts of Diverse Fluvial Depositional Environments on Hydraulic Fracture Growth in Tight Gas Reservoirs
From Abstract: In an attempt to enhance the understanding of fracture growth in fluvial systems, this paper provides an analysis of the impact of depositional environments and associated heterogeneities on hydraulic fracturing growth in fluvial tight gas reservoirs. A 3D geostatistical reservoir model, representing a 160-acre field area, was created based on a 3D meandering fluvial tight gas geologic model developed from outcrop... see full abstract.
- Shale Gas: A Provisional Assessment of Climate Change and Environmental Impacts
This report provides a provisional review and assessment of shale gas development. It outlines potential greenhouse gas emissions at the regional (United Kingdom) and global scales resulting from the exploitation of shale gas. It also explores the health and environmental risks associated with gas extraction. Reliable data has been a huge problem associated with extraction to prevent exploitation. Information on health and environmental variables vary in quality and a better system is needed to ensure the accuracy of information. Shale gas poses potential risks to human health and the environment. Shale gas exploitation will most likely lead to an increase in global carbon emission and delay low carbon technologies.
- Thickness trends and sequence stratigraphy of the Middle Devonian Marcellus Formation: Implications for Acadian foreland basin evolution
This is a technical article addressing the complex stratigraphy, i.e., the sedimentary layers, of the Marcellus Shale formation.
- Public Perception of Desalinated Produced Water from Oil and Gas Field Operations: A Replication
From abstract: This study is a replication of Theodori et al.’s (2009) research on public perception of desalinated produced water from oil and gas field operations. The data used in this paper were collected in twelve Texas counties. Overall, the findings of this investigation paralleled those uncovered in Theodori et al.’s original exploration. Our data reveal that small percentages of respondents are extremely familiar with the process of desalination... see full abstract
- The Marcellus Shale: Resources for Stakeholders in the Upper Delaware Watershed Region
This report presents research-based information on best management practices that address concerns raised by stakeholders and may help to mitigate the potential impacts of gas drilling. The report provides an objective review of the current status of regulations affecting gas drilling in the region as a common resource for all stakeholders. The report discusses those resources identified as important to stakeholders and worthy of consideration when siting gas drilling and pipeline infrastructure because of potential impacts on environmental, economic or social resources.
- Predicting Shale Characteristics with Integrated, Multi-Variate Statistics
From Abstract: Oil and gas production in shale resource plays is dependent upon a number of factors including: rock strength, horizontal stresses, stress anisotropy, total organic carbon, thermal maturity, natural fractures, as well as a range of drilling and completions parameters. Traditional critical reservoir characteristics of thickness, matrix permeability, porosity and oil/gas saturation are also important - but far less dominant in shale resource plays. Effective unconventional interpretation in these plays demands integration... see full abstract.
- Development of a Regional Model to Assess Marcellus Shale Resource and Reservoir Potential
From Abstract: ...A regional study was set up to evaluate the Marcellus shale-gas potential utilising a series of profiles across the basin to correlate key wells with good quality log and core data. In each area the Marcellus section was subdivided into units based on... see full abstract.
- Gas storage in the Upper Devonian-Lower Mississippian Woodford Shale, Arbuckle Mountains, Oklahoma -- How Much of a Role Do the Cherts Play?
From Abstract: How gas is stored in shale-gas systems is a critical element in characterizing these potentially prolific, low-porosity/permeability reservoirs. An integrated mineralogic, geochemical, and porosity/permeability study is of the Upper Devonian-Lower Mississippian Woodford Shale, Arbuckle Mountains, southern Oklahoma, at locations previously described through detailed stratigraphic and spectral gamma surveys, was undertaken to provide insights into possible mechanisms by which natural gas might be stored in Woodford reservoirs in the adjacent Anadarko Basin... see full abstract.
- Effects of Petrophysical and Engineering Factors on Fluid Flow and Production in Gas Shales
From Abstract: Shale quality, gas deliverability, and production sustainability determine the success of a shale-gas play. With the evolution of horizontal-well and multistage-fracturing technologies, many high-quality shale resources have become productive and the most interesting reservoirs today. The objective of this study was to investigate some unique properties of gas shales, and their influence on fluid flow and production... see full abstract.
- NMR Gas Relaxation Signature for Organic Shale Reservoir Rocks
From Abstract: A powerful application of NMR logging is to identify gas in conventional reservoirs. NMR logging methods have the potential in organic shale reservoirs not to just identify the presence of gas but to provide significant quantitative information. Because of the nature of shale gas reservoir rocks NMR logging can acting as a stand-alone logging tool accurately estimate the total number of moles of free hydrocarbon gas in the reservoir... see full abstract.
- Hydraulic Fracturing Treatments and the Impact of Formation Heterogeneity
From Abstract: It goes without saying that hydrocarbon bearing formations are not homogeneous and isotropic. However, that is the way they are often looked at when considering hydraulic fracturing. Unconventional shale reservoirs are plagued by these assumptions also. Completion strategies in many shale operations call for horizontal sections up to 4500 ft. or longer... see full abstract.
- Fracture-Matrix Interaction and Gas Recovery in the Barnett Shale
From Abstract: ... Here we describe a new study of pore structure (pore connectivity, pore-size distribution) and gas desorption from both shale cores and crushed shale particles, and the subsequent gas transport into the hydraulic fractures. The low gas diffusivity is likely due to low pore connectivity, which also has not been systematically studied in the Barnett Shale... see full short paper.
- Earthquakes Induced by Fluid Injection in Texas and Elsewhere: What Further Research Could Teach Us
From Abstract: Between 31 October 2008 and 16 May 2009, Dallas-Fort Worth (DFW) residents felt nine earthquakes with magnitudes between 2.5 and 3.3, and news stories expressed concern they might be caused by ‘drilling’ for natural gas in the Barnett Shale. We have analyzed data collected by temporary local seismograph networks operated in the DFW area in November and December 2008, and near DFW and Cleburne, TX... see full abstract.
- Gas Shale Evaluation Techniques -- Things to Think About
From Abstract: The explosive growth in gas shale development has led to some interesting petrophysical challenges. What type, accuracy and precision of analysis are needed in the development of these plays to maximize value?... see full abstract.
- Indications from Shale Cores of Stress and Stress Induced Failure
From Abstract: Fine grained rocks, such as Shale (or Mudstones), often exhibit stress induced/related failures within the matrix which can be used as indicators of past or present stress conditions. Identifying stress induced failures in shale cores like petal-centerline or bedding-centerline fractures that are often associated with the current maximum stress orientation increases confidence in selecting a lateral well alignment which can maximize hydraulic fracture growth...see full abstract.
- Modern Reservoir Modeling and Simulation of Wells in Shale Resource Plays
From Abstract: Shale recourse plays are the current rage in the E&P industry and have opened a new era for oil and gas production. Organically rich shales, once ignored by drillers seeking easier plays and faster returns on their investments, are now boosting the fortunes of midsized producers across the United States... see full abstract.
- Permian Lacustrine Shale Exploration, Cooper Basin Australia
From Abstract: Beach Energy has commenced an exploration program to assess the shale gas potential of Permian lacustrine shales within the Cooper Basin, Australia. The program while designed to investigate the geochemistry, mineralogy, porosity, gas content and mechanical properties of the shales; the extensive data set obtained will also allow comparison of a lacustrine source system with lacustrine systems in China and the marine shale systems being commercially developed in the USA... see full abstract.
- Quantifying and Linking Shale Properties at a Variable Scale
From Abstract: At least three characteristics of shale are key to asset evaluation and development: (a) the presence of organic matter and free gas; (b) the porosity and permeability of the shale matrix; and (c) the susceptibility of the matrix to fracturing. Only a favorable combination of these three factors allows for discriminating good from poor shale reservoir... see full abstract.
- Issues in Simulation of Shale Gas Reservoirs
From Abstract: A valid reservoir simulator is a key enabling technology for the characterization, development, and management of a producing reservoir. Furthermore it provides a platform to integrate geologic, geochemical, geophysical, and petrophysical parameters, and examine their effects on production. The ability to use simulation to investigate the sensitivity of production to reservoir parameters is particularly important for reservoirs such as shale gas reservoirs where traditional core measurements are difficult or impractical to perform... see full abstract
- The Life Cycle of an Unconventional Gas Opportunity: Quantifying Risk Versus Reward
From Abstract: The early phases of exploitation of an Unconventional Gas opportunity differ significantly from that fora conventional play. Typically, the phases that precede full scale development are... see full abstract.
- Insights and Barriers to Effective Assessment
From Abstract: Effective assessment on the nature and scope of shale resource plays can be impeded by several factors. These factors tend to be related to the low permeability of the reservoir, and the attendant challenges of monetizing the resource base... see full abstract.
- Carbon and hydrogen isotopic evidence for the origin of combustible gases in water-supply wells in north-central Pennsylvania
The origin of the combustible gases in groundwater from glacial-outwash and fractured-bedrock aquifers was investigated in northern Tioga County, Pennsylvania. Thermogenic methane (CH4) and ethane (C2H6) and microbial CH4 were found. Microbial CH4 is from natural in situ processes in the shale bedrock and occurs chiefly in the bedrock aquifer. The δ13C values of CH4 and C2H6 for the majority of thermogenic gases from water wells either matched or were between values for the samples of non-native storage-field gas from injection wells and the samples of gas from storage-field observation wells. Traces of C2H6 with microbial CH4 and a range of C and H isotopic compositions of CH4 indicate gases of different origins are mixing in sub-surface pathways; gas mixtures are present in groundwater. Pathways for gas migration and a specific source of the gases were not identified. Processes responsible for the presence of microbial gases in groundwater could be elucidated with further geochemical study.
- Summary: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Proved Reserves 2009: US Department of Energy Report
Here the U.S. Energy Information Agency (EIA) provides 2009 data on proved reserves of United States crude oil, natural gas, and natural gas liquids. Each year the U.S. Energy Information Administration surveys approximately 1,200 domestic operators and uses the filed responses to estimate annually the proved reserves of crude oil, natural gas, and natural gas liquids (NGL). Reserves estimates change from year to year as new discoveries are made, existing reserves are produced, and as prices and technologies change.
- Inorganic geochemistry of Marcellus Shale natural gas hydrofracturing waters
An analysis of inorganic chemistry for five flowback water samples from the Marcellus Shale, plus 85 additionally gathered chemical analyses of flowback water from other sources. Measurements include total dissolved solids (TDS), cations, anions, alkalinity, acidity. Based on r2 values for linear fits, positive correlations with TDS follow the order: Cl > Na > Ca > Br > Mg ≈ Spec Cond ≈ Sr > Hardness > K ≈ Li. The geochemical model PHREEQC was used to simulate chemical changes upon injection of water and subsequent equilibration but does not adequately explain high Ba and Sr concentrations, which may be related to Ba and Sr complexation by organics.
- Southwestern Pennsylvania Marcellus Shale Short-Term Ambient Air Sampling Report
Pennsylvania Department of Environmental Protection (PA DEP) reports findings from a short-term air quality sampling program in the southwest region of PA during a five-week period in 2010. Sampling took place in Greene and Washington counties while background air samples were collected in Washington County. Detection of methane, ethane, propane, and benzene in air samples (compounds for which health standards have not been set).
- Determination of shale stiffness tensor from standard logs
A technique allowing inversion of the shale stiffness tensor from standard logging data: sonic velocities, density, porosity and clay content is developed. The inversion is based on the effective medium theory. The testing of the technique on laboratory measurements of the elastic wave velocities in shale samples shows that the inversion makes it possible to predict the elastic wave velocities VP, VS1 andVS2 in any direction within an error of a few per cent.
- Potential of Tight Gas in Pakistan: Productive, Economic and Policy Aspects
From Abstract: ... Reservoir engineering and exploitation of tight gas coupled with low cost factors, and higher gas prices has lead to augmented interest in tight gas as a favored alternative or complementary resource globally, in general and in Pakistan in particular... see full abstract.
- Effect of Gel Damage on Fracture Fluid Cleanup and Long-term Recovery in Tight Gas Reservoirs
One major source of new natural gas supplies for the world will be gas from low-permeability reservoirs. Currently, natural gas from tight sandstones, carbonates, coal seams and shales accounts for over 25% of the annual gas production in the United States. Global production of gas from similar reservoirs world wide will be expected in the next few decades. For such reservoirs, the wells have to be successfully fracture treated to produce at commercial gas flow rates.
In many situations, the designed created length was probably achieved, and maybe even the designed propped length was achieved. However, due to insufficient proppant concentration, or insufficient proppant transport, or the use of the wrong propping agent, or a fracture fluid that does not break to a low viscosity fluid, the effective fracture length is significantly less than the designed length and does not provide optimal production results.
It is our opinion that insufficient fracture fluid cleanup is the primary cause of poor results when the optimal effective fracture length is not achieved. Fracture fluid cleanup is affected by gel damage, which includes the static yield stress, the flowing yield stress, the amount of polymer residue in the fracture after the fracture closes, and the amount of polymer that forms a filter cake on the walls of the fracture. In addition, there are other issues such as proppant crushing and non-Darcy flow effects that also affect fracture fluid cleanup.
In this research, we have used a reservoir simulator to model how polymers in the fracture affect fracture fluid cleanup. We have incorporated mathematical expressions for static yield stress. We have included the effects of proppant crushing, gel residue plugging and the formation of a filter cake on the cleanup behavior and the resulting gas flow rates. With our model, we are able to simulate many of the problems we observe in field data and problems documented in the petroleum literature. Even though real solutions to these problems still remain to be developed, we think we can explain the issues behind most fracture fluid cleanup problems and offer a few ideas on what can be done to solve them.
- Pennsylvania Energy Impacts Assessment. Report 1: Marcellus Shale Natural Gas and Wind
How will energy development affect conservation efforts in Pennsylvania? This study conducted by the Nature Conservancy focuses on just two types of development activities, both of which are expected to experience substantial growth in the near future: Marcellus shale natural gas and wind energy. The study reviews impacts of these energy sources with regard to high-priority conservation areas in Pennsylvania. The impacts detailed are for forest, freshwater, and rare species habitats, but does not include impacts on water withdrawals, water or air quality, or migratory patterns.
- Inorganic chemistry of formation waters from Devonian strata in the Appalachian Basin--preliminary observations from Pennsylvania, New York, and West Virginia
A meta-analysis was performed on a subset of available inorganic chemistry data for co-produced waters from Marcellus shale hydraulic fracturing wells ranging from fresh to formation waters. Data were obtained from the published literature and other publicly available sources.
- Drilling in the Marcellus Shale: An Overview of the Process & Issues in West Virginia
The West Virginia Rivers Coalition looked into the process of hydraulic fracturing. They found that West Virginia regulations were not up to par with the challenge. Many areas are discussed, including the step-by-step hydraulic fracturing process as well as land and mineral rights.
- Improved Proppant Transport System for Slickwater Shale Fracturing
- Comparative Sequence Stratigraphy and Organic Geochemistry of North American Unconventional Gas Shales: Commonality or Coincidence?
From Abstract: Increased interest in North American, unconventional gas shales (i.e. the “Magnificent Seven”) as a major energy source has led to a plethora of recent published (and unpublished) geologic studies, including sequence stratigraphic and geochemical characterization. In this paper, we compare these characteristics of the shales to determine if there are commonalities which may lead to a unifying geologic model for their formation and characteristics...see full abstract.
- Resilience, community, and perceptions of Marcellus Shale development in the Pennsylvania wilds: Reframing the discussion
From Abstract: The development of natural gas from Marcellus Shale has created a period of intense change within Pennsylvania. This change has been accompanied by an increase in polarizing action and discourse amongst the state‘s residents. While development of the Marcellus is new, the process used to extract the gas is not. The question thus emerges: what makes Marcellus Shale development such the polarizing process?... see full text.
- Chemistry and Origin of Oil and Gas Well Brines in Western Pennsylvania
From Abstract: Brines having moderate to high salt content (up to 343 grams per liter [g/L]) occupy most pore spaces in rocks below a depth of a few thousand feet in Pennsylvania and are brought to the surface during oil and gas operations. Forty analyses of brines from a range of geologic environments in western Pennsylvania are reported here, accompanied by brief descriptions of analytical methods required to obtain valid and accurate data, especially for unstable parameters such as pH and oxidation state... see full text.
- Structural Characterization of Gas Shales on the Micro- and Nano-Scales
The structure of shales from nine different formations, including the Marcellus Shale, was compared using focused ion beam (FIB) and scanning electron microscopy (SEM) technology. Shale pore volume or porosity is an important characteristic that can have a significant effect on gas production by affecting gas flow through the shale. The different shales exhibited a range in calculated porosity. In addition, shales varied in kerogen content, another factor that influences gas production. When present, the kerogen in some shales was found to have porosities of up to 50%.
- Insights into Shale Gas Production & Storage From Gas Chemistry--What Is It Telling Us?
From Abstract: In this paper, we present results and methodology from a sub-regional field area looking into shale gas chemistry (composition and isotopes) from long term (1800+ hrs.) shale gas canister desorption experiments compared with shale TOC, adsorption isotherms and pore size distribution... See full abstract.
- A number of implications; yes, Virginia, there is induced seismicity.
- Energy-Water Nexus: A Better and Coordinated Understanding of Water Resources Could Help Mitigate the Impacts of Potential Oil Shale Development
This is a Government Accountability Office (GAO) analysis of oil shale deposits in Colorado, Utah, and Wyoming, in particular, the majority of oil shale located beneath federal lands. This report addresses (1) what is known about the potential impacts of oil shale development on surface water and groundwater, (2) what is known about the amount of water that may be needed for commercial oil shale development, (3) the extent to which water will likely be available for commercial oil shale development and its source, and (4) federal research efforts to address impacts to water resources from commercial oil shale development. GAO examined environmental impacts and water needs studies and interviewed Department of Energy (DOE), Department of the Interior (Interior), and industry officials.
- A New Core Measurement Methodology to Quantify Total Gas Storage
From Abstract: The storage of gas in organic shales occurs both as a sorbed phase mainly adsorbed on the surface of the organic materials and/or absorbed in the organic material, and as free gas in pore space. The standard method to measure the total storage is to make two separate measurements. The first is a measurement of the sorbed gas storage done on crushed samples at reservoir temperature, and the second is a standard low-pressure helium pycnometer measurement again done on crushed samples... see full abstract.
- Worldwide Shale Resource Plays and Potential
From Abstract: ...As need for hydrocarbon resources has escalated, efforts are now underway worldwide to develop shalegas. Exploration efforts are underway in Europe, Africa, South America, Asia, and Australia-New Zealand. The purpose of this paper is to provide general characteristics of the existing and potential shale resource plays in North America as well as globally... see full abstract.
- Kinetics and Mechanism of Shale Gas Formation: A Quantitative Interpretation of Gas Isotope "Rollover" for Shale Gas Formation
From Summary: The production and geochemical data show that the potential and characteristics of hydrocarbon generated and remaining in shales at high maturity are different from the prediction using the methods for conventional gas reservoirs, rending the difficulties in resource assessment. Quantitative studies of carbon isotope composition of methane, ethane, propane and CO2 in shale gas and other high maturity gas reservoirs, along with isotope kinetic fractionation, indicate that water-reforming of high-mature organic matter and the consequent Fischer-Tropsch process is a highly possible mechanism for shale gas generation... See Full Text
- Benchmarks for Assessing the Potential Impact of a Natural Gas Severance Tax on the Pennsylvania Economy
This detailed report provides background and overview of the debate in the Pennsylvania General Assembly over a potential severance tax which would generate revenue on natural gas produced from the Marcellus Shale. The report estimates the economic impact of a severance tax for Pennsylvania by "benchmarking" (i.e., choosing as standard value for comparison) the impact of $100 million collected from a severance tax. A main finding is that a severance tax would increase costs for gas drilling companies, but increased state revenue could yield small net positive impacts on the economy. The authors are scholars affiliated with the Pennsylvania State University Institute for Research in Training and Development.
- NY DEC SGEIS Information Requests
By letter dated April 12, 2010, the New York State Department of Environmental Conservation (DEC), Division of Mineral Resources, requested additional technical information from the Independent Oil and Gas Association of New York (IOGA) regarding high volume hydraulic fracturing (HVHF) as it is addressed by the draft Supplemental Generic Environmental Impact Statement (dSGEIS). Additional technical questions were received from DEC in communications dated April 20, 2010, and May 27, 2010. ALL Consulting facilitated this collaborative effort between IOGA member companies to address DEC's information requests. ALL Consulting compiled responses from the participants in the preparation of this report. This report summarizes DEC's questions and responses by presenting each question as phrased by DEC followed by the applicable composite response representing IOGA's industry perspective. The table of contents of this report refers to each question in the order presented by DEC. A copy of the Marcellus Shale Coalition study, "Sampling and Analysis of Water Streams Associated with the Development of Marcellus Shale Gas," dated December 31, 2009 is provided in Attachment A.
- Study of Unusual Responses from Multiple Resistivity Tools in the Bossier Formation of the Haynesville Shale Play
From Abstract: Over the years reports have been made of anomalous wireline induction log responses in some shale formations. Anderson (Anderson, 2000) suggested an extremely large dielectric effect as an explanation. As shale formations such as the Woodford, Bossier, and Haynesville plays have gained attention as reservoir rocks, it is important that we understand the reasons for these anomalies. This paper examines resistivity wireline logs run in the Bossier Shale, Louisiana... see full abstract.
- The Impacts of Horizontal Hydraulic Fracturing In New York Shale Formations on Human Health and the Environment
Osetgo 2000, an environmental preservation organization, comments on the draft of the New York Department of Energy Conservation Environmental Impact Statement. The statement was said to be insufficient in explaining the impacts of hydraulic fracturing in New York. Water contamination, treatment of radioactive elements, and lack of knowledge of long-term hydraulic fracturing impact are discussed.
- Technology Integration - A Methodology to Enhance Production and Maximize Economics in Horizontal Marcellus Shale Wells
This paper discusses a new procedure to enhance production in Marcellus Shale that will also improve economics. This procedure uses minifrac, a type of fracturing technology for shale gas production. Analysis, diagnostic fracture injection tests and post-closure analysis are a few of the procedures used. This technique will help optimize production and help predict production behaviors and economics of the multi-stage wells.
- Optimization of Completions in Unconventional Reservoirs for Ultimate Recovery
From Abstract: ...This presentation will introduce unconventional reservoirs, describe the main methods of horizontal, multi-stage completions, discuss how the choice of method can affect good fracturing practices and provide case study examples from a variety of unconventional reservoirs including tight sandstone, limestone and shale... see full abstract.
- Will flowback or produced water do?
From Introduction: iIn the near future, increased water demand will lead to shortages of freshwater available for fracturing. In addition, produced and flowback water from the fracturing treatment are becoming more costly to dispose of due to increasing trucking and disposal costs. Further, several areas have acid mine drainage (AMD) water available... See Full Text
- Development of Marcellus Shale in Pennsylvania
From Abstract: A review of technologies and practices used for exploration and production of natural gas from the Marcellus Shale in Pennsylvania is given while shedding light on the entire process of natural gas production in the Marcellus Shale region of Pennsylvania. Entailing drilling and completions operations, production operations and transportation of natural gas tied together with regulation and policy in Pennsylvania. Horizontal drilling technology is used... see full abstract.
- Proppant Selection and Its Effect on the Results of Fracturing Treatments Performed in Shale Formations
From Introduction: This paper reviews a number of fracturing treatments performed in three active areas in the United States; the Fayetteville Shale in Arkansas, the Bakken Shale in North Dakota, and the Haynesville Shale in north Louisiana. Reservoir characteristics, proppant type, and post fracture treatment production results were examined in each area. The proppants compared in this study were routinely utilized in the three areas... see full introduction.
- Gas Shale Reservoir Characterization: A North Africa Case
From Abstract: In the last period with the rising price of oil and gas, the exploration and development of unconventional plays, that are already an economic reality in North America, are gaining more attention worldwide. It is common opinion that Gas Shale reservoirs are not peculiar only to the North America Basins. ENI E&P has focused attention on this type of unconventional reservoir, both in new countries and in the areas where it has historically been successful in conventional plays and where large amount of data are available... see full abstract.
- Volumetric Fracture Modeling Approach (VFMA): Incorporating Microseismic Data in the Simulation of Shale Gas Reservoirs
From Abstract: ...It is possible to estimate the extent of the stimulated volume for each stage of a hydraulic fracturing job from microseismic data. The Volumetric Fracture Modeling Approach (VFMA) then models the fracture network as a 3D volume with fracture properties described by variations of dual porosity parameters. The VFMA was successfully applied to modeling a horizontal well in the Barnett Shale with multiple hydraulic fractures... see full abstract.
- Hydraulic Fracture Monitoring to Reservoir Simulation: Maximizing Value
From Abstract: Hydraulic fracture monitoring with microseismic mapping is now routinely used to measure hydraulic fracture geometry, location, and complexity, providing an abundance of information that can be essential to optimizing stimulation treatments and well completions. Although microseismic mapping has added significant value in many different environments, we have yet to fully utilize microseismic data... see full abstract.
- Thirty Years of Gas Shale Fracturing: What Have We Learned?
From Abstract: ...This work surveyed over 350 shale completion, fracturing and operations publications, linking geosciences and engineering information together to relay learnings that will identify both intriguing information on selective opening and stabilizing of micro-fracture systems within the shales and new fields of endeavor needed to achieve the next level of shale development advancement... see full abstract.
- Shale Gas Potential in the Eastern Cordillara of Columbia
From Abstract: A preliminary estimation of the shale gas potential of the Eastern Cordillera reveals a gas resource of 37 TCF which was calculated on the basis of organic-rich shales, vitrinite reflectance, formation thickness and size of the large structures in the Cordillera. The Eastern Cordillera of Colombia contains a thick sedimentary sequence that ranges from Late Paleozoic to Middle Miocene in age... see full abstract.
- Evaluating, Classifying and Disclosing Unconventional Resources
From Abstract: The results of evaluations of hydrocarbon resources are used for many purposes, from international energy studies, government resource management, field development, to financial activities. As a result of the increase in unconventional resource activity, the assets of many companies increasingly lie in categories other than reserves, such as contingent or prospective resources. The evaluation, classification and disclosure of these present challenges not encountered for conventional resources... see full abstract.
- Innovation and Regulation Can Coexist: New York's Approach to Regulating Shale Gas Development
From Abstract: Though New York's first gas well was drilled into shale, these reservoirs have contributed little to gas production in the state. Today, innovative drilling and completion methods make shale attractive. As with other industries, innovation has a tendency to race beyond the existing regulatory framework... see full abstract.
- The Origin of Natural Fractures in the Antrim Shale, Michigan
From Abstract: The Antrim Shale of the Michigan Basin is black organic shale that was deposited in the Late Devonian. The Antrim is the primary unconventional gas target in Michigan and is ranked number thirteen in term of gas volume in the United States. The shale produces from a depth ranging from 300 to 1800 feet in an area of northern Michigan where the Antrim is naturally fractured. The natural gas produced is believed to be biogenic in origin... see full abstract.
- Applying 3-D Seismic in Marcellus Shale Development, Greene County Pennsylvania
From Abstract: The Marcellus Shale in the area of the Mather and Garards Fort quadrangles east of Waynesburg, Greene County, Pennsylvania is buried at an average depth of approximately 8,000’. The majority of the petroleum development activities in the area prior to the Marcellus Shale activity were focused on Upper Devonian tight gas sandstones... see full abstract.
- High Resolution Spectral Gamma Ray Log (HRSGR): Applications for Unconventional Reservoirs
Frmom Abstract: The development of a high resolution spectral gamma ray logging procedure for use with conventional whole core analysis provides detailed definition of geochemical and geological data in unconventional reservoirs, such as the Marcellus, Haynesville, and Barnett formations. Increasing the spectral gamma ray sampling rate from the industry standard of two measurements per foot to five samples per foot provides superior data quality that is used to show small-scale changes... see full abstract.
- International Shale Reservoirs; Tiering Them Into Four Levels
From Abstract: The purpose of this paper is twofold: (1) develop criteria to identify the various tiers of shale reservoirs (tier I through tier IV where tier IV basins being the most promising) and (2) the second being the identifications of the basins and resource based on the criteria. Examples are presented... see full abstract.
- North Carolina Shale Gas -- A Progress Report: Sanford Sub-basin, Deep River Basin, Lee, Chatham, and Moore Counties
From Abstract: Leasing in the Sanford-sub basin began in January 2010; up to three groups were active. No drilling permits were submitted by May 2010. Pipeline build-out continues to provide natural gas for accelerated conversion of coal-fired electric plants by Progress Energy – the major public utility in central- and eastern North Carolina. These pipelines, located near the Sanford sub-basin, provide a ready natural gas market... see full abstract.
- Petrophysical Evaluation for Enhancing Hydraulic Stimulation in Horizontal Shale Gas Wells
From Abstract: This paper presents a comprehensive approach to the evaluation of an unconventional resource play drilled in the Haynesville Shale in east Texas. Using openhole and logging-while-drilling (LWD) logs, conventional core analysis, and a chemostratigraphy analysis of drill cuttings, a shale analysis linking mineralogy, free gas, effective porosity, a shale brittleness index, and a clay linked transverse anisotropy is verified on separate vertical and horizontal control wells. Beyond that, pulsed neutron spectroscopy logs were run... see full abstract.
- 3-D Visualization and Classification of Pore Structure and Pore Filling in Gas Shales
From Abstract: Shale gas is a growing resource worldwide as many basins are being explored and produced. However, little is still known and understood about two key parameters in gas shales: the gas-filled porosity and permeability. Digital rock physics technique, presented in this paper, contains three basic steps: (a) 3D CT imaging at 200 nanometer resolution, and/or FIB-SEM (focused ion beam combined with SEM) imaging at 3-15 nanometer resolution (b) segmentation of the digital volume to quantitatively identify the components, including the mineral phases, organic-filled pores, and free-gas inclusions; and (c) computations of TOC (Total Organic Content), porosity, pore connectivity, and permeability in three axis... see full abstract.
- Rock Typing in Gas Shales
From Abstract: Conventional methods of rock typing based on porosity-permeability cross-plots do not work in shales due to lack of dynamic range and difficulties involved in the direct measurements of most of the petrophysical parameters.. Here we present a methodology for rock typing in Barnett shale by integrating geological core description with porosity, total organic carbon (TOC), mineralogy and mercury injection capillary pressure which are relatively easy to measure... see abstract.
- Characteristics of the Utica Black Shale in NY and PA: Black Shale Blanket or Complex Facies Mosaic?
From Abstract: Although the Late Ordovician Utica black shale appears to be a homogeneous unit in single outcrops and wells, local and regional variations controlled by both eustatic sea level change and fault block motion significantly influenced the local deposition. Therefore, it should not be surprising that TOC and other measures of importance for the gas industry vary across the region... see full abstract.
- Multi-scale detection of organic and inorganic signatures provides insights into gas shale properties and evolution
Organic geochemical analyses, including solvent extraction or pyrolysis, followed by gas chromatography and mass spectrometry, are generally conducted on bulk gas shale samples to evaluate their source and reservoir properties. While organic petrology has been directed at unravelling the matrix composition and textures of these economically important unconventional resources, their spatial variability in chemistry and structure is still poorly documented at the sub-micrometre scale. Here, a combination of techniques including transmission electron microscopy and a synchrotron-based microscopy tool, scanning transmission X-ray microscopy, have been used to characterize at a multiple length scale an overmature organic-rich calcareous mudstone from northern Germany.
- Comments on the Scope of the EPA's Proposed Study of Hydraulic Fracturing
The article shows concern for Ostego County in New York. The area is plagued by gas seepage. It is also in an area desired for Marcellus Shale drilling. The concern is that hydraulic fracturing of the area will increase the gas seepage in the area, contaminating watersheds and endangering the residents.
- Natural Gas Plays in the Marcellus Shale: Challenges and Potential Opportunities
Challenges involved in extracting shale gas include the depth of the resource, hydraulic fracturing, need for water withdrawals, and health and environmental impacts. Opportunities for solutions to these issues are also discussed.
- The Marcellus Shale: Resources and Reservations
From Abstract: The Marcellus Shale is an organic-rich, sedimentary rock formation in the Appalachian Basin of the northeastern United States that contains significant quantities of natural gas. Published estimates of the amount of gas that may be recoverable from the Marcellus Shale have been higher than 1.42 trillion cubic meters, or 50 trillion cubic feet. The recovery of commercial quantities of gas from a low-permeability rock like the Marcellus became economically possible with the application of directional drilling technology, which allows horizontal boreholes to penetrate kilometers of rock, combined with staged hydraulic fracturing to create permeable flow paths into the shale... see full abstract.
- Addressing the Environmental Risks from Shale Gas Development
This briefing paper explains the processes of horizontal drilling and hydraulic fracturing for extracting shale gas, examines the environmental risks of shale gas extractions, and outlines the industry practices and government regulations that will facilitate creation of a low-carbon economy.
- The Economic Impacts of the Marcellus Shale: Implications for New York, Pennsylvania, and West Virginia
This report estimates multi-state economic impacts of current and future Marcellus development, using three scenarios for the pace of future drilling activity and the amount of recoverable gas.
- Water Management Technologies Used By Marcellus Shale Gas Producers
Natural gas is an important energy source to the United States. Traditional production of natural gas used vertical wells but operators are increasingly using new technology to extract gas from sources like gas shales, coal bed methane and tight gas sands.
- Well performance analysis for low to ultra-low permeability reservoir systems
From the abstract: Unconventional reservoir systems can best be described as petroleum (oil and/or gas) accumulations which are difficult to be characterized and produced by conventional technologies. In this work we present the development of a systematic procedure to evaluate well performance in unconventional (i.e., low to ultra-low permeability) reservoir systems.... See full abstract
- The Potential of Gas Shale
Natural gas extraction in Pennsylvania has the potential to be highly economical. This article discusses related hydraulic fracturing techniques at various existing shale formations in the United States. Industry methods for extraction processes used in the United States are discussed, and applied to the Marcellus Shale formation. The potential for natural gas recovery as an important economic resource is stressed.
- Challenges Facing Developers of the Marcellus Shale in Appalachian Basin
From Introduction: Development of the Marcellus Shale play will result in 1000s to 10,000s of new wells over the next decade, a several-fold increase in regional natural gas production, and a wide range of regional economic benefits. NETL is helping to develop technology solutions that reduce risks, increase the efficiency of development, and inform state and Federal regulators. This article provides a brief overview of the status of the Marcellus Shale play,and outlines the technical challenges facing operators and the efforts of NETL in meeting those challenges... see full text.
- Community Impacts of Marcellus Shale Development: Preliminary Research Findings
This research in progress discusses social and community impacts from Marcellus Shale development in four Pennsylvania counties as interpreted through 73 interviews. Interviews targeted the residents' perceptions of development impacts. The researchers have preliminary findings that show that as development in lower population density areas increases, public awareness increases. Some concerns relate to issues of wealth, rural life, agriculture, and road strain.
- New methods about the productivity contribution evaluation and development features of natural fractures in ultra-low permeability reservoir
According to the data such as outcrops, cores, well logging with imaging, and thin sections, the natural fractures are developed in ultra-low permeability reservoirs. The fracture types are with tectonic shear fractures as the dominated which appear in groups and en echelon arrangement. Natural fractures are most developed in sandstone and siltstone, but rarely developed in mudstone.
- Water Management Associated with Hydraulic Fracturing: American Petroleum Institute Guidance Document HF2
- Natural gas plays in the Marcellus Shale: challenges and potential opportunities
see full text
- Geochemical modeling and analysis of the frac water used in the hydraulic fracturing of the Marcellus Formation, Pennsylvania
Excerpt from abstract: The hydraulic fracturing of the Marcellus Formation creates a byproduct known as frac water. Five frac water samples were collected in Bradford County, PA. Inorganic chemical analysis, field parameters analysis, alkalinity titrations, total dissolved solids (TDS), total suspended solids (TSS), biological oxygen demand (BOD), and chemical oxygen demand (COD) were conducted on each sample to characterize frac water. A database of frac water chemistry results from across the state of Pennsylvania from multiple sources was compiled in order to provide the public and research community with an accurate characterization of frac water.... link to full abstract
- Radioactivity in Marcellus Shale
This technical report examines whether drilling waste products (such as cuttings and fluids) contain naturally elevated concentrations of radium originating in formation waters. Ra-226 is a highly water soluble radioactive leachate that will dissolve in water under the temperature and pressure found in Marcellus Shale. Ra-226 can be found within drill cuttings and appear in landfills that house these cuttings. The hazards of dewatered Marcellus Shale drill cuttings and drilling fluid in landfills has not been fully evaluated.
- Key Considerations for Hydraulic Fracturing in Gas Shales
The focus of this presentation is on hydraulic fracture geometry in shales, the materials used in the fracturing process, and treatment monitoring via microseismic.
- "Unconventional" Discovery Thinking in Resource Plays: Haynesville Trend, North Louisiana
- The Oil and Gas Industry in the Empire State: Past, Present and Future
From Abstract: New York has supplied many firsts for the oil and gas industry: the first natural gas well, the first natural gas company, the first geological survey, and the first state-chartered energy R&D organization. The article reviews the historical context of resource development in New York State, the current state of the industry, and the direction it is likely headed in the future... see full abstract.
- Effects of natural gas development on forest ecosystems
From Abstract: In 2004, an energy company leased the privately owned minerals that underlie the Fernow Experimental Forest in West Virginia. The Fernow, established in 1934, is dedicated to long-term research. In 2008, a natural gas well was drilled on the Fernow and a pipeline and supporting infrastructure constructed. We describe the impacts of natural gas development... See Full Abstract
- A numerical model for fluid injection induced seismicity at Soultz-sous-Forêts
During fluid injection experiments at the geothermal site of Soultz-sous-Forêts (France), more than 114,000 induced seismic events with magnitudes between −2.0 and +2.9 were detected by a local downhole monitoring network. Of these, 35,039 events are sufficiently constrained to be located. Hypocenters align along a sub-vertical, planar structure with the apparent width being dominated by data scattering indicating that seismic activity predominantly occurs along a (pre-existing) larger scale fault structure. For this scenario, we present a numerical model to simulate hydraulic overpressures.... See full abstract
- Real-Time Borehole-Based Microseismic Monitoring of Hydraulic Fracturing Treatments in Adjacent Horizontal Wells in the Barnett Shale: Example of a Faulted Reservoir
From Abstract: ... To avoid making assumptions and to better understand created fracture geometry, borehole-based monitoring of the induced microseismicity may be used. We present the results of a multi-stage, multi-lateral microseismic monitoring campaign performed in the Barnett Shale formation in Denton County, Texas. The primary objectives of this project were to drill and to successfully complete Barnett shale wells in and around faults located on the prospect acreage using 3D surface seismic and microseismic monitoring of the hydraulic fracture process... see full abstract.
- Natural Fractures in the New Albany Shale, Illinois Basin, and Their Importance for Shale-Gas Production
From Abstract: Success in the New Albany Shale gas play in southern Indiana and western Kentucky, where gas is mostly thermogenic, is partly dependent on understanding how the natural fracture system impacts hydraulic fracture treatments. We consider both the potential for natural fractures to provide permeability enhancement and their potential effects on hydraulic fracture treatment efficiency. We present observations from... see full abstract.
- Manning Canyon Shale: Utah's Newest Shale Gas Resource
From Abstract: The Manning Canyon Shale in north-central Utah, which has had good gas shows in the past, once again has attracted industry attention. At the north end of the San Rafael Swell, the 22 exploration wells that fully penetrate the Manning Canyon Shale, two of which were drilled in 2008, define a 600-square mile potential shale gas play area... see full abstract.
- Devonian Shale Plays of the Black Warrior Basin and Appalachian Thrust Belt in Alabama
From Abstract: The Black Warrior basin and Appalachian thrust belt of Alabama are frontier areas for shale gas production, and diverse opportunities for development exist in Devonian strata. The Chattanooga Shale is being developed along the southeast margin of the Black Warrior basin. Unnamed pre-Chattanooga shale, by comparison, is prospective in the interior of the Appalachian thrust belt. Integrated geological analysis indicates that the characteristics of each area differ markedly, and these characteristics should be taken into account during exploration and development... see full abstract.
- An Integrated Workflow for Shale Gas in the Western Canadian Sedimentary Basin: Surface Seismic to Stimulation
From Abstract: ... In this paper we present a case study from an active shale gas play in the Triassic age Montney Formation, Western Canada, which integrates surface seismic amplitude and elastic property volumes with petrophysical data and micro-seismic monitoring results. The integration of reflection seismic data and appropriate attributes brings more geophysical rigor to a traditionally engineering dominated play type... see full abstract.
- The Effects and Distribution of Moisture in Gas Shale Reservoir Systems
From Abstract: The moisture content is an important component within the gas shale reservoir system as the amount and distribution of water can have adverse effects on the volume of sorbed and free gas, relative permeability/diffusivity and solution gas may be a measurable contributor to total gas in place. The variation in the effects of moisture content depends on the mineralogy, maturity, kerogen type, and pore size distribution... see full abstract.
- Hydraulic Fracture Propogation in Fractured Media
From Abstract: ...The paper uses the state of the art in the modeling of the hydraulic fracture propagation in fractured media. When the hydraulic fracture does not cross directly a natural fracture and starts to follow the path of the natural fracture, the model checks whether the maximum tensile stress at any location along the natural fracture is high enough to initiate a new hydraulic fracture branch... see full abstract.
- A High-Definition Mineralogical Examination of Potential Gas Shales
From Abstract: ... In this study, we utilize QEMSCAN, a high definition, automated mineralogical analysis tool, to evaluate the mineralogy and micro textures of potential gas shales. QEMSCAN allows a detailed evaluation far beyond the resolution of conventional thin section petrography and at a speed much faster than conventional SEM analysis. We present a brief summary of data from a diverse selection of North American shales over a broad geological time frame... see full abstract.
- Just How Enormous is the "Enormous" U.S. Gas Resource? Implications for Future Supply
From Abstract: With the increasing development of unconventional gas resources in general and shale gas resources in particular, the U.S. is now said to have “ENORMOUS” gas resources. These resources are perceived to create new opportunities for energy policy, particularly a massive increase in the use of natural gas to generate electricity and a substantial replacement of gasoline by natural gas in the transportation sector. However, just how enormous is the allegedly “ENORMOUS” resource? This paper examines both the currently known and the range of estimated potential U.S. gas resources by type... see full abstract.
- Accumulation and Exploration Prospects of Shale Oil and Gas in Songliao Basin, Eastern China
From Abstract: ... This article describes the primary geological and geochemical characteristics of the black mud-shale in the Nenjiang and Qingshankou formations. Furthermore, on the basis of comprehensive evaluation of the geology, geochemistry, well logging and seismic data, its exploration potential is analyzed.. see full abstract.
- Stratigraphy and Depositional Dynamics of the Haynesville Bossier Sequence: Inferences from Whole Rock Elemental Data
From Abstract: The organic-rich mudstone facies of the late Jurassic Haynesville Formation were deposited under arid climatic conditions in a restricted instrashelf basin on the evolving Gulf Coast passive margin. A high-resolution (< 2 feet sampling) whole-rock elemental geochemical study was performed on cored wells from across the basin in order to: 1) establish a chemostratigraphic zonation that could be integrated with conventional data, 2) assess depositional conditions effective in concentrating organic matter, and 3) assess provenance of siliciclastic input versus carbonate input... see full abstract.
- Stratigraphy and Petrophysics of the Middle Devonian Black Shale Interval in West Virginia and Southwest Pennsylvanian
From Abstract: In the Central Appalachian Basin, the Middle Devonian organic-rich shale interval, including the Marcellus Shale, has become a major target for natural gas exploration and production. This unconventional gas reservoir is widespread across the basin and has significant potential to produce large volumes of gas... see full abstract.
- Applying Economic Lessons from Unconventional Plays Back to Conventional Projects
From Abstract: The traditional metric for capital efficiency goes by various names (P/I, DPI, PVI), but it usually involves dividing net present value (NPV) by the present value of the pre-tax capital spend (PV(Investment)). When unconventional resources began to draw attention some years ago, an economic paradox became apparent. When measured by P/I, unconventional plays almost always look terrible. Yet, many companies pursuing these plays were clearly making money and getting a respectable return on their investment... see full abstract.
- Direct Method for Determining Organic Shale Potential from Porosity and Resistivity Logs to Identify Possible Resource Plays
From Abstract: Today many geoscientists are faced with identifying possible resource plays throughout the world. Determination of potential organic content of the shale sections is one of the first estimations that is often made, and time and again there is a lack of information readily and inexpensively available to make these preliminary estimates. As Passey (AAPG, 1990) and others have shown, there are several methods that can be used to determine the organic content by interpretation of various electric logs... see full abstract.
- Key Attributes of Canadian and U.S. Productive Shales: Scale and Variability
From Abstract: Shale gas reservoirs have come of age. This class of reservoirs has changed the landscape of gas resources in North America. Gas shale geochemical, mineralogical and textural attributes within a shale-gas system approach is needed. These reservoirs are heavily engineered, and understanding scale and variability is needed for continuous production improvement... see full presentation.
- Haynesville Play Development: Sustainability Analysis of Local Fresh Groundwater Resources in Northwest Louisiana
From Abstract: The rapid development of Haynesville Shale, an unconventional gas play, and its reliance on local groundwater resources, has resulted in friction between public and industrial interests. The play is located in a fast-growing area of northwest Louisiana, where no pre-existing water resource management plans exist, and limited potable water resources are available. The proposed approach for the Haynesville of northwestern Louisiana is to drill the production well, and subsequently open the formation to enhance natural gas flow, using hydraulic fracture stimulation (HFS)... see full abstract
- Decomposition of Organic Matter and Impact on Shale Resource Play Assessments
From Abstract: High gas content in shale is dependent on the generation of products from both kerogen (primary cracking) and on the cracking of generated products retained in the source-reservoir system. To predict gas yields of these systems, a mass balance compositional model of organic matter decomposition was derived from a series of experimental data sets on low sulfur Type II marine shale (Toarcian Shale, Paris Basin)... see full abstract.
- Shale Gas in the Posidonia Shale, Hils Area, Germany
From Abstract: Shale gas is a self-sourced resource in which thermogenic or biogenic hydrocarbon gases are contained within a fine-grained, organic-rich, low permeability matrix, occurring in free, adsorbed and dissolved states. While no commercial shale-gas enterprises are currently known outside North America, many parts of Europe contain prime targets for shale gas exploration. One of these is the Posidonia Shale (Lias ε) of northern Germany... see full abstract
- Shale Gas and America's Future
From Summary: Recent natural gas shale discoveries have changed the energy picture in America. Current political leaders have great incentive to support more natural gas usage as a bridge to their carbon-light energy future. Increased market share for natural gas vs. coal for electricity consumption and vs. oil for transportation will provide the demand growth needed to absorb the new 1100 tcf of new U.S. gas shale reserves found in past five years in the Big 4 shale plays, while reducing GHG’s substantially... see full abstract.
- The Appalachian Marcellus Shale Play: Discovery Thinking, Timing and Technology
- Geochemical investigation of Marcellus Shale hydrofracturing waters
An analysis of inorganic chemistry for a subset of flowback water samples from the Marcellus Shale, plus additionally gathered chemical analyses of flowback water from other sources. Measurements include total dissolved solids (TDS), cations, anions, alkalinity, acidity. Based on r2 values for linear fits, positive correlations with TDS follow the order: Cl > Na > Ca > Br > Mg &asymp Spec Cond &asymp Sr > Hardness > K &asymp Li. The geochemical model PHREEQC was used to simulate chemical changes upon injection of water and subsequent equilibration but does not adequately explain high Ba and Sr concentrations, which may be related to Ba and Sr complexation by organics.
- Natural Gas Drilling in the Marcellus Shale: Regional Economic Opportunities and Infrastructure Challenges
This issue brief discusses the strain on local transportation networks and types of infrastructure and concerns on environmental impacts caused by heightened drilling activity. It also examines how regional development organizations in Pennsylvania and New York are addressing these issues and what measures can be taken to minimize future negative effects.
- Unanswered Questions About The Economic Impact of Gas Drilling In the Marcellus Shale: Don't Jump to Conclusions
The economic impacts of drilling for natural gas in the Marcellus Shale, particularly in New York State, are discussed. Drilling had been halted in New York because of a moratorium. To determine the potential impact on the economy, the following factors and studies are discussed: the economic impact in Texas and Pennsylvania as a result of drilling, the impact on tourism, the economic health of gas companies (employment, income, etc.), the Draft Supplemental Generic Environmental Impact Statement (SGEIS) in New York, the Penn State study, and the Broome County study. The author concludes that, if it proceeds, drilling in New York might likely cause negative economic impacts.
- Feasibility of using specific conductance for monitoring stream for Marcellus Shale hydrofracturing water
Investigates specific conductance as a technique for monitoring water quality of streams in the drilling zone of the Marcellus Shale. A mixing model developed for this task is described. Criteria for use include stream size, precipitation event size, and other conditions.
- Projecting the Economic Impact of Marcellus Shale Gas Development in West Virginia: A Preliminary Analysis Using Publicly Available Data
From Executive Summary: Natural gas production from hydrocarbon rich shale formations, known as “shale gas,” is one of the most rapidly expanding trends in onshore domestic oil and gas exploration and production today. Due to its high energy content, versatility, and low emissions, natural gas is a key component of the U.S. energy supply. Shale gas is already an important contributor to U.S. natural gas supply, and is predicted to have a significant and increasing role in the domestic energy portfolio in the future... See full summary
- Current geologic issues in New York State: From carbon dioxide storage to landsliding
This study estimates carbon dioxide storage potential in the Upper Ordovician Queenston Formation by assessing well log, core, seismic, and outcrop data at a coal-fired power plant. The results show an area of 25 square miles under the power plant could store about 18 years of carbon dioxide emissions. The author believes that the Queenston Formation does not have enough porosity for carbon dioxide storage. Secondly, this work examines the factors that affect landslide movement, such as heavy rainstorms, rise in ground water levels due to precipitation, and erosion of landslide toes caused by streams, are determined. Recent changes like the increase in average precipitation, streamflow erosion, and harvesting of trees have also added to landslide movement.
- Prospects for Geosynthetic Containment Systems at Marcellus Formation Shale-Gas Drilling Projects
The Marcellus Formation is a marine sedimentary rock found in the Northeast. The shale contains a large supply of untapped natural gas and the proximity to high demand markets makes it an attractive target for energy development.
- Structure and vein isotopic signatures of a cambro-ordovician 360M core from Saratoga Springs region, New York state: Implications for tectonics, gas exploration, and CO2 sequestration
From the abstract: The Ordovician section in the Mohawk Valley has served as a model for Taconic plate tectonics, for Trenton-Black River gas production, and now for Utica black shale gas production. I conducted a detailed fracture analysis on a 635m (2084ft) unoriented core (75-NY-2, Charlton, NY; housed at NYS Museum) that penetrates the Cambro-Ordovician section from Schenectady Formation down to Grenville basement.... See full abstract
- Impact Assessment of Natural Gas Production in the NYC Water Supply Watershed
The process used to extract gas from shales is called hydraulic fracturing. This is done by injecting water, sand and chemicals into the formation which allow the gas to be delivered to the surface. Wells are drilled horizontally to increase the area of production. Portions of the Northeast have seen a substantial rise in shale gas production. Over 65% of the NYC watershed could be exploited for shale gas drilling and potentially harm the unfiltered drinking water. The goal of the project is to identify potential threats to the water supply for NYC.
- Marcellus Hydrofracture Flowback and Production Wastewater Treatment, Recycle and Disposal Technologies
It is estimated that Marcellus Shale development in Pennsylvania, New York and West Virginia will generate 7000 Million gallons of hydrofracture flowback and wastewater per year. This wastewater contains substantial amounts of toxic barium and large amounts of other elements and compounds. Three methods for managing this wastewater are viable today. Pretreated prior to additional treatment and discharge to stream through publicly owned treatment works, evaporation and chemical precipitation processes.
- Chemical and isotopic tracers of the contribution of microbial gas in Devonian organic-rich shales and reservoir sandstones, northern Appalachian Basin
Discusses the stable isotopic signature (carbon, deuterium, oxygen) of shales and sandstones in the northern Appalachian Basin estimated from samples of formation water and dissolved gases. Stable isotopes can be used to distinguish between shallow biogenic gas (e.g., landfill gas or wetland gas) and deeper origin gas produced under high temperature and pressure.
- Isolating Potential Flow Zones During Well Construction: API Standard, Part 2
- The Future of Unconventional Gas: Legal, Policy and Environmental Challenges to the Development of North American Shale Gas
- Ozone impacts of natural gas development in the Haynesville Shale
From abstract: The Haynesville Shale is a subsurface rock formation located beneath the Northeast Texas/Northwest Louisiana border near Shreveport. This formation is estimated to contain very large recoverable reserves of natural gas, and during the two years since the drilling of the first highly productive wells in 2008, has been the focus of intensive leasing and exploration activity. The development of natural gas resources within the Haynesville Shale is likely to be economically important but may also generate significant emissions of ozone precursors... see full abstract
- Utica emerges in Quebec; shale play extends to Canada
The Utica Formation in North America is an Ordovician-age, black calcareous shale with productive equivalents in the U.S. Appalachian basins. This brief article discussing prospects for development of the Utica shale in Quebec, Canada.
- Citizens' Guide to Marcellus Shale in Pennsylvania
Marcellus Shale is an attractive source for natural gas to decrease Americas dependence on foreign sources. As production has increased in New York, Pennsylvania, Ohio and West Virginia, residents have begun to express concern over the natural gas extraction. There is a significant impact on the environment from wastewater and surface water from drilling. Production also causes habitat fragmentation and invasive species invasion. This report is to educate residents who are seeking information about Marcellus Shale.
- An integrated paleomagnetic and diagenetic investigation of the Barnett shale and underlying Ellenburger Group carbonates, Fort Worth Basin, Texas
From the abstract: The Ordovician Ellenburger Group carbonates are extensively karsted and brecciated throughout portions of the western half of the Fort Worth Basin, Texas, where it underlies the Mississippian Barnett Shale gas reservoir and source rock. An integrated geochemical/petrographic, paleomagnetic and rock magnetic study was conducted to better understand the nature and timing of diagenetic events in the unit. Samples from three scribe oriented conventional drill cores of the uppermost Ellenburger Group carbonates were analyzed for their diagenetic and paleomagnetic properties.... See full abstract
- Worldwide Gas Shales and Unconventional Gas: A Status Report
This conference report discusses the shift toward using unconventional gas, which includes natural gas from tight gas sands, coalbed methane, and gas shales. It analyzes the economic affordability of gas shale and the magnitude its role could play in the future. These topics are discussed pertaining to North America specifically and then to the world. Three key challenges concerning building confidence in natural gas supplies, addressing environmental barriers, and building demand for natural gas are also outlined.
- Sampling and Analysis of Water Streams Associated with the Development of Marcellus Shale Gas
Shale gas water characterization for 17 member companies of the Marcellus Shale Coalition (MSC) who volunteered samples from 19 locations where shale gas wells were scheduled to be hydraulically fractured. Sampling of influent water streams took place at Day 0; for flowback water streams, at 1, 5, 14, and 90 days following the fracturing. Approx. 80 pages of inorganic and organic chemistry data are provided. No data are provided on radioactivity parameters.
- Is New York's Marcellus Shale Too Hot to Handle?
New York State is currently holding an environmental review of natural gas production from Marcellus Shale. This review is in conjunction with the New York Department of Environmental Conservation. The review looks at wastewater from Marcellus Shale hydraulic fracturing and tests for pollutants. The purpose of this review is to look at human health implications arising from natural gas production.
- Operational and Business Efficiency in Unconventional Projects
From Abstract: In order to extract maximum value and benefit from unconventional oil and gas projects, companies must recognize the need for a fully integrated business and operational approach. An integrated approach starts with a probabilistic assessment of the production potential of a region based on a solid geotechnical foundation, but true maximization of value can only be realized from operational efficiency within an integrated business context... see full abstract.
- Risk Analysis of Unconventional Plays
From Abstract: The valuation and assessment of unconventional or “continuous resource” opportunities is not feasible using traditional probabilistic, volumetric-based methods. While a fully stochastic business, value-chain model is the best way to assess the potential of an unconventional play, we continue to lack a solid definition of Chance elements similar to what we have traditionally applied to conventional accumulations... see full abstract.
- Development of the Natural Gas Resources in the Marcellus Shale: New York, Pennsylvania, Virginia, West Virginia, Ohio, Tennessee, and Maryland
This report exmaines the environmental and socioeconomic impacts resulting from development of the Marcellus Shale, focusing on specific impacts to the approximate 35 National Park System (NPS) units within the area of concern, plus an added number of significant NPS features (such as trails, places and sites) which lie adjacent or close to the shale areas in question.
- Doubts about shale plays: Examples from the Barnett, Fayetteville and Haynesville Shales.
From Abstract: The investment community now believes that as a result of shale gas plays, the United States has almost an inexhaustible natural gas supply. The balance sheets of many of the key operators in shale plays, however, tell a different story, characterized by substantial debt, ongoing asset sales, and low cash reserves. Our analyses indicate that the reserve levels claimed by certain operators and analysts for shale gas plays are difficult to justify by standard decline-curve methods unless production is projected decades beyond any reasonable economic limit... See Full Abstract
- Unconventional Resource Recovery Improvement Using Conventional Reservoir Engineering Strategies
From Abstract: This article shows, via models and actual field results, how unconventional resource developments, while pursing profitable wells, often do so at the expense of leaving considerable bypassed resources behind that will never be economic to recover. These decisions can result in sub-par overall economic performance for the operators utilizing this strategy. Some emerging technologies and workflows are discussed... see full abstract.
- Hydraulic Fracturing Operations-- Well Construction and Integrity Guidelines
Technical guidance document. Provides guidance on industry recommended practices for construction of wells (vertical, horizontal, directional types) intended for hydrofracturing. Information on design and motivation for well integrity
- Integration Of Gas Markets And Security Of Gas Supply And Demand
From Introduction: With the beginning of the new century security of the international gas trade has become of the hottest issues on the global agenda. For many decades gas markets had been functioning in an extremely reliable way, but paradoxically now with their integration and globalisation, concerns about security issues in gas trade are increasing. Disruptions in gas supply, transit conflicts, severe price disputes, rigid pipeline competition and increasing misunderstanding and mistrust between consumers and producers are becoming commonplace in the modern gas markets...See Full Text
- Shale Gas: Material, Profitable and Technologically Complex
From Overview: The application of technology in shale gas requires the integration of many disciplines. This paper illustrates how petroleum systems, geology, geophysics, petrophysics, reservoir engineering, drilling and completion engineering, petroleum engineering and surface facilities engineering and operations are all important to commercial success. The majority of examples are from a Woodford and Fayetteville Shale play analysis conducted over the last few years... See Full Text
- Unconventional Gas Shales: Development, Technology and Policy Issues
An objective and thorough review of unconventional shales prepared by the U.S. Congressional Research Service. Advances in well drilling and reservoir stimulation have increased gas production from unconventional shales that were considered in the past to be locked within impermeable shale. The USGS estimates that 200 trillion cubic feet of natural gas can be recovered from shales. The hydraulic fracturing used to stimulate gas production from shales have stirred environmental concerns over waters consumption and contamination. The saline flowback water pumped back to the surface poses environmental management challenges. Gas shale development takes place on both private and public lands.
- Geoecological Risk Management for Stable Development of Gas Industry
From Abstract: Paper describes methodological approaches and case studies of quantitative assessment of environmental risks caused by the impact of gas industry facilities. The proposed technology is based on system analysis used together with the baselines of risk assessment and critical loads methodologies. The study is aimed at the development of methods to manage environmental risks in gas industry in order to provide medium-term and long-term environmental safety and sustainable development of the industry... See Full Text
- Solvent-free consolidation system controls proppant flowback
From Introduction: Halting or minimizing proppant flowback after fracturing or installation of liners can increase productivity and reduce operating costs to turn marginally commercial fields into profitable assets... See Full Text
- The Application of Hydraulic Fracturing and Acidizing Stimulation Technology and Its Future Trend in Complex Natural Gas Fields in China
From Abstract: Since the year of 2000, the gas production in China has been increasing dramatically as a result of the large-scale application of the advanced practicable fracturing and acidizing technology, of which the annual averaged increment being more than 16%. In view of the complexity of natural gas fields in China, such as low-permeability sandstone, carbonate, fissured volcano and ultra-high temperature and in-situ stress, etc, the main fracturing and acidizing technologies and their countermeasures corresponding to above mentioned formation types are put forward in the paper... See Full Text
- Applying New Technology to Tight Gas Developments
From Introduction: The development of tight gas resources brings new challenges to the industry. Many tight gas resources that are being targeted today were not considered to have significant production potential as recently as five years ago, and the ability to routinely produce these hydrocarbon resources at an economic rate can still be a major barrier. Technology can help to address this barrier... See Full Text
- Waterfracs: A Perspective Of 8+ Years Of Intense Study And A Review Of 60+ Years Of Field Work
From Abstract: A review of the history of hydraulic fracturing shows that we have come full circle in our industry on the type of fluids utilized. Several lessons have been learned in the past eight years with regards to the design and implementation of waterfracs as well as how they differ and are similar when applied to conventional and unconventional reservoirs. I will discuss design aspects, utilization of 3D models and all of the rationale for success versus more conventional high viscosity fluids... see full abstract.
- Characterization Of The Barnett Shale Using Borehole Images And Other Tools
- Treatment/disposal options for wastewaters from shale gas drilling
- Draft Supplemental Generic Environmental Impact Statement on the Oil, Gas and Solution Mining Regulatory Program
This document addresses potential environmental effects from horizontal drilling and high-volume hydraulic fracturing in the Marcellus Shale formation. The Draft Supplemental Generic Environmental Impact Statement (SGEIS) focuses on environmental impacts from natural gas extraction in watersheds in the state of New York. The document has ten sections, all publicly available electronically, as well as a glossary and bibliography. Potential Environmental Impacts (Section VI) addresses effects on water resources, ecosystems, air quality, transportation, and many other topics. Mitigation Measures (Section VII) discusses strategies for protection of water resources, mitigation of greenhouse gas emissions, noise, and radioactive materials, air quality problems, and other concerns. Comparative information on drilling and fracturing experiences in Pennsylvania is also provided. This document has been revised. Note: file sizes can be quite large and the language of the document can be technical.
- Hydraulic Fracturing Operations - Well Construction and Integrity Guidelines: American Petroleum Institute Guidance Document HF1
- Produced Water Volumes and Management Practices in the United States
From the Executive Summary: Produced water volume generation and management in the United States are not well characterized at a national level. The U.S. Department of Energy asked Argonne National Laboratory to compile data on produced water associated with oil and gas production to better understand the production volumes and management of this water.
This report provides a current estimate for the volume of produced water generated from oil and gas production in the United States. The volume estimate represents a compilation of data obtained from numerous state oil and gas agencies and several federal agencies for 2007, where possible. The total volume of produced water estimated for 2007 is about 21 billion bbl.....
- Analytical Characterization of Flowback Waters In The Field
From the abstract: As the development of unconventional gas sources increases, larger amounts of fresh water are needed in fracturing operations and more flowback water is being produced. Water use in various gas shale plays is becoming an issue due to limited availability of water resources, transportation issues, contamination concerns and regulatory pressures. Operators and services companies, therefore, increasingly seek ways to reuse the flowback water generated from fracturing operations so as to minimize the environmental and economical impact. Frequently, the additives in fracturing fluids are not compatible with the flowback water....
- Top-Down Intelligent Reservoir Modeling of New Albany Shale
From Abstract: Although the New Albany Shale of the Illinois Basin has been estimated to contain approximately 86 TCF of natural gas in place, the full development of this potentially large resource has not yet occurred. The intent of this study is to reassess the potential of New Albany shale using a novel integrated workflow, which incorporates field production data and well logs using a series of traditional reservoir engineering analyses with artificial intelligence & data mining techniques... see full abstract.
- Shale Gas Potential in Triassic Strata of the Deep River Basin, Lee and Chatham Counties, North Carolina, USA
From Abstract: The Deep River Basin is a 150-mile long northeast-trending half-graben with a steeply-dipping eastern border fault in central North Carolina. The basin is filled with ~7,000 feet of Triassic strata, which are divided into the following three formations in descending stratigraphic order: (1) Sanford Formation (red and gray siltstone and shale); (2) Cumnock Formation (black shale, with some beds of gray shale, sandstone, and coal); and (3) Pekin Formation (gray sandstone and shale)... see full abstract.
- Shale Gas Potential of the Quebec Sedimentary Basins
From Abstract: Recent interest in unconventional gas resources has attracted several oil and gas explorers to sedimentary basins in Southern Quebec. The main target of this interest is the Middle Ordovician Utica Shale. Current knowledge of the area’s geology led industry tosubdivide the Shale-gas potential into different plays. JUNEX subdivided it into five different plays... see full abstract.
- Paradoxical Perceptions of Problems Associated with Unconventional Natural Gas Development
From Abstract: Data collected in a general population survey from a random sample of individuals in two counties located in the Barnett Shale region of Texas were used to empirically explore potentially problematic issues associated with unconventional natural gas development. Moderate support was found for the hypothesis that individuals residing in places with diverse levels of energy development exhibit dissimilar perceptions of potentially problematic issues... see full abstract.
- Water: A Natural Resource Critical for Development of Unconventional Resource Plays
From Abstract: The rapid development of unconventional resource plays throughout numerous geographical areas of the United States have one thing in common, they all are associated with the use of large amounts of water. All of the plays either need large amounts of water for development or large amounts of water are withdrawn in order to facilitate development. Unconventional natural gas resources include tight gas sands, coal-bed methane, and shale gas.... see full abstract.
- The Haynesville Play: A New Opportunity to Prove the Strategic Value of Natural Gas in Peak Oil Mitigation
From Abstract: ... According to the Hirsch Report, mitigation of a liquid fuels shortage without serious repercussions requires twenty years. However, it is likely that the world will encounter such a shortfall within two years. Thus, mitigation steps need to be implemented immediately. There will be no single solution for this problem; the solution path needs to follow what has sometimes been referred to as the all of the above plan. One short-term, partial mitigation step could be the widespread utilization of natural gas vehicles. Natural gas offers the only current alternative to gasoline and diesel as transportation fuel. And, thanks to the Haynesville, Marcellus, Fayetteville, and Barnett shale gas plays, natural gas is available in plentiful supplies... see full abstract.
- Screening Criteria for Shale-Gas Systems
From Abstract: In North America alone, more than 70 shale-gas plays have been identified. With this rapid increase in shale-gas production, shale-gas systems have presented many new challenges to production technology and the basic understanding of shale-gas reservoirs. Because gas shales are complicated and highly variable, the objective of this study was to indentify key controls on shale-gas productivity and to develop criteria for screening shale-gas systems... see full abstract.
- The Expanding Role of the Geologist in the Estimation of Resources/Reserves in Shale Gas Reservoirs
From Abstract: Resource and reserves estimation methodology for conventional oil and gas reservoirs is based in large part on the historic precedent of geologic and engineering evaluation over the last 150 years. Conversely, the methods used for shale gas reservoirs are recently developed and still evolving. Gas shale formations display complex reservoir characteristics, including free and adsorbed gas, natural fractures, and very low matrix permeability... see full abstract.
- The Role of the Geoscientist in the U.S. Federal Government
From Abstract: ... The Federal Government needs to understand the resource endowment of the United States, as well as the world, in order to craft energy policy, determine the best course for the country in light of its resource base, and manage Federal resources. Industry, on the other hand, determines oil and gas resources/reserves at a different scale (generally at the project level), in order to drill and develop the resource for a profit. The geoscientist working for a government entity may accordingly have a decidedly different perspective than one employed in the industry sector...see full abstract.
- Special Report: Gas Shale -1: Seven Plays Dominate North America Activity
The article reviews seven major gas shale plays in North America. The Barnett shale in Northern Texas was the first major play of the period. Chronologically, this was followed by Fayetteville, Woodford, Haynesville and Marcellus. The Horn River and Montney shales in British Columbia are also discussed. Gas production potential of American shales on average is 3-4 MMcfe/d (million cubic feet per day). The Marcellus shale (in its "sweet spots") averages about 5-9 MMcfe/d.
- Haynesville vs. Barnett; is my shale better than your shale?
A short industry piece comparing the maturity (a term referring to the type of hydrocarbons found in shale, which can be assessed with isotope analysis) of the Haynesville and Barnett shales. Leakage rates and permeability are also discussed.
- Siting and Permitting of Class II Brine Disposal Wells Associated with Development of the Marcellus Shale
Addresses siting and permitting issues for Class II disposal wells for brine disposal relating to drilling. Reviews the "regulatory environment in the Appalachian region, permitting timeframes, regulatory and permitting requirements, formations being considered for brine water disposal and the associated challenges."
- Fracture-Stimulation in the Marcellus Shale -- Lessons Learned in Fluid Selection and Execution
Describes lessons learned from early exploration days to current full-scale development phase of Marcellus shale in Pennsylvania. Discusses techniques to optimize fracture stimulation performance. Methods include empirical testing and trial and error approach. Evaluation and preparation of standing operating procedure (SOP) are highlighted.
- Where is All the Salt Coming from and What are the Implications?
Presents two possible arguments for elevated salt and TDS content after hydraulic fracturing: salt being dissolved from the shale, or are deep saline aquifers being breached. Results from 100 flowback analyses are discussed
- Deep Shale Natural Gas: Abundant, Affordable, and Surprisingly Water Efficient
Compares water efficiency of drilling in deep shale versus other activities
- Potential Economic and Fiscal Impacts from Natural Gas Production in Broome County, New York
Discusses benefits to Broome County of natural gas development, recommends no severance tax and regulatory environment that will encourage development. No discussion of potential costs.
- Marcellus 2008: Report Card on the Breakout Year for Gas Production in the Appalachian Basin
The article describes the potential for development of the Marcellus Shale. The formation has the potential to meet the natural gas demands of the United States for an estimated twenty years, given the current rate of consumption.
- Holistic Fracture Diagnostics: Consistent Interpretation of Prefrac Injection Tests Using Multiple Analysis Methods
Since the introduction of the G-function derivative analysis, prefrac diagnostic injection tests have become a valuable and commonly used technique. Unfortunately, the technique is frequently misapplied or misinterpreted, leading to confusion and misdiagnosis of fracturing parameters. This paper presents a consistent method of analysis of the G-function, its derivatives, and its relationship to other diagnostic techniques including square-root(time) and log(Δpwf)-log(Δt) plots and their appropriate diagnostic derivatives.
- An Emerging Giant: Prospects and Economic Impacts of Developing the Marcellus Shale Natural Gas Play
Summarizes economic benefits to PA from gas development and production. Discussion of threats to development including SDWA regulation and severance tax. No discussion of negative economic costs.
- Public Perception of Desalinated Water from Oil and Gas Field Operations: Data from Texas
This is a technical document detailing research on public perception of desalinated water and its safety. Data collected was used to explore issues associated with public perception of desalinated water from oil and gas field operations. The data, collected from two counties in central Texas, show that small percentages of respondents are familiar with the process of desalination and extremely confident that desalinated water could meet human drinking water quality and purity standards. Respondents are more favorably disposed toward the use of desalinated water for purposes other than ingestion by humans or animals. Respondents who are more familiar with desalination technology are more likely than to believe that desalinated oil and gas field water could be safely used.
- Environmental Protection for Onshore Oil and Gas Production Operations and Leases: American Petroleum Institute Recommended Practice 51R
- Fossil Fuel Extraction as a County Economic Development Strategy
Using a county-specific approach, this report discusses the positive and negative aspects of energy development in the western United States (1970-2005). The main findings of the report suggest that the counties which invest in natural resource extraction and energy development are underperforming in the long run compared to counties that value wildlife and recreation assets.
- Joint sets that enhance production from Middle and Upper Devonian gas shales of the Appalachian Basin
Technical discussion of structural characteristics of fractures (joints) in unconventional reservoirs in the Marcellus Shale
- Marcellus Shale Workforce Needs Assessment
From Abstract: The purpose of the Marcellus Shale Workforce Needs Assessment was to examine the expanding workforce of the natural gas industry currently engaged in developing the Marcellus Shale region and to determine the education and training needs required to support this expanding workforce. This assessment was created by the Marcellus Shale Education & Training Center (MSETC), which was formed to serve as a primary workforce development resource for the natural gas industry... see full text.
- The Contribution of Shale Gas to Future U.S. Production: A View of the Resource Base
From Abstract: Projections published in 2008 by the United States government indicated that annual U.S. gas demand could increase from the current 22 Tcf (trillion cubic feet) to 24 Tcf by the year 2016 and then decline to 23 Tcf by 2030. This would occur during a period of declining Canadian gas imports and increasing U.S. reliance on LNG imports, a commodity only available in a highly competitive market. To put these numbers into perspective, a 1 Tcf/year increase is a challenge: domestic gas production was flat for nine years prior to 2006... see full abstract
- Gas Shale Reservoir Characteristics from the Pennsylvanian of Southeastern Utah, USA
From Abstract: Calcareous, organic-rich, dark brown-gray mudstones from the Paradox Basin of southeastern Utah are now recognized as gasproductive. These comparatively thin deposits (less than 80 feet each based on log analysis), belonging to the Hovenweep, Gothic, and Chimney Rock shales of the Paradox Formation cycles, possess modest TOC values (1-2%) and appear transitional (oil to gas window) in terms of locally-pertinent thermal maturation... see full abstract.
- Marcellus Shale -- Geologic Controls on Production
From Abstract: The modern era of Marcellus Shale production in the Appalachian Basin began in 2004 when Range Resources completed the Renz Unit #1 well in Washington County, Pennsylvania using a large Barnett style slick water frac. This well tested at commercial rates and led to the current drilling boom targeting the Marcellus Shale... see full abstract.
- The Middle Devonian Marcellus Shale - a Record of Eustacy and Basin Dynamics
From Abstract: The stratigraphy of the Middle Devonian Marcellus Shale of the Appalachian Basin reflects the interplay of Acadian-related flexural loading of the Laurentian craton and two rapid sea level rises. Accumulation of the Union Springs Shale, the lower unit of the Marcellus Shale, over the variably eroded Onondaga Limestone was coincident with a middle Eifelian rise in sea level (T-R Cycle 1d) and the onset of Tectophase II of the Acadian Orogeny... see full abstract.
- Structural Attribute Analysis Used in Barnett Resource Development, Fort Worth Basin, Texas
From Abstract: Successful completions in the shale of the Barnett Formation require a combination of high quality geology and geophysics in association with high technology drilling and completion engineering. Large areas of the Barnett play contain challenging conditions that make economic completions more difficult. These challenges can be geological (faulting and karsting), geophysical (gas effects and velocities), and engineering (Barnett thickness and lack of frac barriers)... see full abstract.
- Sequence Stratigraphy, Depositional Environments, and Production Fairways of the Haynesville Shale-Gas Play in East Texas
From Abstract: The upper Jurassic (Kimmeridgian) Haynesville shale is an important shale-gas resource play in East Texas and Louisiana. Estimated recoverable reserves are as much as 60 Tcf, with each well producing on the average of 6.5 Bcf. Haynesville carbonates are known for their excellent production from carbonate shoals and pinnacle reefs in the East Texas Salt Basin. However, sequence stratigraphy and depositional setting of the Haynesville shale is not well documented... see full abstract.
- Fracture Interpretation in the Barnett Shale Using Macro and Microseismic Data
From Abstract: The Barnett Shale was deposited in the Fort Worth Basin during the Mississippian in a marine setting and unconformably overlies Ordovician carbonates. In the area of this study, the underlying Viola limestone has been eroded, juxtaposing the Barnett Shale against the porous and water-bearing Ellenberger Limestone. We explore the challenge of Barnett Shale development: to maximize stimulated reservoir volume within the shale, without tapping the adjacent Ellenberger water reservoir... see full abstract.
- The Geologist and the Engineer -- In Need of Each Other More than Ever
From Abstract: Historically, earth scientists ponder maps, logs and other data in search of prospective hydrocarbon traps. A map with a carefully placed location would be provided to the engineering group. The well was then designed and drilled. The groups would exchange information to insure the target was hit in an optimal position and, if successful, completed in the target formation... see full abstract.
- Lithofacies, Depositional Environment, Burial History and Calculation of Organic Richness from Wireline Logs: A Study of the Barnett Shale in the Delaware Basin, Pecos Co., West Texas, and Comparison with the Barnett Shale in the Fort Worth Basin
From Abstract: Studies of core and logs through the Barnett Shale in Pecos County in the southern part of the Delaware Basin have allowed us to compare the lithofacies and depositional environment of the Mississippian in this area with that in the Fort Worth Basin. Overall, mudrock facies are similar although, in contrast, the studied core contains no skeletal debris layers. Limestone concretions were not seen, but there is substantial dolomite in many horizons... see full abstract.
- Preliminary Investigation of the Thermal Maturity of Pearsall Formation Shales in the Maverick Basin, South Texas
From Abstract: The Aptian Pearsall Formation, a regionally occurring limestone and shale package of 500-600 ft maximum thickness, is being evaluated as part of an ongoing U.S. Geological Survey assessment of undiscovered hydrocarbon resources in onshore Lower Cretaceous strata of the northern Gulf of Mexico. Pearsall Formation units are, in ascending stratigraphic order, the Pine Island Shale, James Limestone, and Bexar Shale members... see full abstract.
- Eagleford Shale Exploration Models: Depositional Controls on Reservoir Properties
From Abstract: ... This study focuses on an area extending from LaSalle County in the southwest through Atascosa, Wilson, and Gonzales to Fayette County on the northeast and down-dip through Webb, McMullen, Live Oak, Karnes, and Dewitt counties. Two fundamental plays are found in this region, separated by the Stuart City Edwards reef trend. Up-dip of the reef margin, the Eagleford is normally pressured, primarily an oil reservoir, characterized by significant lateral variability in organic-rich shale abundance and reservoir quality related to reef margin controlled depocenters... see full abstract.
- Water Resources and Natural Gas Production from the Marcellus Shale
From Introduction: ...The production of commercial quantities of gas from this shale requires large volumes of water to drill and hydraulically fracture the rock. This water must be recovered from the well and disposed of before the gas can flow. Concerns about the availability of water supplies needed for gas production, and questions about wastewater disposal have been raised by water-resource agencies and citizens throughout the Marcellus Shale gas development region. This Fact Sheet explains the basics of Marcellus Shale gas production, with the intent of helping the reader better understand the framework of the water-resource questions and concerns... see full text.
- The nanogranular acoustic signature of shale
From Abstract: A multiscale, micromechanics model has been developed for the prediction of anisotropic acoustic properties of shale. The model is based on the recently identified nanogranular mechanical response of shale through indentation experiments. It recognizes the dominant role of the anisotropic elastic properties of compacted clay in the anisotropic elasticity of shale at different length scales compared to contributions of shape and orientation of particles... see full abstract.
- A simplified model of effective elasticity for anisotropic shales
A simple method to deal with cracklike pores in anisotropic matrix rock such as shales enhances analytical models and their applications. Actually, clayrocks (shales, in particular) are the dominant clastic component in sedimentary basins, representing about two-thirds of all sedimentary rocks. Shales are usually assumed to be transversely isotropic (TI) media. They are known to be highly anisotropic because of (1) intrinsic elastic anisotropy of the solid phase (matrix) forming the rock (more or less ordered clay layers) and (2) anisotropy induced by the presence of cracklike pores. We focus on this second component of anisotropy. Current analytical models deal with it, but they are complex and are restricted in the case of matrix TI symmetry to cracks lying in the symmetry plane. We simplify such models within a reasonably good approximation and develop an analysis scheme in which cracklike pore effects are calculated in an equivalent isotropic matrix. This simplifies the theoretical approach and potentially broadens its application to any crack and/or pore orientation, e.g., damaged shale with horizontal and vertical (perpendicular to the bedding plane) cracks. A high-pressure confinement test provides experimental data for checking the proposed tool against a reference model in the case of cracklike pores lying in the bedding plane. The results (in terms of Thomsen parameters) are consistent with results from large-scale field data.
- Rate transient analysis in shale gas reservoirs with transient linear behavior.
From Abstract: Many hydraulically fractured shale gas horizontal wells in the Barnett shale have been observed to exhibit transient linear behavior. This transient linear behavior is characterized by a one-half slope on a log-log plot of rate against time. This transient linear flow regime is believed to be caused by transient drainage of low permeability matrix blocks into adjoining fractures... See Full Abstract
- State Oil and Natural Gas Regulations Designed to Protect Water Resources
The GroundWater Protection Council conducted a study to answer the question, "Do state oil and gas regulations protect water?" In short, yes they do. The study consists of the history of environmental regulations from the 1930's, when water was seen as a nuisance, to modern day. In regards to regulations, the GroundWater Protection Council sought to review oil and gas regulations in eight areas. These areas include hydraulic fracturing, tanks, waste handling and spills, and permitting.
- Modern Shale Gas Development in the U.S.: A Primer
Summarizes gas shale development in progress; gives an overview of the relevant regulatory framework; covers environmental considerations such as radioactive material, management of water returning from drilled wells, air quality, etc.
- Pore throat sizes in sandstones, tight sandstones, and shales
Pore-throat sizes in siliciclastic rocks form a continuum from the submillimeter to the nanometer scale. That continuum is documented in this article using previously published data on the pore and pore-throat sizes of conventional reservoir rocks, tight-gas sandstones, and shales. For measures of central tendency (mean, mode, median), pore-throat sizes (diameters) are generally greater than 2 m in conventional reservoir rocks, range from about 2 to 0.03 m in tight-gas sandstones, and range from 0.1 to 0.005 m in shales. Hydrocarbon molecules, asphaltenes, ring structures, paraffins, and methane, form another continuum, ranging from 100 A (0.01 m) for asphaltenes to 3.8 A (0.00038 m) for methane. The pore-throat size continuum provides a useful perspective for considering (1) the emplacement of petroleum in consolidated siliciclastics and (2) fluid flow through fine-grained source rocks now being exploited as reservoirs.
- Compositional variety complicates processing plans for US shale gas
- Getting to the nitty of Barnett's gritty; studies shedding shale's secrets
This brief industry article discusses ongoing research efforts by a University of Oklahoma team on the stratigraphic and physical characteristics of the Barnett Shale in the Fort Worth Basin. The study involves systematic mapping and resevoir characterization.
- Drill Baby Drill: The Rush for Natural Gas from the Marcellus Shale Formation in NY
The environmental impacts of natural gas development on water resources, with an emphasis on distribution of costs and benefits.
- An Enduring Resource: A Perspective on the Past, Present, and Future Contribution of the Barnett Shale to the Economy of Fort Worth and the Surrounding Area
This article describes how activity in the Barnett Shale has improved the economy of Fort Worth and the surrounding area. Fort Worth has been able to withstand economic downturn because the Barnett Shale provides an important source of stimulus. The number of jobs provided by the Barnett Shale activity has benefited Texas¿s economy overall, although exploration has been temporarily slowing. Ultimately, this article supports the Barnett Shale as an enduring resource that Forth Worth¿s economy is healthier with than without.
- Final scope for draft Supplemental Generic Environmental Impact Statement (dSGEIS) on the oil, gas and solution mining regulatory program well permit issuance for horizontal drilling and high-volume hydraulic fracturing to develop the Marcellus Shale and other low-permeability gas reservoirs
In NY State, realization of environmental impacts from high-volume hydraulic fracturing necessitated preparation of a special EIS (a dSGEIS) prior to state-wide well permit issuance. This Final Scope covers several impacts: (1) water withdrawals, (2) transportation of water to site, (3) additives involved in hydraulic fracturing, (4) on-site space and facilities required for handling of water and additives, (5) removal of spent fracturing fluid from site (6) impacts of multiple wells; and includes consideration of public comments
- Accommodating a New Straw in the Water: Extracting Natural Gas From the Marcellus Shale in the Susquehanna River Basin
The Marcellus Shale underlies approximately 72% of the area of the Susquehanna River Basin. The Susquehanna River Basin Commission (SRBC) is charged with managing water resources in the Susquehanna River Basin and has authority over water withdrawals in the basin. Concerns over water withdrawal in regards to the Marcellus Shale, as stated by the article, are focused not on quantity, but rather the location and timing of withdrawals and on their impacts on smaller order streams. The SRBC has made projections regarding the impact of Marcellus Shale extraction on aquatic life and the basin as a whole. Such effects include but are not limited to: water contamination, excessive lowering of water levels, and causing permanent loss of aquifer capacity. This source concludes that while the cumulative impact of water consumption for gas extraction is significant, this demand can be accommodated given mitigation standards currently in place.
- The Influence of the Pace and Scale of Energy Development on Communities: Lessons from the Natural Gas Drilling Boom in the Rocky Mountains
Both the number of oil and gas wells drilled annually2 (U.S. Department of Interior [U.S.D.I.], Bureau of Land Management 2009) and the number of producing natural gas wells3 (U.S. Department of Energy 2009) in the Rocky Mountain region4 more than doubled from 1998 to 2008. The proportion of U.S. natural gas production from the region increased from 16% in 1997 to 23% in 2007 (U. S. Department of Energy 2009) and the number of drilling rigs operating in the region grew from 131 in 2002 to 318 in 2009.5 This increase in natural gas drilling in the region has created boomtown conditions in several rural communities.
- Marcellus gas well water supply and wastewater disposal, treatment, and recycle technology
- The Not-So-Safe Drinking Water Act: Why We Must Regulate Hydraulic Fracturing at the Federal Level
From Introduction: ...This note will explore the weaknesses embodied within the Safe Drinking Water Act that merely permit the EPA to create national mandatory drinking water regulations at its discretion. It will suggest that with respect to hydraulic fracturing, permissive attitudes cannot be tolerated; in order to cure the obvious water contamination problems this process creates, nothing short of a national mandatory scheme will suffice.... see full text.
- Morphology, genesis, and distribution of nanometer-scale pores in siliceous mudstones of the Mississippian Barnett Shale
From Abstract: Research on mudrock attributes has increased dramatically since shale-gas systems have become commercial hydrocarbon production targets. One of the most significant research questions now being asked focuses on the nature of the pore system in these mudrocks. Our work on siliceous mudstones from the Mississippian Barnett Shale of the Fort Worth Basin, Texas, shows that the pores in these rocks are dominantly nanometer in scale (nanopores). We used scanning electron microscopy to characterize Barnett pores from a number of cores and have imaged pores as small as 5 nm... see full text.
- Introduction to Hydromechanical Well Tests in Fractured Rock Aquifers
This article introduces hydromechanical well tests as a viable field method for characterizing fractured rock aquifers. These tests involve measuring and analyzing small displacements along with pressure transients. Recent developments in equipment and analyses have simplified hydromechanical well tests, and this article describes initial field results and interpretations during slug and constant-rate pumping tests conducted at a site underlain by fractured biotite gneiss in South Carolina. The field data are characterized by displacements of 0.3 μm to more than 10 μm during head changes up to 10 m. Displacements are a hysteretic function of hydraulic head in the wellbore, with displacements late in a well test always exceeding those at similar wellbore pressures early in the test. Displacement measurements show that hydraulic aperture changes during well tests, and both scaling analyses and field data suggest that T changed by a few percent per meter of drawdown during slug and pumping tests at our field site. Preliminary analyses suggest that displacement data can be used to improve estimates of storativity and to reduce nonuniqueness during hydraulic well tests involving single wells.
- The velocity and attenuation anisotropy of shale at ultrasonic frequency
The velocity and attenuation anisotropy of dry and oil-saturated shale were measured at laboratory ultrasonic frequency by using the transmission technique. Our purpose is to find the variation rules of wave velocity and attenuation in different directions as a function of effective pressure in dry and oil-saturated situations, and those intrinsic factors that result in such anisotropy. Using x-ray diffraction techniques and a scanning electron microscope, the causative factors for the velocity anisotropy are found to be mainly due to the alignment of clay mineral and microcracks. The attenuation of P- and S-waves also shows apparent directional dependence, but different from that of velocities. Attenuation anisotropy can be interpreted in terms of grain and pore geometry. For dry shale samples, the dominant attenuation mechanism is phase hysteresis due to static friction. On one hand, the Biot flow plays a key role in causing wave attenuation for the P-wave propagating parallel to bedding for fluid-saturated samples. On the other hand, the fluid-related attenuation is mainly attributed to the mechanisms of squirt flow for the P-wave propagating vertical to bedding.
- Measuring the Economic and Energy Impacts of Proposals to Regulate Hydraulic Fracturing
- Stress-dependent anisotropy in transversely isotropic rocks: Comparison between theory and laboratory experiment on shale
Understanding the effect of stress and pore pressure on seismic velocities is important for overpressure prediction and for 4D reflection seismic interpretation. A porosity-deformation approach (originally called the piezosensitivity theory) and its anisotropic extension describe elastic moduli of rocks as nonlinear functions of the effective stress. This theory assumes a presence of stiff and compliant parts of the pore space. The stress-dependent geometry of the compliant pore space predominantly controls stress-induced changes in elastic moduli. We show how to apply this theory to a shale that is transversely isotropic (TI) under unloaded conditions. The porosity-deformation approach shows that components of the compliance tensor depend on exponential functions of the principal components of the effective stress tensor. In the case of a hydrostatic loading of a TI rock, only the diagonal elements of this tensor, expressed in contracted notation, are significantly stress dependent.
- An Introduction to Natural Gas Development and Workforces
This article describes the four phases involved in natural gas drilling: predevelopment or exploratory phase, development phase, production phase, and reclamation phase. Each phase's activities and required workforce are outlined. It includes a glossary of oil and gas terms.
- A review of the potential effects of coal bed natural gas development activities on fish assemblages of the Powder River geologic basin
From the abstract: Coal bed natural gas (CBNG) development in the Powder River geologic basin (PRGB) may alter water quality, quantity, or aquatic habitats. CBNG product water is generally higher than surface waters in dissolved sodium and bicarbonate and sometimes exceeds toxicity levels for fathead minnows and daphnids. Montana and Wyoming water quality standards do not account for differential ion toxicity; toxicity data for most fishes of the PRGB are lacking, and there are minimal data available on composition of CBNG product water. One field study suggests that CBNG may limit fish distribution. See full abstract
- Factors affecting erosion on a natural gas pipeline in the central Appalachians
From the abstract: High fuel prices have created an economic climate in which oil and gas development is increasingly profitable, and consequently increasing rapidly in the United States. This is especially true in the northern Appalachian region where the relatively undeveloped Marcellus shale formation is located. The Marcellus formation has been called a "super giant" gas reservoir possibly containing 50 trillion cubic feet... See full abstract
- Assessment of Industry Water-Use in the Gas-Producing Barnett Shale Area (Fort Worth Basin)
- Energy Boomtowns and Natural Gas: Implications for Marcellus Shale Local Governments and Rural Communities
From Executive Summary:... It is the goal of this paper to provide information that will assist officials, researchers, and citizens engaged in Marcellus Shale to better analyze and prepare for both the positive and negative impacts facing their communities. This paper is organized into three areas, (1) a compendium of summaries and prominent research on the Boomtown Impact Model, (2) a comprehensive overview of the contemporary example of natural gas drilling in the area of Sublette County, Wyoming, and (3) a discussion on the similarities and contrasts to, and some of the implications for, the Marcellus Shale region... see full text.
- Drilling Around the Law
Companies that drill for natural gas are skirting federal law and injecting toxic chemicals, threatening drinking water supplies. These chemicals often contain high levels of carcinogens. These chemicals are injected through hydraulic fracturing.
- Emissions from Natural Gas Production in the Barnett Shale Area and Opportunities for Cost-Effective Improvements
Natural gas production is prevelant in the Barnett Shale region of Texas. Natural gas has many environmental benefits over coal as an energy source. Oil and gas production from Barnett Shale can impact air quality and release greenhouse gases. The objective of this study is to develop an emissions inventory and identify cost-effective emission controls.
- Sustainable Development and Design of Marcellus Shale Play in Susquehanna, PA
Natural gas production has been increasing through the development of gas shales. Marcellus Shale produces an unconventional gas because the gas occurs in a formation where it is unable to flow easily. Drilling into Ohio's Marcellus Shale will be more complex than in New York, Pennsylvania, and West Virginia because the gas is usually accompanied by petroleum or other liquids which must be separated. Part of this report will focus on developing a sustainable project for Susquehanna County for exploration and production of natural gas.
- Regulation and Permitting of Marcellus Shale Drilling
Regulating Marcellus Shale requires federal, state and local levels of government. Because of the rapid demand to develop natural gas, authorities and agencies are forced to balance long-term concerns with industry demands for expedited drilling permits. Economic concerns and the desire to promote energy independence accelerate this timeline.
- Evaluation of High TDS Concentrations in the Monongahela River
Addresses the issue of flowback waters from the natural gas industry being disposed of in wastewater and sewage treatment plants. A 16-month study from 2007 - 2008 looking at sources contributing to total dissolved solids (TDS) and mass loadings of sulfate in the Monongahela River of Pennsylvania. Compares the influence of discharge from natural gas development relative to other environmental sources such as mine drainage, as well as broader factors like drought.
- Analysis of hydraulic fracture propagation in fractured reservoirs: An improved model for the interaction between induced and natural fractures
From the abstract: Large volumes of natural gas exist in tight fissured reservoirs. Hydraulic fracturing is one of the main stimulating techniques to enhance recovery from these fractured reservoirs. Although hydraulic fracturing has been used for decades for the stimulation of tight gas reservoirs, a thorough understanding of the interaction between induced hydraulic fractures and natural fractures is still lacking. Recent examples of hydraulic fracture diagnostic data suggest complex, multi-stranded hydraulic fracture geometry is a common occurrence. The interaction between pre-existing natural fractures and the advancing hydraulic fracture is a key condition leading to complex fracture patterns.... See full abstract.
- Got a light, shaler?
- Fracturing of layered reservoir rocks
- Barnett Shale (Mississippian) lithofacies, Fort Worth Basin, Texas
From the abstract: Five facies are present in the Barnett Shale (Mississippian) in a core taken in the southern part of the Fort Worth basin. Facies A is a laminated, silty claystone to siltstone with glauconite grains and sand-sized shale rip-up clasts.... See full abstract.
- A study of the effects of well and fracture design in a typical Marcellus shale well
From the abstract: The problem with typical Marcellus shale wells is the lack of information that has been accumulated and the amount of information that is commercially available to the public.... Through reservoir simulation, the Marcellus could be studied to find effects of these parameters. The objective of this study is to compare and contrast the gas production in vertical wells.... See full abstract
- Production decline analysis of horizontal well in gas shale reservoirs
From Introduction: Conventional hydrocarbon reservoirs have been a major supplier of natural gas in the United States for the past years, however, these reservoirs are running out of supply and are becoming extremely difficult to locate and exploit with the present technology and techniques available. Conventional reservoirs are formed when... See Full Introduction
- Local Leaders' Perceptions of Energy Development in the Barnett Shale
From Abstract: In recent decades, the production of natural gas from unconventional reservoirs (i.e., tight gas sands,coalbed methane resources, and gas shales) has become commonplace within the U.S. energy industry. The Newark East Fort Worth Basin field–called in the vernacular, the Barnett Shale–in north-central Texas is oneof the largest unconventional natural gas fields (by production volume) in the United States. Unlike many conventional energy development projects... See Full Abstract.
- Untested Waters: The Rise of Hydraulic Fracturing in Oil and Gas Production and the Need to Revisit Regulation
From Abstract:... This Article describes the process of hydraulic fracturing, existing studies of the environmental effects of hydraulic fracturing, and the laws and regulations that apply to the practice. It argues that there is no direct federal regulation of the fracing process (the pumping of fluids into a wellbore), that court guidance in this area is limited, and that state regulations differ substantially... see full text.
- Effect of well configurations on productivity index of gas well producing from shale
From Abstract: This study investigates the effect of various well configurations (designs) and their impact on the productivity index of shale gas wells. Five different well configurations (Multilateral wells) are compared with a single horizontal well, which is taken as a base case (BC). Both the base case and the different well configurations have the same drainage area, the initial gas in place and the total lateral lengths are equal... See Full Abstract
- Potential Development of the Natural Gas Resources in the Marcellus Shale: New York, Pennsylvania, West Virginia, and Ohio
Impacts and concerns regarding oil and gas development on areas overlain or near National Park lands, including environmental impacts, visitor health and safety, quality of visitor experience. Suggestions for mitigating actions.
- The Economic Impact of the Oil and Gas Industry in Pennsylvania
An economic impact study of the oil and gas industry in PA. Examines industry's annual positive impact on state economy using the "IMPLAN" model and using 2007 as a baseline. No discussion of negative economic costs.
- Critical Evaluations of Additives Used in Shale Slickwater Fracs
From Abstract: ...The purpose of this work is to examine water treatment techniques and critically evaluate the performance of additives that are employed in slickwater fracs of shale reservoirs and give guidelines for selecting additives that will optimize performance during pumping, fluid recovery and production. Comments will be made on the topic of proppant selection... see full abstract.
- Marcellus Shale Exploration and Farmland Preservation in Pennsylvania
The recent boom in drilling for natural gas will have an effect on the farmland and land trusts within the Marcellus Shale region. Preserved land will feel pressured to permit drilling if the concentration of natural gas is large enough. This paper will discuss the itnersection of drilling and farmland preservation.
- Using ArcGIS to Estimate Thermogenic Gas Generation Volumes by Upper and Middle Devonian Shales in the Appalachian Basin
From Abstract: Using ArcGIS and a geochemical database from GeoMark’s Appalachian Basin Petroleum System Study, we estimate the volume of high maturity thermogenic gas generated by both the Marcellus and the Ohio sections of the Appalachian Devonian Shale. A new parameter, TOCgen, that represents the amount of organic carbon attributable to hydrocarbon generation, was calculated using TOCpd (present day TOC) and TOCo (original TOC) maps for the Devonian Marcellus and Ohio Shales... see full abstract.
- Faulting and fracture heterogeneity in black shales of the Appalachian Basin of New York State
From Abstract: Numerous fault systems in the Appalachian Basin of NYS were reactivated during the development of the Ordovician and Devonian shale basins. These faults influenced not only the depositional patterns of the black shales, but also influenced later localized fracturing of the shales. These fault systems include (among others) reactivated intra-Grenvillian sutures and Iapetan-opening faults. The reactivated and newly developed fault systems resulted in local stress deviations of a regularly varying far-field SH... see full abstract.
- Regional Geochemical Evaluation of the Ordovician Utica Shale Gas Play in Quebec
From Abstract: ... Rock-Eval analyses were performed on 50 outcrops and more than 60 wells (>700 cuttings samples) to evaluate the regional geochemical variability of the Utica Shale, and ultimately to identify “sweet spots”. XRD analyses were also carried out to determine the mineralogical composition of the shales. Preliminary results show that the Utica has TOC values generally ranging between 0.3 and 5 percent (average of 1.2% TOC), with 25% of the values being above 1.5% TOC. The mineralogy consists mainly of illite, calcite and quartz, which suggests good “fracturability” potential... see full abstract.
- Tectonism, estimated water depths, and the accumulation of organic matter in the Devonian-Mississippian black shales of the northern Appalachian basin
Water depths during deposition of the Devonian-Mississippian black shales of eastern North America have been estimated at anywhere from “knee-deep” to thousands of meters, but both end-member estimates are probably incorrect. Similarly, physical, paleontological, and geochemical bathymetric indicators suggest overall deepening with time, but offer little evidence of the depths involved. Nonetheless, occurrence of the black-shale sequence in the northern Appalachian Basin as alternating units of black shale and intervening coarser clastic wedges not only reflects the cyclic nature of Acadian tectonism in adjacent orogenic source areas, but also provides a means for approximating water depths during black-shale deposition. These black shales clearly accumulated in a foreland-basin setting in which each black-shale unit represents an episode of rapid, foreland, tectonic subsidence below the pycnocline (anaerobic conditions) and subsequent infilling of the basin with shales and coarser clastics into higher, dysaerobic and aerobic parts of the water column. Due to the largely, one-time nature of any subsidence event, measuring the thickness of a clastic wedge from the top of the basinal black shale to a sea-level datum in the overlying coarser-clastic counterpart provides an approximation of absolute depth. Because some basins were underfilled and because the varying effects of compaction cannot be easily considered, the estimates are minimal at best. Nonetheless, the exercise provides order-of-magnitude estimates and reflects depths ranging from 80 to 310 m during deposition of Lower Devonian- through-Lower Mississippian black shales in the northern Appalachian Basin. The estimates not only show a general deepening with time, but also reflect shallowing-upward, third-order cycles that coincide with the timing of unconformity-bound sequences containing one or more, black shale-clastic wedge cycles. To confirm the origin of the cycles, the distribution of black shales in each cycle was mapped in space and time, which showed that black-shale units clearly tracked the progress of Acadian tectonism as predicted by flexural models.
Increasing depths over time probably in large part reflect the cumulative effects of tectonic loading, but the Devonian was also a time of eustatic sea-level rise, and this, together with a unique paleogeographic setting, probably ensured large areas of enhanced organic productivity and the deep, stratified waters necessary to preserve it. It is probably no accident that the youngest — and deepest — of the black shales contains the highest amounts of organic matter. Hence, attention to estimated depths, combined with the extent of respective black-shale basins, may provide information about the likelihood and location of the most organic-rich source rocks.
- Pyrite Laminae In Black Shale-An Additional Source of Permeability In Unconventional Reservoirs
Study looks at the connection between the presence of abundant pyrite and increased permeability for gas in Devonian shale reservoirs in the Marcellus Shale.
- Hydraulic Fracturing Considerations for Natural Gas Wells of the Marcellus Shale
From Abstract: The issue of hydraulic fracturing has raised many concerns from the public as well as government officials. This paper will review the history and evolution of hydraulic fracturing, including environmental and regulatory considerations. Additionally, technical and environmental considerations will be presented applicable to hydraulic fracturing in the unconventional arena of gas shales with an emphasis on the Marcellus Shale of the Appalachians. Topics addressed in the paper will include... see full abstract.
- Potential Exposure-Related Human Health Effects of Oil and Gas Development: A White Paper
Scientific research has shown that human health risks and social impacts stem from oil and gas development. This research supports the need for a Health Impact Assessment to accompany each Environmental Impact Statement. This paper focuses on Garfield County, Colorado to show potential exposure-related health impacts from oil and gas development.
- Barnett shale showcases tight-gas development
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- Hydrocarbon potential of the Barnett Shale (Mississippian), Delaware Basin, west Texas and southeastern New Mexico
The Barnett Shale (Mississippian) in the Delaware Basin has the potential to be a prolific gas producer. The shale is organic rich and thermallymature over large parts of the basin.Depths to the Barnett range from 7000 ft (2133 m) along the western edge of the basin to more than 18,000 ft (5486 m) along the basin axis. The Barnett Shale began generating petroleum about 250 Ma and reached its maximum temperature about 260 Ma. Present-day thermal maturity is indicative of maximumburial and temperature.Wells in northern ReevesCounty are in the gas window based on measured vitrinite reflectance values and kerogen transformation ratios. The shale can be divided into an upper clastic unit and a lower limy unit by changes in resistivity. The lower unit can be subdivided into five subunits by distinctivewell-logmarkers. Preliminary analyses
suggest that intervals in the lower Barnett marked by high resistivity and high neutron porosity readings on well logs have high gas contents. Areas in which to focus the future exploration in the lower Barnett can be delineated by mapping a net resistivity greater than 50 ohm m. The Barnett Shale contains significant gas resources in the Delaware Basin. Realizing the potential of these resources depends on the current efforts to optimize drilling and completion techniques for this shale-gas
- What Lies Beneath: Natural-Gas Drilling in the Northeastern U.S. Threatens Water Quality
This news article discusses environmental consequences of the Marcellus Shale gas boom. The rapid development has lead to rapid changes within Pennsylvania. The water pumped out of wells contains metals, sulfides, radioactive material and some additives. This can have adverse effects on drinking water. Some operations have been shut down after improper well construction or waste disposal. Long-term solutions are needed to help offset current problems.
- The Economic Impact of the Natural Gas Industry in West Virginia
Examines direct and indirect economic benefits of gas development in WV.
- A field study in optimizing completion strategies for fracture initiation in Barnett Shale horizontal wells
The Barnett shale is an unconventional gas reservoir that currently extends over an estimated 54,000 sq miles. In an effort to improve well economics and to reduce the number of surface locations in populated areas, the number of wells being drilled and completed has rapidly increased. With this change in development strategy, operators and service companies alike have had to search for innovative solutions to overcome challenges faced in horizontal completions.
Inefficient fracture initiation is the largest reoccurring problem encountered when completing horizontal Barnett shale wells. These difficulties have manifested themselves as high-fracture initiation and propagation pressures, which lead to low injection rates and high treating pressures. These losses reduce the efficiency of proppant placement and stimulation. As drilling activity has increased over the past couple of years, fracture-initiation problems are now a substantial source of expense and downtime.
This field study examines 256 horizontal Barnett shale wells in an effort to identify the causes of these near-wellbore issues and to offer corrective solutions for future completions. The goal of this study is to recommend an optimized completion strategy to minimize these near-wellbore problems, increase stimulation coverage, and decrease unplanned completion expenses.
In 2005, 19% of the stages in horizontal wells examined encountered near-wellbore difficulties. This field study inspects the major contributors to fracture initiation, specifically focusing on cemented vs. uncemented laterals, horizontal-stress anisotropy, perforation strategy, cementing strategy, and stimulation design.
The paper offers statistics on which changes have had the greatest effect on stimulation placement. These problems can cost operators an additional 25% per stage or more. Using these optimized strategies has reduced by 74% the number of stages in which fracture-initiation difficulties have been encountered.
- Development of Produced Water Management and Treatment Strategies
From Abstract: Produced water management and treatment has the potential to substantially enhance production and reduce the overall cost of developing unconventional petroleum resources, while minimizing adverse environmental impacts. In many locations, unconventional gas production is limited because adequate water management strategies have not been developed... There is a clear need and strong economic drivers to develop integrated approaches to improve treatment, handling, disposal, and beneficial use of produced water... see full abstract.
- Marcellus Shale Play's Vast Resource Potential Creating Stir In Appalachia
Background information, including brief history, geologic discussion of joints, fractures, and faults, and hydraulic fracturing prepared by two professors of geoscience.
- The Economic Impact of Marcellus Shale in Northeastern Pennsylvania
In this report, the Joint Urban Studies Center (JUSC) examines increased business activity and population growth in northeastern Pennsylvania due to increased natural gas production and industry employment. This report also looks at natural gas plays in other U.S. regions, including Dallas/Fort Worth, Texas region (Denton County) and the Fayetteville Shale area in Arkansas (Faulkner and White Counties). In the case studies discussed, communities experienced economic growth through significant employment and revenue increases. The report outlines the potential cash flow of typical Pennsylvania wells and potential royalties a landowner may receive.
- Development of Marcellus Shale-Water Resource Challenges
This document principally addresses the implications of natural gas drilling fracturing from a water law and water rights perspective. The main emphasis of the report is on hydraulic fracturing in the Marcellus Shale, and more specifically, what is the effect of consumptive water use? Riparian rights and watershed impacts are also discussed. A brief explanation is given of regulations from certain Marcellus Shale states, like Pennsylvania and New York, as well as neighboring states like Ohio and Kentucky. A hypothetical example of water use is also used to describe water rights.
- Shale Gas: Focus on the Marcellus Shale
Sponsored by the Oil & Gas Accountability Project/Earthworks. This report provides summary and background information on some of the potential issues (including radioactivity and water use concerns) that may be important to consider if full-scale development occurs in the Marcellus shale.
- Shale Gas Opportunities and Challenges
- A Mushwad of Floyd Shale in the Appalachian Thrust Belt in Alabama, Combining the Structure of the Conasauga Gas Play with the Stratigraphy of the Floyd Gas Play
From Abstract: In the southern Appalachian thrust belt in Alabama, tectonically thickened, ductilely deformed duplexes (mushwads) of the Middle Cambrian shale-dominated Conasauga Formation recently have become an important shale gas objective. Meanwhile, the Upper Mississippian Floyd Shale (an approximate lithologic and temporal equivalent of the Barnett Shale) is a shale gas prospect in the Black Warrior foreland basin in northeastern Mississippi and northwestern Alabama... see full abstract.
- Advanced Horizontal Technologies Improve Drilling Performance in the Barnett Shale
From Abstract: The Barnett Shale is the producing reservoir in the most productive and fastest growing natural gas field in North America. It has a multi-trillion cubic feet equivalent upside potential but poses several drilling and completion challenges. A precise evaluation of the bedding planes, natural and induced fractures is critical to maximize the shale gas recovery... see full abstract.
- Natural Fractures in Shales: Origins, Characteristics and Relevance for Hydraulic Fracture Treatments
From Abstract: Most shales contain natural fractures. We review common fracture types and their characteristics based on core and outcrop studies from several different shales, including Devonian Woodford shales from the Permian basin and the Mississippian Barnett Shale of the Fort Worth basin. We measured the subcritical crack index of different shale facies. Geomechanical modeling using the index as an input parameter allows prediction of fracture clustering... see full abstract.
- Use of Fracture-Mapping Technologies to Improve Well Completions in Shale Reservoirs
From Abstract: ... This paper will present recent case studies on different types of shale fracture completions along with microseismic mapping results of actual fracture network growth. Over two-hundred wells have been mapped in shale reservoirs with microseismic imaging and tiltmeter fracture mapping over the past several years. The fracture mapping allows for direct measurement of the fracture network orientation, height, length and width, as well as interaction with local geology such as faults and karsts... see full abstract.
- Overview of Shale Gas Stimulation Techniques
From Abstract: ...This presentation briefly reviews the evolution of stimulation practices in the Barnett Shale of North Texas and expands into the current efforts that are ongoing in the other major shale plays such as the Woodford in Oklahoma, the Woodford and Barnett in West Texas, the Fayetteville in Arkansas, the Devonian and New Albany in the Appalachian region, and the Floyd in Alabama... see full abstract.
- The Fayetteville Shale Play of North-Central Arkansas -- A Project Update
From Abstract: ...Overall, drilling activity within the Fayetteville Shale Play has been ramping up at a rapid pace as Southwestern Energy now has 19 rigs active in the play, Chesapeake has increased their rig count to 13, and other operators continue to move into the area (+/-10 rigs). Currently, a core area has been established in the play consisting of southern Van Buren, Cleburne, northern Conway, northern Faulkner, and northern White Counties in north-central Arkansas... see full abstract.
- Developing a New Gas Resource in the Heart of the Northeastern U.S. Market: New York's Utica Shale
From Abstract: After significant research, industry is now investing in leasing, exploratory drilling and modern completion methods for the Utica Shale. When developed, this play will represent the easternmost natural gas field in the USA. The prospective fairway includes 17 counties bounded by the Hudson River, the Finger Lakes, the Mohawk Valley and the Pennsylvania border... see full abstract.
- Evaluating Devonian Gas-Shales from the Appalachian Basin, U.S.A.
From Abstract: Desorbed core gas quantities, kerogen and methane carbon isotopes, total organic carbon (TOC), pyrolysis parameters, and detailed mineralogy were determined for approximately 200 Devonian shale core samples in the Appalachian Basin from New York, Virginia, West Virginia, Kentucky, Pennsylvania, and Ohio. The data from core samples indicate varying levels of thermal maturity, total organic carbon (TOC) content, mineralogy, and gas content... see full abstract.
- Overview and Significance of Unconventional Resources
- Innovative Methods for Flow Unit and Pore Structure Analysis in a Tight Gas Reservoir, Montney Formation, NE, BC, Canada
From Abstract: ... We investigate the use of non-routine methods to characterize permeability heterogeneity and pore structure of a tight gas reservoir for use in flow unit identification. Profile permeability is used to characterize fine-scale (< 1 inch) vertical heterogeneity in a tight gas core; over 500 measurements were made. Profile permeability, while useful for characterizing heterogeneity, will not provide in-situ estimates of permeability; further, the scale of measurement is much smaller than logscale... see full abstract.
- Recent Advances in the Analytical Methods Used for Shale Gas Reservoir Gas-in-Place Assessment
From Abstract: Shale gas reservoirs are a commingling between conventional (compressed) and unconventional (adsorbed;, i.e., CBM) gas reservoirs. Therefore, shale gas-in-place (GIP) evaluations require the use of analytical methods originally developed for each specific reservoir system. Unfortunately, many analytical techniques used to determine GIP and permeability for conventional and CBM reservoirs do not translate well when evaluating shale due to its complex lithology... see full abstract.
- Geologic controls and reservoir characterization of the Bradley Brook Field; Madison County, New York
In this study, the effects of the Oswego Sandstone subcrop located below the Oreida Sandstone are determined. The best natural gas wells in Bradley Brook field in Madison County, New York State contain gas from the Oreida Sandstone and are found along the faults that bind the Oswego Sandstone. Two faults were proposed based on geophysical well logs and 2-D seismic data. Oswego Sandstone, unlike the Oreida Sandstone, is not affected by water saturation and porosity because its faults control those factors. So, the Oswego Sandstone acts like a carrier bed for the movement of gas into the Oneida Sandstone, providing evidence on why the best wells are found along the fault bound Oswego Sandstone subcrop.
- Michigan's Antrim Gas Shale Play: A Two-Decade Template for Successful Devonian Gas Shale Development
From Abstract: Although key wells drilled by early visionaries from the 1940’s to 1960’s proved play viability, it was not until the late 1980’s that Michigan’s Devonian Antrim Shale play established a strong economic foothold. The combination of improved completion technology, regional pipeline capacity seeking new gas in the twilight of the Niagaran pinnacle play, and non-conventional gas tax incentives led to a dramatic burst in Antrim development roughly 20 years ago. Today, over 9,000 completed wells... See Full Abstract
- U.S. Shale Gas -- Trends and Expansion
From Abstract: High prices and increased success in exploration and production are the incentives behind the sharp increase in shale gas exploration in the U.S. Without doubt the Barnett has the most recent completions and a continuous increase in production. However, other gas shales in the U.S. are proving to be highly productive, and these plays are expanding and the center of sharply increased activity in several areas of the county... see full abstract.
- A Petrophysical Study on Floyd Shale
From Abstract: With shale plays becoming increasingly important source of natural gas, it has become all the more important to characterize shales. This paper attempts to improve the overall understanding of gas shales using laboratory based petrophysical measurements... see full abstract.
- The Importance of Pore Structural Heterogeneities for Shale Gas Reservoir Evaluation
From Abstract: Elucidating the controls upon gas capacities in fine-grained strata and accurately determining reservoir potential requires knowledge of shale physical structure. However, the intricate, heterogeneous pore network of shales is difficult to assess because pore-throats can be smaller than 2 nm. Shale gas reservoir evaluations rely upon scaling laboratory data to regional reservoir magnitudes, but failure to recognize nano-scale heterogeneities will lead to erroneous economic assessments... see full abstract.
- Lower Cretaceous Gas Shales of Northeastern British Columbia: Geological Controls on Gas Capacity and Regional Evaluation of a Potential Resource
From Abstract: The regional shale gas potential of the Lower Cretaceous Buckinghorse Formation and stratigraphically equivalent strata have been investigated. Methane sorption capacities range between 0.03 to 1.86 cm3/g (1.0 to 59.5 scf/ton) at hydrostatic pressures between 2.9 and 17.6 MPa... see full abstract.
- Middle and Late Paleozoic Organic-Rich Gas Shales of the North American Midcontinent
From Abstract: Black organic-rich gas producing shales are abundant in outcrop and subsurface in the North American Midcontinent. The middle Paleozoic Woodford and Chattanooga black shales (Frasnian-Tournisian) consist of fissile black shales in shelfal settings, abundant chert and black shale interbeds in distal shelf and slope settings, and novaculite with black shale interbeds in basinal settings... see full abstract.
- Woodford Shale Gas in Oklahoma
From Abstract: The Woodford Shale in Oklahoma has produced hydrocarbons since 1939; however, it was not until 2004 that drilling and completion activity increased from an average completion of 2 wells per year to 35 Woodford completions. In 2007 over 200 horizontal Woodford wells have been drilled and completed. The majority of activity is in the Arkoma Basin with the most successful wells being drilled in Hughes and Coal Counties where the shale is 150' thick... see full abstract.
- U. S. Shale Gas Resources: Classic and Emerging Plays, the Resource Pyramid and a Perspective from Future E&P
From Abstract: Projections by the United States government indicate that annual U.S. gas demand could increase from the current 22 Tcf (trillion cubic feet) to 26 Tcf by the year 2030. This would occur during a period of declining Canadian gas imports and increasing U.S. reliance on LNG imports, a commodity only available in a highly competitive market. The robustness of the North American gas resource base, particularly shale gas, coalbed methane, and tight sands gas needs to be quantified... see full abstract.
- Utah's Shale Gas: A Developing Resource Play
From Abstract: In Utah, several organic-rich shale units are in the early stages of natural gas production or are being seriously evaluated for their shale gas potential. Spurred by the availability of appropriate fracture stimulation technology, exploitation of Upper Cretaceous Mancos Shale gas already has begun... see full abstract.
- The nano-mechanical morphology of shale
Shale, the sealing formations in most hydrocarbon reservoirs, is made of highly compacted clay particles of sub-micrometer size, nanometric porosity and different mineralogy. In this paper, we propose and validate a technique to identify the nano-mechanical morphology of such a nanocomposite material. In particular, by means of a massive nanoindentation campaign at two different scales on a large range of shale materials, we show that the highly compacted plate- or sheet-like clay particles have a distinct nano-mechanical morphology with no privileged orientation of the particle-to-particle contact surface, as evidenced by a mechanical percolation threshold of η0 ¿ 0.5. Furthermore, the nanoindentation results provide strong evidence that the nano-mechanical elementary building block of shales is transversely isotropic in stiffness, and isotropic and frictionless in strength.
- Lower Cretaceous gas shales in northeastern British Columbia, part I: Geological controls on methane sorption capacity
The geological controls on methane sorption capacity for the Lower Cretaceous Buckinghorse Formation and equivalent strata in northeastern British Columbia, Canada have been investigated. The methane sorption capacity ranges between 0.04 to 1.89 cm3/g at 6 MPa (3.2 to 60.4 scf/ton at 870 PSIA) and the corresponding total organic carbon (TOC) content is between 0.5 and 17 wt%. Equilibrium moisture content is between 1.5 and 11 wt% and the organic maturity measured by Tmax ranges between 416°C (immature) and 476°C (overmature).
TOC content is the most significant control on methane sorption capacity, however, other important factors include the kerogen type, maturity and clay content, in particular the abundance of illite. A positive correlation exists between the TOC content and methane capacity. Samples with higher surface area have higher methane sorption capacities. The micro- and mesoporous surface area increase with TOC and illite content. On a per unit TOC volume basis, type II/III and III kerogens have higher methane sorption capacity compared to types I and II because of their higher micropore volumes. Micropore volume on a per unit TOC volume basis increases with maturity for all kerogen types. Across the study area there is a decrease in TOC concentration with increasing maturity which, in part, is attributed to hydrocarbon generation but also coincidently reflects the different depositional environments. The amount of illite also increases with maturity through the process of illitization. No correlation exists between moisture content and methane capacity. Samples with high moisture content can have high methane capacities which indicate water and methane molecules occupy different sorption sites.
- Lower Cretaceous gas shales in northeastern British Columbia, part II: Evaluation of regional potential gas resources
- The Marcellus shale--An old new gas reservoir in Pennsylvania
Overview, historical perspective on Marcellus Formation: organic shale and reasons it has not yet been developed. Includes overview of hydrofracturing process
- Elastic anisotropy, maturity, and maceral microstructure in organic-rich shales
- A stochastic methodology for the portfolio analysis of proved petroleum assets
- Well-Production Data and Gas-Reservoir Heterogeneity¿Reserve Growth Applications
From Abstract: Oil and gas well production parameters, including peakmonthly production (PMP), peak-consecutive-twelve month production (PYP), and cumulative production (CP), are tested as tools to quantify and understand the heterogeneity of reservoirs in fields where current monthly production is 10 percent or less of PMP. Variation coefficients, defined as VC= (F5-F95)/F50, where F5, F95, and F50 are the 5th, 95th, and 50th (median) fractiles of a probability distribution, are calculated for peak and cumulative production and examined with respect to internal consistency, type of production parameter, conventional versus unconventional accumulations, and reservoir depth... See Full Text
- Marcellus Shale Water Management Challenges in Pennsylvania
From abstract: The management of water resources poses considerable challenges to the Pennsylvania Oil and Gas Industry as it begins to expand the development of the Marcellus Shale. Although the play overlies a seemingly water-rich region the sourcing of fresh water for drilling and completions operations are far from straight forward due to regulatory restrictions. Development companies planning to operate in the state must seek to understand an evolving regulatory landscape... see full text.
- The expansive effects of concentrated pyritic zones in shales of the Marcellus formation
The Marcellus Shale contains the mineral pyrite, which is responsible for acid mine drainage and acid rain in association with coal/metal mining and coal-fired power plants, respectively, but not natural gas extraction. When weathered at the Earth's surface, pyrite weathers and can form iron hydroxides (much like rust), causing expansion of the rock. Crushing the rock exacerbates the effect. When used in construction, pyrite-containing materials like the Marcellus shale can cause structural damage to roads and buildings. This dissertation is a rather technical look at this expansion phenomenon.
- Geologic Controls on the Growth of Petroleum Reserves
From Abstract:The geologic characteristics of selected siliciclastic (largely sandstone) and carbonate (limestone and dolomite) reservoirs in North America (largely the continental United States) were investigated to improve our understanding of the role of geology in the growth of petroleum reserves. Reservoirs studied were deposited in (1) eolian environments... See Full Text
- Lithofacies and sequence stratigraphic framework of the Barnett Shale, Northeast Texas
From the abstract: The depositional history and sequence stratigraphy of the Barnett Shale is not fully known. This dissertation establishes Barnett Shale sequence stratigraphy based on observations of continuous cores and wireline logs, integrated with analytical data. Four continuous long cores from Denton, Wise, and Parker counties, Texas have been studied to document the detailed internal stratigraphy and architecture of the Barnett Shale. Visual, petrographic and mineralogic analysis reveals nine distinct lithofacies within the Barnett Shale in the study area. The study indicates significance of depositional processes which have constrained the vertical facies successions and cyclicity in the study area.... See full abstract
- Electrostratigraphy, thickness, and petrophysical evaluation of the Woodford Shale, Arkoma basin, Oklahoma
From the abstract: Scope and method of study. This study was intended to evaluate the gas-shale potential of the Woodford Shale in the Arkoma basin and address four questions: (1) Can well-logs be used to construct the informal stratigraphy of the Woodford? (2) What is the distribution of these informal units? (3) Can log-derived characteristics delineate higher gas-volume producing areas within the Woodford gas-shale play? (4) What other analyses are useful in evaluating Woodford production potential in untested areas? See full abstract
- Study of Barite Solubility and the Release of Trace Components to the Marine Environment
Summarizes the results from a study on concentrations of trace metals in barite
and their likelihood of release (via dissolution) of these metals and barium from the barite to the environment depending on environmental conditions such as oxygen level, and sediments versus waters. This issue is relevant to offshore drilling as barite is used as a weighting material in drilling muds (e.g. in the Gulf of Mexico.) Although mercury was note found to be a significant dissolution threat, other selected heavy metals were detected.
- Anisotropy effects on microseismic event location
Seismic anisotropy in sedimentary environments is significant—microseismic waveforms often show strong shear-wave splitting, with differences reaching 40% between horizontally and vertically-polarized shear-wave velocities. Failure to account for this anisotropy is shown to result in large microseismic event location errors. A method is presented here for determining the five elastic parameters of a homogeneous, vertical transverse-isotropic (VTI) model from calibration shot data. The method can also use data from mining-induced seismic events, which are then simultaneously located. This simple model provides a good fit to arrival times from coal-environment data, and results in dramatic shifts in interpreted event locations.
- Development of a successful chemical treatment for gas wells with condensate or water blocking damage
From Abstract: Significant productivity loss occurs in gas condensate reservoirs due to condensate and water accumulation near the production well. Our experimental study shows that gas relative permeability decreases by more than 95% due to liquid blockage (high water saturation along with condensate accumulation) and the reduction is even more pronounced in presence of mobile water... See Full Abstract
- Natural Gas Compressor Stations on the Interstate Pipeline Network: Developments Since 1996
This report looks at the use of natural gas pipeline compressor stations on the interstate natural gas pipeline network that serves the lower 48 states. It examines the compression facilities added over the past 10 years and how the expansions have supported pipeline capacity growth intended to meet the increasing demand for natural gas.
- Drilling Down: Protecting Western Communities from the Health and Environmental Effects of Oil and Gas Production
This report explains the relationship between oil and gas production and their negative impacts on the Rocky Mountain region's human health, air, water, and land. Also mentioned are possible simple solutions to the problems posed by oil and gas pollution such as the widely accepted "reduce, reuse, recycle" concept.
- The Oil and Gas Industry's Exclusions and Exemptions to Major Environmental Statutes
This report addresses oil and gas industry exemptions from several major Federal environmental statutes, which in turn put human health and the environment at risk. Individual environmental statutes are analyzed, and the report concludes with recommendations for further regulation for the oil and gas industry.
- Collaboration Across all Domains for Optimized Unconventional Resource Development Programs
From Abstract: The development of unconventional resources prior to the end of the last century was overlooked for many reasons – most of which were due to lack of understanding of these complex and challenging reservoirs along with the lack of mainstream technologies necessary to develop them. Now, with the arrival of what have become widely available advanced drilling systems, as well as quickly evolving innovations in completions practices, the exploitation of unconventional resources has moved to the forefront with promises of significant contributions to worldwide oil and gas supplies... See Full Abstract
- The effect of the nanogranular nature of shale on their poroelastic behavior
From Abstract: Natural composite materials are highly heterogeneous porous materials, with porosities that manifest themselves at scales much below the macroscale of engineering applications. A typical example is shale, the transverse isotropic sealing formation of most hydrocarbon bearing reservoirs. By means of a closed loop approach of microporomechanics modeling, calibration and validation of elastic properties at multiple length scales of shale, we show that the nanogranular nature of this highly heterogeneous material translates into a unique poroelastic signature. The self-consistent scaling of the porous clay stiffness with the clay packing density minimizes the anisotropy of the Biot pore pressure coefficients... see full abstract.
- Field-based monitoring of sediment runoff from natural gas well sites in Denton County, Texas, USA
This study looks at sediment runoff from three different gas well sites in Denton, Texas, showing that these sites increase erosion and sediment runoff to levels much higher than sites which are undisturbed. The gas well pad sites themselves show rates of sediment runoff that are extremely elevated initially, but gradually stabilize over time, while the disturbed areas surrounding the pad sites show sustained high levels of runoff for longer periods of time. Erosion within these areas, and growth of debris lobes caused by sediment runoff began to diminish after approximately a year, when the area began to naturally re-vegetate. Based on these findings, Williams et al. suggest that gas well development sites should be required to comply with erosion control regulations similar to those of small construction sites, since sediment runoff from these areas are within the legal range for construction sites but much greater than that of undisturbed lands.
- Update on the Regional Assessment of Gas Potential in the Devonian Marcellus and Ordovician Utica Shales in New York
This is a geochemical characterization of the Marcellus and Utica shale formations in a region of New York state for the purposes of defining areas for gas exploration. Data analyzed include total organic carbon (TOC), transformation ratio, and hydrogen index maps. The analysis includes spatial data intended for a technical audience.
- Production History and Reservoir Characteristics of the Antrim Shale Gas Play, Michigan Basin
MI 49008, firstname.lastname@example.org
The Upper Devonian Antrim Shale is a major gas producer in the Michigan Basin.
Although there had been occasional Antrim producing wells since 1940, the recent
development began in the late 1980’s as a result of new technology, access to underutilized
Silurian Niagaran Reef play infrastructure, and a federal nonconventional fuels
tax credit. To date, the Antrim Shale in Northern Michigan, has produced over 2.5 TCF
of gas from over 8,800 wells. Production in 2006 was nearly 140 BCF. The Antrim Shale
is a classic black shale that produces natural gas by desorption processes into a complex
network of fractures. The distribution of high total organic carbon and natural fractures
are keys to good productivity. Although thermally immature in the producing area, the
large accumulation of natural gas has been generated mainly by biogenic processes. Numerous cores in the collection of the Michigan Geological Repository for Research and Education (MGRRE) at Western Michigan University have been studied for facies distribution, organic content, and fracture characteristics. Cores show vertical and lateral facies variation through the basin and facies control on the distribution of natural
fractures. Gas in place can be measured by geochemical rock analyses and suggest 0.5 to
1.0 BCF per 40 acres in the northern part of the basin. Variable production history of project areas can be explained by reservoir rock properties measurable from core, logs,
and drill cuttings.
- Optimization of Hydraulic Fracturing Performance in the Fractured Utica Shale of Northeastern United States
From Abstract: The primary purpose of stimulating fractured shale reservoirs is the extension of the drainage radius via creation of a long fracture sand pack that connects with natural fractures, thereby establishing a flow channel network to the wellbore. However, there is limited understanding of a successful method capable of stimulating Utica shale reservoirs. Indeed, most attempts to date have yielded undesirable results. This could be due to several factors, including... See Full Abstract
- Open-Hole Completion Ion System Enables Multi-Stage Fracturing and Stimulation Along Horizontal Wellbores
Horizontal drilling and improved technology has allowed for a more comprehensive exploitation of natural gas from deep unconventional reservoirs. Multi-stage fracturing, which allows for more rapid cumulative gas extraction, has grown in popularity over the years. This article details a horizontal drilling method aimed at decreasing well construction time and speeding production. Cementing and/or lining the "open-hole" well is no longer needed, reducing costs. According to this source, more than 600 pre-assembled systems (called "StackFRAC") have been successfully installed in horizontal open-hole wells in various types of shale formations.
- Framing Perceptions of Oil Development and Social Disruption
From Abstract: This paper examines the perceived relationship between the presence and growth of the offshore oil industry in Louisiana and patterns of social disruption, particularly crime. Interview data were obtained from long-time residents in the coastal region of Louisiana, and a social constructionist perspective was used to frame the perceptions of these individuals... see full abstract.
- Cherty stringers in the Barnett Shale are agglutinated foraminifera
From Abstract: Masses of microcrystalline quartz are abundant within several lithologies in the Barnett Shale (lower Mississippian) of central Texas. A typical quartz mass is elongated parallel to bedding and contains a central planar microporous structure that suggests collapse of a formerly hollow spheroidal or tubular body. An integrated imaging approach, utilizing transmitted polarized light microscopy, secondary and back-scattered electron imaging, cathodoluminescence imaging, and X-ray mapping reveals these quartz masses to be composed primarily of quartz-cemented silt-size detrital quartz with a minor admixture of detrital Caplagioclase and dolomite... see full text.
- Downhole Pressure Boosting in Natural Gas Wells: Well Candidate Selection and Project Progress
In recent years, gas exploration and production (E&P) companies have acknowledged that pressure boosting in close proximity to a reservoir can accelerate production rates as well as increase the recovery of reserves beyond that possible by conventional central compression alone. This paper summarizes the key well and reservoir parameters that determine the production enhancement potential of downhole gas compression (DGC).
- Unconventional shale gas systems: The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessment
Shale-gas resource plays can be distinguished by gas type and system characteristics. The Newark East gas field, located in the Fort Worth Basin, Texas, is defined by thermogenic gas production from low-porosity and low-permeability Barnett Shale. The Barnett Shale gas system, a self-contained source-reservoir system, has generated large amounts of gas in the key productive areas because of various characteristics and processes, including (1) excellent original organic richness and generation potential; (2) primary and secondary cracking of kerogen and retained oil, respectively; (3) retention of oil for cracking to gas by adsorption; (4) porosity resulting from organic matter decomposition; and (5) brittle mineralogical composition.
The calculated total gas in place (GIP) based on estimated ultimate recovery that is based on production profiles and operator estimates is about 204 bcf/section (5.78 109 m3/1.73 104 m3). We estimate that the Barnett Shale has a total generation potential of about 609 bbl of oil equivalent/ac-ft or the equivalent of 3657 mcf/ac-ft (84.0 m3/m3). Assuming a thickness of 350 ft (107 m) and only sufficient hydrogen for partial cracking of retained oil to gas, a total generation potential of 820 bcf/section is estimated. Of this potential, approximately 60% was expelled, and the balance was retained for secondary cracking of oil to gas, if sufficient thermal maturity was reached. Gas storage capacity of the Barnett Shale at typical reservoir pressure, volume, and temperature conditions and 6% porosity shows a maximum storage capacity of 540 mcf/ac-ft or 159 scf/ton.
- Barnett Shale gas production, Fort Worth basin: issues and discussion
Newark East (Barnett Shale) field, Fort Worth Basin, Texas, is currently the most productive gas field in Texas in terms of daily production and is growing at an annual rate of more than 10%. However, despite the fact that the Barnett play has been studied intensely by very capable geologists and engineers from several companies over a period of many years, there continues to be several misunderstandings concerning fundamental factors controlling the success of the Barnett play of north Texas.
Barnett gas production is poorer in areas near faults and structural flexures (anticlines and synclines). Fractures, which are most abundant in these structural settings, are detrimental to Barnett production. Open natural fractures are rare in the Barnett and have little or nothing to do with Barnett productivity. In areas where Barnett Shale is thermally mature with respect to gas generation, it is slightly overpressured (about 0.52 psi/ft [11.76 kPa/m]). Limestone beds within the Barnett formation are the product of debris flows that originated on a carbonate shelf to the north of the present basin center. It appears that the Barnett can be used as an exploration model for other basins, especially analogous basins of the Ouachita trend.
The history of the development of the Barnett reservoir in north Texas provides an excellent example of how persistence can lead to success in nonconventional gas plays.
Kent A. Bowker has been studying the Barnett Shale since 1997, when Chevron's Non-Conventional Gas Team drilled a vertical wildcat well in Johnson County. He began his career with Gulf Oil in 1980 after earning his master's degree from Oklahoma State University. He worked at Mitchell Energy from 1998 to 2002 and is now an independent producer and consultant.
- Natural fractures in the Barnett Shale and their importance for hydraulic fracture treatments
Gas production from the Barnett Shale relies on hydraulic fracture stimulation. Natural opening-mode fractures reactivate during stimulation and enhance efficiency by widening the treatment zone. Knowledge of both the present-day maximum horizontal stress, which controls the direction of hydraulic fracture propagation, and the geometry of the natural fracture system, which we discuss here, is therefore necessary for effective hydraulic fracture
- Shale Gas Reservoir Systems: Insights from North of the Border
From Abstract: Organic-rich Devonian and Jurassic strata are considered to be excellent candidates for gas shales in Western Canada. These strata have TOC contents ranging between 1-40 wt%, thermal maturities into the dry-gas window, and thicknesses in places over 1700 m. The ratio of total organic carbon (TOC) to gas sorption varies markedly from unit to unit depending on pore-structure, thermal maturation, moisture and inorganic composition... see full abstract.
- Total petroleum system assessment of undiscovered resources in the giant Barnett Shale continuous (unconventional) gas accumulation, Fort Worth Basin, Texas
Undiscovered natural gas having potential for additions to reserves in the Mississippian Barnett Shale of the Fort Worth Basin, north-central Texas, was assessed using the total petroleum system assessment unit concept and a cell-based methodology for continuous-type (unconventional) resources. The Barnett-Paleozoic total petroleum system is defined in the Bend arch–Fort Worth Basin as encompassing the area in which the organic-rich Barnett is the primary source rock for oil and gas produced from Paleozoic carbonate and clastic reservoirs. Exploration, technology, and drilling in the Barnett Shale play have rapidly evolved in recent years, with about 3500 vertical and 1000 horizontal wells completed in the Barnett through 2005 and more than 85% of the them completed since 1999. Using framework geology and historical production data, assessment of the Barnett Shale was performed by the U.S. Geological Survey using vertical wells at the peak of vertical well completions and before a transition to completions with horizontal wells. The assessment was performed after (1) mapping critical geological and geochemical parameters to define assessment unit areas with future potential, (2) defining distributions of drainage area (cell size) and estimating ultimate recovery per cell, and (3) estimating future success rates.
Two assessment units are defined and assessed for the Barnett Shale continuous gas accumulation, resulting in a total mean undiscovered volume having potential for additions to reserves of 26.2 TCFG. The greater Newark East fracture-barrier continuous Barnett Shale gas assessment unit represents a core-producing area where thick, organic-rich, siliceous Barnett Shale is within the thermal window for gas generation (Ro 1.1%) and is overlain and underlain by impermeable limestone barriers (Pennsylvanian Marble Falls Limestone and Ordovician Viola Limestone, respectively) that serve to confine induced fractures during well completion to maximize gas recovery. The extended continuous Barnett Shale gas assessment unit, which had been less explored, defines a geographic area where Barnett Shale is (1) within the thermal window for gas generation, (2) greater than 100 ft (30 m) thick, and (3) where at least one impermeable limestone barrier is absent. Mean undiscovered gas having potential for additions to reserves in the greater Newark East assessment unit is estimated at 14.6 tcf, and in the less tested extended assessment unit, a mean resource is estimated at 11.6 TCFG. A third hypothetical basin-arch Barnett Shale oil assessment unit was defined but not assessed because of a lack of production data.
- Devonian Aged Shale Gas Potential of the Southern Tier of New York
This technical work examines the characteristics that may make deep geologic structures in the Southern Tier of New York and Pennsylvania potentially suitable for stimulation via horizontal drilling. Evidence from mineralogical, geochemical and shale desorption data collected from cores, cuttings and outcrop samples is discussed.
- Three things we thought we understood about shale gas, but were afraid to ask...
From Abstract: Shale-gas plays are largely evaluated and interpreted on the basis of performance data from a limited number of field areas supplemented with even more limited core data. The Barnett Shale at Newark East Field in the Ft.WorthBasin is the standard by which most shale plays are compared. We suggest this leads to a highly skewed view of these play-types and that three fundamental areas of uncertainty exist requiring additional research... see full abstract.
- History of the Newark East field and the Barnett Shale as a gas reservoir
- Modeling of gas generation from the Barnett Shale, Fort Worth Basin, Texas
The generative gas potential of the Mississippian Barnett Shale in the Fort Worth Basin, Texas, was quantitatively evaluated by sealed gold-tube pyrolysis. Kinetic parameters for gas generation and vitrinite reflectance (Ro) changes were calculated from pyrolysis data and the results used to estimate the amount of gas generated from the Barnett Shale at geologic heating rates. Using derived kinetics for Ro evolution and gas generation, quantities of hydrocarbon gas generated at Ro 1.1% are about 230 L/t (7.4 scf/t) and increase to more that 5800 L/t (186 scf/t) at Ro 2.0% for a sample with an initial total organic carbon content of 5.5% and Ro = 0.44%. The volume of shale gas generated will depend on the organic richness, thickness, and thermal maturity of the shale and also the amount of petroleum that is retained in the shale during migration. Gas that is reservoired in shales appears to be generated from the cracking of kerogen and petroleum that is retained in shales, and that cracking of the retained petroleum starts by Ro 1.1%. This result suggests that the cracking of petroleum retained in source rocks occurs at rates that are faster than what is predicted for conventional siliciclastic and carbonate reservoirs, and that contact of retained petroleum with kerogen and shale mineralogy may be a critical factor in shale-gas generation. Shale-gas systems, together with overburden, can be considered complete petroleum systems, although the processes of petroleum migration, accumulation, and trap formation are different from what is defined for conventional petroleum systems.
- Economic Fluctuation and Crime: A Time Series Analysis of the Effects of Oil Development in the Coastal Regions of Louisiana
From Abstract: This research examines the relationship between patterns of crime and the development of the oil and gas industry in the coastal regions of Louisiana using pooled time-series analysis. The suggestion to a link between these phenomena has often been made, but little systematic research has been conducted to determine if there is indeed a crime-oil development nexus... see full abstract.
- Inupiat Health and Proposed Alaskan Oil Development: Results of the First Integrated Health Impact Assessment/ Environmental Impact Statement for Proposed Oil Development on Alaska's North Slope
This journal article discusses the first Health Impact Assessment for Alaska's North Slope Region and looks at potential adverse and beneficial impacts of drilling for the culture and health of North Slope Inupiats. Possible negative health outcomes include diabetes, metabolic conditions, substance abuse, domestic abuse, asthma, organic pollution exposure such as carcinogens and endocrine disrupters and suicide. Some benefits from development are: funding for health care, increased employment and income. Environmental Impact Statements typically do not look at health. The inclusion of public health concerns within an EIS may offer a new focus on public health.
- Lithofacies summary of the Mississippian Barnett Shale, Mitchell 2 T.P. Sims well, Wise County, Texas
The Mississippian Barnett Shale is an important hydrocarbon source rock and has recently developed into a very active gas-shale play. Commonly viewed as a homogeneous black shale, the Barnett actually consists of a variety of organic-rich lithofacies of siliceous, calcareous, or phosphatic composition. Recognition of the different lithofacies is an important step in the evaluation of gas in place, flow capacity, and mechanical properties of the Barnett. Petrographic study of conventional core samples from the lower part of the Barnett has led to the recognition of the following rock types: organic-rich black shale, fossiliferous shale, dolomite rhomb shale, dolomitic shale, phosphatic shale, and concretionary carbonate. Measured total organic carbon values, averaged by rock type, range by a factor of nearly two, with the organic-rich shale and phosphatic shale having the highest values. The development of these lithofacies is a result of suspension fallout and sediment gravity flows combined with the extensive early microbial alteration of abundant organic matter. The lithofacies vary in petrophysical and mechanical properties, as well as organic content.
- Four Perspectives on Public Participation Process in Environmental Assessment and Decision Making: Combined results from 10 case studies
From Abstract: Knowing how people think about public participation processes and knowing what people want from these processes is essential to crafting a legitimate and effective process and delivering a program that is widely viewed as meaningful and successful. This article reports on research to investigate the nature of diversity among participants' perceptions of what is the most appropriate public participation process for environmental assessment and decision making in 10 different cases. Results show that there are clearly distinct perspectives on what an appropriate public participation process should be... see full abstract.
- The role of friction and secondary flaws on deflection and re-initiation of hydraulic fractures at orthogonal pre-existing fractures
From Abstract: In this study, we explore the nature of plane-strain hydraulic fracture growth in the presence of pre-existing fractures such as joints without or with secondary flaws. The 2-D plane-strain fracture studied can be taken as a cross-section through the short dimensions of an elongated 3-D fracture or as an approximate representation of the leading edge of a 3-D fracture where the edge curvature is negligible. The fluid-driven fracture intersects a pre-existing fracture to which it is initially perpendicular and is assumed not to immediately cross, but is rather deflected into the pre-existing fracture... see full abstract.
- Offsite Commercial Disposal of Oil and Gas Exploration and Production Waste: Availability, Options, and Costs
From the Summary: A survey conducted in 1995 by the American Petroleum Institute (API) found that the U.S. exploration and production (E&P) segment of the oil and gas industry generated more than 149 million bbl of drilling wastes, almost 18 billion bbl of produced water, and 21 million bbl of associated wastes. The results of that survey, published in 2000, suggested that 3% of drilling wastes, less than 0.5% of produced water, and 15% of associated wastes are sent to offsite
commercial facilities for disposal.
Argonne National Laboratory (Argonne) collected information on commercial E&P waste disposal companies in different states in 1997. While the information is nearly a decade old, the report has proved useful. In 2005, Argonne began collecting current information to update and expand the data. This report describes the new 2005–2006 database and focuses on the availability of offsite commercial disposal companies, the prevailing disposal methods, and estimated disposal costs....
- Conformance through chemistry
From Introduction: Although hydraulic fracturing has proven to be extremely successful, one problem has continued to plague operators for years: increased water production after a treatment has been pumped. Typically, this produced water results from uncontrolled fracture height growth that contacts a water-bearing interval...See Full Text
- Projecting the Economic Impact of the Fayetteville Shale Play for 2008¿201
- The Upper Devonian Rhinestreet Shale, Western New York State: from Seal to Fractured Reservoir
From Abstract: The Upper Devonian Rhinestreet black shale of the Catskill Delta complex, western New York State, reflects a complex burial and overpressure history that resulted in the generation of multiple sets of vertical joints interpreted to be natural hydraulic fractures (NHFs). The EASY%R chemical kinetic model was used in this study to model an average vitrinite reflectance value of 0.74% measured on samples collected from along the Lake Erie shoreline... see full abstract.
- Winter Habitat Selection of Mule Deer Before and During Development of a Natural Gas Field
From the abstract: Increased levels of natural gas exploration, development, and production across the Intermountain West have created a variety of concerns for mule deer (Odocoileus hemionus) populations, including direct habitat loss to road and well-pad construction and indirect habitat losses that
may occur if deer use declines near roads or well pads. We examined winter habitat selection patterns of adult female mule deer before and during the first 3 years of development in a natural gas field in western Wyoming. We used global positioning system (GPS) locations collected from a sample of adult female mule deer to model relative frequency or probability of use as a function of habitat variables. Model coefficients and predictive maps suggested mule deer were less likely to occupy areas in close proximity to well pads.... See full abstract
- Observations on a Montana Water Quality Proposal
This is a fairly specific report detailing the aftermath of a 2005 proposal by the Montana Board of Environmental Review (BER) to amend that state's water quality regulations. At issue were potential restrictions regarding coal bed natural gas production. The Argonne National Laboratory and Sandia National Laboratory were both requested to provide an evaluation of the BER proposal. This document summarizes the Argonne Lab's findings.
- Producing Gas from its Source
Shale, the most abundant sedimentary rock, is finally becoming economically productive. In the past it was unknown that shale could hold liquid within it's pores and drillers had often drilled through the shale and onto a more lucrative formation. Thanks to the right technology and geology, organic-rich shales are being leased out for drilling rights to discover the next shale-gas concentration.
- Assessment of Appalachian Basin Oil and Gas Resources: Devonian Shale--Middle and Upper Paleozoic Total Petroleum System
This report covers the U.S. Geological Survey (USGS)'s recently completed assessment of the technically recoverable undiscovered hydrocarbon resources in the Appalachian Basin Province. The assessment was based on six major petroleum systems in ten states. The Devonian Shale- Middle and Upper Paleozoic Total Petroleum System, which extends from New York to Tennessee, was divided into ten assessment units. In this report, the probability of the assessment amount for oil, gas, natural gas in TPS are recorded and discussed.
- Central Theory and the Role of Citizen Involvement in Environmental Decision Making: A Re-examination
From Abstract: Much of the administrative literature on public participation in environmental decision making assumes that citizen involvement contributes to reflexive deliberations, communication, effective representation, and consensus building in the public sphere. We will argue that for all the intuitive appeal of public participation, it may ironically limit the boundaries of possible change all under the normative guise of democracy and fair and open deliberations... see full text.
concerning environmental issues
- Formation Evaluation Challenges in Unconventional Tight Hydrocarbon Reservoirs
- A Regulators' Guide to the Management of Radioactive Residuals from Drinking Water Treatment Technologies
The EPA has laid out the minimum standards waste management regulators should follow. The article describes different types of radiation and guidelines on how to use available technologies. For example, reverse osmosis (RO) and lime softening can be used to treat waters with radium and uranium but RO should be used for alpha and beta radiation. The guide is divided into two parts, an overview and an in-depth review of treatment technologies.
- Hydraulic fracturing of poorly consolidated formations: Considerations on rock properties and failure mechanisms
- Emerging Technology Promises New Solutions for Produced Water
- Oxidation of fugitive methane in ground water linked to bacterial sulfate reduction
- The boom-bust-recovery cycle: Dynamics of change in community satisfaction and social integration in Delta, Utah
From the abstract: To better understand the long-term effects of rapid boom growth, we reexamine four subjective indicators of community satisfaction and social integration in Delta, Utah, that were originally analyzed by Brown, Geertsen, and Krannich in 1989. With 24 years of longitudinal data, we find that within approximately a decade of the boom period three of the four indicators returned to or exceeded pre-boom levels.... See full abstract
- Mineralogical analysis of Upper Devonian black shales in western New York
From the abstract: Mineral composition and the percent of total organic carbon (TOC) in black shales of Dunkirk and Hume formations were determined by X-ray diffraction. Dunkirk and Hume formations are potential source rocks for oil and gas-producing reservoirs. To examine the burial depth and temperature of the black shales, the extent of illite-smectite diagenesis was examined. Mineral composition of the black shales was determined quantitatively using the Rock Jock software.... See full abstract
- Tremors in the Cooperative Environmental Federalism Arena: What Happens When a State Wants to Assume Only Portions of a Primacy Program or Return a Primacy Program? - The Underground Injection Control Program Under the Safe Drinking Water Act as a Case Study
- Assessment of Undiscovered Natural Gas Resources in Devonian Black Shales, Appalachian Basin, Eastern U.S.A.
This is a collection of figures showing undiscovered continuous hydrocarbon resources of the Devonian shale. The images were created by USGS as part of its Appalachian Basin assessment. The assessed Devonian shale constitutes the distal deposits of the Catskill delta from New York to West Virginia, Ohio, and eastern Kentucky. The Devonian shale was divided into four assessment units: the Northwestern Ohio Shale, Greater Big Sandy, Devonian siltstone and shale, and the Marcellus Shale. Together, they contain 12.2 TCFG and 159 MMBNGL at the statistical mean. The assessment units were defined by the net thickness of radioactive black shale, thermal maturity, and stratigraphy.
- Building Sustainable Communities in Forested Regions
- The Study of A New Concept of Low Damage Fracturing Technology In Low Permeable Exploration Wells
- Multiple controls on the preservation of organic matter in Devonian-Mississippian marine black shales: geochemical and petrographic evidence
From Abstract: Geochemical and petrographic analysis of an interval of black shales between the Huron Shale Member of the New Albany Shale (Upper Devonian, Famennian) and the Sunbury Shale (Lower Mississippian, Tournaisian) suggests that multiple controls influenced the accumulation of organic matter. Stratigraphic trends were determined following detailed analysis of a core from the central Appalachian Basin (D6, Montgomery County, KY)... see full abstract.
- Mississippian Barnett Shale, Fort Worth basin, north-central Texas: Gas-shale play with multitrillion cubic foot potential
From Abstract: The Mississippian Barnett Shale serves as source, seal, and reservoir to a world-class unconventional natural-gas accumulation in the Fort Worth basin of north-central Texas. The formation is a lithologically complex interval of low permeability that requires artificial stimulation to produce. At present, production is mainly confined to a limited portion of the northern basin where the Barnett Shale is relatively thick (300 ft; 92 m), organic rich (present-day total organic carbon 3.0%), thermally mature (vitrinite reflectance 1.1%), and enclosed by dense limestone units able to contain induced fractures... See full abstract.
- Predicting the composition of natural gas generated by the Duvernay Formation (Western Canada Sedimentary Basin) using a compositional kinetic approach
The formation and composition of natural gas generated from the Duvernay Formation was simulated by heating immature kerogens in a closed system (MSSV pyrolysis) at three different heating rates (0.1, 0.7 and 5.0 °C/min). It was not possible to evaluate reasonable kinetic parameters for the formation of single compounds using accepted protocols, because even at the highest pyrolysis temperatures there is still methane formation, while ethane and propane formations show a significant heating rate dependency of their maximum yields. To circumvent these obstacles a new method was developed utilising the following observations:
bulk gas fraction C1−5 does not show any heating rate dependency of its maximum yield,
omitting either ethane or propane, the generation of both of which are heating rate dependent, from the total gas fraction (which gives the C1−5 − C2 as well as C1−5 − C3) resulted in yields which were not heating rate-dependent.
- Thermal maturity of the Barnett Shale determined from well-log analysis
Intensive development with large-scale fracturing treatments has made the Barnett Shale play (Newark East field) in the Fort Worth Basin the largest shale-gas field in the world. The Mississippian Barnett Shale is an organic-rich, self-sourced reservoir rock. Thermal maturity, thickness, and total organic carbon are the most important geological factors for commercial gas production from this shale formation. The log-derived thermal-maturity index (MI) has been developed in an effort to better understand and predict hydrocarbon phases across the basin. Maturity index was calculated using three types of open-hole logs: neutron porosity, deep resistivity, and density porosity (or bulk density). The derivation of MI is based on the hypotheses that shale gas is generated and stored locally without apparent migration from outside sources, and that the water saturation and the density of generated hydrocarbons decrease with an increase in thermal maturity. Maturity index correlates well with initial gas:oil ratios (GOR) from well production data. Based on this correlation, an empirical relationship has been demonstrated for the Fort Worth Basin. This method is useful in understanding the thermal-maturity levels of Barnett Shale source rock in the gas-generation window. Mapping MI, GOR, and gas heating value from hundreds of wells identifies the various maturity stages and areas of Barnett Shale that generate oil, condensate, wet gas, or dry gas in the Fort Worth Basin.
- Hydraulic fracturing in particulate materials
From the abstract: For more than five decades, hydraulic fracturing has been widely used to enhance oil and gas production. Hydraulic fracturing in solid materials (e.g., rock) has been studied extensively. The main goal of this thesis is a comprehensive study of the physical mechanisms of hydraulic fracturing in cohesionless sediments. For this purpose, experimental techniques are developed to quantify the initiation and propagation of hydraulic fractures in dry particulate materials. We have conducted a comprehensive experimental series by varying such controlling parameters.... See full abstract
- Slick Water and Hybrid Fracs in the Bossier: Some Lessons Learnt
In order to better understand the process of fracturing tight gas sands, a comprehensive data set was gathered and analyzed for the Bossier formation in the Dowdy Ranch field. The dataset collected on the APC Anderson #2 well represents one of the most comprehensive datasets ever collected for a commercial gas well. The entire interval was cored, and a complete set of core analysis was performed across the sands. Stress profiles derived from dipole sonic logs across the pay zone and in the shales below were calibrated with stress tests. The frac jobs were micro-seismically monitored with downhole geophones and included breakdown and mini-frac stages. Post fracture data collection included pressure buildup testing, production logs with multiple passes, and tracer logs with multiple isotopes. Additional data was collected on five offset wells in the field. Results from these wells will be presented in a companion paper.
The bottomhole treating pressures were found to be higher than expected based on the measured stress profiles. However, the higher treating pressures encountered did not result in excessive fracture height growth. This may be partially attributed to unexpected faulting providing a conduit for fluid leak-off, resulting in low efficiency and narrow fractures. Propped or effective fracture lengths derived from pressure buildup analysis and history matching production data were significantly shorter than designed frac lengths (or those predicted from uncalibrated frac models). The net pressure plots showed some evidence of proppant bridging even at low proppant concentrations, again indicating only limited fracture widths were being achieved. The data collected and analyzed provide valuable insight into the performance of water and hybrid fracs in tight gas formations. Recommendations for the design of future fracture treatments are made based on the findings.
- Fractured Shale Gas Potential in New York
From Abstract: ...A very large number of wells are required to economically and systematically develop a fractured gas shale play. Over 20,000 Devonian Shale wells are producing today in the Appalachian Basin. Over 7,000 Antrim Shale wells are producing in the Michigan Basin and over 1,200 Barnett Shale wells are producing in the Fort Worth Basin today. Each individual play has been defined, tested and expanded based on understanding the resource distribution, natural fracture patterns, and limitations of the reservoir, and each play has required solutions to problems and issues required for commercial production... see full text.
- Petroleum geology and geochemistry of the Council Run gas field, north central Pennsylvania
Summary is under development.
- A tale of shales: the relative roles of production, decomposition, and dilution in the accumulation of organic-rich strata, Middle-Upper Devonian, Appalachian basin
From Abstract: A new consensus on the processes responsible for organic carbon burial in ancient epeiric seas has emerged. More firmly grounded in the uniformitarian framework of modern oceanography and biogeochemistry, this consensus recognizes the interdependent roles of sedimentation, primary production, and microbial metabolism in favor of earlier end-member models (e.g., ‘‘production vs. preservation’’). In this study, one of the classic stratigraphic sequences upon which the ‘‘preservation’’end-member was based is re-interpreted in light of this new consensus...see Full Text
- Anisotropy correction for deviated-well sonic logs: Application to seismic well tie
- Meeting the Nation's Natural Gas Needs: Industry and Government Cooperation Needed
From Abstract: Natural gas supply and demand, unlike that for crude oil, is controlled by domestic and sometimes, regional market forces. Currently, natural gas provides 25% of our total energy needs. United States produces one-fourth and consumes one-third of the world’s daily supply... see full abstract.
- Assessing Undiscovered Resources of the Barnett-Paleozoic Total Petroleum System, Bend Arch, Fort Worth Basin Province, Texas.
From Abstract: Organic-rich Barnett Shale (Mississippian-Pennsylvanian) is the primary source rock for oil and gas that is produced from Paleozoic reservoir rocks in the Bend Arch–Fort Worth Basin Province. Areal distribution and geochemical typing of hydrocarbons in this mature petroleum province indicates generation and expulsion from the Barnett at a depocenter coincident with a paleoaxis of the Fort Worth Basin. Barnett-sourced hydrocarbons migrated..See full abstract
- Seismic anisotropy in sedimentary rocks, part 2: Laboratory data
From Abstract: Part one of this paper presents a method for measuring seismic velocities and transverse isotropy in rocks using a single core plug. This method saves at least two-thirds of the time for preparing core samples and measuring velocities in transversely isotropic (TI) rocks. Using this method, we have measured velocity and anisotropy of many shale and reservoir rocks from oil and gas fields around the world. We present some of the data in this paper, which include seismic velocity and anisotropy in... see full abstract.
- Seismic anisotropy in sedimentary rocks, part 1: A single-plug laboratory method
From Abstract: A single-plug method for measuring seismic velocities and transverse isotropy in rocks has been rigorously validated and laboratory tested. The method requires only one sample to measure the velocities needed to derive the five independent elastic constants for transversely isotropic materials. In this method, piezoelectric transducers are fitted to the top, bottom, and sides of the cylindrical sample... see full abstract.
- Carbon-sulfur-iron relationships in condensed intervals of the Cretaceous Mancos shale
Although numerous studies have focused on the seismic, well log, or biostratigraphical
expression of condensed sections, few detailed geochemical analyses of these strata
exist. This study examines C-S-Fe relationships in condensed intervals from the
Cretaceous Mancos Shale.
The River Gas Utah #1 well is located in the southern Uinta basin in Carbon County, Utah
and penetrated the Tununk Shale (76 ft), Ferron Sandstone (243 ft), and main body of the
Mancos Shale (1621 ft). Two intervals (770-820 ft and 1162-1209 ft) of thinly laminated
dark gray shale with abundant fossil fragments and high gamma activity (60 API units over
baseline) are interpreted to be condensed intervals.
Preliminary results obtained from 50 samples analyzed for C and S demonstrate that the
condensed intervals contain more organic carbon than the surrounding rocks. The average
total organic carbon (TOC) values for the upper and lower condensed intervals are 2.2%
and 1.8%, respectively, whereas the rest of the Mancos Shale main body has an average
TOC value of 1.2%. Although the total sulfur (TS) content of the condensed intervals is
higher than the surrounding rocks, the TS:TOC ratios are lower in the condensed intervals.
Elevated TOC values observed in condensed sections are typically considered to reflect
slow sedimentation rates and limited dilution by clastic detritus. These data suggest that
variations in diagenesis or organic matter reactivity also play a significant role in the
preservation of greater amounts of organic carbon in condensed intervals.
- Regulatory Issues Affecting Management Of Produced Water From Coal Bed Methane Wells
From the introduction: Coal bed methane (CBM) wells are being developed in increasing numbers throughout the United States. These are wells that are drilled into coal seams to withdraw ground water (produced water) to reduce the hydrostatic pressure on the coal seam. The reduced pressure allows methane gas to migrate to the well bore where it moves to the surface and is collected. Where possible, operators prefer to discharge the produced water into nearby streams, rivers, or other surface water bodies. Depending on the chemical characteristics of the produced water, different levels of treatment are applied to the produced water before discharge. In some locations, produced water cannot be discharged and is injected, reused, or evaporated.
Although the CBM industry is producing “natural” gas, such gas may not necessarily be covered under the existing national regulations for discharges from the oil and gas industry. This paper describes the existing national discharge regulations, the ways in which CBM produced water is currently being managed, the current CBM discharge permitting practices, and how these options might change as the volume of produced water increases because of the many new wells being
- An integrated assessment of a "type euxinic" deposit: Evidence for multiple controls on black shale deposition in the middle Devonian Oatka Creek formation
- Origin, migration and mixing of oilfield brines: Stable isotopic evidence from Kuqa Foreland Basin
Strontium, deuterium and oxygen isotopes were analyzed from a basin in China along with chemistry of oil-field brine
- Role of shale thickness on vertical connectivity of fractures: application of crack-bridging theory to the Austin Chalk, Texas
From Abstract: Contrasting material properties of alternating chalk and shale layers control vertical connectivity of fractures. Our field observations within the Austin Chalk, Texas indicate that: (1) the majority of vertical fractures occur in chalk layers and abut against contacts with shale layers, (2) thicker shale layers have greater resistance to fracture propagation than thinner shale layers. From these observations we hypothesize both the resistance of shale to fracturing and the thickness of shale layers may inhibit fracture propagation across the shale and into the next chalk layer... see full abstract.
- A changing landscape: Environmental conditions and consequences of the 1920s Union County oil booms
(pdf format is available for full text)
- Bacteriogenic ethane in near-surface aquifers: Implications for leaking hydrocarbon well bores
From Abstract: ...For well bore leakage cases in the Western Canadian Sedimentary Basin, the characterization of a bacteriogenic end-member permits the quantitative resolution of the contribution of shallow aquifer gas versus deeper commercial reservoir gas to well bore leakage. Bacteriogenic near-surface aquifer ethane can account for 4−28% of the ethane from the production casing and for 29−36% of the ethane in gas bubbles traveling to the surface along the outside of the surface casing... see full abstract.
- Recognition of facies, bounding surfaces and stratigraphic patterns in foreland-ramp successions: an example from the Upper Devonian, Appalachian Basin, USA
From Abstract: A detailed stratigraphic study of the Upper Devonian Lock Haven Formation in the Appalachian basin provides new interpretations applicable to understanding sedimentation and stratigraphic architecture in the foreland-ramp setting. The common occurrence of graded beds, hummocky cross stratification, and shell lags indicates that storm processes played an important role in deposition. Gradational-based, coarsening-upward shoreface sequences of interbedded sandstone and mudstone formed during gradual fall in relative sea level... see full abstract.
- The kinetics of in-reservoir oil destruction and gas formation: constraints from experiments and empirical data, and from thermodynamics
From Abstract: Experimental kinetic data on the reactions of pure chemicals, destruction of heavy hydrocarbons, and gas formation have been combined with thermodynamic theory and empirical data on oil and gas occurrences to constrain the range of plausible activation energies and frequency factors for oil destruction and gas formation in nature. It is assumed explicitly here that the kinetics of oil destruction and gas formation can be adequately described using a set of parallel first-order reactions... see full abstract.
- Black shale deposition and faunal overturn in the Devonian Appalachian Basin: Clastic starvation, seasonal water-column mixing, and efficient biolimiting nutrient recycling
Integrated geochemical data suggest that black shale deposition in the Devonian Geneseo Formation of western New York was initiated by the coincidence of siliciclastic starvation and the intensification of seasonal water column stratification and mixing. Once established, however, black shale deposition was maintained through efficient recycling of biolimiting nutrients which enhanced primary productivity. Recycling efficiency was achieved through a positive feedback loop of oscillating benthic redox conditions that enhanced N and P regeneration from sediments, sustained high primary productivity by returning nutrients to the photic zone during mixing, and ensured a downward flux of organic matter that drove or enhanced the episodic development of benthic anoxia during stratification. This feedback was ultimately disrupted by rising siliciclastic influx, which diluted organic matter and restored benthic redox stability. The abrupt overturn of diverse, long-standing Appalachian basin marine communities may have been the result of trophic resource destabilization during Geneseo deposition.
- Gas productive fractured shales: An overview and update
- Evaluating Reservoir Production Mechanisms and Hydraulic Fracture Geometry in the Lewis Shale, San Juan Basin
- Environmental Benefits of Advanced Oil and Gas Exploration and Production
Documents innovations in oil and gas exploration and production over the last 30 years. These advances have enabled the domestic petroleum industry to increase the efficiency of its exploration and production efforts, while improving its environmental track record.
- 3-D moveout inversion in azimuthally anisotropic media with lateral velocity variation: Theory and a case study
Reflection moveout recorded over an azimuthally
anisotropic medium (e.g., caused by vertical or dipping
fractures) varies with the azimuth of the source-receiver
line. Normal-moveout (NMO) velocity, responsible for
the reflection traveltimes on conventional-length spreads,
forms an elliptical curve in the horizontal plane.
While this result remains valid in the presence of arbitrary
anisotropy and heterogeneity, the inversion of the
NMO ellipse for the medium parameters has been discussed so far only for horizontally homogeneous models
above a horizontal or dipping reflector.
Here, we develop an analytic moveout correction for
weak lateral velocity variation in horizontally layered
azimuthally anisotropic media. The correction term is
proportional to the curvature of the zero-offset traveltime surface at the common midpoint and, therefore, can be estimated from surface seismic data. After the influence of lateral velocity variation on the effective NMO ellipses has been stripped, the generalized Dix equation can be used to compute the interval ellipses and evaluate the magnitude of azimuthal anisotropy (measured by P-wave NMO velocity) within the layer of interest
- A refraction-seismic field study to determine the anisotropic parameters of shales
hales are known to be transversely isotropic (TI), which can lead to incorrect subsurface imaging if isotropic behavior is assumed. By knowing the anisotropic parameters of the shales, it is possible to correct for the anisotropic effects in seismic data, thereby obtaining a more correct subsurface image. Two P-wave refraction-seismic field studies were undertaken in areas of steeply dipping marine shales of the Wapiabi Formation to determine the anisotropic parameters of these shales in situ. The first survey was located in Jumpingpound Creek, Alberta, Canada, and the other location was west of Longview, Alberta, Canada. Seismic lines were laid out parallel, perpendicular, and 45° to the local strike directions. At both locations, the compressional headwave velocities along strike were determined to be faster than the velocities perpendicular to strike. Analysis of the Jumpingpound Creek data location yielded anisotropic parameters of = 0.14 ± 0.05 and = 0.00 ± 0.08, whereas at Longview, the anisotropic parameters were determined to be = 0.25 ± 0.06 and = 0.00 ± 0.06. The difference in is attributed to variations in the shale facies between the two sites.
- An Investigation of Naturally Occurring Radioactive Materials (NORM) in Oil and Gas Wells in New York State
Summarizes results of research and analyses of samples taken at oil and gas sites to determine the levels of NORMs. It was concluded that the analyses found no levels of NORM that would adversely effect the public health or environment.
- Genetic and temporal relations between formation waters and biogenic methane - Upper Devonian Antrim Shale, Michigan Basin, USA
From Abstract: Controversy remains regarding how well geochemical criteria can distinguish microbial from thermogenic methane. Natural gas in most conventional deposits has migrated from a source rock to a reservoir, rarely remaining associated with the original or cogenetic formation waters. We investigated an unusual gas reservoir, the Late Devonian Antrim Shale, in which large volumes of variably saline water are coproduced with gas... see full abstract.
- Injection Water Quality: A Key Factor to Successful Waterflooding
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- Linked to What? Economic Linkages in an Extractive Economy
- Field observations and analytical modeling of fracture network permeability in hydrocarbon reservoirs
Faults, and composite fault and joint networks are common structural and hydrologic elements in reservoirs. The structural and hydrologic architecture of faults is complicated by the formation of striated slip surfaces, cataclasite and gouge, deformation of the adjacent wall rock, and hydrothermal mineralization. A prototype, analytical computer algorithm is presented to model faults as anisotropic fluid conduits, and joints as isotropic conduits. The permeability tensor of the rock mass is determined by the volume averaged contribution of each fault and joint in the population via tensor rotation from the local coordinate system of each fracture to the global, geographic reference frame. Permeability across the fracture walls and the permeability of the rock matrix are also considered in the algorithm. Application to a synthetic network of conjugate fractures illustrates that the anisotropic surface texture of faults is a fundamental feature determining the permeability of the rock mass. Modeling is also conducted to illustrate how changes in the stress tensor affect permeability anisotropy.
- Model Predictive Control of a Natural Gas Turbine Installation
Model Prediction Control (MPC) predicts the change in dependent variable when independent variable are changed. In the article, surge and maximum turbine inlet were a concern. Should surge occur, a violent dynamic pulsation will go throughout the machine. The study looks to create a control strategy using the MPC system.
- Water and Hydrocarbon Phase Trapping in Porous Media - Diagnosis, Prevention and Treatment
The entrapment of extraneous phases within porous media can occur in a number of different situations during drilling, completion, workover and production operations. The introduction of an additional immiscible phase, or an increase in an existing phase saturation within porous media can cause deleterious relative permeability effects which can substantially impact the permeability and relative permeability to oil or gas. This phenomenon is commonly described as aqueous phase trapping or hydrocarbon phase trapping, depending on the situation under consideration. This paper describes specific conditions required for the establishment of aqueous and hydrocarbon phase traps and provides diagnostic equations to evaluate the potential severity of an aqueous phase trap in a given reservoir situation. Specific procedures are recommended for the prevention of aqueous phase traps during drilling, completion and production operations and, in a situation where phase traps are determined to exist in a reservoir, a variety of treatment techniques are presented to attempt to remove or reduce the severity of the aqueous or hydrocarbon phase trapping phenomenon.
- Gas Storage Reservoir Performance Optimization Through the Application of Drainage and Imbibition Relative Permeability Data
Gas storage reservoirs are utilized in many locations to seasonally store gas in summer months for periods of high demand in the winter. This generally involves the cyclic pressurization and depressurization of the reservoir on an annual basis. If the storage reservoir overlies an aquifer or residual oil leg, this may involve the cyclic motion of the gas-liquid contact and gas zone. This paper documents an extensive series of reservoir condition relative permeability experiments conducted on core material from a gas storage reservoir in southern Ontario to investigate the effects of cyclical pressurization and depressurization on reservoir performance. The tests illustrate how the cycling of applied net overburden pressure and the presence of trapped gas and water saturations in the dynamic gas-liquid transition zone can affect the production and injection of gas in the storage reservoir. Applications of the data, and extensions to field performance are also presented.
- Environmental Federalism and the Third Sovereign: Limits on State Authority to Regulate Water Quality in Indian Country
- 3-D seismic evidence of the effects of carbonate karst collapse on overlying clastic stratigraphy and reservoir compartmentali