Shale Gas in Europe: pragmatic perspectives and actions

NASA Astrophysics Data System (ADS)

Hübner, A.; Horsfield, B.; Kapp, I.

2012-10-01

Natural gas will continue to play a key role in the EU's energy mix in the coming years, with unconventional gas' role increasing in importance as new resources are exploited worldwide. As far as Europe's own shale gas resources are concerned, it is especially the public's perception and level of acceptance that will make or break shale gas in the near-term. Both the pros and cons need to be discussed based on factual argument rather than speculation. Research organizations such as ours (GFZ German Research Centre for Geosciences) have an active and defining role to play in remedying this deficiency. As far as science and technology developments are concerned, the project "Gas Shales in Europe" (GASH) and the shale gas activities of "GeoEnergie" (GeoEn) are the first major initiatives in Europe focused on shale gas. Basic and applied geoscientific research is conducted to understand the fundamental nature and interdependencies of the processes leading to shale gas formation. When it comes to knowledge transfer, the perceived and real risks associated with shale gas exploitation need immediate evaluation in Europe using scientific analysis. To proactively target these issues, the GFZ and partners are launching the European sustainable Operating Practices (E-SOP) Initiative for Unconventional Resources. The web-based Shale Gas Information Platform (SHIP) brings these issues into the public domain.

Western Greece unconventional hydrocarbon potential from oil shale and shale gas reservoirs

NASA Astrophysics Data System (ADS)

Karakitsios, Vasileios; Agiadi, Konstantina

2013-04-01

It is clear that we are gradually running out of new sedimentary basins to explore for conventional oil and gas and that the reserves of conventional oil, which can be produced cheaply, are limited. This is the reason why several major oil companies invest in what are often called unconventional hydrocarbons: mainly oil shales, heavy oil, tar sand and shale gas. In western Greece exist important oil and gas shale reservoirs which must be added to its hydrocarbon potential1,2. Regarding oil shales, Western Greece presents significant underground immature, or close to the early maturation stage, source rocks with black shale composition. These source rock oils may be produced by applying an in-situ conversion process (ICP). A modern technology, yet unproven at a commercial scale, is the thermally conductive in-situ conversion technology, developed by Shell3. Since most of western Greece source rocks are black shales with high organic content, those, which are immature or close to the maturity limit have sufficient thickness and are located below 1500 meters depth, may be converted artificially by in situ pyrolysis. In western Greece, there are several extensive areas with these characteristics, which may be subject of exploitation in the future2. Shale gas reservoirs in Western Greece are quite possibly present in all areas where shales occur below the ground-water level, with significant extent and organic matter content greater than 1%, and during their geological history, were found under conditions corresponding to the gas window (generally at depths over 5,000 to 6,000m). Western Greece contains argillaceous source rocks, found within the gas window, from which shale gas may be produced and consequently these rocks represent exploitable shale gas reservoirs. Considering the inevitable increase in crude oil prices, it is expected that at some point soon Western Greece shales will most probably be targeted. Exploration for conventional petroleum reservoirs

The flora of the New Albany shale; Part 2, The Calamopityeae and their relationships

USGS Publications Warehouse

Read, Charles B.

1937-01-01

Material referable to Calamopitys americana, Calamopitys foerstei, Stenomyelon muratum, Kalymma lirata, Kalymma resinosa, and Kalymma auriculata, from the upper portion of the New Albany shale in central Kentucky, is described. All these species are based on the internal structure of stems and petioles. The suggestion is made that the genus Stenomyelon should be included in the family Calamopityeae rather than in a separate family. Relationships of the several species and genera belonging to the Calamopityeae are discussed, and it is recommended that the name Calamopitys be restricted to manoxylic forms (C. saturni Unger, etc.), that Eristophyton be used for the pycnoxylic species which have in the past been placed in Calamopitys, and that Sphenoxylon be adopted for the American species which has been called Calamopitys eupunctata. It is pointed out that the Calamopityeae may be divided, naturally, into two major groups-a manoxylic, protostelic group and a pycnoxylic, medullated group. Stenomyelon is probably in the lineage of the more primitive Calamopityeae, and Endoxylon is presumably the most advanced type now known.

Shale Gas Well, Hydraulic Fracturing, and Formation Data to Support Modeling of Gas and Water Flow in Shale Formations

NASA Astrophysics Data System (ADS)

Edwards, Ryan W. J.; Celia, Michael A.

2018-04-01

The potential for shale gas development and hydraulic fracturing to cause subsurface water contamination has prompted a number of modeling studies to assess the risk. A significant impediment for conducting robust modeling is the lack of comprehensive publicly available information and data about the properties of shale formations, shale wells, the process of hydraulic fracturing, and properties of the hydraulic fractures. We have collated a substantial amount of these data that are relevant for modeling multiphase flow of water and gas in shale gas formations. We summarize these data and their sources in tabulated form.

Map of assessed shale gas in the United States, 2012

USGS Publications Warehouse

,; Biewick, Laura R. H.

2013-01-01

The U.S. Geological Survey has compiled a map of shale-gas assessments in the United States that were completed by 2012 as part of the National Assessment of Oil and Gas Project. Using a geology-based assessment methodology, the U.S. Geological Survey quantitatively estimated potential volumes of undiscovered gas within shale-gas assessment units. These shale-gas assessment units are mapped, and square-mile cells are shown to represent proprietary shale-gas wells. The square-mile cells include gas-producing wells from shale intervals. In some cases, shale-gas formations contain gas in deeper parts of a basin and oil at shallower depths (for example, the Woodford Shale and the Eagle Ford Shale). Because a discussion of shale oil is beyond the scope of this report, only shale-gas assessment units and cells are shown. The map can be printed as a hardcopy map or downloaded for interactive analysis in a Geographic Information System data package using the ArcGIS map document (file extension MXD) and published map file (file extension PMF). Also available is a publications access table with hyperlinks to current U.S. Geological Survey shale gas assessment publications and web pages. Assessment results and geologic reports are available as completed at the U.S. Geological Survey Energy Resources Program Web Site, http://energy.usgs.gov/OilGas/AssessmentsData/NationalOilGasAssessment.aspx. A historical perspective of shale gas activity in the United States is documented and presented in a video clip included as a PowerPoint slideshow.

Water management practices used by Fayetteville shale gas producers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veil, J. A.

2011-06-03

Water issues continue to play an important role in producing natural gas from shale formations. This report examines water issues relating to shale gas production in the Fayetteville Shale. In particular, the report focuses on how gas producers obtain water supplies used for drilling and hydraulically fracturing wells, how that water is transported to the well sites and stored, and how the wastewater from the wells (flowback and produced water) is managed. Last year, Argonne National Laboratory made a similar evaluation of water issues in the Marcellus Shale (Veil 2010). Gas production in the Marcellus Shale involves at least threemore » states, many oil and gas operators, and multiple wastewater management options. Consequently, Veil (2010) provided extensive information on water. This current study is less complicated for several reasons: (1) gas production in the Fayetteville Shale is somewhat more mature and stable than production in the Marcellus Shale; (2) the Fayetteville Shale underlies a single state (Arkansas); (3) there are only a few gas producers that operate the large majority of the wells in the Fayetteville Shale; (4) much of the water management information relating to the Marcellus Shale also applies to the Fayetteville Shale, therefore, it can be referenced from Veil (2010) rather than being recreated here; and (5) the author has previously published a report on the Fayetteville Shale (Veil 2007) and has helped to develop an informational website on the Fayetteville Shale (Argonne and University of Arkansas 2008), both of these sources, which are relevant to the subject of this report, are cited as references.« less

Employment Creation of Shale Gas Investment in China

NASA Astrophysics Data System (ADS)

Wang, Xuecheng; Zhang, Baosheng; Wu, Meiling; Li, Xiang; Lin, Yuying

2018-01-01

An ambitious shale gas extraction plan has been proposed. The huge investment of shale gas may put an effect on the whole China’s economy, especially for employment. However, there is few study to date has quantified these effects. The aim of this paper is to quantify these effects especially employment creation and figures out whether shale gas investment in China is a good choice or not. Input-output analysis has been utilized in this study to estimate the employment creation in four different Chinese regions. Our findings show that shale gas investment will result in creating 660000, 370000, 140000 and 58000 equivalent jobs in Sichuan, Chongqing, Inner Mongolia and Guizhou, respectively. Considering the potential risks of environmental issues, we suggest that it may be a better strategy for the government, at least in the current situation, to slow down shale gas development investment.

Shale gas development impacts on surface water quality in Pennsylvania.

PubMed

Olmstead, Sheila M; Muehlenbachs, Lucija A; Shih, Jhih-Shyang; Chu, Ziyan; Krupnick, Alan J

2013-03-26

Concern has been raised in the scientific literature about the environmental implications of extracting natural gas from deep shale formations, and published studies suggest that shale gas development may affect local groundwater quality. The potential for surface water quality degradation has been discussed in prior work, although no empirical analysis of this issue has been published. The potential for large-scale surface water quality degradation has affected regulatory approaches to shale gas development in some US states, despite the dearth of evidence. This paper conducts a large-scale examination of the extent to which shale gas development activities affect surface water quality. Focusing on the Marcellus Shale in Pennsylvania, we estimate the effect of shale gas wells and the release of treated shale gas waste by permitted treatment facilities on observed downstream concentrations of chloride (Cl(-)) and total suspended solids (TSS), controlling for other factors. Results suggest that (i) the treatment of shale gas waste by treatment plants in a watershed raises downstream Cl(-) concentrations but not TSS concentrations, and (ii) the presence of shale gas wells in a watershed raises downstream TSS concentrations but not Cl(-) concentrations. These results can inform future voluntary measures taken by shale gas operators and policy approaches taken by regulators to protect surface water quality as the scale of this economically important activity increases.

Shale gas development impacts on surface water quality in Pennsylvania

PubMed Central

Olmstead, Sheila M.; Muehlenbachs, Lucija A.; Shih, Jhih-Shyang; Chu, Ziyan; Krupnick, Alan J.

2013-01-01

Concern has been raised in the scientific literature about the environmental implications of extracting natural gas from deep shale formations, and published studies suggest that shale gas development may affect local groundwater quality. The potential for surface water quality degradation has been discussed in prior work, although no empirical analysis of this issue has been published. The potential for large-scale surface water quality degradation has affected regulatory approaches to shale gas development in some US states, despite the dearth of evidence. This paper conducts a large-scale examination of the extent to which shale gas development activities affect surface water quality. Focusing on the Marcellus Shale in Pennsylvania, we estimate the effect of shale gas wells and the release of treated shale gas waste by permitted treatment facilities on observed downstream concentrations of chloride (Cl−) and total suspended solids (TSS), controlling for other factors. Results suggest that (i) the treatment of shale gas waste by treatment plants in a watershed raises downstream Cl− concentrations but not TSS concentrations, and (ii) the presence of shale gas wells in a watershed raises downstream TSS concentrations but not Cl− concentrations. These results can inform future voluntary measures taken by shale gas operators and policy approaches taken by regulators to protect surface water quality as the scale of this economically important activity increases. PMID:23479604

Shale Gas: Development Opportunities and Challenges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zoback, Mark D.; Arent, Douglas J.

2014-03-01

The use of horizontal drilling and multistage hydraulic fracturing technologies has enabled the production of immense quantities of natural gas, to date principally in North America but increasingly in other countries around the world. The global availability of this resource creates both opportunities and challenges that need to be addressed in a timely and effective manner. There seems little question that rapid shale gas development, coupled with fuel switching from coal to natural gas for power generation, can have beneficial effects on air pollution, greenhouse gas emissions, and energy security in many countries. In this context, shale gas resources representmore » a critically important transition fuel on the path to a decarbonized energy future. For these benefits to be realized, however, it is imperative that shale gas resources be developed with effective environmental safeguards to reduce their impact on land use, water resources, air quality, and nearby communities.« less

Multiparameter Analysis of Gas Transport Phenomena in Shale Gas Reservoirs: Apparent Permeability Characterization.

PubMed

Shen, Yinghao; Pang, Yu; Shen, Ziqi; Tian, Yuanyuan; Ge, Hongkui

2018-02-08

The large amount of nanoscale pores in shale results in the inability to apply Darcy's law. Moreover, the gas adsorption of shale increases the complexity of pore size characterization and thus decreases the accuracy of flow regime estimation. In this study, an apparent permeability model, which describes the adsorptive gas flow behavior in shale by considering the effects of gas adsorption, stress dependence, and non-Darcy flow, is proposed. The pore size distribution, methane adsorption capacity, pore compressibility, and matrix permeability of the Barnett and Eagle Ford shales are measured in the laboratory to determine the critical parameters of gas transport phenomena. The slip coefficients, tortuosity, and surface diffusivity are predicted via the regression analysis of the permeability data. The results indicate that the apparent permeability model, which considers second-order gas slippage, Knudsen diffusion, and surface diffusion, could describe the gas flow behavior in the transition flow regime for nanoporous shale. Second-order gas slippage and surface diffusion play key roles in the gas flow in nanopores for Knudsen numbers ranging from 0.18 to 0.5. Therefore, the gas adsorption and non-Darcy flow effects, which involve gas slippage, Knudsen diffusion, and surface diffusion, are indispensable parameters of the permeability model for shale.

Mechanical Properties of Gas Shale During Drilling Operations

NASA Astrophysics Data System (ADS)

Yan, Chuanliang; Deng, Jingen; Cheng, Yuanfang; Li, Menglai; Feng, Yongcun; Li, Xiaorong

2017-07-01

The mechanical properties of gas shale significantly affect the designs of drilling, completion, and hydraulic fracturing treatments. In this paper, the microstructure characteristics of gas shale from southern China containing up to 45.1% clay were analyzed using a scanning electron microscope. The gas shale samples feature strongly anisotropic characteristics and well-developed bedding planes. Their strength is controlled by the strength of both the matrix and the bedding planes. Conventional triaxial tests and direct shear tests are further used to study the chemical effects of drilling fluids on the strength of shale matrix and bedding planes, respectively. The results show that the drilling fluid has a much larger impact on the strength of the bedding plane than that of the shale matrix. The impact of water-based mud (WBM) is much larger compared with oil-based mud. Furthermore, the borehole collapse pressure of shale gas wells considering the effects of drilling fluids are analyzed. The results show that the collapse pressure increases gradually with the increase of drilling time, especially for WBM.

Water Resources and Natural Gas Production from the Marcellus Shale

USGS Publications Warehouse

Soeder, Daniel J.; Kappel, William M.

2009-01-01

The Marcellus Shale is a sedimentary rock formation deposited over 350 million years ago in a shallow inland sea located in the eastern United States where the present-day Appalachian Mountains now stand (de Witt and others, 1993). This shale contains significant quantities of natural gas. New developments in drilling technology, along with higher wellhead prices, have made the Marcellus Shale an important natural gas resource. The Marcellus Shale extends from southern New York across Pennsylvania, and into western Maryland, West Virginia, and eastern Ohio (fig. 1). 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.

Shale Gas Exploration and Development Progress in China and the Way Forward

NASA Astrophysics Data System (ADS)

Chen, Jianghua

2018-02-01

Shale gas exploration in China started late but is progressing very quickly with the strong support from Central Government. China has 21.8 tcm technically recoverable shale gas resources and 764.3 bcm proved shale gas reserve, mainly in marine facies in Sichuan basin. In 2016, overall shale gas production in China is around 7.9 bcm, while it is set to reach 10 bcm in 2017 and 30 bcm in 2020. BP is the only remaining IOC actor in shale gas exploration in China partnering with CNPC in 2 blocks in Sichuan basin. China is encouraging shale gas business both at Central level and at Provincial level through establishing development plan, continuation of subsidies and research funding. Engineering services for shale gas development and infrastructures are developing, while the overall cost and gas marketing conditions will be key factors for the success in shale gas industry.

Liquid oil production from shale gas condensate reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng, James J.

A process of producing liquid oil from shale gas condensate reservoirs and, more particularly, to increase liquid oil production by huff-n-puff in shale gas condensate reservoirs. The process includes performing a huff-n-puff gas injection mode and flowing the bottom-hole pressure lower than the dew point pressure.

Dry Volume Fracturing Simulation of Shale Gas Reservoir

NASA Astrophysics Data System (ADS)

Xu, Guixi; Wang, Shuzhong; Luo, Xiangrong; Jing, Zefeng

2017-11-01

Application of CO2 dry fracturing technology to shale gas reservoir development in China has advantages of no water consumption, little reservoir damage and promoting CH4 desorption. This paper uses Meyer simulation to study complex fracture network extension and the distribution characteristics of shale gas reservoirs in the CO2 dry volume fracturing process. The simulation results prove the validity of the modified CO2 dry fracturing fluid used in shale volume fracturing and provides a theoretical basis for the following study on interval optimization of the shale reservoir dry volume fracturing.

Rapid gas development in the Fayetteville shale basin, Arkansas

EPA Science Inventory

Advances in drilling and extraction of natural gas have resulted in rapid expansion of wells in shale basins. The rate of gas well installation in the Fayetteville shale is 774 wells a year since 2005 with thousands more planned. The Fayetteville shale covers 23,000 km2 although ...

Geochemical and isotopic evidence for paleoredox conditions during deposition of the Devonian-Mississippian New Albany Shale, southern Indiana

NASA Technical Reports Server (NTRS)

Beier, J. A.; Hayes, J. M.

1989-01-01

The upper part of the New Albany Shale is divided into three members. In ascending order, these are (1) the Morgan Trail Member, a laminated brownish-black shale; (2) the Camp Run Member, an interbedded brownish-black and greenish-gray shale; and (3) the Clegg Creek Member, also a laminated brownish-black shale. The Morgan Trail and Camp Run Members contain 5% to 6% total organic carbon (TOC) and 2% sulfide sulfur. Isotopic composition of sulfide in these members ranges from -5.0% to -20.0%. C/S plots indicate linear relationships between abundances of these elements, with a zero intercept characteristic of sediments deposited in a non-euxinic marine environment. Formation of diagenetic pyrite was carbon limited in these members. The Clegg Creek Member contains 10% to 15% TOC and 2% to 6% sulfide sulfur. Isotopic compositions of sulfide range from -5.0% to -40%. The most negative values occur in the uppermost Clegg Creek Member and are characteristic of syngenetic pyrite, formed within an anoxic water column. Abundances of carbon and sulfur are greater and uncorrelated in this member, consistent with deposition in as euxinic environment. In addition, DOP (degree of pyritization) values suggest that formation of pyrite was generally iron limited throughout Clegg Creek deposition, but sulfur isotopes indicate that syngenetic (water-column) pyrite becomes an important component in the sediment only in the upper part of the member. At the top of the Clegg Creek Member, a zone of phosphate nodules and trace-metal enrichment coincides with maximal TOC values. During euxinic deposition, phosphate and trace metals accumulated below the chemocline because of limited vertical circulation in the water column. Increased productivity would have resulted in an increased flux of particulate organic matter to the sediment, providing an effective sink for trace metals in the water column. Phosphate and trace metals released from organic matter during early diagenesis resulted in

The shale gas revolution: Barriers, sustainability, and emerging opportunities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Middleton, Richard S.; Gupta, Rajan; Hyman, Jeffrey D.

Shale gas and hydraulic refracturing has revolutionized the US energy sector in terms of prices, consumption, and CO 2 emissions. However, key questions remain including environmental concerns and extraction efficiencies that are leveling off. For the first time, we identify key discoveries, lessons learned, and recommendations from this shale gas revolution through extensive data mining and analysis of 23 years of production from 20,000 wells. Discoveries include identification of a learning-by-doing process where disruptive technology innovation led to a doubling in shale gas extraction, how refracturing with emerging technologies can transform existing wells, and how overall shale gas production ismore » actually dominated by long-term tail production rather than the high-profile initial exponentially-declining production in the first 12 months. We hypothesize that tail production can be manipulated, through better fracturing techniques and alternative working fluids such as CO 2, to increase shale gas recovery and minimize environmental impacts such as through carbon sequestration.« less

The shale gas revolution: Barriers, sustainability, and emerging opportunities

DOE PAGES

Middleton, Richard S.; Gupta, Rajan; Hyman, Jeffrey D.; ...

2017-08-01

Shale gas and hydraulic refracturing has revolutionized the US energy sector in terms of prices, consumption, and CO 2 emissions. However, key questions remain including environmental concerns and extraction efficiencies that are leveling off. For the first time, we identify key discoveries, lessons learned, and recommendations from this shale gas revolution through extensive data mining and analysis of 23 years of production from 20,000 wells. Discoveries include identification of a learning-by-doing process where disruptive technology innovation led to a doubling in shale gas extraction, how refracturing with emerging technologies can transform existing wells, and how overall shale gas production ismore » actually dominated by long-term tail production rather than the high-profile initial exponentially-declining production in the first 12 months. We hypothesize that tail production can be manipulated, through better fracturing techniques and alternative working fluids such as CO 2, to increase shale gas recovery and minimize environmental impacts such as through carbon sequestration.« less

Development of Porosity Measurement Method in Shale Gas Reservoir Rock

NASA Astrophysics Data System (ADS)

Siswandani, Alita; Nurhandoko, BagusEndar B.

2016-08-01

The pore scales have impacts on transport mechanisms in shale gas reservoirs. In this research, digital helium porosity meter is used for porosity measurement by considering real condition. Accordingly it is necessary to obtain a good approximation for gas filled porosity. Shale has the typical effective porosity that is changing as a function of time. Effective porosity values for three different shale rocks are analyzed by this proposed measurement. We develop the new measurement method for characterizing porosity phenomena in shale gas as a time function by measuring porosity in a range of minutes using digital helium porosity meter. The porosity of shale rock measured in this experiment are free gas and adsorbed gas porosoty. The pressure change in time shows that porosity of shale contains at least two type porosities: macro scale porosity (fracture porosity) and fine scale porosity (nano scale porosity). We present the estimation of effective porosity values by considering Boyle-Gay Lussaac approximation and Van der Waals approximation.

Testing marine shales' ability to generate catalytic gas at low temperature

NASA Astrophysics Data System (ADS)

Wei, L.; Schimmelmann, A.; Drobniak, A.; Sauer, P. E.; Mastalerz, M.

2013-12-01

Hydrocarbon gases are generally thought to originatevia low-temperature microbial or high-temperature thermogenicpathways (Whiticar, 1996) that can be distinguished by compound-specific hydrogen and carbon stable isotope ratios. An alternative low-temperature catalytic pathway for hydrocarbon generation from sedimentary organic matter has been proposed to be active at temperatures as low as 50oC (e.g.,Mango and Jarvie,2009,2010; Mango et al., 2010; Bartholomew et al., 1999). This hypothesis, however, still requires rigoroustesting by independent laboratory experiments.The possibility of catalytic generation of hydrocarbons in some source rocks (most likely in relatively impermeable and organic-rich shales where reduced catalytic centers can be best preserved) would offer an explanation for the finding of gas of non-microbial origin in formations that lack the thermal maturity for generating thermogenic gas.It is unknown whether catalytically generated methane would be isotopically different from thermogenicmethane (δ13CCH4>-50‰, δ2HCH4from -275‰ to -100‰) ormicrobially generated methane (δ13CCH4from -40‰ to -110‰, δ2HCH4from -400‰to -150‰) (Whiticar, 1998). In order to test for catalytic gas generationin water-wet shales and coals, we are conductinglaboratory experiments at three temperatures (60°C, 100°C, 200°C)and three pressures (ambient pressure, 107 Pa, 3x107 Pa)over periods of six months to several years. So far, our longest running experiments have reached one year. We sealed different types of thermally immature, pre-evacuatedshales (Mowry, New Albany, and Mahoganyshales) and coals (SpringfieldCoal and Wilcoxlignite)with isotopically defined waters in gold cells in the absence of elemental oxygen.Preliminary results show that these samples, depending on conditions, can generate light hydrocarbon gases (methane, ethane and propane) and CO2. Methane, CO2, and traces of H2havebeen generated at 60°C, whereas experiments at 100°C and 200�

Water use for Shale-gas production in Texas, U.S.

PubMed

Nicot, Jean-Philippe; Scanlon, Bridget R

2012-03-20

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 Mm(3) (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 Mm(3) Texas-Haynesville, 18 Mm(3) 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 Mm(3), peaking at 145 Mm(3) in the mid-2020s and decreasing to 23 Mm(3) in 2060. Current freshwater use may shift to brackish water to reduce competition with other users.

Assessment of undiscovered shale gas and shale oil resources in the Mississippian Barnett Shale, Bend Arch–Fort Worth Basin Province, North-Central Texas

USGS Publications Warehouse

Marra, Kristen R.; Charpentier, Ronald R.; Schenk, Christopher J.; Lewan, Michael D.; Leathers-Miller, Heidi M.; Klett, Timothy R.; Gaswirth, Stephanie B.; Le, Phuong A.; Mercier, Tracey J.; Pitman, Janet K.; Tennyson, Marilyn E.

2015-12-17

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean volumes of 53 trillion cubic feet of shale gas, 172 million barrels of shale oil, and 176 million barrels of natural gas liquids in the Barnett Shale of the Bend Arch–Fort Worth Basin Province of Texas.

Economic Impacts Analysis of Shale Gas Investment in China

NASA Astrophysics Data System (ADS)

Han, Shangfeng; Zhang, Baosheng; Wang, Xuecheng

2018-01-01

Chinese government has announced an ambitious shale gas extraction plan, which requires significant investment. This has the potential to draw investment from other areas and may affect the whole China’s economy. There is few study to date has quantified these shale gas investment’s effects on Chinese economy. The aim of this paper is to quantify the economic effect and figures out whether shale gas investment in China is a good choice or not. Input-output analysis has been utilized in this study to estimate the economic impacts in four different Chinese regions. Our findings show that shale gas investment will result in approximately 868, 427, 115 and 42 Billion RMB economic impacts in Sichuan, Chongqing, Inner Mongolia and Guizhou, respectively. The total economic impact is only around 1453 Billion RMB, which is not significant compared to the economic impact of coalbed methane investment. Considering the potential risks of environmental issues, we suggest that it may be a better strategy for the government, at least in the current situation, to slow down shale gas development investment.

Shale gas development: a smart regulation framework.

PubMed

Konschnik, Katherine E; Boling, Mark K

2014-01-01

Advances in directional drilling and hydraulic fracturing have sparked a natural gas boom from shale formations in the United States. Regulators face a rapidly changing industry comprised of hundreds of players, operating tens of thousands of wells across 30 states. They are often challenged to respond by budget cuts, a brain drain to industry, regulations designed for conventional gas developments, insufficient information, and deeply polarized debates about hydraulic fracturing and its regulation. As a result, shale gas governance remains a halting patchwork of rules, undermining opportunities to effectively characterize and mitigate development risk. The situation is dynamic, with research and incremental regulatory advances underway. Into this mix, we offer the CO/RE framework--characterization of risk, optimization of mitigation strategies, regulation, and enforcement--to design tailored governance strategies. We then apply CO/RE to three types of shale gas risks, to illustrate its potential utility to regulators.

Impact of Shale Gas Development on Water Resource in Fuling, China

NASA Astrophysics Data System (ADS)

Yang, Hong; Huang, Xianjin; Yang, Qinyuan; Tu, Jianjun

2015-04-01

As a low-carbon energy, shale gas rapidly developed in U.S. in last years due to the innovation of the technique of hydraulic fracture, or fracking. Shale gas boom produces more gas with low price and reduced the reliance on fuel import. To follow the American shale gas success, China made an ambitious plan of shale gas extraction, 6.5 billion m3 by 2015. To extract shale gas, huge amount water is needed to inject into each gas well. This will intensify the competition of water use between industry, agricultural and domestic sectors. It may finally exacerbate the water scarcity in China. After the extraction, some water was returned to the ground. Without adequate treatment, the flowback water can introduce heavy metal, acids, pesticides, and other toxic material into water and land. This may inevitably worsen the water and land contamination. This study analysed the potential water consumption and wastewater generation in shale gas development in Fuling, Southwest China. The survey found the average water consumption is 30,000 cubic meter for one well, higher than shale well in U.S. Some 2%-20% water flowed back to the ground. The water quality monitoring showed the Total Suspended Solid (TSS) and Chemical Oxygen Demand (COD) were the main factors above those specified by China's water regulation. Shale gas is a lower-carbon energy, but it is important to recognize the water consuming and environmental pollution during the fracking. Strict monitoring and good coordination during the shale gas exploitation is urgently needed for the balance of economic development, energy demand and environmental protection.

Pore-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix

PubMed Central

Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.

2017-01-01

Extremely low permeability due to nano-scale pores is a distinctive feature of gas transport in a shale matrix. The permeability of shale depends on pore pressure, porosity, pore throat size and gas type. The pore network model is a practical way to explain the macro flow behavior of porous media from a microscopic point of view. In this research, gas flow in a shale matrix is simulated using a previously developed three-dimensional pore network model that includes typical bimodal pore size distribution, anisotropy and low connectivity of the pore structure in shale. The apparent gas permeability of shale matrix was calculated under different reservoir pressures corresponding to different gas exploitation stages. Results indicate that gas permeability is strongly related to reservoir gas pressure, and hence the apparent permeability is not a unique value during the shale gas exploitation, and simulations suggested that a constant permeability for continuum-scale simulation is not accurate. Hence, the reservoir pressures of different shale gas exploitations should be considered. In addition, a sensitivity analysis was also performed to determine the contributions to apparent permeability of a shale matrix from petro-physical properties of shale such as pore throat size and porosity. Finally, the impact of connectivity of nano-scale pores on shale gas flux was analyzed. These results would provide an insight into understanding nano/micro scale flows of shale gas in the shale matrix. PMID:28772465

Pore-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix.

PubMed

Zhang, Pengwei; Hu, Liming; Meegoda, Jay N

2017-01-25

Extremely low permeability due to nano-scale pores is a distinctive feature of gas transport in a shale matrix. The permeability of shale depends on pore pressure, porosity, pore throat size and gas type. The pore network model is a practical way to explain the macro flow behavior of porous media from a microscopic point of view. In this research, gas flow in a shale matrix is simulated using a previously developed three-dimensional pore network model that includes typical bimodal pore size distribution, anisotropy and low connectivity of the pore structure in shale. The apparent gas permeability of shale matrix was calculated under different reservoir pressures corresponding to different gas exploitation stages. Results indicate that gas permeability is strongly related to reservoir gas pressure, and hence the apparent permeability is not a unique value during the shale gas exploitation, and simulations suggested that a constant permeability for continuum-scale simulation is not accurate. Hence, the reservoir pressures of different shale gas exploitations should be considered. In addition, a sensitivity analysis was also performed to determine the contributions to apparent permeability of a shale matrix from petro-physical properties of shale such as pore throat size and porosity. Finally, the impact of connectivity of nano-scale pores on shale gas flux was analyzed. These results would provide an insight into understanding nano/micro scale flows of shale gas in the shale matrix.

Water Availability for Shale Gas Development in Sichuan Basin, China.

PubMed

Yu, Mengjun; Weinthal, Erika; Patiño-Echeverri, Dalia; Deshusses, Marc A; Zou, Caineng; Ni, Yunyan; Vengosh, Avner

2016-03-15

Unconventional shale gas development holds promise for reducing the predominant consumption of coal and increasing the utilization of natural gas in China. While China possesses some of the most abundant technically recoverable shale gas resources in the world, water availability could still be a limiting factor for hydraulic fracturing operations, in addition to geological, infrastructural, and technological barriers. Here, we project the baseline water availability for the next 15 years in Sichuan Basin, one of the most promising shale gas basins in China. Our projection shows that continued water demand for the domestic sector in Sichuan Basin could result in high to extremely high water stress in certain areas. By simulating shale gas development and using information from current water use for hydraulic fracturing in Sichuan Basin (20,000-30,000 m(3) per well), we project that during the next decade water use for shale gas development could reach 20-30 million m(3)/year, when shale gas well development is projected to be most active. While this volume is negligible relative to the projected overall domestic water use of ∼36 billion m(3)/year, we posit that intensification of hydraulic fracturing and water use might compete with other water utilization in local water-stress areas in Sichuan Basin.

Understanding Shale Gas: Recent Progress and Remaining Challenges

DOE PAGES

Striolo, Alberto; Cole, David R.

2017-08-27

Because of a number of technological advancements, unconventional hydrocarbons, and in particular shale gas, have transformed the US economy. Much is being learned, as demonstrated by the reduced cost of extracting shale gas in the US over the past five years. However, a number of challenges still need to be addressed. Many of these challenges represent grand scientific and technological tasks, overcoming which will have a number of positive impacts, ranging from the reduction of the environmental footprint of shale gas production to improvements and leaps forward in diverse sectors, including chemical manufacturing and catalytic transformations. This review addresses recentmore » advancements in computational and experimental approaches, which led to improved understanding of, in particular, structure and transport of fluids, including hydrocarbons, electrolytes, water, and CO 2 in heterogeneous subsurface rocks such as those typically found in shale formations. Finally, the narrative is concluded with a suggestion of a few research directions that, by synergistically combining computational and experimental advances, could allow us to overcome some of the hurdles that currently hinder the production of hydrocarbons from shale formations.« less

Shale Gas and Oil in Germany - Resources and Environmental Impacts

NASA Astrophysics Data System (ADS)

Ladage, Stefan; Blumenberg, Martin; Houben, Georg; Pfunt, Helena; Gestermann, Nicolai; Franke, Dieter; Erbacher, Jochen

2017-04-01

In light of the controversial debate on "unconventional" oil and gas resources and the environmental impacts of "fracking", the Federal Institute for Geosciences and Natural Resources (BGR) conducted a comprehensive resource assessment of shale gas and light tight oil in Germany and studied the potential environmental impacts of shale gas development and hydraulic fracturing from a geoscientific perspective. Here, we present our final results (BGR 2016), incorporating the majority of potential shale source rock formations in Germany. Besides shale gas, light tight oil has been assessed. According to our set of criteria - i.e. thermal maturity 0.6-1.2 %vitrinite reflectance (VR; oil) and >1.2 % VR (gas) respectively, organic carbon content > 2%, depth between 500/1000 m and 5000 m as well as a net thickness >20 m - seven potentially generative shale formations were indentified, the most important of them being the Lower Jurassic (Toarcian) Posidonia shale with both shale gas and tight oil potential. The North German basin is by far the most prolific basin. The resource assessment was carried out using a volumetric in-place approach. Variability inherent in the input parameters was accounted for using Monte-Carlo simulations. Technically recoverable resources (TRR) were estimated using recent, production-based recovery factors of North American shale plays and also employing Monte-Carlo simulations. In total, shale gas TRR range between 320 and 2030 bcm and tight oil TRR between 13 and 164 Mio. t in Germany. Tight oil potential is therefore considered minor, whereas the shale gas potential exceeds that of conventional resources by far. Furthermore an overview of numerical transport modelling approaches concerning environmental impacts of the hydraulic fracturing is given. These simulations are based on a representative lithostratigraphy model of the North-German basin, where major shale plays can be expected. Numerical hydrogeological modelling of frac fluid

18 CFR 270.303 - Natural gas produced from Devonian shale.

Code of Federal Regulations, 2013 CFR

2013-04-01

... from Devonian shale. A person seeking a determination that natural gas is produced from Devonian shale... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Natural gas produced from Devonian shale. 270.303 Section 270.303 Conservation of Power and Water Resources FEDERAL ENERGY...

18 CFR 270.303 - Natural gas produced from Devonian shale.

Code of Federal Regulations, 2012 CFR

2012-04-01

... from Devonian shale. A person seeking a determination that natural gas is produced from Devonian shale... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Natural gas produced from Devonian shale. 270.303 Section 270.303 Conservation of Power and Water Resources FEDERAL ENERGY...

18 CFR 270.303 - Natural gas produced from Devonian shale.

Code of Federal Regulations, 2014 CFR

2014-04-01

... from Devonian shale. A person seeking a determination that natural gas is produced from Devonian shale... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Natural gas produced from Devonian shale. 270.303 Section 270.303 Conservation of Power and Water Resources FEDERAL ENERGY...

Environmental baselines: preparing for shale gas in the UK

NASA Astrophysics Data System (ADS)

Bloomfield, John; Manamsa, Katya; Bell, Rachel; Darling, George; Dochartaigh, Brighid O.; Stuart, Marianne; Ward, Rob

2014-05-01

Groundwater is a vital source of freshwater in the UK. It provides almost 30% of public water supply on average, but locally, for example in south-east England, it is constitutes nearly 90% of public supply. In addition to public supply, groundwater has a number of other uses including agriculture, industry, and food and drink production. It is also vital for maintaining river flows especially during dry periods and so is essential for maintaining ecosystem health. Recently, there have been concerns expressed about the potential impacts of shale gas development on groundwater. The UK has abundant shales and clays which are currently the focus of considerable interest and there is active research into their characterisation, resource evaluation and exploitation risks. The British Geological Survey (BGS) is undertaking research to provide information to address some of the environmental concerns related to the potential impacts of shale gas development on groundwater resources and quality. The aim of much of this initial work is to establish environmental baselines, such as a baseline survey of methane occurrence in groundwater (National methane baseline study) and the spatial relationships between potential sources and groundwater receptors (iHydrogeology project), prior to any shale gas exploration and development. The poster describes these two baseline studies and presents preliminary findings. BGS are currently undertaking a national survey of baseline methane concentrations in groundwater across the UK. This work will enable any potential future changes in methane in groundwater associated with shale gas development to be assessed. Measurements of methane in potable water from the Cretaceous, Jurassic and Triassic carbonate and sandstone aquifers are variable and reveal methane concentrations of up to 500 micrograms per litre, but the mean value is relatively low at < 10 micrograms per litre. These values compare with much higher levels of methane in aquicludes

The flux of radionuclides in flowback fluid from shale gas exploitation.

PubMed

Almond, S; Clancy, S A; Davies, R J; Worrall, F

2014-11-01

This study considers the flux of radioactivity in flowback fluid from shale gas development in three areas: the Carboniferous, Bowland Shale, UK; the Silurian Shale, Poland; and the Carboniferous Barnett Shale, USA. The radioactive flux from these basins was estimated, given estimates of the number of wells developed or to be developed, the flowback volume per well and the concentration of K (potassium) and Ra (radium) in the flowback water. For comparative purposes, the range of concentration was itself considered within four scenarios for the concentration range of radioactive measured in each shale gas basin, the groundwater of the each shale gas basin, global groundwater and local surface water. The study found that (i) for the Barnett Shale and the Silurian Shale, Poland, the 1 % exceedance flux in flowback water was between seven and eight times that would be expected from local groundwater. However, for the Bowland Shale, UK, the 1 % exceedance flux (the flux that would only be expected to be exceeded 1 % of the time, i.e. a reasonable worst case scenario) in flowback water was 500 times that expected from local groundwater. (ii) In no scenario was the 1 % exceedance exposure greater than 1 mSv-the allowable annual exposure allowed for in the UK. (iii) The radioactive flux of per energy produced was lower for shale gas than for conventional oil and gas production, nuclear power production and electricity generated through burning coal.

Shale Gas Development and Drinking Water Quality.

PubMed

Hill, Elaine; Ma, Lala

2017-05-01

The extent of environmental externalities associated with shale gas development (SGD) is important for welfare considerations and, to date, remains uncertain (Mason, Muehlenbachs, and Olmstead 2015; Hausman and Kellogg 2015). This paper takes a first step to address this gap in the literature. Our study examines whether shale gas development systematically impacts public drinking water quality in Pennsylvania, an area that has been an important part of the recent shale gas boom. We create a novel dataset from several unique sources of data that allows us to relate SGD to public drinking water quality through a gas well's proximity to community water system (CWS) groundwater source intake areas.1 We employ a difference-in-differences strategy that compares, for a given CWS, water quality after an increase in the number of drilled well pads to background levels of water quality in the geographic area as measured by the impact of more distant well pads. Our main estimate finds that drilling an additional well pad within 1 km of groundwater intake locations increases shale gas-related contaminants by 1.5–2.7 percent, on average. These results are striking considering that our data are based on water sampling measurements taken after municipal treatment, and suggest that the health impacts of SGD 1 A CWS is defined as the subset of public water systems that supplies water to the same population year-round. through water contamination remains an open question.

Modeling of gas generation from the Barnett Shale, Fort Worth Basin, Texas

USGS Publications Warehouse

Hill, R.J.; Zhang, E.; Katz, B.J.; Tang, Y.

2007-01-01

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. Copyright ?? 2007. The American Association of Petroleum Geologists. All rights reserved.

Discussion on upper limit of maturity for marine shale gas accumulation

NASA Astrophysics Data System (ADS)

Huang, Jinliang; Dong, Dazhong; Zhang, Chenchen; Wang, Yuman; Li, Xinjing; Wang, Shufang

2017-04-01

The sedimentary formations of marine shale in China are widely distributed and are characterized by old age, early hydrocarbon-generation and high thermal evolution degree, strong tectonic deformation and reformation and poor preservation conditions. Therefore whether commercial shale gas reservoirs can be formed is a critical issue to be studied. The previous studies showed that the upper threshold of maturity (Ro%) for the gas generation of marine source rocks is 3.0%. Based on comparative studies of marine shale gas exploration practices at home and abroad and reservoir experimental analysis results, we proposed in this paper that the upper threshold of maturity (Ro%) for marine shale gas accumulation is 3.5%. And the main proofs are as follows: (1) There is still certain commercial production in the area with the higher than 3.0% in Marcellus and Woodford marine shale gas plays in North America; (2) The Ro of the Silurian Longmaxi shale in the Sichuan Basin in China is between 2.5% and 3.3%. However, the significant breakthrough has been made in shale gas exploration and the production exceeds 7 billion m3 in 2016; (3) The TOC of the Cambrian Qiongzhusi organic-rich shale in Changning Region in the Sichuan Basin ranges 2% to 7.1% and the Ro is greater than 3.5%. And the resistivity logging of organic-rich shale appears low-ultra low resistivity and inversion of Rt curve. It's suggested that the organic matters in Qiongzhusi organic-rich shale occurs partial carbonization which leads to stronger conductivity; (4) Thermal simulation experiments showed that the specific surface of shale increases with Ro. And the specific surface and adsorptive capacity both reach maximum when the Ro is 3.5%; (5) The analysis of physical properties and SEM images of shale reservoirs indicated that when Ro is higher than 3.5%, the dominant pores of Qiongzhusi shale are micro-pores while the organic pores are relatively poor-developed, and the average porosity is less than 2%.

Microbial production of natural gas from coal and organic-rich shale

USGS Publications Warehouse

Orem, William

2013-01-01

Natural gas is an important component of the energy mix in the United States, producing greater energy yield per unit weight and less pollution compared to coal and oil. Most of the world’s natural gas resource is thermogenic, produced in the geologic environment over time by high temperature and pressure within deposits of oil, coal, and shale. About 20 percent of the natural gas resource, however, is produced by microorganisms (microbes). Microbes potentially could be used to generate economic quantities of natural gas from otherwise unexploitable coal and shale deposits, from coal and shale from which natural gas has already been recovered, and from waste material such as coal slurry. Little is known, however, about the microbial production of natural gas from coal and shale.

Environmental Public Health Dimensions of Shale and Tight Gas Development

PubMed Central

Hays, Jake; Finkel, Madelon L.

2014-01-01

Background: The United States has experienced a boom in natural gas production due to recent technological innovations that have enabled this resource to be produced from shale formations. Objectives: We reviewed the body of evidence related to exposure pathways in order to evaluate the potential environmental public health impacts of shale gas development. We highlight what is currently known and identify data gaps and research limitations by addressing matters of toxicity, exposure pathways, air quality, and water quality. Discussion: There is evidence of potential environmental public health risks associated with shale gas development. Several studies suggest that shale gas development contributes to ambient air concentrations of pollutants known to be associated with increased risk of morbidity and mortality. Similarly, an increasing body of studies suggest that water contamination risks exist through a variety of environmental pathways, most notably during wastewater transport and disposal, and via poor zonal isolation of gases and fluids due to structural integrity impairment of cement in gas wells. Conclusion: Despite a growing body of evidence, data gaps persist. Most important, there is a need for more epidemiological studies to assess associations between risk factors, such as air and water pollution, and health outcomes among populations living in close proximity to shale gas operations. Citation: Shonkoff SB, Hays J, Finkel ML. 2014. Environmental public health dimensions of shale and tight gas development. Environ Health Perspect 122:787–795; http://dx.doi.org/10.1289/ehp.1307866 PMID:24736097

18 CFR 270.303 - Natural gas produced from Devonian shale.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Natural gas produced... DETERMINATION PROCEDURES Requirements for Filings With Jurisdictional Agencies § 270.303 Natural gas produced from Devonian shale. A person seeking a determination that natural gas is produced from Devonian shale...

18 CFR 270.303 - Natural gas produced from Devonian shale.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Natural gas produced... DETERMINATION PROCEDURES Requirements for Filings With Jurisdictional Agencies § 270.303 Natural gas produced from Devonian shale. A person seeking a determination that natural gas is produced from Devonian shale...

An exploratory study of air emissions associated with shale gas development and production in the Barnett Shale.

PubMed

Rich, Alisa; Grover, James P; Sattler, Melanie L

2014-01-01

Information regarding air emissions from shale gas extraction and production is critically important given production is occurring in highly urbanized areas across the United States. Objectives of this exploratory study were to collect ambient air samples in residential areas within 61 m (200 feet) of shale gas extraction/production and determine whether a "fingerprint" of chemicals can be associated with shale gas activity. Statistical analyses correlating fingerprint chemicals with methane, equipment, and processes of extraction/production were performed. Ambient air sampling in residential areas of shale gas extraction and production was conducted at six counties in the Dallas/Fort Worth (DFW) Metroplex from 2008 to 2010. The 39 locations tested were identified by clients that requested monitoring. Seven sites were sampled on 2 days (typically months later in another season), and two sites were sampled on 3 days, resulting in 50 sets of monitoring data. Twenty-four-hour passive samples were collected using summa canisters. Gas chromatography/mass spectrometer analysis was used to identify organic compounds present. Methane was present in concentrations above laboratory detection limits in 49 out of 50 sampling data sets. Most of the areas investigated had atmospheric methane concentrations considerably higher than reported urban background concentrations (1.8-2.0 ppm(v)). Other chemical constituents were found to be correlated with presence of methane. A principal components analysis (PCA) identified multivariate patterns of concentrations that potentially constitute signatures of emissions from different phases of operation at natural gas sites. The first factor identified through the PCA proved most informative. Extreme negative values were strongly and statistically associated with the presence of compressors at sample sites. The seven chemicals strongly associated with this factor (o-xylene, ethylbenzene, 1,2,4-trimethylbenzene, m- and p-xylene, 1

Shale gas development and cancer incidence in southwest Pennsylvania.

PubMed

Finkel, M L

2016-12-01

To what extent does unconventional gas development lead to an increase in cancer incidence in heavily drilled Southwest Pennsylvania? Ecological study. Data for urinary bladder, thyroid and leukaemia were abstracted from the Pennsylvania Cancer Registry (PCR). Cancer incidence among counties with high, moderate and minimal number of producing wells is compared before drilling activity and thereafter. Observed vs expected cases, standardized incidence ratio and 95% confidence intervals are presented. Data are presented by county, diagnosis and sex for the years 2000-2004, 2004-2008 and 2008-2012. The percent difference between the observed cases from 2000 to 2004 and 2008-2012 was calculated. The observed number of urinary bladder cases was higher than expected in both sexes in counties with shale gas activity. In counties with the fewest number of producing wells, the increase was essentially non-existent. The number of observed cases of thyroid cancer increased substantially among both sexes over the time period in all counties regardless of the number of wells drilled. The pattern for leukaemia was mixed among males and females and among the counties regardless of the extent of shale gas development activities. Potential risk factors other than shale gas development must be taken into account to explain the higher than expected cancer cases in counties with and without shale gas wells before and during unconventional shale gas activity. Copyright © 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Sedimentology of gas-bearing Devonian shales of the Appalachian Basin

NASA Astrophysics Data System (ADS)

Potter, P. E.; Maynard, J. B.; Pryor, W. A.

1981-01-01

Sedimentology of the Devonian shales and its relationship to gas, oil, and uranium are reported. Information about the gas bearing Devonian shales of the Appalachian Basin is organized in the following sections: paleogeography and basin analysis; lithology and internal stratigraphy; paleontology; mineralogy, petrology, and chemistry; and gas oil, and uranium.

[Chemical hazards arising from shale gas extraction].

PubMed

Pakulska, Daria

2015-01-01

The development of the shale industry is gaining momentum and hence the analysis of chemical hazards to the environment and health of the local population is extreiely timely and important. Chemical hazards are created during the exploitation of all minerals, but in the case of shale gas production, there is much more uncertainty as regards to the effects of new technologies application. American experience suggests the increasing risk of environmental contamination, mainly groundwater. The greatest, concern is the incomplete knowledge of the composition of fluids used for fracturing shale rock and unpredictability of long-term effects of hydraulic fracturing for the environment and health of residents. High population density in the old continent causes the problem of chemical hazards which is much larger than in the USA. Despite the growing public discontent data on this subject are limited. First of all, there is no epidemiological studies to assess the relationship between risk factors, such as air and water pollution, and health effects in populations living in close proximity to gas wells. The aim of this article is to identify and discuss existing concepts on the sources of environmental contamination, an indication of the environment elements under pressure and potential health risks arising from shale gas extraction.

Environmental public health dimensions of shale and tight gas development.

PubMed

Shonkoff, Seth B C; Hays, Jake; Finkel, Madelon L

2014-08-01

The United States has experienced a boom in natural gas production due to recent technological innovations that have enabled this resource to be produced from shale formations. We reviewed the body of evidence related to exposure pathways in order to evaluate the potential environmental public health impacts of shale gas development. We highlight what is currently known and identify data gaps and research limitations by addressing matters of toxicity, exposure pathways, air quality, and water quality. There is evidence of potential environmental public health risks associated with shale gas development. Several studies suggest that shale gas development contributes to ambient air concentrations of pollutants known to be associated with increased risk of morbidity and mortality. Similarly, an increasing body of studies suggest that water contamination risks exist through a variety of environmental pathways, most notably during wastewater transport and disposal, and via poor zonal isolation of gases and fluids due to structural integrity impairment of cement in gas wells. Despite a growing body of evidence, data gaps persist. Most important, there is a need for more epidemiological studies to assess associations between risk factors, such as air and water pollution, and health outcomes among populations living in close proximity to shale gas operations.

The Shale Gas potential of Lower Carboniferous Sediments in Germany

NASA Astrophysics Data System (ADS)

Kerschke, D.; Mihailovic, A.; Schulz, H., -M.; Horsfield, B.

2012-04-01

Organic-rich Carboniferous sediments are proven source rocks for conventional gas systems in NW Europe and are likely gas shale candidates. Within the framework of GeoEnergie, an initiative to strengthen scientific excellence, funded by the German Ministry of Education and Research (BMBF), the influence of palaeogeography and basin dynamics on sedimentology and diagenesis is being investigated. Our aim is to unravel the evolution of shale gas-relevant properties which control gas prospectivity and production parameters like porosity, brittleness, etc. for the Lower Carboniferous in Germany. Northern Germany is underlain by thick, mudstone-bearing Carboniferous successions with a wide range of thermal maturities. Some of these mudstone horizons are rich in organic carbon which is either of marine and/or terrigenous origin. During the Carboniferous deposition of fine-grained, TOC-rich basinal sediments changed into shallow marine to paralic siliciclastic sediments (carbonates during the Lower Carboniferous) in the north, and grade into coarse-grained sediments close to the uprising Variscan mountains in the south. As a result different architectural elements including TOC-rich fine-grained sediments like basinal shales, fine-grained parts of turbidites, and shallow marine mudstones occur in both the Lower and the Upper Carboniferous section. A high shale gas potential occurs in basinal shales of Namurian age with marine organic material and TOC contents of up to 8 % (Rhenish Alum Shales). Such sediments with thermal maturities between 1.3 to 3.0 % vitrinite reflectance and sufficient quartz contents occur in wide areas of present-day Central European Basins System (CEBS), and are at favourable depth for shale gas exploration predominantly along the southern CEBS margin.

Shale Gas Exploration and Exploitation Induced Risks - SHEER

NASA Astrophysics Data System (ADS)

Capuano, Paolo; Orlecka-Sikora, Beata; Lasocki, Stanislaw; Cesca, Simone; Gunning, Andrew; jaroslawsky, Janusz; Garcia-Aristizabal, Alexander; Westwood, Rachel; Gasparini, Paolo

2017-04-01

Shale gas operations may affect the quality of air, water and landscapes; furthermore, it can induce seismic activity, with the possible impacts on the surrounding infrastructure. The SHEER project aims at setting up a probabilistic methodology to assess and mitigate the short and the long term environmental risks connected to the exploration and exploitation of shale gas. In particular we are investigating risks associated with groundwater contamination, air pollution and induced seismicity. A shale gas test site located in Poland (Wysin) has been monitored before, during and after the fracking operations with the aim of assessing environmental risks connected with groundwater contamination, air pollution and earthquakes induced by fracking and injection of waste water. The severity of each of these hazards depends strongly on the unexpected enhanced permeability pattern, which may develop as an unwanted by-product of the fracking processes and may become pathway for gas and fluid migration towards underground water reservoirs or the surface. The project is devoted to monitor and understand how far this enhanced permeability pattern develops both in space and time. The considered hazards may be at least partially inter-related as they all depend on this enhanced permeability pattern. Therefore they are being approached from a multi-hazard, multi parameter perspective. We expect to develop methodologies and procedures to track and model fracture evolution around shale gas exploitation sites and a robust statistically based, multi-parameter methodology to assess environmental impacts and risks across the operational lifecycle of shale gas. The developed methodologies are going to be applied and tested on a comprehensive database consisting of seismicity, changes of the quality of ground-waters and air, ground deformations, and operational data collected from the ongoing monitoring episode (Wysin) and past episodes: Lubocino (Poland), Preese Hall (UK), Oklahoma (USA

Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix

PubMed Central

Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.; Gao, Shengyan

2015-01-01

The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir. PMID:26310236

Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix.

PubMed

Zhang, Pengwei; Hu, Liming; Meegoda, Jay N; Gao, Shengyan

2015-08-27

The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir.

Assessment of potential unconventional lacustrine shale-oil and shale-gas resources, Phitsanulok Basin, Thailand, 2014

USGS Publications Warehouse

Schenk, Christopher J.; Charpentier, Ronald R.; Klett, Timothy R.; Mercier, Tracey J.; Tennyson, Marilyn E.; Pitman, Janet K.; Brownfield, Michael E.

2014-01-01

Using a geology-based assessment methodology, the U.S. Geological Survey assessed potential technically recoverable mean resources of 53 million barrels of shale oil and 320 billion cubic feet of shale gas in the Phitsanulok Basin, onshore Thailand.

Assessing Radium Activity in Shale Gas Produced Brine

NASA Astrophysics Data System (ADS)

Fan, W.; Hayes, K. F.; Ellis, B. R.

2015-12-01

The high volumes and salinity associated with shale gas produced water can make finding suitable storage or disposal options a challenge, especially when deep well brine disposal or recycling for additional well completions is not an option. In such cases, recovery of commodity salts from the high total dissolved solids (TDS) of the brine wastewater may be desirable, yet the elevated concentrations of the naturally occurring radionuclides such as Ra-226 and Ra-228 in produced waters (sometimes substantially greater than the EPA limit of 5 pCi/L) may concentrate during these steps and limit salt recovery options. Therefore, assessing the potential presence of these Ra radionuclides in produced water from shale gas reservoir properties is desirable. In this study, we seek to link U and Th content within a given shale reservoir to the expected Ra content of produced brine by accounting for secular equilibrium within the rock and subsequent release to Ra to native brines. Produced brine from a series of Antrim shale wells and flowback from a single Utica-Collingwood shale well in Michigan were sampled and analyzed via ICP-MS to measure Ra content. Gamma spectroscopy was used to verify the robustness of this new Ra analytical method. Ra concentrations were observed to be up to an order of magnitude higher in the Antrim flowback water samples compared to those collected from the Utica-Collingwood well. The higher Ra content in Antrim produced brines correlates well with higher U content in the Antrim (19 ppm) relative to the Utica-Collingwood (3.5 ppm). We also observed an increase in Ra activity with increasing TDS in the Antrim samples. This Ra-TDS relationship demonstrates the influence of competing divalent cations in controlling Ra mobility in these clay-rich reservoirs. In addition, we will present a survey of geochemical data from other shale gas plays in the U.S. correlating shale U, Th content with produced brine Ra content. A goal of this study is to develop a

Searching for anomalous methane in shallow groundwater near shale gas wells

NASA Astrophysics Data System (ADS)

Li, Zhenhui; You, Cheng; Gonzales, Matthew; Wendt, Anna K.; Wu, Fei; Brantley, Susan L.

2016-12-01

Since the 1800s, natural gas has been extracted from wells drilled into conventional reservoirs. Today, gas is also extracted from shale using high-volume hydraulic fracturing (HVHF). These wells sometimes leak methane and must be re-sealed with cement. Some researchers argue that methane concentrations, C, increase in groundwater near shale-gas wells and that ;fracked; wells leak more than conventional wells. We developed techniques to mine datasets of groundwater chemistry in Pennsylvania townships where contamination had been reported. Values of C measured in shallow private water wells were discovered to increase with proximity to faults and to conventional, but not shale-gas, wells in the entire area. However, in small subareas, C increased with proximity to some shale-gas wells. Data mining was used to map a few hotspots where C significantly correlates with distance to faults and gas wells. Near the hotspots, 3 out of 132 shale-gas wells ( 2%) and 4 out of 15 conventional wells (27%) intersect faults at depths where they are reported to be uncased or uncemented. These results demonstrate that even though these data techniques do not establish causation, they can elucidate the controls on natural methane emission along faults and may have implications for gas well construction.

Searching for anomalous methane in shallow groundwater near shale gas wells.

PubMed

Li, Zhenhui; You, Cheng; Gonzales, Matthew; Wendt, Anna K; Wu, Fei; Brantley, Susan L

2016-12-01

Since the 1800s, natural gas has been extracted from wells drilled into conventional reservoirs. Today, gas is also extracted from shale using high-volume hydraulic fracturing (HVHF). These wells sometimes leak methane and must be re-sealed with cement. Some researchers argue that methane concentrations, C, increase in groundwater near shale-gas wells and that "fracked" wells leak more than conventional wells. We developed techniques to mine datasets of groundwater chemistry in Pennsylvania townships where contamination had been reported. Values of C measured in shallow private water wells were discovered to increase with proximity to faults and to conventional, but not shale-gas, wells in the entire area. However, in small subareas, C increased with proximity to some shale-gas wells. Data mining was used to map a few hotspots where C significantly correlates with distance to faults and gas wells. Near the hotspots, 3 out of 132 shale-gas wells (~2%) and 4 out of 15 conventional wells (27%) intersect faults at depths where they are reported to be uncased or uncemented. These results demonstrate that even though these data techniques do not establish causation, they can elucidate the controls on natural methane emission along faults and may have implications for gas well construction. Copyright © 2016 Elsevier B.V. All rights reserved.

Measurements of Methane Emissions and Volatile Organic Compounds from Shale Gas Operations in the Marcellus Shale

NASA Astrophysics Data System (ADS)

Omara, M.; Subramanian, R.; Sullivan, M.; Robinson, A. L.; Presto, A. A.

2014-12-01

The Marcellus Shale is the most expansive shale gas reserve in play in the United States, representing an estimated 17 to 29 % of the total domestic shale gas reserves. The rapid and extensive development of this shale gas reserve in the past decade has stimulated significant interest and debate over the climate and environmental impacts associated with fugitive releases of methane and other pollutants, including volatile organic compounds. However, the nature and magnitude of these pollutant emissions remain poorly characterized. This study utilizes the tracer release technique to characterize total fugitive methane release rates from natural gas facilities in southwestern Pennsylvania and West Virginia that are at different stages of development, including well completion flowbacks and active production. Real-time downwind concentrations of methane and two tracer gases (acetylene and nitrous oxide) released onsite at known flow rates were measured using a quantum cascade tunable infrared laser differential absorption spectrometer (QC-TILDAS, Aerodyne, Billerica, MA) and a cavity ring down spectrometer (Model G2203, Picarro, Santa Clara, CA). Evacuated Silonite canisters were used to sample ambient air during downwind transects of methane and tracer plumes to assess volatile organic compounds (VOCs). A gas chromatograph with a flame ionization detector was used to quantify VOCs following the EPA Method TO-14A. A preliminary assessment of fugitive emissions from actively producing sites indicated that methane leak rates ranged from approximately 1.8 to 6.2 SCFM, possibly reflecting differences in facility age and installed emissions control technology. A detailed comparison of methane leak rates and VOCs emissions with recent published literature for other US shale gas plays will also be discussed.

The Value of Water in Extraction of Natural Gas from the Marcellus Shale

NASA Astrophysics Data System (ADS)

Rimsaite, R.; Abdalla, C.; Collins, A.

2013-12-01

Hydraulic fracturing of shale has increased the demand for the essential input of water in natural gas production. Increased utilization of water by the shale gas industry, and the development of water transport and storage related infrastructure suggest that the value of water is increasing where hydraulic fracturing is occurring. Few studies on the value of water in industrial uses exist and, to our knowledge, no studies of water's value in extracting natural gas from shale have been published. Our research aims to fill this knowledge gap by exploring several key dimensions of the value of water used in shale gas development. Our primary focus was to document the costs associated with water acquisition for shale gas extraction in West Virginia and Pennsylvania, two states located in the gas-rich Marcellus shale formation with active drilling and extraction underway. This research involved a) gathering data on the sources of and costs associated with water acquisition for shale gas extraction b) comparing unit costs with prices and costs paid by the gas industry users of water; c) determining factors that potentially impact total and per unit costs of water acquisition for the shale gas industry; and d) identifying lessons learned for water managers and policy-makers. The population of interest was all private and public entities selling water to the shale gas industry in Pennsylvania and West Virginia. Primary data were collected from phone interviews with water sellers and secondary data were gathered from state regulatory agencies. Contact information was obtained for 40 water sellers in the two states. Considering both states, the average response rate was 49%. Relatively small amounts of water, approximately 11% in West Virginia and 29% in Pennsylvania, were purchased from public water suppliers by the shale gas industry. The price of water reveals information about the value of water. The average price charged to gas companies was 6.00/1000 gallons and 7

Albany v. 3.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salinger, Andrew; Phipps, Eric; Ostien, Jakob

2016-01-13

The Albany code is a general-purpose finite element code for solving partial differential equations (PDEs). Albany is a research code that demonstrates how a PDE code can be built by interfacing many of the open-source software libraries that are released under Sandia's Trilinos project. Part of the mission of Albany is to be a testbed for new Trilinos libraries, to refine their methods, usability, and interfaces. Albany includes hooks to optimization and uncertainty quantification algorithms, including those in Trilinos as well as those in the Dakota toolkit. Because of this, Albany is a desirable starting point for new code developmentmore » efforts that wish to make heavy use of Trilinos. Albany is both a framework and the host for specific finite element applications. These applications have project names, and can be controlled by configuration option when the code is compiled, but are all developed and released as part of the single Albany code base, These include LCM, QCAD, FELIX, Aeras, and ATO applications.« less

Assessment of potential shale gas and shale oil resources of the Norte Basin, Uruguay, 2011

USGS Publications Warehouse

Schenk, Christopher J.; Kirschbaum, Mark A.; Charpentier, Ronald R.; Cook, Troy; Klett, Timothy R.; Gautier, Donald L.; Pollastro, Richard M.; Weaver, Jean N.; Brownfield, Michael

2011-01-01

Using a performance-based geological assessment methodology, the U.S. Geological Survey estimated mean volumes of 13.4 trillion cubic feet of potential technically recoverable shale gas and 0.5 billion barrels of technically recoverable shale oil resources in the Norte Basin of Uruguay.

Small-Angle and Ultrasmall-Angle Neutron Scattering (SANS/USANS) Study of New Albany Shale: A Treatise on Microporosity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bahadur, Jitendra; Radlinski, Andrzej P.; Melnichenko, Yuri B.

We applied small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques to study the microstructure of several New Albany shales of different maturity. It has been established that the total porosity decreases with maturity and increases somewhat for post-mature samples. A new method of SANS data analysis was developed, which allows the extraction of information about the size range and number density of micropores from the relatively flat scattering intensity observed in the limit of the large scattering vector Q. Macropores and significant number of mesopores are surface fractals, and their structure can be described in terms of themore » polydisperse spheres (PDSP) model. The model-independent Porod invariant method was employed to estimate total porosity, and the results were compared with the PDSP model results. It has been demonstrated that independent evaluation of incoherent background is crucial for accurate interpretation of the scattering data in the limit of large Q-values. Moreover, pore volumes estimated by the N 2 and CO 2 adsorption, as well as via the mercury intrusion technique, have been compared with those measured by SANS/USANS, and possible reasons for the observed discrepancies are discussed.« less

Small-Angle and Ultrasmall-Angle Neutron Scattering (SANS/USANS) Study of New Albany Shale: A Treatise on Microporosity

DOE PAGES

Bahadur, Jitendra; Radlinski, Andrzej P.; Melnichenko, Yuri B.; ...

2014-12-17

We applied small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques to study the microstructure of several New Albany shales of different maturity. It has been established that the total porosity decreases with maturity and increases somewhat for post-mature samples. A new method of SANS data analysis was developed, which allows the extraction of information about the size range and number density of micropores from the relatively flat scattering intensity observed in the limit of the large scattering vector Q. Macropores and significant number of mesopores are surface fractals, and their structure can be described in terms of themore » polydisperse spheres (PDSP) model. The model-independent Porod invariant method was employed to estimate total porosity, and the results were compared with the PDSP model results. It has been demonstrated that independent evaluation of incoherent background is crucial for accurate interpretation of the scattering data in the limit of large Q-values. Moreover, pore volumes estimated by the N 2 and CO 2 adsorption, as well as via the mercury intrusion technique, have been compared with those measured by SANS/USANS, and possible reasons for the observed discrepancies are discussed.« less

Methanogenic archaea in marcellus shale: a possible mechanism for enhanced gas recovery in unconventional shale resources.

PubMed

Tucker, Yael Tarlovsky; Kotcon, James; Mroz, Thomas

2015-06-02

Marcellus Shale occurs at depths of 1.5-2.5 km (5000 to 8000 feet) where most geologists generally assume that thermogenic processes are the only source of natural gas. However, methanogens in produced fluids and isotopic signatures of biogenic methane in this deep shale have recently been discovered. This study explores whether those methanogens are indigenous to the shale or are introduced during drilling and hydraulic fracturing. DNA was extracted from Marcellus Shale core samples, preinjected fluids, and produced fluids and was analyzed using Miseq sequencing of 16s rRNA genes. Methanogens present in shale cores were similar to methanogens in produced fluids. No methanogens were detected in injected fluids, suggesting that this is an unlikely source and that they may be native to the shale itself. Bench-top methane production tests of shale core and produced fluids suggest that these organisms are alive and active under simulated reservoir conditions. Growth conditions designed to simulate the hydrofracture processes indicated somewhat increased methane production; however, fluids alone produced relatively little methane. Together, these results suggest that some biogenic methane may be produced in these wells and that hydrofracture fluids currently used to stimulate gas recovery could stimulate methanogens and their rate of producing methane.

Shale Gas Information Platform SHIP: first year of fact-based communication

NASA Astrophysics Data System (ADS)

Hübner, Andreas; Horsfield, Brian; Petrow, Theresia

2013-04-01

Natural gas produced from shale, already on stream in the USA, and under development in many regions worldwide, has brought about a fundamental change in energy resource distribution and energy politics. According to recent IEA publications, shale gas production will continue to rise globally and will be embraced by many more countries than at present. Shale gas production, especially in densely populated regions, brings with it a new dimension of risk alongside potential benefits. A fact-based discussion of the pros and cons, however, has been hampered in part by a scarcity of scientific knowledge on the related risks, and by a lack of appropriate, i.e. transparent and balanced, communication of the academic research perspective. With the Shale Gas Information Platform SHIP, the GFZ German Research Centre for Geosciences engages in the public discussion of technical and environmental issues related to shale gas exploration and production. The project was launched online in early 2012, at a propitious time: the public debate was until then dominated by voices from industry and from environmental groups, which were often biased and/or lacking sound factual background. Significant academic research on the risks related to shale gas development and hydraulic fracturing operations in particular only started in 2011 and continued to expand in 2012. This was reflected in an increased output of peer-reviewed publications and academic reports. SHIP puts these into perspective and brings them to the attention of the broader public. With just one year of online presence, SHIP has already effectively filled the void in fact-based information on shale gas. This can be seen by a continuing demand for subscriptions to our News Email Alert Service, and by invitations SHIP has received to conferences and workshops, in order to share our experience of science-based and balanced information dissemination. SHIP's web content is expanding and so is its expert network. Collaborations

Wastewater management and Marcellus Shale gas development: trends, drivers, and planning implications.

PubMed

Rahm, Brian G; Bates, Josephine T; Bertoia, Lara R; Galford, Amy E; Yoxtheimer, David A; Riha, Susan J

2013-05-15

Extraction of natural gas from tight shale formations has been made possible by recent technological advances, including hydraulic fracturing with horizontal drilling. Global shale gas development is seen as a potential energy and geopolitical "game-changer." However, widespread concern exists with respect to possible environmental consequences of this development, particularly impacts on water resources. In the United States, where the most shale gas extraction has occurred, the Marcellus Shale is now the largest natural gas producing play. To date, over 6,000,000 m(3) of wastewater has been generated in the process of extracting natural gas from this shale in the state of Pennsylvania (PA) alone. Here we examine wastewater management practices and trends for this shale play through analysis of industry-reported, publicly available data collected from the Pennsylvania Department of Environmental Protection Oil and Gas Reporting Website. We also analyze the tracking and transport of shale gas liquid waste streams originating in PA using a combination of web-based and GIS approaches. From 2008 to 2011 wastewater reuse increased, POTW use decreased, and data tracking became more complete, while the average distance traveled by wastewater decreased by over 30%. Likely factors influencing these trends include state regulations and policies, along with low natural gas prices. Regional differences in wastewater management are influenced by industrial treatment capacity, as well as proximity to injection disposal capacity. Using lessons from the Marcellus Shale, we suggest that nations, states, and regulatory agencies facing new unconventional shale development recognize that pace and scale of well drilling leads to commensurate wastewater management challenges. We also suggest they implement wastewater reporting and tracking systems, articulate a policy for adapting management to evolving data and development patterns, assess local and regional wastewater treatment

Shale Gas Information Platform SHIP: the scientific perspective in all that hype

NASA Astrophysics Data System (ADS)

Hübner, A.; Horsfield, B.; Kapp, I.

2012-04-01

With the Shale Gas Information Platform SHIP, the GFZ German Research Centre for Geosciences engages in the public discussion of technical and environmental issues related to shale gas exploration and production. Unconventional fossil fuels, already on stream in the USA, and now under rapid development globally, have brought about a fundamental change in energy resource distribution and energy politics. Among these resources, shale gas is currently most discussed, with the public perspective focusing on putative environmental risk rather than on potential benefits. As far as Europe's own shale gas resources are concerned, scientific and technological innovations will play key roles in defining the dimension of future shale gas production, but it is especially the public's perception and level of acceptance that will make or break shale gas in the near-term. However, opinions on environmental risks diverge strongly: risks are minor and controllable according to industry, while environmental groups often claim the opposite. The Shale Gas Information Platform SHIP brings the perspective of science to the discussion on technical and environmental issues related to shale gas exploration and production. SHIP will not only showcase but discuss what is known and what is not yet know about environmental challenges and potential risks. SHIP features current scientific results and best practice approaches and builds on a network of international experts. The project is interactive and aims to spark discussion among all stakeholders. The Shale Gas Information Platform SHIP covers basic information and news on shale gas, but at the heart of SHIP is the Knowledge Base, a collection of scientific reviews from international experts. The articles give an overview on the current state of knowledge on a certain topic including knowledge gaps, and put this into context of past experiences, current best practices, and opinions expressed by different stakeholders. The articles are open

Considerations for the development of shale gas in the United Kingdom.

PubMed

Hays, Jake; Finkel, Madelon L; Depledge, Michael; Law, Adam; Shonkoff, Seth B C

2015-04-15

The United States shale gas boom has precipitated global interest in the development of unconventional oil and gas resources. Recently, government ministers in the United Kingdom started granting licenses that will enable companies to begin initial exploration for shale gas. Meanwhile, concern is increasing among the scientific community about the potential impacts of shale gas and other types of unconventional natural gas development (UGD) on human health and the environment. Although significant data gaps remain, there has been a surge in the number of articles appearing in the scientific literature, nearly three-quarters of which has been published since the beginning of 2013. Important lessons can be drawn from the UGD experience in the United States. Here we explore these considerations and argue that shale gas development policies in the UK and elsewhere should be informed by empirical evidence generated on environmental, public health, and social risks. Additionally, policy decisions should take into account the measured effectiveness of harm reduction strategies as opposed to hypothetical scenarios and purported best practices that lack empirical support. Copyright © 2015 Elsevier B.V. All rights reserved.

World Shale Gas Resources: An Initial Assessment of 14 Regions Outside the United States

EIA Publications

2011-01-01

The Energy Information Administration sponsored Advanced Resources International, Inc., to assess 48 gas shale basins in 32 countries, containing almost 70 shale gas formations. This effort has culminated in the report: World Shale Gas Resources: An Initial Assessment of 14 Regions Outside the United States.

Noble Gas Signatures in Antrim Shale Gas in the Michigan Basin - Assessing Compositional Variability and Transport Processes

NASA Astrophysics Data System (ADS)

Wen, T.; Castro, M. C.; Ellis, B. R.; Hall, C. M.; Lohmann, K. C.; Bouvier, L.

2014-12-01

Recent studies in the Michigan Basin looked at the atmospheric and terrigenic noble gas signatures of deep brines to place constraints on the past thermal history of the basin and to assess the extent of vertical transport processes within this sedimentary system. In this contribution, we present noble gas data of shale gas samples from the Antrim shale formation in the Michigan Basin. The Antrim shale was one of the first economic shale-gas plays in the U.S. and has been actively developed since the 1980's. This study pioneers the use of noble gases in subsurface shale gas in the Michigan Basin to clarify the nature of vertical transport processes within the sedimentary sequence and to assess potential variability of noble gas signatures in shales. Antrim Shale gas samples were analyzed for all stable noble gases (He, Ne, Ar, Kr, Xe) from samples collected at depths between 300 and 500m. Preliminary results show R/Ra values (where R and Ra are the measured and atmospheric 3He/4He ratios, respectively) varying from 0.022 to 0.21. Although most samples fall within typical crustal R/Ra range values (~0.02-0.05), a few samples point to the presence of a mantle He component with higher R/Ra ratios. Samples with higher R/Ra values also display higher 20Ne/22Ne ratios, up to 10.4, and further point to the presence of mantle 20Ne. The presence of crustally produced nucleogenic 21Ne and radiogenic 40Ar is also apparent with 21Ne/22Ne ratios up to 0.033 and 40Ar/36Ar ratios up to 312. The presence of crustally produced 4He, 21Ne and 40Ar is not spatially homogeneous within the Antrim shale. Areas of higher crustal 4He production appear distinct to those of crustally produced 21Ne and 40Ar and are possibly related the presence of different production levels within the shale with varying concentrations of parent elements.

The Complex Physical-Chemical Interaction of Fracking Fluids with Gas Shale

NASA Astrophysics Data System (ADS)

Cathles, L. M.; Engelder, T.; Bryndzia, T.

2014-12-01

The chemical aspects of hydrofracturing might seem straight forward: Inject a fluid with sand and some chemicals, recover the injected water now contaminated with chemicals from the shale, and produce gas. But there are some complications that turn out to be very interesting. First of all, it is possible to recover only about 20% of the injected water. Secondly, the fresh injected water (1-5 kppm) has been turned into a very saline bine (~200 kppm). It's easy to say the water has just been imbibed into the gas-filled dry shale, like water into a dry sponge, except the organic parts of the shale which host nearly all the porosity are hydrophobic. The shale is strongly oil wet; nevertheless it imbibes water. It's easy to say the water just mixed with water in the shale and became salty, but there is almost no water in the shale, and no salt either. How the water becomes salty begs easy explanation. The talk will quantitatively discuss these issues in light of experiments we have carried out, concluding that powerful capillary and osmotic forces draw fracking water into the shale while making the return waters salty. How this is achieved will certainly tell us something about the fracture network and its connections. The practical implication is that hydrofracture fluids will be locked into the same "permeability jail" that sequestered overpressured gas for over 200 million years. If one wants to dispose of fracking waters, one could probably not choose a safer way to do so that to inject them into a gas shale.

Life cycle carbon footprint of shale gas: review of evidence and implications.

PubMed

Weber, Christopher L; Clavin, Christopher

2012-06-05

The recent increase in the production of natural gas from shale deposits has significantly changed energy outlooks in both the US and world. Shale gas may have important climate benefits if it displaces more carbon-intensive oil or coal, but recent attention has discussed the potential for upstream methane emissions to counteract this reduced combustion greenhouse gas emissions. We examine six recent studies to produce a Monte Carlo uncertainty analysis of the carbon footprint of both shale and conventional natural gas production. The results show that the most likely upstream carbon footprints of these types of natural gas production are largely similar, with overlapping 95% uncertainty ranges of 11.0-21.0 g CO(2)e/MJ(LHV) for shale gas and 12.4-19.5 g CO(2)e/MJ(LHV) for conventional gas. However, because this upstream footprint represents less than 25% of the total carbon footprint of gas, the efficiency of producing heat, electricity, transportation services, or other function is of equal or greater importance when identifying emission reduction opportunities. Better data are needed to reduce the uncertainty in natural gas's carbon footprint, but understanding system-level climate impacts of shale gas, through shifts in national and global energy markets, may be more important and requires more detailed energy and economic systems assessments.

Harmonization of initial estimates of shale gas life cycle greenhouse gas emissions for electric power generation.

PubMed

Heath, Garvin A; O'Donoughue, Patrick; Arent, Douglas J; Bazilian, Morgan

2014-08-05

Recent technological advances in the recovery of unconventional natural gas, particularly shale gas, have served to dramatically increase domestic production and reserve estimates for the United States and internationally. This trend has led to lowered prices and increased scrutiny on production practices. Questions have been raised as to how greenhouse gas (GHG) emissions from the life cycle of shale gas production and use compares with that of conventionally produced natural gas or other fuel sources such as coal. Recent literature has come to different conclusions on this point, largely due to differing assumptions, comparison baselines, and system boundaries. Through a meta-analytical procedure we call harmonization, we develop robust, analytically consistent, and updated comparisons of estimates of life cycle GHG emissions for electricity produced from shale gas, conventionally produced natural gas, and coal. On a per-unit electrical output basis, harmonization reveals that median estimates of GHG emissions from shale gas-generated electricity are similar to those for conventional natural gas, with both approximately half that of the central tendency of coal. Sensitivity analysis on the harmonized estimates indicates that assumptions regarding liquids unloading and estimated ultimate recovery (EUR) of wells have the greatest influence on life cycle GHG emissions, whereby shale gas life cycle GHG emissions could approach the range of best-performing coal-fired generation under certain scenarios. Despite clarification of published estimates through harmonization, these initial assessments should be confirmed through methane emissions measurements at components and in the atmosphere and through better characterization of EUR and practices.

Harmonization of initial estimates of shale gas life cycle greenhouse gas emissions for electric power generation

PubMed Central

Heath, Garvin A.; O’Donoughue, Patrick; Arent, Douglas J.; Bazilian, Morgan

2014-01-01

Recent technological advances in the recovery of unconventional natural gas, particularly shale gas, have served to dramatically increase domestic production and reserve estimates for the United States and internationally. This trend has led to lowered prices and increased scrutiny on production practices. Questions have been raised as to how greenhouse gas (GHG) emissions from the life cycle of shale gas production and use compares with that of conventionally produced natural gas or other fuel sources such as coal. Recent literature has come to different conclusions on this point, largely due to differing assumptions, comparison baselines, and system boundaries. Through a meta-analytical procedure we call harmonization, we develop robust, analytically consistent, and updated comparisons of estimates of life cycle GHG emissions for electricity produced from shale gas, conventionally produced natural gas, and coal. On a per-unit electrical output basis, harmonization reveals that median estimates of GHG emissions from shale gas-generated electricity are similar to those for conventional natural gas, with both approximately half that of the central tendency of coal. Sensitivity analysis on the harmonized estimates indicates that assumptions regarding liquids unloading and estimated ultimate recovery (EUR) of wells have the greatest influence on life cycle GHG emissions, whereby shale gas life cycle GHG emissions could approach the range of best-performing coal-fired generation under certain scenarios. Despite clarification of published estimates through harmonization, these initial assessments should be confirmed through methane emissions measurements at components and in the atmosphere and through better characterization of EUR and practices. PMID:25049378

Risks and risk governance in unconventional shale gas development.

PubMed

Small, Mitchell J; Stern, Paul C; Bomberg, Elizabeth; Christopherson, Susan M; Goldstein, Bernard D; Israel, Andrei L; Jackson, Robert B; Krupnick, Alan; Mauter, Meagan S; Nash, Jennifer; North, D Warner; Olmstead, Sheila M; Prakash, Aseem; Rabe, Barry; Richardson, Nathan; Tierney, Susan; Webler, Thomas; Wong-Parodi, Gabrielle; Zielinska, Barbara

2014-01-01

A broad assessment is provided of the current state of knowledge regarding the risks associated with shale gas development and their governance. For the principal domains of risk, we identify observed and potential hazards and promising mitigation options to address them, characterizing current knowledge and research needs. Important unresolved research questions are identified for each area of risk; however, certain domains exhibit especially acute deficits of knowledge and attention, including integrated studies of public health, ecosystems, air quality, socioeconomic impacts on communities, and climate change. For these, current research and analysis are insufficient to either confirm or preclude important impacts. The rapidly evolving landscape of shale gas governance in the U.S. is also assessed, noting challenges and opportunities associated with the current decentralized (state-focused) system of regulation. We briefly review emerging approaches to shale gas governance in other nations, and consider new governance initiatives and options in the U.S. involving voluntary industry certification, comprehensive development plans, financial instruments, and possible future federal roles. In order to encompass the multiple relevant disciplines, address the complexities of the evolving shale gas system and reduce the many key uncertainties needed for improved management, a coordinated multiagency federal research effort will need to be implemented.

Selling 'Fracking': Legitimation of High Speed Oil and Gas Extraction in the Marcellus Shale Region

NASA Astrophysics Data System (ADS)

Matz, Jacob R.

The advent of horizontal hydraulic fracture drilling, or 'fracking,' a technology used to access oil and natural gas deposits, has allowed for the extraction of deep, unconventional shale gas and oil deposits in various shale seams throughout the United States and world. One such shale seam, the Marcellus shale, extends from New York State, across Pennsylvania, and throughout West Virginia, where shale gas development has significantly increased within the last decade. This boom has created a massive amount of economic activity surrounding the energy industry, creating jobs for workers, income from leases and royalties for landowners, and profits for energy conglomerates. However, this bounty comes with risks to environmental and public health, and has led to divisive community polarization over the issue in the Marcellus shale region. In the face of potential environmental and social disruption, and a great deal of controversy surrounding 'fracking,' the oil and gas industry has had to undertake a myriad of public relations campaigns and initiatives to legitimize their extraction efforts in the Marcellus shale region, and to project the oil and gas industry in a positive light to residents, policy makers, and landowners. This thesis describes one such public relations initiative, the Energy in Depth Northeast Marcellus Initiative. Through qualitative content analysis of Energy in Depth's online web material, this thesis examines the ways in which the oil and gas industry narrates the shale gas boom in the Marcellus shale region, and the ways in which the industry frames the discourse surrounding natural gas development. Through the use of environmental imagery, appeals to scientific reason, and appeals to patriotism, the oil and gas industry uses Energy in Depth to frame the shale gas extraction process in a positive way, all the while framing those who question or oppose the processes of shale gas extraction as irrational obstructionists.

Can Switching from Coal to Shale Gas Bring Net Carbon Reductions to China?

PubMed

Qin, Yue; Edwards, Ryan; Tong, Fan; Mauzerall, Denise L

2017-03-07

To increase energy security and reduce emissions of air pollutants and CO 2 from coal use, China is attempting to duplicate the rapid development of shale gas that has taken place in the United States. This work builds a framework to estimate the lifecycle greenhouse gas (GHG) emissions from China's shale gas system and compares them with GHG emissions from coal used in the power, residential, and industrial sectors. We find the mean lifecycle carbon footprint of shale gas is about 30-50% lower than that of coal in all sectors under both 20 year and 100 year global warming potentials (GWP 20 and GWP 100 ). However, primarily due to large uncertainties in methane leakage, the upper bound estimate of the lifecycle carbon footprint of shale gas in China could be approximately 15-60% higher than that of coal across sectors under GWP 20 . To ensure net GHG emission reductions when switching from coal to shale gas, we estimate the breakeven methane leakage rates to be approximately 6.0%, 7.7%, and 4.2% in the power, residential, and industrial sectors, respectively, under GWP 20 . We find shale gas in China has a good chance of delivering air quality and climate cobenefits, particularly when used in the residential sector, with proper methane leakage control.

Two-Stage Fracturing Wastewater Management in Shale Gas Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xiaodong; Sun, Alexander Y.; Duncan, Ian J.

Here, management of shale gas wastewater treatment, disposal, and reuse has become a significant environmental challenge, driven by an ongoing boom in development of U.S. shale gas reservoirs. Systems-analysis based decision support is helpful for effective management of wastewater, and provision of cost-effective decision alternatives from a whole-system perspective. Uncertainties are inherent in many modeling parameters, affecting the generated decisions. In order to effectively deal with the recourse issue in decision making, in this work a two-stage stochastic fracturing wastewater management model, named TSWM, is developed to provide decision support for wastewater management planning in shale plays. Using the TSWMmore » model, probabilistic and nonprobabilistic uncertainties are effectively handled. The TSWM model provides flexibility in generating shale gas wastewater management strategies, in which the first-stage decision predefined by decision makers before uncertainties are unfolded is corrected in the second stage to achieve the whole-system’s optimality. Application of the TSWM model to a comprehensive synthetic example demonstrates its practical applicability and feasibility. Optimal results are generated for allowable wastewater quantities, excess wastewater, and capacity expansions of hazardous wastewater treatment plants to achieve the minimized total system cost. The obtained interval solutions encompass both optimistic and conservative decisions. Trade-offs between economic and environmental objectives are made depending on decision makers’ knowledge and judgment, as well as site-specific information. In conclusion, the proposed model is helpful in forming informed decisions for wastewater management associated with shale gas development.« less

Two-Stage Fracturing Wastewater Management in Shale Gas Development

DOE PAGES

Zhang, Xiaodong; Sun, Alexander Y.; Duncan, Ian J.; ...

2017-01-19

Here, management of shale gas wastewater treatment, disposal, and reuse has become a significant environmental challenge, driven by an ongoing boom in development of U.S. shale gas reservoirs. Systems-analysis based decision support is helpful for effective management of wastewater, and provision of cost-effective decision alternatives from a whole-system perspective. Uncertainties are inherent in many modeling parameters, affecting the generated decisions. In order to effectively deal with the recourse issue in decision making, in this work a two-stage stochastic fracturing wastewater management model, named TSWM, is developed to provide decision support for wastewater management planning in shale plays. Using the TSWMmore » model, probabilistic and nonprobabilistic uncertainties are effectively handled. The TSWM model provides flexibility in generating shale gas wastewater management strategies, in which the first-stage decision predefined by decision makers before uncertainties are unfolded is corrected in the second stage to achieve the whole-system’s optimality. Application of the TSWM model to a comprehensive synthetic example demonstrates its practical applicability and feasibility. Optimal results are generated for allowable wastewater quantities, excess wastewater, and capacity expansions of hazardous wastewater treatment plants to achieve the minimized total system cost. The obtained interval solutions encompass both optimistic and conservative decisions. Trade-offs between economic and environmental objectives are made depending on decision makers’ knowledge and judgment, as well as site-specific information. In conclusion, the proposed model is helpful in forming informed decisions for wastewater management associated with shale gas development.« less

Potential restrictions for CO2 sequestration sites due to shale and tight gas production.

PubMed

Elliot, T R; Celia, M A

2012-04-03

Carbon capture and geological sequestration is the only available technology that both allows continued use of fossil fuels in the power sector and reduces significantly the associated CO(2) emissions. Geological sequestration requires a deep permeable geological formation into which captured CO(2)can be injected, and an overlying impermeable formation, called a caprock, that keeps the buoyant CO(2) within the injection formation. Shale formations typically have very low permeability and are considered to be good caprock formations. Production of natural gas from shale and other tight formations involves fracturing the shale with the explicit objective to greatly increase the permeability of the shale. As such, shale gas production is in direct conflict with the use of shale formations as a caprock barrier to CO(2) migration. We have examined the locations in the United States where deep saline aquifers, suitable for CO(2) sequestration, exist, as well as the locations of gas production from shale and other tight formations. While estimated sequestration capacity for CO(2) sequestration in deep saline aquifers is large, up to 80% of that capacity has areal overlap with potential shale-gas production regions and, therefore, could be adversely affected by shale and tight gas production. Analysis of stationary sources of CO(2) shows a similar effect: about two-thirds of the total emissions from these sources are located within 20 miles of a deep saline aquifer, but shale and tight gas production could affect up to 85% of these sources. These analyses indicate that colocation of deep saline aquifers with shale and tight gas production could significantly affect the sequestration capacity for CCS operations. This suggests that a more comprehensive management strategy for subsurface resource utilization should be developed.

Shale gas characteristics of the Lower Toarcian Posidonia Shale in Germany: from basin to nanometre scale

NASA Astrophysics Data System (ADS)

Schulz, Hans-Martin; Bernard, Sylvain; Horsfield, Brian; Krüger, Martin; Littke, Ralf; di primio, Rolando

2013-04-01

The Early Toarcian Posidonia Shale is a proven hydrocarbon source rock which was deposited in a shallow epicontinental basin. In southern Germany, Tethyan warm-water influences from the south led to carbonate sedimentation, whereas cold-water influxes from the north controlled siliciclastic sedimentation in the northwestern parts of Germany and the Netherlands. Restricted sea-floor circulation and organic matter preservation are considered to be the consequence of an oceanic anoxic event. In contrast, non-marine conditions led to sedimentation of coarser grained sediments under progressively terrestrial conditions in northeastern Germany The present-day distribution of Posidonia Shale in northern Germany is restricted to the centres of rift basins that formed in the Late Jurassic (e.g., Lower Saxony Basin and Dogger Troughs like the West and East Holstein Troughs) as a result of erosion on the basin margins and bounding highs. The source rock characteristics are in part dependent on grain size as the Posidonia Shale in eastern Germany is referred to as a mixed to non-source rock facies. In the study area, the TOC content and the organic matter quality vary vertically and laterally, likely as a consequence of a rising sea level during the Toarcian. Here we present and compare data of whole Posidonia Shale sections, investigating these variations and highlighting the variability of Posidonia Shale depositional system. During all phases of burial, gas was generated in the Posidonia Shale. Low sedimentation rates led to diffusion of early diagenetically formed biogenic methane. Isochronously formed diagenetic carbonates tightened the matrix and increased brittleness. Thermogenic gas generation occurred in wide areas of Lower Saxony as well as in Schleswig Holstein. Biogenic methane gas can still be formed today in Posidonia Shale at shallow depth in areas which were covered by Pleistocene glaciers. Submicrometric interparticle pores predominate in immature samples. At

Modeling the Relative GHG Emissions of Conventional and Shale Gas Production

PubMed Central

2011-01-01

Recent reports show growing reserves of unconventional gas are available and that there is an appetite from policy makers, industry, and others to better understand the GHG impact of exploiting reserves such as shale gas. There is little publicly available data comparing unconventional and conventional gas production. Existing studies rely on national inventories, but it is not generally possible to separate emissions from unconventional and conventional sources within these totals. Even if unconventional and conventional sites had been listed separately, it would not be possible to eliminate site-specific factors to compare gas production methods on an equal footing. To address this difficulty, the emissions of gas production have instead been modeled. In this way, parameters common to both methods of production can be held constant, while allowing those parameters which differentiate unconventional gas and conventional gas production to vary. The results are placed into the context of power generation, to give a ″well-to-wire″ (WtW) intensity. It was estimated that shale gas typically has a WtW emissions intensity about 1.8–2.4% higher than conventional gas, arising mainly from higher methane releases in well completion. Even using extreme assumptions, it was found that WtW emissions from shale gas need be no more than 15% higher than conventional gas if flaring or recovery measures are used. In all cases considered, the WtW emissions of shale gas powergen are significantly lower than those of coal. PMID:22085088

Modeling the relative GHG emissions of conventional and shale gas production.

PubMed

Stephenson, Trevor; Valle, Jose Eduardo; Riera-Palou, Xavier

2011-12-15

Recent reports show growing reserves of unconventional gas are available and that there is an appetite from policy makers, industry, and others to better understand the GHG impact of exploiting reserves such as shale gas. There is little publicly available data comparing unconventional and conventional gas production. Existing studies rely on national inventories, but it is not generally possible to separate emissions from unconventional and conventional sources within these totals. Even if unconventional and conventional sites had been listed separately, it would not be possible to eliminate site-specific factors to compare gas production methods on an equal footing. To address this difficulty, the emissions of gas production have instead been modeled. In this way, parameters common to both methods of production can be held constant, while allowing those parameters which differentiate unconventional gas and conventional gas production to vary. The results are placed into the context of power generation, to give a ″well-to-wire″ (WtW) intensity. It was estimated that shale gas typically has a WtW emissions intensity about 1.8-2.4% higher than conventional gas, arising mainly from higher methane releases in well completion. Even using extreme assumptions, it was found that WtW emissions from shale gas need be no more than 15% higher than conventional gas if flaring or recovery measures are used. In all cases considered, the WtW emissions of shale gas powergen are significantly lower than those of coal.

Characterization of nanoporous shales with gas sorption

NASA Astrophysics Data System (ADS)

Joewondo, N.; Prasad, M.

2017-12-01

The understanding of the fluid flow in porous media requires the knowledge of the pore system involved. Fluid flow in fine grained shales falls under different regime than transport regime in conventional reservoir due to the different average pore sizes in the two materials; the average pore diameter of conventional sandstones is on the micrometer scale, while of shales can be as small as several nanometers. Mercury intrusion porosimetry is normally used to characterize the pores of conventional reservoir, however with increasingly small pores, the injection pressure required to imbibe the pores becomes infinitely large due to surface tension. Characterization of pores can be expressed by a pore size distribution (PSD) plot, which reflects distribution of pore volume or surface area with respect to pore size. For the case of nanoporous materials, the surface area, which serves as the interface between the rock matrix and fluid, becomes increasingly large and important. Physisorption of gas has been extensively studied as a method of nanoporous solid characterization (particularly for the application of catalysis, metal organic frameworks, etc). The PSD is obtained by matching the experimental result to the calculated theoretical result (using Density Functional Theory (DFT), a quantum mechanics based modelling method for molecular scale interactions). We present the challenges and experimental result of Nitrogen and CO2 gas sorption on shales with various mineralogy and the interpreted PSD obtained by DFT method. Our result shows significant surface area contributed by the nanopores of shales, hence the importance of surface area measurements for the characterization of shales.

Habitat loss and modification due to gas development in the Fayetteville shale.

PubMed

Moran, Matthew D; Cox, A Brandon; Wells, Rachel L; Benichou, Chloe C; McClung, Maureen R

2015-06-01

Hydraulic fracturing and horizontal drilling have become major methods to extract new oil and gas deposits, many of which exist in shale formations in the temperate deciduous biome of the eastern United States. While these technologies have increased natural gas production to new highs, they can have substantial environmental effects. We measured the changes in land use within the maturing Fayetteville Shale gas development region in Arkansas between 2001/2002 and 2012. Our goal was to estimate the land use impact of these new technologies in natural gas drilling and predict future consequences for habitat loss and fragmentation. Loss of natural forest in the gas field was significantly higher compared to areas outside the gas field. The creation of edge habitat, roads, and developed areas was also greater in the gas field. The Fayetteville Shale gas field fully developed about 2% of the natural habitat within the region and increased edge habitat by 1,067 linear km. Our data indicate that without shale gas activities, forest cover would have increased slightly and edge habitat would have decreased slightly, similar to patterns seen recently in many areas of the southern U.S. On average, individual gas wells fully developed about 2.5 ha of land and modified an additional 0.5 ha of natural forest. Considering the large number of wells drilled in other parts of the eastern U.S. and projections for new wells in the future, shale gas development will likely have substantial negative effects on forested habitats and the organisms that depend upon them.

The role of ethics in shale gas policies.

PubMed

de Melo-Martín, Inmaculada; Hays, Jake; Finkel, Madelon L

2014-02-01

The United States has experienced a boom in natural gas production due to recent technological innovations that have enabled natural gas to be produced from unconventional sources, such as shale. There has been much discussion about the costs and benefits of developing shale gas among scientists, policy makers, and the general public. The debate has typically revolved around potential gains in economics, employment, energy independence, and national security as well as potential harms to the environment, the climate, and public health. In the face of scientific uncertainty, national and international governments must make decisions on how to proceed. So far, the results have been varied, with some governments banning the process, others enacting moratoria until it is better understood, and others explicitly sanctioning shale gas development. These policies reflect legislature's preferences to avoid false negative errors or false positive ones. Here we argue that policy makers have a prima facie duty to minimize false negatives based on three considerations: (1) protection from serious harm generally takes precedence over the enhancement of welfare; (2) minimizing false negatives in this case is more respectful to people's autonomy; and (3) alternative solutions exist that may provide many of the same benefits while minimizing many of the harms. © 2013.

Ozone impacts of natural gas development in the Haynesville Shale.

PubMed

Kemball-Cook, Susan; Bar-Ilan, Amnon; Grant, John; Parker, Lynsey; Jung, Jaegun; Santamaria, Wilson; Mathews, Jim; Yarwood, Greg

2010-12-15

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. Using well production data from state regulatory agencies and a review of the available literature, projections of future year Haynesville Shale natural gas production were derived for 2009-2020 for three scenarios corresponding to limited, moderate, and aggressive development. These production estimates were then used to develop an emission inventory for each of the three scenarios. Photochemical modeling of the year 2012 showed increases in 2012 8-h ozone design values of up to 5 ppb within Northeast Texas and Northwest Louisiana resulting from development in the Haynesville Shale. Ozone increases due to Haynesville Shale emissions can affect regions outside Northeast Texas and Northwest Louisiana due to ozone transport. This study evaluates only near-term ozone impacts, but the emission inventory projections indicate that Haynesville emissions may be expected to increase through 2020.

Feasibility Assessment of CO2 Sequestration and Enhanced Recovery in Gas Shale Reservoirs

NASA Astrophysics Data System (ADS)

Vermylen, J. P.; Hagin, P. N.; Zoback, M. D.

2008-12-01

CO2 sequestration and enhanced methane recovery may be feasible in unconventional, organic-rich, gas shale reservoirs in which the methane is stored as an adsorbed phase. Previous studies have shown that organic-rich, Appalachian Devonian shales adsorb approximately five times more carbon dioxide than methane at reservoir conditions. However, the enhanced recovery and sequestration concept has not yet been tested for gas shale reservoirs under realistic flow and production conditions. Using the lessons learned from previous studies on enhanced coalbed methane (ECBM) as a starting point, we are conducting laboratory experiments, reservoir modeling, and fluid flow simulations to test the feasibility of sequestration and enhanced recovery in gas shales. Our laboratory work investigates both adsorption and mechanical properties of shale samples to use as inputs for fluid flow simulation. Static and dynamic mechanical properties of shale samples are measured using a triaxial press under realistic reservoir conditions with varying gas saturations and compositions. Adsorption is simultaneously measured using standard, static, volumetric techniques. Permeability is measured using pulse decay methods calibrated to standard Darcy flow measurements. Fluid flow simulations are conducted using the reservoir simulator GEM that has successfully modeled enhanced recovery in coal. The results of the flow simulation are combined with the laboratory results to determine if enhanced recovery and CO2 sequestration is feasible in gas shale reservoirs.

78 FR 7394 - Foreign-Trade Zone 121-Albany, NY; Authorization of Production Activity; Albany Molecular...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-01

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-72-2012] Foreign-Trade Zone 121--Albany, NY; Authorization of Production Activity; Albany Molecular Research, Inc.; Subzone 121A (Pharmaceutical Chemicals Production); Rensselaer, NY On September 26, 2012, Albany Molecular Research, Inc., submitted a notification...

The challenges of a possible exploitation of shale gas in Denmark

NASA Astrophysics Data System (ADS)

Jacobsen, Ole S.; Kidmose, Jacob; Johnsen, Anders R.; Gravesen, Peter; Schovsbo, Niels H.

2017-04-01

Extraction of shale gas has in recent years attracted increasing interest internationally and in Denmark. The potential areas for shale gas extraction from Alum shale in Denmark are defined as areas where Alum shale is at least 20 m thick, gas mature and buried at 1.5 to 7 km depth. Sweet Spots are areas where Alum shale potentially has a high utility value. Sweet Spots are identified and cover an area of approximately 6,800 km2 and are divided into two subareas; where the shale is at 1.5-5 km depth (2,400 km2) or at 5-7 km depth (4,400 km2). The shale in the upper depth interval has the greatest interest, as these areas are localized most accurate as the production from the deep interval is less costly. Many potential risks has been identified by exploitation of unconventional gas, of which groundwater contamination, waste management and radioactive substances are classified as the most important. The international literature reports a water demand with an average of about 18,000 m3 for older wells whereas newer fracking methods have less water usage. Based heron the estimated water consumption is between 20 million to 66 million m3 water in Danish shale gas production well and thus significantly in the total water budget. Consumption of water for shale gas will however be distributed over a number of years. The temporal development in water usage will depend on how quickly the gas wells are developed. The available groundwater resource in Denmark is estimated to about 1 billion m3 / year. Groundwater abstraction has been slightly falling the last decades and is now totally 700 million m3 / year. The use of surface water in Denmark is thus negligible. Although groundwater attraction is only 70 % of the available, the resource is overexploited in many areas due to water consumption is very unevenly distributed varying from region to region. The composition of potential hydraulic fracturing liquids in Denmark is at present unknown, but is expected to be selected

Fundamental Study of Disposition and Release of Methane in a Shale Gas Reservoir

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yifeng; Xiong, Yongliang; Criscenti, Louise J.

The recent boom in shale gas production through hydrofracturing has reshaped the energy production landscape in the United States. Wellbore production rates vary greatly among the wells within a single field and decline rapidly with time, thus bring up a serious concern with the sustainability of shale gas production. Shale gas production starts with creating a fracture network by injecting a pressurized fluid in a wellbore. The induced fractures are then held open by proppant particles. During production, gas releases from the mudstone matrix, migrates to nearby fractures, and ultimately reaches a production wellbore. Given the relatively high permeability ofmore » the induced fractures, gas release and migration in low-permeability shale matrix is likely to be a limiting step for long-term wellbore production. Therefore, a clear understanding of the underlying mechanisms of methane disposition and release in shale matrix is crucial for the development of new technologies to maximize gas production and recovery. Shale is a natural nanocomposite material with distinct characteristics of nanometer-scale pore sizes, extremely low permeability, high clay contents, significant amounts of organic carbon, and large spatial heterogeneities. Our work has shown that nanopore confinement plays an important role in methane disposition and release in shale matrix. Using molecular simulations, we show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~ 30 - 47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. The long-term production decline appears controlled by the second stage of gas release. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The

Sustainability of UK shale gas in comparison with other electricity options: Current situation and future scenarios.

PubMed

Cooper, Jasmin; Stamford, Laurence; Azapagic, Adisa

2018-04-01

Many countries are considering exploitation of shale gas but its overall sustainability is currently unclear. Previous studies focused mainly on environmental aspects of shale gas, largely in the US, with scant information on socio-economic aspects. To address this knowledge gap, this paper integrates for the first time environmental, economic and social aspects of shale gas to evaluate its overall sustainability. The focus is on the UK which is on the cusp of developing a shale gas industry. Shale gas is compared to other electricity options for the current situation and future scenarios up to the year 2030 to investigate whether it can contribute towards a more sustainable electricity mix in the UK. The results obtained through multi-criteria decision analysis suggest that, when equal importance is assumed for each of the three sustainability aspects shale gas ranks seventh out of nine electricity options, with wind and solar PV being the best and coal the worst options. However, it outranks biomass and hydropower. Changing the importance of the sustainability aspects widely, the ranking of shale gas ranges between fourth and eighth. For shale gas to become the most sustainable option of those assessed, large improvements would be needed, including a 329-fold reduction in environmental impacts and 16 times higher employment, along with simultaneous large changes (up to 10,000 times) in the importance assigned to each criterion. Similar changes would be needed if it were to be comparable to conventional or liquefied natural gas, biomass, nuclear or hydropower. The results also suggest that a future electricity mix (2030) would be more sustainable with a lower rather than a higher share of shale gas. These results serve to inform UK policy makers, industry and non-governmental organisations. They will also be of interest to other countries considering exploitation of shale gas. Copyright © 2017 Elsevier B.V. All rights reserved.

Shale gas activity and increased rates of sexually transmitted infections in Ohio, 2000-2016.

PubMed

Deziel, Nicole C; Humeau, Zoe; Elliott, Elise G; Warren, Joshua L; Niccolai, Linda M

2018-01-01

The growing shale gas ("fracking") industry depends on a mobile workforce, whose influx could have social impacts on host communities. Sexually transmitted infections (STIs) can increase through sexual mixing patterns associated with labor migration. No prior studies have quantified the relationship between shale gas activity and rates of three reportable STIs: chlamydia, gonorrhea, and syphilis. We conducted a longitudinal, ecologic study from 2000-2016 in Ohio, situated in a prolific shale gas region in the United States (US). Data on reported cases of chlamydia, gonorrhea, and syphilis by county and year were obtained from the Ohio Department of Health. All 88 counties were classified as none, low, and high shale gas activity in each year, using data from the Ohio Department of Natural Resources. Annual rate ratios (RR) and 95% confidence intervals (95% CIs) were calculated from mixed-effects Poisson regression models evaluating the relationship between shale gas activity and reported annual STI rates while adjusting for secular trends and potential confounders obtained from the US Census. Compared to counties with no shale gas activity, counties with high activity had 21% (RR = 1.21; 95%CI = 1.08-1.36) increased rates of chlamydia and 19% (RR = 1.27; 95%CI 0.98-1.44) increased rates of gonorrhea, respectively. No association was observed for syphilis. This first report of a link between shale gas activity and increased rates of both chlamydia and gonorrhea may inform local policies and community health efforts.

Shale gas characterization based on geochemical and geophysical analysis: Case study of Brown shale, Pematang formation, Central Sumatra Basin

NASA Astrophysics Data System (ADS)

Haris, A.; Nastria, N.; Soebandrio, D.; Riyanto, A.

2017-07-01

Geochemical and geophysical analyses of shale gas have been carried out in Brown Shale, Middle Pematang Formation, Central Sumatra Basin. The paper is aimed at delineating the sweet spot distribution of potential shale gas reservoir, which is based on Total Organic Carbon (TOC), Maturity level data, and combined with TOC modeling that refers to Passey and Regression Multi Linear method. We used 4 well data, side wall core and 3D pre-stack seismic data. Our analysis of geochemical properties is based on well log and core data and its distribution are constrained by a framework of 3D seismic data, which is transformed into acoustic impedance. Further, the sweet spot of organic-rich shale is delineated by mapping TOC, which is extracted from inverted acoustic impedance. Our experiment analysis shows that organic materials contained in the formation of Middle Pematang Brown Shale members have TOC range from 0.15 to 2.71 wt.%, which is classified in the quality of poor to very good. In addition, the maturity level of organic material is ranging from 373°C to 432°C, which is indicated by vitrinite reflectance (Ro) of 0.58. In term of kerogen type, this Brown shale formation is categorized as kerogen type of II I III, which has the potential to generate a mixture of gasIoil on the environment.

Statistical evaluation of the impact of shale gas activities on ozone pollution in North Texas.

PubMed

Ahmadi, Mahdi; John, Kuruvilla

2015-12-01

Over the past decade, substantial growth in shale gas exploration and production across the US has changed the country's energy outlook. Beyond its economic benefits, the negative impacts of shale gas development on air and water are less well known. In this study the relationship between shale gas activities and ground-level ozone pollution was statistically evaluated. The Dallas-Fort Worth (DFW) area in north-central Texas was selected as the study region. The Barnett Shale, which is one the most productive and fastest growing shale gas fields in the US, is located in the western half of DFW. Hourly meteorological and ozone data were acquired for fourteen years from monitoring stations established and operated by the Texas Commission on Environmental Quality (TCEQ). The area was divided into two regions, the shale gas region (SGR) and the non-shale gas (NSGR) region, according to the number of gas wells in close proximity to each monitoring site. The study period was also divided into 2000-2006 and 2007-2013 because the western half of DFW has experienced significant growth in shale gas activities since 2007. An evaluation of the raw ozone data showed that, while the overall trend in the ozone concentration was down over the entire region, the monitoring sites in the NSGR showed an additional reduction of 4% in the annual number of ozone exceedance days than those in the SGR. Directional analysis of ozone showed that the winds blowing from areas with high shale gas activities contributed to higher ozone downwind. KZ-filtering method and linear regression techniques were used to remove the effects of meteorological variations on ozone and to construct long-term and short-term meteorologically adjusted (M.A.) ozone time series. The mean value of all M.A. ozone components was 8% higher in the sites located within the SGR than in the NSGR. These findings may be useful for understanding the overall impact of shale gas activities on the local and regional ozone

Wellsite, laboratory, and mathematical techniques for determining sorbed gas content of coals and gas shales utilizing well cuttings

USGS Publications Warehouse

Newell, K.D.

2007-01-01

Drill cuttings can be used for desorption analyses but with more uncertainty than desorption analyses done with cores. Drill cuttings are not recommended to take the place of core, but in some circumstances, desorption work with cuttings can provide a timely and economic supplement to that of cores. The mixed lithologic nature of drill cuttings is primarily the source of uncertainty in their analysis for gas content, for it is unclear how to apportion the gas generated from both the coal and the dark-colored shale that is mixed in usually with the coal. In the Western Interior Basin Coal Basin in eastern Kansas (Pennsylvanian-age coals), dark-colored shales with normal (??? 100 API units) gamma-ray levels seem to give off minimal amounts of gas on the order of less than five standard cubic feet per ton (scf/ton). In some cuttings analyses this rule of thumb for gas content of the shale is adequate for inferring the gas content of coals, but shales with high-gamma-ray values (>150 API units) may yield several times this amount of gas. The uncertainty in desorption analysis of drill cuttings can be depicted graphically on a diagram identified as a "lithologic component sensitivity analysis diagram." Comparison of cuttings desorption results from nearby wells on this diagram, can sometimes yield an unique solution for the gas content of both a dark shale and coal mixed in a cuttings sample. A mathematical solution, based on equating the dry, ash-free gas-contents of the admixed coal and dark-colored shale, also yields results that are correlative to data from nearby cores. ?? 2007 International Association for Mathematical Geology.

Three mechanisms model of shale gas in real state transport through a single nanopore

NASA Astrophysics Data System (ADS)

Li, Dongdong; Zhang, Yanyu; Sun, Xiaofei; Li, Peng; Zhao, Fengkai

2018-02-01

At present, the apparent permeability models of shale gas consider only the viscous flow and Knudsen diffusion of free gas, but do not take into account the influence of surface diffusion. Moreover, it is assumed that shale gas is in ideal state. In this paper, shale gas is assumed in real state, a new apparent permeability model for shale gas transport through a single nanopore is developed that captures many important migration mechanisms, such as viscous flow and Knudsen diffusion of free gas, surface diffusion of adsorbed gas. According to experimental data, the accuracy of apparent permeability model was verified. What’s more, the effects of pressure and pore radius on apparent permeability, and the effects on the permeability fraction of viscous flow, Knudsen diffusion and surface diffusion were analysed, separately. Finally, the results indicate that the error of the developed model in this paper was 3.02%, which is less than the existing models. Pressure and pore radius seriously affect the apparent permeability of shale gas. When the pore radius is small or pressure is low, the surface diffusion cannot be ignored. When the pressure and the pore radius is big, the viscous flow occupies the main position.

Passive thermal infrared hyperspectral imaging for quantitative imaging of shale gas leaks

NASA Astrophysics Data System (ADS)

Gagnon, Marc-André; Tremblay, Pierre; Savary, Simon; Farley, Vincent; Guyot, Éric; Lagueux, Philippe; Morton, Vince; Giroux, Jean; Chamberland, Martin

2017-10-01

There are many types of natural gas fields including shale formations that are common especially in the St-Lawrence Valley (Canada). Since methane (CH4), the major component of shale gas, is odorless, colorless and highly flammable, in addition to being a greenhouse gas, methane emanations and/or leaks are important to consider for both safety and environmental reasons. Telops recently launched on the market the Hyper-Cam Methane, a field-deployable thermal infrared hyperspectral camera specially tuned for detecting methane infrared spectral features under ambient conditions and over large distances. In order to illustrate the benefits of this novel research instrument for natural gas imaging, the instrument was brought on a site where shale gas leaks unexpectedly happened during a geological survey near the Enfant-Jesus hospital in Quebec City, Canada, during December 2014. Quantitative methane imaging was carried out based on methane's unique infrared spectral signature. Optical flow analysis was also carried out on the data to estimate the methane mass flow rate. The results show how this novel technique could be used for advanced research on shale gases.

Measurements and modeling to quantify emissions of methane and VOCs from shale gas operations: Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Presto, Albert A

The objectives of the project were to determine the leakage rates of methane and ozone-forming Volatile Organic Compounds (VOCs) and the emission rates of air toxics from Marcellus shale gas activities. Methane emissions in the Marcellus Shale region were differentiated between “newer” sources associated with shale gas development and “older” sources associated with coal or conventional natural gas exploration. This project conducted measurements of methane and VOC emissions from both shale and non-shale natural gas resources. The initial scope of the project was the Marcellus Shale basin, and measurements were conducted in both the western wet gas regions (southwest PAmore » and WV) and eastern dry gas region (northeast PA) of the basin. During this project, we obtained additional funding from other agencies to expand the scope of measurements to include additional basins. The data from both the Marcellus and other basins were combined to construct a national analysis of methane emissions from oil & gas production activities.« less

Data set for Journal article "The shale gas revolution: barriers, sustainability, and emerging opportunities"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Middleton, Richard Stephen

Shale gas and hydraulic refracturing has revolutionized the US energy sector in terms of prices, consumption, and CO 2 emissions. However, key questions remain including environmental concerns and extraction efficiencies that are leveling off. For the first time, we identify key discoveries, lessons learned, and recommendations from this shale gas revolution through extensive data mining and analysis of 23 years of production from 20,000 wells. Discoveries include identification of a learning-bydoing process where disruptive technology innovation led to a doubling in shale gas extraction, how refracturing with emerging technologies can transform existing wells, and how overall shale gas production ismore » actually dominated by long-term tail production rather than the high-profile initial exponentially-declining production in the first 12 months. We hypothesize that tail production can be manipulated, through better fracturing techniques and alternative working fluids such as CO 2, to increase shale gas recovery and minimize environmental impacts such as through carbon sequestration.« less

Shale Gas Petrophysical Models: an evaluation of contrasting approaches and assumptions

NASA Astrophysics Data System (ADS)

Inwood, Jennifer; Lovell, Mike; Davies, Sarah; Fishwick, Stewart; Taylor, Kevin

2015-04-01

Shale gas refers to fine-grained formations, or mudstones, where organic matter has matured sufficiently to produce predominantly gas, but that gas has not migrated any significant distance and hence the source rock is effectively the reservoir. Due to the success of shale gas extraction in the USA, many European countries are assessing their potential resources. A key uncertainty in evaluating the resource is the estimation of gas in place and most models are based on North American plays. However, it would seem that no single model to date can confidently predict the gas in place for a 'new' shale formation. Shale gas is frequently characterized by two distinct gas components: free gas is able to move and occupies the pores, while adsorbed gas is fixed onto organic surfaces and held in place by pressure. There are a number of different published methodologies that attempt to take account for this complicated distribution of gas within the rock ranging from models where the importance of the adsorbed gas is assumed to be negligible to those where all gas is assumed to exist within the organic pores and none within the mineral pore spaces. Models that assume both components are important and occupy adjacent volumes need to consider how to separate out the two to avoid double counting. Due to the heterogeneity of mudstones the most appropriate model may vary downhole as well as across adjacent wells. In this pilot study we consider the underlying assumptions and categorize models dependent on the deterministic or probabilistic approach used. We use an initial dataset from North America to test and compare a number of different approaches before expanding the analysis to further formations that span a range of geological and petrophysical characteristics. We then review and evaluate the models, identifying key variables and, where possible, determining their importance through sensitivity analysis. This work aims to establish guidelines for selecting the most

Modelling the deployment of CO₂ storage in U.S. gas-bearing shales

DOE PAGES

Davidson, Casie L.; Dahowski, Robert T.; Dooley, James J.; ...

2014-12-31

The proliferation of commercial development in U.S. gas-bearing shales helped to drive a twelve-fold increase in domestic gas production between 2000 and 2010, and the nation's gas production rates continue to grow. While shales have long been regarded as a desirable caprock for CCS operations because of their low permeability and porosity, there is increasing interest in the feasibility of injecting CO₂ into shales to enhance methane recovery and augment CO₂ storage. Laboratory work published in recent years observes that shales with adsorbed methane appear to exhibit a stronger affinity for CO₂ adsorption, offering the potential to drive additional CH₄more » recovery beyond primary production and perhaps the potential to store a larger volume of CO₂ than the volume of methane displaced. Recent research by the authors on the revenues associated with CO₂-enhanced gas recovery (CO₂-EGR) in gas-bearing shales estimates that, based on a range of EGR response rates, the average revenue per ton of CO₂ for projects managed over both EGR and subsequent storage-only phases could range from $0.50 to $18/tCO₂. While perhaps not as profitable as EOR, for regions where lower-cost storage options may be limited, shales could represent another “early opportunity” storage option if proven feasible for reliable EGR and CO₂ storage. Significant storage potential exists in gas shales, with theoretical CO₂ storage resources estimated at approximately 30-50 GtCO₂. However, an analysis of the comprehensive cost competitiveness of these various options is necessary to understand the degree to which they might meaningfully impact U.S. CCS deployment or costs. This preliminary analysis shows that the degree to which EGR-based CO₂ storage could play a role in commercial-scale deployment is heavily dependent upon the offsetting revenues associated with incremental recovery; modeling the low revenue case resulted in only five shale-based projects, while under

Mechanistic Processes Controlling Gas Sorption in Shale Reservoirs

NASA Astrophysics Data System (ADS)

Schaef, T.; Loring, J.; Ilton, E. S.; Davidson, C. L.; Owen, T.; Hoyt, D.; Glezakou, V. A.; McGrail, B. P.; Thompson, C.

2014-12-01

Utilization of CO2 to stimulate natural gas production in previously fractured shale-dominated reservoirs where CO2 remains in place for long-term storage may be an attractive new strategy for reducing the cost of managing anthropogenic CO2. A preliminary analysis of capacities and potential revenues in US shale plays suggests nearly 390 tcf in additional gas recovery may be possible via CO2 driven enhanced gas recovery. However, reservoir transmissivity properties, optimum gas recovery rates, and ultimate fate of CO2 vary among reservoirs, potentially increasing operational costs and environmental risks. In this paper, we identify key mechanisms controlling the sorption of CH4 and CO2 onto phyllosilicates and processes occurring in mixed gas systems that have the potential of impacting fluid transfer and CO2 storage in shale dominated formations. Through a unique set of in situ experimental techniques coupled with molecular-level simulations, we identify structural transformations occurring to clay minerals, optimal CO2/CH4 gas exchange conditions, and distinguish between adsorbed and intercalated gases in a mixed gas system. For example, based on in situ measurements with magic angle spinning NMR, intercalation of CO2 within the montmorillonite structure occurs in CH4/CO2 gas mixtures containing low concentrations (<5 mol%) of CO2. A stable montmorillonite structure dominates during exposure to pure CH4 (90 bar), but expands upon titration of small fractions (1-3 mol%) of CO2. Density functional theory was used to quantify the difference in sorption behavior between CO2 and CH4 and indicates complex interactions occurring between hydrated cations, CH4, and CO2. The authors will discuss potential impacts of these experimental results on CO2-based hydrocarbon recovery processes.

Characterising the vertical separation of shale-gas source rocks and aquifers across England and Wales (UK)

NASA Astrophysics Data System (ADS)

Loveless, Sian E.; Bloomfield, John P.; Ward, Robert S.; Hart, Alwyn J.; Davey, Ian R.; Lewis, Melinda A.

2018-03-01

Shale gas is considered by many to have the potential to provide the UK with greater energy security, economic growth and jobs. However, development of a shale gas industry is highly contentious due to environmental concerns including the risk of groundwater pollution. Evidence suggests that the vertical separation between exploited shale units and aquifers is an important factor in the risk to groundwater from shale gas exploitation. A methodology is presented to assess the vertical separation between different pairs of aquifers and shales that are present across England and Wales. The application of the method is then demonstrated for two of these pairs—the Cretaceous Chalk Group aquifer and the Upper Jurassic Kimmeridge Clay Formation, and the Triassic sandstone aquifer and the Carboniferous Bowland Shale Formation. Challenges in defining what might be considered criteria for `safe separation' between a shale gas formation and an overlying aquifer are discussed, in particular with respect to uncertainties in geological properties, aquifer extents and determination of socially acceptable risk levels. Modelled vertical separations suggest that the risk of aquifer contamination from shale exploration will vary greatly between shale-aquifer pairs and between regions and this will need to be considered carefully as part of the risk assessment and management for any shale gas development.

Perceptions of Shale Gas Development: Differences in Urban and Rural Communities

NASA Astrophysics Data System (ADS)

Melby, G.; Grubert, E.; Brandt, A. R.

2016-12-01

Shale gas development in Pennsylvania has been shown to have a large impact on nearby rural communities, but almost no research has been done on how development of the Marcellus Shale affects urban residents in neighboring cities. The goal of this project is to examine how the social and environmental priorities of urban and rural communities differ and to determine how well informed urban residents are on shale gas development. An anonymous web survey was used to survey 250 residents of Pennsylvania's largest cities on topics like how respondents prioritize different environmental and social factors and how well informed they feel about shale gas development. The results of this survey were compared to findings of previous surveys on rural communities located near energy development. In terms of environmental priorities, urban residents are more concerned about climate change and air pollution than rural residents. Both urban and rural respondents agreed that healthcare and education were their top social concerns, but urban respondents also prioritized housing and employment. Most urban respondents said that they were unfamiliar with shale gas development, although many were still concerned about what its environmental impacts might be. We also found that our results displayed two well known demographic trends: first, Democrats are far more likely to self identify as environmentalists than those who vote Republican, and second, that people of color are far less likely to identify as environmentalists than white respondents. As a result, there are disproportionately fewer self-identifying environmentalists in urban and largely Democrat-leaning areas with racially diverse populations. Our data displayed known trends in urban populations as well as new information on how urban residents differ from their rural counterparts in their views on shale gas development and their broader social and environmental priorities.

Assessment of Factors Influencing Effective CO 2 Storage Capacity and Injectivity in Eastern Gas Shales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Godec, Michael

Building upon advances in technology, production of natural gas from organic-rich shales is rapidly developing as a major hydrocarbon supply option in North America and around the world. The same technology advances that have facilitated this revolution - dense well spacing, horizontal drilling, and hydraulic fracturing - may help to facilitate enhanced gas recovery (EGR) and carbon dioxide (CO 2) storage in these formations. The potential storage of CO 2 in shales is attracting increasing interest, especially in Appalachian Basin states that have extensive shale deposits, but limited CO 2 storage capacity in conventional reservoirs. The goal of this cooperativemore » research project was to build upon previous and on-going work to assess key factors that could influence effective EGR, CO 2 storage capacity, and injectivity in selected Eastern gas shales, including the Devonian Marcellus Shale, the Devonian Ohio Shale, the Ordovician Utica and Point Pleasant shale and equivalent formations, and the late Devonian-age Antrim Shale. The project had the following objectives: (1) Analyze and synthesize geologic information and reservoir data through collaboration with selected State geological surveys, universities, and oil and gas operators; (2) improve reservoir models to perform reservoir simulations to better understand the shale characteristics that impact EGR, storage capacity and CO 2 injectivity in the targeted shales; (3) Analyze results of a targeted, highly monitored, small-scale CO 2 injection test and incorporate into ongoing characterization and simulation work; (4) Test and model a smart particle early warning concept that can potentially be used to inject water with uniquely labeled particles before the start of CO 2 injection; (5) Identify and evaluate potential constraints to economic CO 2 storage in gas shales, and propose development approaches that overcome these constraints; and (6) Complete new basin-level characterizations for the CO 2 storage

Mixed integer simulation optimization for optimal hydraulic fracturing and production of shale gas fields

NASA Astrophysics Data System (ADS)

Li, J. C.; Gong, B.; Wang, H. G.

2016-08-01

Optimal development of shale gas fields involves designing a most productive fracturing network for hydraulic stimulation processes and operating wells appropriately throughout the production time. A hydraulic fracturing network design-determining well placement, number of fracturing stages, and fracture lengths-is defined by specifying a set of integer ordered blocks to drill wells and create fractures in a discrete shale gas reservoir model. The well control variables such as bottom hole pressures or production rates for well operations are real valued. Shale gas development problems, therefore, can be mathematically formulated with mixed-integer optimization models. A shale gas reservoir simulator is used to evaluate the production performance for a hydraulic fracturing and well control plan. To find the optimal fracturing design and well operation is challenging because the problem is a mixed integer optimization problem and entails computationally expensive reservoir simulation. A dynamic simplex interpolation-based alternate subspace (DSIAS) search method is applied for mixed integer optimization problems associated with shale gas development projects. The optimization performance is demonstrated with the example case of the development of the Barnett Shale field. The optimization results of DSIAS are compared with those of a pattern search algorithm.

Louisiana waterthrush and benthic macroinvertebrate response to shale gas development

USGS Publications Warehouse

Wood, Petra; Frantz, Mack W.; Becker, Douglas A.

2016-01-01

Because shale gas development is occurring over large landscapes and consequently is affecting many headwater streams, an understanding of its effects on headwater-stream faunal communities is needed. We examined effects of shale gas development (well pads and associated infrastructure) on Louisiana waterthrush Parkesia motacilla and benthic macroinvertebrate communities in 12 West Virginia headwater streams in 2011. Streams were classed as impacted (n = 6) or unimpacted (n = 6) by shale gas development. We quantified waterthrush demography (nest success, clutch size, number of fledglings, territory density), a waterthrush Habitat Suitability Index, a Rapid Bioassessment Protocol habitat index, and benthic macroinvertebrate metrics including a genus-level stream-quality index for each stream. We compared each benthic metric between impacted and unimpacted streams with a Student's t-test that incorporated adjustments for normalizing data. Impacted streams had lower genus-level stream-quality index scores; lower overall and Ephemeroptera, Plecoptera, and Trichoptera richness; fewer intolerant taxa, more tolerant taxa, and greater density of 0–3-mm individuals (P ≤ 0.10). We then used Pearson correlation to relate waterthrush metrics to benthic metrics across the 12 streams. Territory density (no. of territories/km of stream) was greater on streams with higher genus-level stream-quality index scores; greater density of all taxa and Ephemeroptera, Plecoptera, and Trichoptera taxa; and greater biomass. Clutch size was greater on streams with higher genus-level stream-quality index scores. Nest survival analyses (n = 43 nests) completed with Program MARK suggested minimal influence of benthic metrics compared with nest stage and Habitat Suitability Index score. Although our study spanned only one season, our results suggest that shale gas development affected waterthrush and benthic communities in the headwater streams we studied. Thus, these ecological effects of

Shale Gas Boom or Bust? Estimating US and Global Economically Recoverable Resources

NASA Astrophysics Data System (ADS)

Brecha, R. J.; Hilaire, J.; Bauer, N.

2014-12-01

One of the most disruptive energy system technological developments of the past few decades is the rapid expansion of shale gas production in the United States. Because the changes have been so rapid there are great uncertainties as to the impacts of shale production for medium- and long-term energy and climate change mitigation policies. A necessary starting point for incorporating shale resources into modeling efforts is to understand the size of the resource, how much is technically recoverable (TRR), and finally, how much is economically recoverable (ERR) at a given cost. To assess production costs of shale gas, we combine top-down data with detailed bottom-up information. Studies solely based on top-down approaches do not adequately account for the heterogeneity of shale gas deposits and are unlikely to appropriately estimate extraction costs. We design an expedient bottom-up method based on publicly available US data to compute the levelized costs of shale gas extraction. Our results indicate the existence of economically attractive areas but also reveal a dramatic cost increase as lower-quality reservoirs are exploited. Extrapolating results for the US to the global level, our best estimate suggests that, at a cost of 6 US$/GJ, only 39% of the technically recoverable resources reported in top-down studies should be considered economically recoverable. This estimate increases to about 77% when considering optimistic TRR and estimated ultimate recovery parameters but could be lower than 12% for more pessimistic parameters. The current lack of information on the heterogeneity of shale gas deposits as well as on the development of future production technologies leads to significant uncertainties regarding recovery rates and production costs. Much of this uncertainty may be inherent, but for energy system planning purposes, with or without climate change mitigation policies, it is crucial to recognize the full ranges of recoverable quantities and costs.

Implications of shale gas development for climate change.

PubMed

Newell, Richard G; Raimi, Daniel

2014-01-01

Advances in technologies for extracting oil and gas from shale formations have dramatically increased U.S. production of natural gas. As production expands domestically and abroad, natural gas prices will be lower than without shale gas. Lower prices have two main effects: increasing overall energy consumption, and encouraging substitution away from sources such as coal, nuclear, renewables, and electricity. We examine the evidence and analyze modeling projections to understand how these two dynamics affect greenhouse gas emissions. Most evidence indicates that natural gas as a substitute for coal in electricity production, gasoline in transport, and electricity in buildings decreases greenhouse gases, although as an electricity substitute this depends on the electricity mix displaced. Modeling suggests that absent substantial policy changes, increased natural gas production slightly increases overall energy use, more substantially encourages fuel-switching, and that the combined effect slightly alters economy wide GHG emissions; whether the net effect is a slight decrease or increase depends on modeling assumptions including upstream methane emissions. Our main conclusions are that natural gas can help reduce GHG emissions, but in the absence of targeted climate policy measures, it will not substantially change the course of global GHG concentrations. Abundant natural gas can, however, help reduce the costs of achieving GHG reduction goals.

Water Saturation Relations and Their Diffusion-Limited Equilibration in Gas Shale: Implications for Gas Flow in Unconventional Reservoirs

NASA Astrophysics Data System (ADS)

Tokunaga, Tetsu K.; Shen, Weijun; Wan, Jiamin; Kim, Yongman; Cihan, Abdullah; Zhang, Yingqi; Finsterle, Stefan

2017-11-01

Large volumes of water are used for hydraulic fracturing of low permeability shale reservoirs to stimulate gas production, with most of the water remaining unrecovered and distributed in a poorly understood manner within stimulated regions. Because water partitioning into shale pores controls gas release, we measured the water saturation dependence on relative humidity (rh) and capillary pressure (Pc) for imbibition (adsorption) as well as drainage (desorption) on samples of Woodford Shale. Experiments and modeling of water vapor adsorption into shale laminae at rh = 0.31 demonstrated that long times are needed to characterize equilibrium in larger (5 mm thick) pieces of shales, and yielded effective diffusion coefficients from 9 × 10-9 to 3 × 10-8 m2 s-1, similar in magnitude to the literature values for typical low porosity and low permeability rocks. Most of the experiments, conducted at 50°C on crushed shale grains in order to facilitate rapid equilibration, showed significant saturation hysteresis, and that very large Pc (˜1 MPa) are required to drain the shales. These results quantify the severity of the water blocking problem, and suggest that gas production from unconventional reservoirs is largely associated with stimulated regions that have had little or no exposure to injected water. Gravity drainage of water from fractures residing above horizontal wells reconciles gas production in the presence of largely unrecovered injected water, and is discussed in the broader context of unsaturated flow in fractures.

A Model To Estimate Carbon Dioxide Injectivity and Storage Capacity for Geological Sequestration in Shale Gas Wells.

PubMed

Edwards, Ryan W J; Celia, Michael A; Bandilla, Karl W; Doster, Florian; Kanno, Cynthia M

2015-08-04

Recent studies suggest the possibility of CO2 sequestration in depleted shale gas formations, motivated by large storage capacity estimates in these formations. Questions remain regarding the dynamic response and practicality of injection of large amounts of CO2 into shale gas wells. A two-component (CO2 and CH4) model of gas flow in a shale gas formation including adsorption effects provides the basis to investigate the dynamics of CO2 injection. History-matching of gas production data allows for formation parameter estimation. Application to three shale gas-producing regions shows that CO2 can only be injected at low rates into individual wells and that individual well capacity is relatively small, despite significant capacity variation between shale plays. The estimated total capacity of an average Marcellus Shale well in Pennsylvania is 0.5 million metric tonnes (Mt) of CO2, compared with 0.15 Mt in an average Barnett Shale well. Applying the individual well estimates to the total number of existing and permitted planned wells (as of March, 2015) in each play yields a current estimated capacity of 7200-9600 Mt in the Marcellus Shale in Pennsylvania and 2100-3100 Mt in the Barnett Shale.

Investigation of Controlling Factors Impacting Water Quality in Shale Gas Produced Brine

NASA Astrophysics Data System (ADS)

Fan, W.; Hayes, K. F.; Ellis, B. R.

2014-12-01

The recent boom in production of natural gas from unconventional reservoirs has generated a substantial increase in the volume of produced brine that must be properly managed to prevent contamination of fresh water resources. Produced brine, which includes both flowback and formation water, is often highly saline and may contain elevated concentrations of naturally occurring radioactive material and other toxic elements. These characteristics present many challenges with regard to designing effective treatment and disposal strategies for shale gas produced brine. We will present results from a series of batch experiments where crushed samples from two shale formations in the Michigan Basin, the Antrim and Utica-Collingwood shales, were brought into contact with synthetic hydraulic fracturing fluids under in situ temperature and pressure conditions. The Antrim has been an active shale gas play for over three decades, while the Utica-Collingwood formation (a grouped reservoir consisting of the Utica shale and Collingwood limestone) is an emerging shale gas play. The goal of this study is to investigate the influence of water-rock interactions in controlling produced water quality. We evaluate toxic element leaching from shale samples in contact with model hydraulic fracturing fluids under system conditions corresponding to reservoir depths up to 1.5 km. Experimental results have begun to elucidate the relative importance of shale mineralogy, system conditions, and chemical additives in driving changes in produced water quality. Initial results indicate that hydraulic fracturing chemical additives have a strong influence on the extent of leaching of toxic elements from the shale. In particular, pH was a key factor in the release of uranium (U) and divalent metals, highlighting the importance of the mineral buffering capacity of the shale. Low pH values persisted in the Antrim and Utica shale experiments and resulted in higher U extraction efficiencies than that

Low-temperature gas from marine shales: wet gas to dry gas over experimental time.

PubMed

Mango, Frank D; Jarvie, Daniel M

2009-11-09

Marine shales exhibit unusual behavior at low temperatures under anoxic gas flow. They generate catalytic gas 300 degrees below thermal cracking temperatures, discontinuously in aperiodic episodes, and lose these properties on exposure to trace amounts of oxygen. Here we report a surprising reversal in hydrocarbon generation. Heavy hydrocarbons are formed before light hydrocarbons resulting in wet gas at the onset of generation grading to dryer gas over time. The effect is moderate under gas flow and substantial in closed reactions. In sequential closed reactions at 100 degrees C, gas from a Cretaceous Mowry shale progresses from predominately heavy hydrocarbons (66% C5, 2% C1) to predominantly light hydrocarbons (56% C1, 8% C5), the opposite of that expected from desorption of preexisting hydrocarbons. Differences in catalyst substrate composition explain these dynamics. Gas flow should carry heavier hydrocarbons to catalytic sites, in contrast to static conditions where catalytic sites are limited to in-place hydrocarbons. In-place hydrocarbons and their products should become lighter with conversion thus generating lighter hydrocarbon over time, consistent with our experimental results. We recognize the similarities between low-temperature gas generation reported here and the natural progression of wet gas to dry gas over geologic time. There is now substantial evidence for natural catalytic activity in source rocks. Natural gas at thermodynamic equilibrium and the results reported here add to that evidence. Natural catalysis provides a plausible and unique explanation for the origin and evolution of gas in sedimentary basins.

Chemical characterization of gas- and oil-bearing shales by instrumental neutron activation analysis

USGS Publications Warehouse

Frost, J.K.; Koszykowski, R.F.; Klemm, R.C.

1982-01-01

The concentration of As, Ba, Ca, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, K, La, Lu, Mn, Mo, Na, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U, Yb, and Zn were determined by instrumental neutron activation analysis in block shale samples of the New Albany Group (Devonian-Mississippian) in the in the Illinois Basin. Uranium content of the samples was as high as 75 ppm and interfered in the determination of samarium, molybdenum, barium and cerium. In the determination of selenium a correction was made for interference from tantalum. U, As, Co, Mo, Ni and Sb as well as Cu, V and pyritic sulphur which were determined by other methods, were found to correlate positively with the organic carbon content of the samples. ?? 1982 Akade??miai Kiado??.

Is the U.S. shale gas boom having an effect on the European gas market?

NASA Astrophysics Data System (ADS)

Yao, Isaac

This thesis focuses on the impact of the American shale gas boom on the European natural gas market. The study presents different tests in order to analyze the dynamics of natural gas prices in the U.S., U.K. and German natural gas market. The question of cointegration between these different markets are analyzed using several tests. More specifically, the ADF tests for the presence of a unit root. The error correction model test and the Johansen cointegration procedure are applied in order to accept or reject the hypothesis of an integrated market. The results suggest no evidence of cointegration between these markets. There currently is no evidence of an impact of the U.S. shale gas boom on the European market.

Life cycle greenhouse gas emissions and freshwater consumption of Marcellus shale gas.

PubMed

Laurenzi, Ian J; Jersey, Gilbert R

2013-05-07

We present results of a life cycle assessment (LCA) of Marcellus shale gas used for power generation. The analysis employs the most extensive data set of any LCA of shale gas to date, encompassing data from actual gas production and power generation operations. Results indicate that a typical Marcellus gas life cycle yields 466 kg CO2eq/MWh (80% confidence interval: 450-567 kg CO2eq/MWh) of greenhouse gas (GHG) emissions and 224 gal/MWh (80% CI: 185-305 gal/MWh) of freshwater consumption. Operations associated with hydraulic fracturing constitute only 1.2% of the life cycle GHG emissions, and 6.2% of the life cycle freshwater consumption. These results are influenced most strongly by the estimated ultimate recovery (EUR) of the well and the power plant efficiency: increase in either quantity will reduce both life cycle freshwater consumption and GHG emissions relative to power generated at the plant. We conclude by comparing the life cycle impacts of Marcellus gas and U.S. coal: The carbon footprint of Marcellus gas is 53% (80% CI: 44-61%) lower than coal, and its freshwater consumption is about 50% of coal. We conclude that substantial GHG reductions and freshwater savings may result from the replacement of coal-fired power generation with gas-fired power generation.

Investigating GHGs and VOCs emissions from a shale gas industry in Germany and the UK

NASA Astrophysics Data System (ADS)

Cremonese, L.; Weger, L.; Denier Van Der Gon, H.; Bartels, M. P.; Butler, T. M.

2017-12-01

The shale gas and shale oil production boom experienced in the US led the country to a significant reduction of foreign fuel imports and an increase in domestic energy security. Several European countries are considering to extract domestic shale gas reserves that might serve as a bridge in the transition to renewables. Nevertheless, the generation of shale gas leads to emissions of CH4 and pollutants such as PM, NOx and VOCs, which in turn impact local and regional air quality and climate. Results from numerous studies investigating greenhouse gas and pollutant emissions from shale oil and shale gas extraction in North America can help in estimating the impact of such industrial activity elsewhere, when local regulations are taken into consideration. In order to investigate the extent of emissions and their distribution from a potential shale gas industry in Germany and the United Kingdom, we develop three drilling scenarios compatible with desired national gas outputs based on available geological information on potential productivity ranges of the reservoirs. Subsequently we assign activity data and emissions factors to wells under development, as well as to producing wells (from activities at the well site up until processing plants) to enable emissions quantification. We then define emissions scenarios to explore different shale gas development pathways: 1) implementation of "high-technology" devices and recovery practices (low emissions); 2) implementation of "low-technology" devices and recovery practices (high emissions), and 3) intermediate scenarios reflecting assumptions on local and national settings, or extremely high emission events (e.g. super-emitters); all with high and low boundaries of confidence driven by uncertainties. A comparison of these unconventional gas production scenarios to conventional natural gas production in Germany and the United Kingdom is also planned. The aim of this work is to highlight important variables and their ranges, to

Shale gas wastewater management under uncertainty.

PubMed

Zhang, Xiaodong; Sun, Alexander Y; Duncan, Ian J

2016-01-01

This work presents an optimization framework for evaluating different wastewater treatment/disposal options for water management during hydraulic fracturing (HF) operations. This framework takes into account both cost-effectiveness and system uncertainty. HF has enabled rapid development of shale gas resources. However, wastewater management has been one of the most contentious and widely publicized issues in shale gas production. The flowback and produced water (known as FP water) generated by HF may pose a serious risk to the surrounding environment and public health because this wastewater usually contains many toxic chemicals and high levels of total dissolved solids (TDS). Various treatment/disposal options are available for FP water management, such as underground injection, hazardous wastewater treatment plants, and/or reuse. In order to cost-effectively plan FP water management practices, including allocating FP water to different options and planning treatment facility capacity expansion, an optimization model named UO-FPW is developed in this study. The UO-FPW model can handle the uncertain information expressed in the form of fuzzy membership functions and probability density functions in the modeling parameters. The UO-FPW model is applied to a representative hypothetical case study to demonstrate its applicability in practice. The modeling results reflect the tradeoffs between economic objective (i.e., minimizing total-system cost) and system reliability (i.e., risk of violating fuzzy and/or random constraints, and meeting FP water treatment/disposal requirements). Using the developed optimization model, decision makers can make and adjust appropriate FP water management strategies through refining the values of feasibility degrees for fuzzy constraints and the probability levels for random constraints if the solutions are not satisfactory. The optimization model can be easily integrated into decision support systems for shale oil/gas lifecycle

A Systematic Procedure to Describe Shale Gas Permeability Evolution during the Production Process

NASA Astrophysics Data System (ADS)

Jia, B.; Tsau, J. S.; Barati, R.

2017-12-01

Gas flow behavior in shales is complex due to the multi-physics nature of the process. Pore size reduces as the in-situ stress increases during the production process, which will reduce intrinsic permeability of the porous media. Slip flow/pore diffusion enhances gas apparent permeability, especially under low reservoir pressures. Adsorption not only increases original gas in place but also influences gas flow behavior because of the adsorption layer. Surface diffusion between free gas and adsorption phase enhances gas permeability. Pore size reduction and the adsorption layer both have complex impacts on gas apparent permeability and non-Darcy flow might be a major component in nanopores. Previously published literature is generally incomplete in terms of coupling of all these four physics with fluid flow during gas production. This work proposes a methodology to simultaneously take them into account to describe a permeability evolution process. Our results show that to fully describe shale gas permeability evolution during gas production, three sets of experimental data are needed initially: 1) intrinsic permeability under different in-situ stress, 2) adsorption isotherm under reservoir conditions and 3) surface diffusivity measurement by the pulse-decay method. Geomechanical effects, slip flow/pore diffusion, adsorption layer and surface diffusion all play roles affecting gas permeability. Neglecting any of them might lead to misleading results. The increasing in-situ stress during shale gas production is unfavorable to shale gas flow process. Slip flow/pore diffusion is important for gas permeability under low pressures in the tight porous media. They might overwhelm the geomechanical effect and enhance gas permeability at low pressures. Adsorption layer reduces the gas permeability by reducing the effective pore size, but the effect is limited. Surface diffusion increases gas permeability more under lower pressures. The total gas apparent permeability might

Demographic response of Louisiana Waterthrush, a stream obligate songbird of conservation concern, to shale gas development

USGS Publications Warehouse

Frantz, Mack W.; Wood, Petra B.; Sheehan, James; George, Gregory

2018-01-01

Shale gas development continues to outpace the implementation of best management practices for wildlife affected by development. We examined demographic responses of the Louisiana Waterthrush (Parkesia motacilla) to shale gas development during 2009–2011 and 2013–2015 in a predominantly forested landscape in West Virginia, USA. Forest cover across the study area decreased from 95% in 2008 to 91% in 2015, while the area affected by shale gas development increased from 0.4% to 3.9%. We quantified nest survival and productivity, a source–sink threshold, riparian habitat quality, territory density, and territory length by monitoring 58.1 km of forested headwater streams (n = 14 streams). Across years, we saw annual variability in nest survival, with a general declining trend over time. Of 11 a priori models tested to explain nest survival (n = 280 nests), 4 models that included temporal, habitat, and shale gas covariates were supported, and 2 of these models accounted for most of the variation in daily nest survival rate. After accounting for temporal effects (rainfall, nest age, and time within season), shale gas development had negative effects on nest survival. Population-level nest productivity declined and individual productivity was lower in areas disturbed by shale gas development than in undisturbed areas, and a source–sink threshold suggested that disturbed areas were more at risk of being sink habitat. Riparian habitat quality scores, as measured by a U.S. Environmental Protection Agency index and a waterthrush-specific habitat suitability index, differed by year and were negatively related to the amount of each territory disturbed by shale gas development. Territory density was not related to the amount of shale gas disturbance, but decreased over time as territory lengths increased. Overall, our results suggest a decline in waterthrush site quality as shale gas development increases, despite relatively small site-wide forest loss.

Water Saturation Relations and Their Diffusion-Limited Equilibration in Gas Shale: Implications for Gas Flow in Unconventional Reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokunaga, Tetsu K.; Shen, Weijun; Wan, Jiamin

Large volumes of water are used for hydraulic fracturing of low permeability shale reservoirs to stimulate gas production, with most of the water remaining unrecovered and distributed in a poorly understood manner within stimulated regions. Because water partitioning into shale pores controls gas release, we measured the water saturation dependence on relative humidity (rh) and capillary pressure (P c) for imbibition (adsorption) as well as drainage (desorption) on samples of Woodford Shale. Experiments and modeling of water vapor adsorption into shale laminae at rh = 0.31 demonstrated that long times are needed to characterize equilibrium in larger (5 mm thick)more » pieces of shales, and yielded effective diffusion coefficients from 9 × 10 -9 to 3 × 10 -8 m 2 s -1, similar in magnitude to the literature values for typical low porosity and low permeability rocks. Most of the experiments, conducted at 50°C on crushed shale grains in order to facilitate rapid equilibration, showed significant saturation hysteresis, and that very large P c (~1 MPa) are required to drain the shales. These results quantify the severity of the water blocking problem, and suggest that gas production from unconventional reservoirs is largely associated with stimulated regions that have had little or no exposure to injected water. Finally, gravity drainage of water from fractures residing above horizontal wells reconciles gas production in the presence of largely unrecovered injected water, and is discussed in the broader context of unsaturated flow in fractures.« less

Water Saturation Relations and Their Diffusion-Limited Equilibration in Gas Shale: Implications for Gas Flow in Unconventional Reservoirs

DOE PAGES

Tokunaga, Tetsu K.; Shen, Weijun; Wan, Jiamin; ...

2017-11-15

Large volumes of water are used for hydraulic fracturing of low permeability shale reservoirs to stimulate gas production, with most of the water remaining unrecovered and distributed in a poorly understood manner within stimulated regions. Because water partitioning into shale pores controls gas release, we measured the water saturation dependence on relative humidity (rh) and capillary pressure (P c) for imbibition (adsorption) as well as drainage (desorption) on samples of Woodford Shale. Experiments and modeling of water vapor adsorption into shale laminae at rh = 0.31 demonstrated that long times are needed to characterize equilibrium in larger (5 mm thick)more » pieces of shales, and yielded effective diffusion coefficients from 9 × 10 -9 to 3 × 10 -8 m 2 s -1, similar in magnitude to the literature values for typical low porosity and low permeability rocks. Most of the experiments, conducted at 50°C on crushed shale grains in order to facilitate rapid equilibration, showed significant saturation hysteresis, and that very large P c (~1 MPa) are required to drain the shales. These results quantify the severity of the water blocking problem, and suggest that gas production from unconventional reservoirs is largely associated with stimulated regions that have had little or no exposure to injected water. Finally, gravity drainage of water from fractures residing above horizontal wells reconciles gas production in the presence of largely unrecovered injected water, and is discussed in the broader context of unsaturated flow in fractures.« less

The Devonian Marcellus Shale and Millboro Shale

USGS Publications Warehouse

Soeder, Daniel J.; Enomoto, Catherine B.; Chermak, John A.

2014-01-01

The recent development of unconventional oil and natural gas resources in the United States builds upon many decades of research, which included resource assessment and the development of well completion and extraction technology. The Eastern Gas Shales Project, funded by the U.S. Department of Energy in the 1980s, investigated the gas potential of organic-rich, Devonian black shales in the Appalachian, Michigan, and Illinois basins. One of these eastern shales is the Middle Devonian Marcellus Shale, which has been extensively developed for natural gas and natural gas liquids since 2007. The Marcellus is one of the basal units in a thick Devonian shale sedimentary sequence in the Appalachian basin. The Marcellus rests on the Onondaga Limestone throughout most of the basin, or on the time-equivalent Needmore Shale in the southeastern parts of the basin. Another basal unit, the Huntersville Chert, underlies the Marcellus in the southern part of the basin. The Devonian section is compressed to the south, and the Marcellus Shale, along with several overlying units, grades into the age-equivalent Millboro Shale in Virginia. The Marcellus-Millboro interval is far from a uniform slab of black rock. This field trip will examine a number of natural and engineered exposures in the vicinity of the West Virginia–Virginia state line, where participants will have the opportunity to view a variety of sedimentary facies within the shale itself, sedimentary structures, tectonic structures, fossils, overlying and underlying formations, volcaniclastic ash beds, and to view a basaltic intrusion.

Environmental contamination due to shale gas development.

PubMed

Annevelink, M P J A; Meesters, J A J; Hendriks, A J

2016-04-15

Shale gas development potentially contaminates both air and water compartments. To assist in governmental decision-making on future explorations, we reviewed scattered information on activities, emissions and concentrations related to shale gas development. We compared concentrations from monitoring programmes to quality standards as a first indication of environmental risks. Emissions could not be estimated accurately because of incomparable and insufficient data. Air and water concentrations range widely. Poor wastewater treatment posed the highest risk with concentrations exceeding both Natural Background Values (NBVs) by a factor 1000-10,000 and Lowest Quality Standards (LQSs) by a factor 10-100. Concentrations of salts, metals, volatile organic compounds (VOCs) and hydrocarbons exceeded aquatic ecotoxicological water standards. Future research must focus on measuring aerial and aquatic emissions of toxic chemicals, generalisation of experimental setups and measurement technics and further human and ecological risk assessment. Copyright © 2016 Elsevier B.V. All rights reserved.

Hazard-Specific Vulnerability Mapping for Water Security in a Shale Gas Context

NASA Astrophysics Data System (ADS)

Allen, D. M.; Holding, S.; McKoen, Z.

2015-12-01

Northeast British Columbia (NEBC) is estimated to hold large reserves of unconventional natural gas and has experienced rapid growth in shale gas development activities over recent decades. Shale gas development has the potential to impact the quality and quantity of surface and ground water. Robust policies and sound water management are required to protect water security in relation to the water-energy nexus surrounding shale gas development. In this study, hazard-specific vulnerability mapping was conducted across NEBC to identify areas most vulnerable to water quality and quantity deterioration due to shale gas development. Vulnerability represents the combination of a specific hazard threat and the susceptibility of the water system to that threat. Hazard threats (i.e. potential contamination sources and water abstraction) were mapped spatially across the region. The shallow aquifer susceptibility to contamination was characterised using the DRASTIC aquifer vulnerability approach, while the aquifer susceptibility to abstraction was mapped according to aquifer productivity. Surface water susceptibility to contamination was characterised on a watershed basis to describe the propensity for overland flow (i.e. contaminant transport), while watershed discharge estimates were used to assess surface water susceptibility to water abstractions. The spatial distribution of hazard threats and susceptibility were combined to form hazard-specific vulnerability maps for groundwater quality, groundwater quantity, surface water quality and surface water quantity. The vulnerability maps identify priority areas for further research, monitoring and policy development. Priority areas regarding water quality occur where hazard threat (contamination potential) coincide with high aquifer susceptibility or high overland flow potential. Priority areas regarding water quantity occur where demand is estimated to represent a significant proportion of estimated supply. The identification

Gas seal for an in situ oil shale retort and method of forming thermal barrier

DOEpatents

Burton, III, Robert S.

1982-01-01

A gas seal is provided in an access drift excavated in a subterranean formation containing oil shale. The access drift is adjacent an in situ oil shale retort and is in gas communication with the fragmented permeable mass of formation particles containing oil shale formed in the in situ oil shale retort. The mass of formation particles extends into the access drift, forming a rubble pile of formation particles having a face approximately at the angle of repose of fragmented formation. The gas seal includes a temperature barrier which includes a layer of heat insulating material disposed on the face of the rubble pile of formation particles and additionally includes a gas barrier. The gas barrier is a gas-tight bulkhead installed across the access drift at a location in the access drift spaced apart from the temperature barrier.

Estimation of Potential Shale Gas Yield Amount and Land Degradation in China by Landcover Distribution regarding Water-Food-Energy and Forest

NASA Astrophysics Data System (ADS)

Kim, N.; Heo, S.; Lim, C. H.; Lee, W. K.

2017-12-01

Shale gas is gain attention due to the tremendous reserves beneath the earth. The two known high reservoirs are located in United States and China. According to U.S Energy Information Administration China have estimated 7,299 trillion cubic feet of recoverable shale gas and placed as world first reservoir. United States had 665 trillion cubic feet for the shale gas reservoir and placed fourth. Unlike the traditional fossil fuel, spatial distribution of shale gas is considered to be widely spread and the reserved amount and location make the resource as energy source for the next generation. United States dramatically increased the shale gas production. For instance, shale gas production composes more than 50% of total natural gas production whereas China and Canada shale gas produce very small amount of the shale gas. According to U.S Energy Information Administration's report, in 2014 United States produced shale gas almost 40 billion cubic feet per day but China only produced 0.25 billion cubic feet per day. Recently, China's policy had changed to decrease the coal powerplants to reduce the air pollution and the energy stress in China is keep increasing. Shale gas produce less air pollution while producing energy and considered to be clean energy source. Considering the situation of China and characteristics of shale gas, soon the demand of shale gas will increase in China. United States invested 71.7 billion dollars in 2013 but it Chinese government is only proceeding fundamental investment due to land degradation, limited water resources, geological location of the reservoirs.In this study, firstly we reviewed the current system and technology of shale gas extraction such as hydraulic Fracturing. Secondly, listed the possible environmental damages, land degradations, and resource demands for the shale gas extraction. Thirdly, invested the potential shale gas extraction amount in China based on the location of shale gas reservoirs and limited resources for the

Shale gas activity and increased rates of sexually transmitted infections in Ohio, 2000–2016

PubMed Central

Humeau, Zoe; Elliott, Elise G.; Warren, Joshua L.; Niccolai, Linda M.

2018-01-01

Background The growing shale gas (“fracking”) industry depends on a mobile workforce, whose influx could have social impacts on host communities. Sexually transmitted infections (STIs) can increase through sexual mixing patterns associated with labor migration. No prior studies have quantified the relationship between shale gas activity and rates of three reportable STIs: chlamydia, gonorrhea, and syphilis. Methods We conducted a longitudinal, ecologic study from 2000–2016 in Ohio, situated in a prolific shale gas region in the United States (US). Data on reported cases of chlamydia, gonorrhea, and syphilis by county and year were obtained from the Ohio Department of Health. All 88 counties were classified as none, low, and high shale gas activity in each year, using data from the Ohio Department of Natural Resources. Annual rate ratios (RR) and 95% confidence intervals (95% CIs) were calculated from mixed-effects Poisson regression models evaluating the relationship between shale gas activity and reported annual STI rates while adjusting for secular trends and potential confounders obtained from the US Census. Results Compared to counties with no shale gas activity, counties with high activity had 21% (RR = 1.21; 95%CI = 1.08–1.36) increased rates of chlamydia and 19% (RR = 1.27; 95%CI 0.98–1.44) increased rates of gonorrhea, respectively. No association was observed for syphilis. Conclusion This first report of a link between shale gas activity and increased rates of both chlamydia and gonorrhea may inform local policies and community health efforts. PMID:29570712

Shale Gas characteristics of Permian black shales (Ecca group, Eastern Cape, South Africa)

NASA Astrophysics Data System (ADS)

Geel, Claire; Booth, Peter; Schulz, Hans-Martin; Horsfield, Brian; de Wit, Maarten

2013-04-01

This study involves a comprehensive and detailed lithological, sedimentalogical, structural and geochemical description of the lower Ecca Group in the Eastern Cape, South Africa. The Ecca group hosts a ~ 245 million year old organic-rich black shale, which has recently been the focus of interest of petroleum companies worldwide. The shale was deposited under anoxic conditions in a setting which formed as a consequence of retro-arc foreland basin development related to the Cape Fold Belt. This sedimentary/tectonic environment provided the conditions for deeply buried black shales to reach maturity levels for development in the gas window. The investigation site is called the Greystone Area and is situated north of Wolwefontein en route to Jansenville. The area has outcrops of the Dwyka, the Ecca and the lower Beaufort Groups. The outcrops were mapped extensively and the data was used in conjunction with GIS software to produce a detailed geological map. North-south cross sections were drawn to give indication of bed thicknesses and formation depths. Using the field work, data two boreholes were accurately sited on the northern limb of a shallow easterly plunging syncline. The first borehole reached 100m and the second was drilled to 292m depth (100m percussion and 192m core). The second borehole was drilled 200m south of the first, to penetrate the formations at a greater depth and to avoid surface weathering. Fresh core from the upper Dwyka Group, the Prince Albert Formation, the Whitehill Formation, Collingham Formation and part of the Ripon Formation were successfully extracted and a detailed stratigraphic log has been drawn up. The core was sampled during extraction and the samples were immediately sent to the GFZ in Potsdam, Germany, for geochemical analyses. As suspected the black shales of the the Whitehill Formation are high in organic carbon and have an average TOC value of 4.5%, whereas the Prince Albert and Collingham Formation are below 1%. Tmax values

Shale Gas and Tight Oil: A Panacea for the Energy Woes of America?

NASA Astrophysics Data System (ADS)

Hughes, J. D.

2012-12-01

Shale gas has been heralded as a "game changer" in the struggle to meet America's demand for energy. The "Pickens Plan" of Texas oil and gas pioneer T.Boone Pickens suggests that gas can replace coal for much of U.S. electricity generation, and oil for, at least, truck transportation1. Industry lobby groups such as ANGA declare "that the dream of clean, abundant, home grown energy is now reality"2. In Canada, politicians in British Columbia are racing to export the virtual bounty of shale gas via LNG to Asia (despite the fact that Canadian gas production is down 16 percent from its 2001 peak). And the EIA has forecast that the U.S. will become a net exporter of gas by 20213. Similarly, recent reports from Citigroup and Harvard suggest that an oil glut is on the horizon thanks in part to the application of fracking technology to formerly inaccessible low permeability tight oil plays. The fundamentals of well costs and declines belie this optimism. Shale gas is expensive gas. In the early days it was declared that "continuous plays" like shale gas were "manufacturing operations", and that geology didn't matter. One could drill a well anywhere, it was suggested, and expect consistent production. Unfortunately, Mother Nature always has the last word, and inevitably the vast expanses of purported potential shale gas resources contracted to "core" areas, where geological conditions were optimal. The cost to produce shale gas ranges from 4.00 per thousand cubic feet (mcf) to 10.00, depending on the play. Natural gas production is a story about declines which now amount to 32% per year in the U.S. So 22 billion cubic feet per day of production now has to be replaced each year to keep overall production flat. At current prices of 2.50/mcf, industry is short about 50 billion per year in cash flow to make this happen4. As a result I expect falling production and rising prices in the near to medium term. Similarly, tight oil plays in North Dakota and Texas have been heralded

Fracture patterns and their origin in the upper Devonian Antrim Shale gas reservoir of the Michigan basin; a review

USGS Publications Warehouse

Ryder, Robert T.

1996-01-01

INTRODUCTION: Black shale members of the Upper Devonian Antrim Shale are both the source and reservoir for a regional gas accumulation that presently extends across parts of six counties in the northern part of the Michigan basin (fig. 1). Natural fractures are considered by most petroleum geologists and oil and gas operators who work the Michigan basin to be a necessary condition for commercial gas production in the Antrim Shale. Fractures provide the conduits for free gas and associated water to flow to the borehole through the black shale which, otherwise, has a low matrix permeability. Moreover, the fractures assist in the release of gas adsorbed on mineral and(or) organic matter in the shale (Curtis, 1992). Depths to the gas-producing intervals (Norwood and Lachine Members) generally range from 1,200 to 1,800 ft (Oil and Gas Journal, 1994). Locally, wells that produce gas from the accumulation are as deep as 2,200 (Oil and Gas Journal, 1994). Even though natural fractures are an important control on Antrim Shale gas production, most wells require stimulation by hydraulic fracturing to attain commercial production rates (Kelly, 1992). In the U.S. Geological Survey's National Assessment of United States oil and gas, Dolton (1995) estimates that, at a mean value, 4.45 trillion cubic feet (TCF) of gas are recoverable as additions to already discovered quantities from the Antrim Shale in the productive area of the northern Michigan trend. Dolton (1995) also suggests that undiscovered Antrim Shale gas accumulations exist in other parts of the Michigan basin. The character, distribution, and origin of natural fractures in the Antrim Shale gas accumulation have been studied recently by academia and industry. The intent of these investigations is to: 1) predict 'sweet spots', prior to drilling, in the existing gas-producing trend, 2) improve production practices in the existing trend, 3) predict analogous fracture-controlled gas accumulations in other parts of the

Towards the development of rapid screening techniques for shale gas core properties

NASA Astrophysics Data System (ADS)

Cave, Mark R.; Vane, Christopher; Kemp, Simon; Harrington, Jon; Cuss, Robert

2013-04-01

Shale gas has been produced for many years in the U.S.A. and forms around 8% of total their natural gas production. Recent testing for gas on the Fylde Coast in Lancashire UK suggests there are potentially large reserves which could be exploited. The increasing significance of shale gas has lead to the need for deeper understanding of shale behaviour. There are many factors which govern whether a particular shale will become a shale gas resource and these include: i) Organic matter abundance, type and thermal maturity; ii) Porosity-permeability relationships and pore size distribution; iii) Brittleness and its relationship to mineralogy and rock fabric. Measurements of these properties require sophisticated and time consuming laboratory techniques (Josh et al 2012), whereas rapid screening techniques could provide timely results which could improve the efficiency and cost effectiveness of exploration. In this study, techniques which are portable and provide rapid on-site measurements (X-ray Fluorescence (XRF) and Infra-red (IR) spectroscopy) have been calibrated against standard laboratory techniques (Rock-Eval 6 analyser-Vinci Technologies) and Powder whole-rock XRD analysis was carried out using a PANalytical X'Pert Pro series diffractometer equipped with a cobalt-target tube, X'Celerator detector and operated at 45kV and 40mA, to predict properties of potential shale gas material from core material from the Bowland shale Roosecote, south Cumbria. Preliminary work showed that, amongst various mineralogical and organic matter properties of the core, regression models could be used so that the total organic carbon content could be predicted from the IR spectra with a 95 percentile confidence prediction error of 0.6% organic carbon, the free hydrocarbons could be predicted with a 95 percentile confidence prediction error of 0.6 mgHC/g rock, the bound hydrocarbons could be predicted with a 95 percentile confidence prediction error of 2.4 mgHC/g rock, mica content

The impact of intensity on perceived risk from unconventional shale gas development.

PubMed

Livy, Mitchell R; Gopalakrishnan, Sathya; Klaiber, H Allen; Roe, Brian E

2018-07-15

The recent boom in the extraction of natural gas from subsurface shale deposits due to advances in hydraulic fracturing and horizontal drilling technologies has raised concern around environmental risks. Reliable measures of how residents view these risks are therefore a necessary first step in evaluating policies that regulate the industry through risk mitigation measures. We conduct a choice experiment targeting residents in an area of Ohio with significant shale drilling activity, and find that households are willing to pay to avoid high intensities of shale development and truck traffic. Our analysis presents new policy-relevant evidence of preferences associated with unconventional shale gas reserves, and highlights the tradeoffs between activity intensity at each site and the number of sites in aggregate. Copyright © 2018 Elsevier Ltd. All rights reserved.

The Impact of a Potential Shale Gas Development in Germany and the United Kingdom on Pollutant and Greenhouse Gas Emissions

NASA Astrophysics Data System (ADS)

Weger, L.; Cremonese, L.; Bartels, M. P.; Butler, T. M.

2016-12-01

Several European countries with domestic shale gas reserves are considering extracting this natural gas resource to complement their energy transition agenda. Natural gas, which produces lower CO2 emissions upon combustion compared to coal or oil, has the potential to serve as a bridge in the transition from fossil fuels to renewables. However, the generation of shale gas leads to emissions of CH4 and pollutants such as PM, NOx and VOCs, which in turn impact climate as well as local and regional air quality. In this study, we explore the impact of a potential shale gas development in Europe, specifically in Germany and the United Kingdom, on emissions of greenhouse gases and pollutants. In order to investigate the effect on emissions, we first estimate a range of wells drilled per year and production volume for the two countries under examination based on available geological information and on regional infrastructural and economic limitations. Subsequently we assign activity data and emissions factors to the well development, gas production and processing stages of shale gas generation to enable emissions quantification. We then define emissions scenarios to explore different storylines of potential shale gas development, including low emissions (high level of regulation), high emissions (low level of regulation) and middle emissions scenarios, which influence fleet make-up, emission factor and activity data choices for emissions quantification. The aim of this work is to highlight important variables and their ranges, to promote discussion and communication of potential impacts, and to construct possible visions for a future shale gas development in the two study countries. In a follow-up study, the impact of pollutant emissions from these scenarios on air quality will be explored using the Weather Research and Forecasting model with chemistry (WRF-Chem) model.

Is shale gas drilling an energy solution or public health crisis?

PubMed

Rafferty, Margaret A; Limonik, Elena

2013-01-01

High-volume horizontal hydraulic fracturing, a controversial new mining technique used to drill for shale gas, is being implemented worldwide. Chemicals used in the process are known neurotoxins, carcinogens, and endocrine disruptors. People who live near shale gas drilling sites report symptoms that they attribute to contaminated air and water. When they seek help from clinicians, a diagnosis is often elusive because the chemicals to which the patients have been exposed are a closely guarded trade secret. Many nurses have voiced grave concern about shale gas drilling safety. Full disclosure of the chemicals used in the process is necessary in order for nurses and other health professionals to effectively care for patients. The economic exuberance surrounding natural gas has resulted in insufficient scrutiny into the health implications. Nursing research aimed at determining what effect unconventional drilling has on human health could help fill that gap. Public health nurses using the precautionary principle should advocate for a more concerted transition from fossil fuels to sustainable energy. Any initiation or further expansion of unconventional gas drilling must be preceded by a comprehensive Health Impact Assessment (HIA). © 2013 Wiley Periodicals, Inc.

Shale gas and non-aqueous fracturing fluids: Opportunities and challenges for supercritical CO₂

DOE PAGES

Middleton, Richard S.; Carey, James William; Currier, Robert P.; ...

2015-06-01

Hydraulic fracturing of shale formations in the United States has led to a domestic energy boom. Currently, water is the only fracturing fluid regularly used in commercial shale oil and gas production. Industry and researchers are interested in non-aqueous working fluids due to their potential to increase production, reduce water requirements, and to minimize environmental impacts. Using a combination of new experimental and modeling data at multiple scales, we analyze the benefits and drawbacks of using CO₂ as a working fluid for shale gas production. We theorize and outline potential advantages of CO₂ including enhanced fracturing and fracture propagation, reductionmore » of flow-blocking mechanisms, increased desorption of methane adsorbed in organic-rich parts of the shale, and a reduction or elimination of the deep re-injection of flow-back water that has been linked to induced seismicity and other environmental concerns. We also examine likely disadvantages including costs and safety issues associated with handling large volumes of supercritical CO₂. The advantages could have a significant impact over time leading to substantially increased gas production. In addition, if CO₂ proves to be an effective fracturing fluid, then shale gas formations could become a major utilization option for carbon sequestration.« less

Gas-fired power in the UK: Bridging supply gaps and implications of domestic shale gas exploitation for UK climate change targets.

PubMed

Turk, Jeremy K; Reay, David S; Haszeldine, R Stuart

2018-03-01

There is a projected shortcoming in the fourth carbon budget of 7.5%. This shortfall may be increased if the UK pursues a domestic shale gas industry to offset projected decreases in traditional gas supply. Here we estimate that, if the project domestic gas supply gap for power generation were to be met by UK shale gas with low fugitive emissions (0.08%), an additional 20.4MtCO 2 e 1 would need to be accommodated during carbon budget periods 3-6. We find that a modest fugitive emissions rate (1%) for UK shale gas would increase global emissions compared to importing an equal quantity of Qatari liquefied natural gas. Additionally, we estimate that natural gas electricity generation would emit 420-466MtCO 2 e (460 central estimate) during the same time period within the traded EU emissions cap. We conclude that domestic shale gas production with even a modest 1% fugitive emissions rate would risk exceedance of UK carbon budgets. We also highlight that, under the current production-based greenhouse gas accounting system, the UK is incentivized to import natural gas rather than produce it domestically. Copyright © 2017 Elsevier B.V. All rights reserved.

Noble gases in gas shales : Implications for gas retention and circulating fluids.

NASA Astrophysics Data System (ADS)

Basu, Sudeshna; Jones, Adrian; Verchovsky, Alexander

2016-04-01

Gas shales from three cores of Haynesville-Bossier formation have been analysed simultaneously for carbon, nitrogen and noble gases (He, Ne, Ar, Xe) to constrain their source compositions and identify signatures associated with high gas retention. Ten samples from varying depths of 11785 to 12223 feet from each core, retrieved from their centres, have been combusted from 200-1200°C in incremental steps of 100°C, using 5 - 10 mg of each sample. Typically, Xe is released at 200°C and is largely adsorbed, observed in two of the three cores. The third core lacked any measureable Xe. High 40Ar/36Ar ratio up to 8000, is associated with peak release of nitrogen with distinctive isotopic signature, related to breakdown of clay minerals at 500°C. He and Ne are also mostly released at the same temperature step and predominantly hosted in the pore spaces of the organic matter associated with the clay. He may be produced from the uranium related to the organic matter. The enrichment factors of noble gases defined as (iX/36Ar)sample/(iX/36Ar)air where iX denotes any noble gas isotope, show Ne and Xe enrichment observed commonly in sedimentary rocks including shales (Podosek et al., 1980; Bernatowicz et al., 1984). This can be related to interaction of the shales with circulating fluids and diffusive separation of gases (Torgersen and Kennedy, 1999), implying the possibility of loss of gases from these shales. Interaction with circulating fluids (e.g. crustal fluids) have been further confirmed using 20Ne/N2, 36Ar/N2 and 4He/N2 ratios. Deviations of measured 4He/40Ar* (where 40Ar* represents radiogenic 40Ar after correcting for contribution from atmospheric Ar) from expected values has been used to monitor gas loss by degassing. Bernatowicz, T., Podosek, F.A., Honda, M., Kramer, F.E., 1984. The Atmospheric Inventory of Xenon and Noble Gases in Shales: The Plastic Bag Experiment. Journal of Geophysical Research 89, 4597-4611. Podosek, F.A., Honda, M., Ozima, M., 1980

Field and Lab-Based Microbiological Investigations of the Marcellus Shale

NASA Astrophysics Data System (ADS)

Wishart, J. R.; Neumann, K.; Edenborn, H. M.; Hakala, A.; Yang, J.; Torres, M. E.; Colwell, F. S.

2013-12-01

The recent exploration of shales for natural gas resources has provided the opportunity to study their subsurface geochemistry and microbiology. Evidence indicates that shale environments are marked by extreme conditions such as high temperature and pressure, low porosity, permeability and connectivity, and the presence of heavy metals and radionuclides. It has been postulated that many of these shales are naturally sterile due to the high pressure and temperature conditions under which they were formed. However, it has been shown in the Antrim and New Albany shales that microbial communities do exist in these environments. Here we review geochemical and microbiological evidence for the possible habitation of the Marcellus shale by microorganisms and compare these conditions to other shales in the U.S. Furthermore, we describe the development of sampling and analysis techniques used to evaluate microbial communities present in the Marcellus shale and associated hydraulic fracturing fluid. Sampling techniques thus far have consisted of collecting flowback fluids from wells and water impoundments and collecting core material from previous drilling expeditions. Furthermore, DNA extraction was performed on Marcellus shale sub-core with a MoBio PowerSoil kit to determine its efficiency. Assessment of the Marcellus shale indicates that it has low porosity and permeability that are not conducive to dense microbial populations; however, moderate temperatures and a natural fracture network may support a microbial community especially in zones where the Marcellus intersects more porous geologic formations. Also, hydraulic fracturing extends this fracture network providing more environments where microbial communities can exist. Previous research which collected flowback fluids has revealed a diverse microbial community that may be derived from hydrofrac fluid production or from the subsurface. DNA extraction from 10 g samples of Marcellus shale sub-core were unsuccessful

Exploring the environmental effects of shale gas development in the Chesapeake Bay watershed

Treesearch

Scientific and Technical Committee [STAC] Chesapeake Bay Program

2013-01-01

On April 11-12, 2012, the Chesapeake Bay Program's Scientific and Technical Advisory Committee (STAC) convened an expert workshop to investigate the environmental effects of shale gas development in the Chesapeake Bay Watershed. The purpose of this workshop was to engage scientists from across the nation in a review of the state-of-the-science regarding shale gas...

Application of Fractal Geometry in Evaluation of Effective Stimulated Reservoir Volume in Shale Gas Reservoirs

NASA Astrophysics Data System (ADS)

Sheng, Guanglong; Su, Yuliang; Wang, Wendong; Javadpour, Farzam; Tang, Meirong

According to hydraulic-fracturing practices conducted in shale reservoirs, effective stimulated reservoir volume (ESRV) significantly affects the production of hydraulic fractured well. Therefore, estimating ESRV is an important prerequisite for confirming the success of hydraulic fracturing and predicting the production of hydraulic fracturing wells in shale reservoirs. However, ESRV calculation remains a longstanding challenge in hydraulic-fracturing operation. In considering fractal characteristics of the fracture network in stimulated reservoir volume (SRV), this paper introduces a fractal random-fracture-network algorithm for converting the microseismic data into fractal geometry. Five key parameters, including bifurcation direction, generating length (d), deviation angle (α), iteration times (N) and generating rules, are proposed to quantitatively characterize fracture geometry. Furthermore, we introduce an orthogonal-fractures coupled dual-porosity-media representation elementary volume (REV) flow model to predict the volumetric flux of gas in shale reservoirs. On the basis of the migration of adsorbed gas in porous kerogen of REV with different fracture spaces, an ESRV criterion for shale reservoirs with SRV is proposed. Eventually, combining the ESRV criterion and fractal characteristic of a fracture network, we propose a new approach for evaluating ESRV in shale reservoirs. The approach has been used in the Eagle Ford shale gas reservoir, and results show that the fracture space has a measurable influence on migration of adsorbed gas. The fracture network can contribute to enhancement of the absorbed gas recovery ratio when the fracture space is less than 0.2 m. ESRV is evaluated in this paper, and results indicate that the ESRV accounts for 27.87% of the total SRV in shale gas reservoirs. This work is important and timely for evaluating fracturing effect and predicting production of hydraulic fracturing wells in shale reservoirs.

Establishing effective sentinels - Setting the baseline for shale gas

NASA Astrophysics Data System (ADS)

Ward, C.; Worrall, F.

2017-12-01

The UK has a nascent shale gas industry and, unlike the US we have the opportunity to establish structures both physical and regulatory to reassure the public that any impact of a developing shale gas will be .properly licensed, regulated, monitored and, if necessary, mitigated. To assess and indeed demonstrate an impact of any activity, let alone those of shale gas exploitation, it is necessary to show, within a reasonable level of certainty, that the industry has changed a environmental state over and above that which was true without the activity present. The need for demonstrating impact not only means that a baseline needs to be established but that the baseline needs to be robustly established within a statistical and probabilistic framework so that certainty of impact can be demonstrated. A number of technologies have been proposed for monitoring the water quality impacts of shale gas developments, however, to be an effective and robust sentinel of change the parameter should have several properties: it should be a lead indicator and not a lag indicator of change; it should have a high contrast with the normal or background activity; it should show a high specificity for the activity of concern and not be associated with other activities; and it should readily deployed in time and space. By far the greatest difference between the waters arising from a shale gas well pad and surface waters is nothing more than salinity or its associated determinds. The salinity of flowback water and deep formation water can be many times greater than seawater let alone greater than the salinity of most UK surface waters. Therefore, we have built a probabilistic model of the salinity of English surface waters. We have developed a generalised linear model of the existing salinity data available for English surface waters. Generalised linear modelling means that we can use all the existing data, the approach is entirely data driven; it does not require parameterisation; and can

Experimental investigation on the coupled effect of effective stress and gas slippage on the permeability of shale.

PubMed

Yang, Diansen; Wang, Wei; Chen, Weizhong; Wang, Shugang; Wang, Xiaoqiong

2017-03-17

Permeability is one of the most important parameters to evaluate gas production in shale reservoirs. Because shale permeability is extremely low, gas is often used in the laboratory to measure permeability. However, the measured apparent gas permeability is higher than the intrinsic permeability due to the gas slippage effect, which could be even more dominant for materials with nanopores. Increasing gas pressure during tests reduces gas slippage effect, but it also decreases the effective stress which in turn influences the permeability. The coupled effect of gas slippage and effective stress on shale permeability remains unclear. Here we perform laboratory experiments on Longmaxi shale specimens to explore the coupled effect. We use the pressure transient method to measure permeability under different stress and pressure conditions. Our results reveal that the apparent measured permeability is controlled by these two competing effects. With increasing gas pressure, there exists a pressure threshold at which the dominant effect on permeability switches from gas slippage to effective stress. Based on the Klinkenberg model, we propose a new conceptual model that incorporates both competing effects. Combining microstructure analysis, we further discuss the roles of stress, gas pressure and water contents on gas permeability of shale.

Material-balance assessment of the New Albany-Chesterian petroleum system of the Illinois basin

USGS Publications Warehouse

Lewan, M.D.; Henry, M.E.; Higley, D.K.; Pitman, Janet K.

2002-01-01

The New Albany-Chesterian petroleum system of the Illinois basin is a well-constrained system from which petroleum charges and losses were quantified through a material-balance assessment. This petroleum system has nearly 90,000 wells penetrating the Chesterian section, a single New Albany Shale source rock accounting for more than 99% of the produced oil, well-established stratigraphic and structural frameworks, and accessible source rock samples at various maturity levels. A hydrogen index (HI) map based on Rock-Eval analyses of source rock samples of New Albany Shale defines the pod of active source rock and extent of oil generation. Based on a buoyancy-drive model, the system was divided into seven secondary-migration catchments. Each catchment contains a part of the active pod of source rock from which it derives a petroleum charge, and this charge is confined to carrier beds and reservoirs within these catchments as accountable petroleum, petroleum losses, or undiscovered petroleum. A well-constrained catchment with no apparent erosional or leakage losses is used to determine an actual petroleum charge from accountable petroleum and residual migration losses. This actual petroleum charge is used to calibrate the other catchments in which erosional petroleum losses have occurred. Petroleum charges determined by laboratory pyrolysis are exaggerated relative to the actual petroleum charge. Rock-Eval charges are exaggerated by a factor of 4-14, and hydrouspyrolysis charges are exaggerated by a factor of 1.7. The actual petroleum charge provides a more meaningful material balance and more realistic estimates of petroleum losses and remaining undiscovered petroleum. The total petroleum charge determined for the New Albany-Chesterian system is 78 billion bbl, of which 11.4 billion bbl occur as a accountable in place petroleum, 9 billion bbl occur as residual migration losses, and 57.6 billion bbl occur as erosional losses. Of the erosional losses, 40 billion bbl

Appraisal of transport and deformation in shale reservoirs using natural noble gas tracers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heath, Jason E.; Kuhlman, Kristopher L.; Robinson, David G.

2015-09-01

This report presents efforts to develop the use of in situ naturally-occurring noble gas tracers to evaluate transport mechanisms and deformation in shale hydrocarbon reservoirs. Noble gases are promising as shale reservoir diagnostic tools due to their sensitivity of transport to: shale pore structure; phase partitioning between groundwater, liquid, and gaseous hydrocarbons; and deformation from hydraulic fracturing. Approximately 1.5-year time-series of wellhead fluid samples were collected from two hydraulically-fractured wells. The noble gas compositions and isotopes suggest a strong signature of atmospheric contribution to the noble gases that mix with deep, old reservoir fluids. Complex mixing and transport of fracturingmore » fluid and reservoir fluids occurs during production. Real-time laboratory measurements were performed on triaxially-deforming shale samples to link deformation behavior, transport, and gas tracer signatures. Finally, we present improved methods for production forecasts that borrow statistical strength from production data of nearby wells to reduce uncertainty in the forecasts.« less

New insights on the Karoo shale gas potential from borehole KZF-1 (Western Cape, South Africa)

NASA Astrophysics Data System (ADS)

Campbell, Stuart A.; Götz, Annette E.; Montenari, Michael

2016-04-01

A study on world shale reserves conducted by the Energy Information Agency (EIA) in 2013 concluded that there could be as much as 390 Tcf recoverable reserves of shale gas in the southern and south-western parts of the Karoo Basin. This would make it the 8th-largest shale gas resource in the world. However, the true extent and commercial viability is still unknown, due to the lack of exploration drilling and modern 3D seismic. Within the framework of the Karoo Research Initiative (KARIN), two deep boreholes were drilled in the Eastern and Western Cape provinces of South Africa. Here we report on new core material from borehole KZF-1 (Western Cape) which intersected the Permian black shales of the Ecca Group, the Whitehill Formation being the main target formation for future shale gas production. To determine the original source potential for shale gas we investigated the sedimentary environments in which the potential source rocks formed, addressing the research question of how much sedimentary organic matter the shales contained when they originally formed. Palynofacies indicates marginal marine conditions of a stratified basin setting with low marine phytoplankton percentages (acritarchs, prasinophytes), good AOM preservation, high terrestrial input, and a high spores:bisaccates ratio (kerogen type III). Stratigraphically, a deepening-upward trend is observed. Laterally, the basin configuration seems to be much more complex than previously assumed. Furthermore, palynological data confirms the correlation of marine black shales of the Prince Albert and Whitehill formations in the southern and south-western parts of the Karoo Basin with the terrestrial coals of the Vryheid Formation in the north-eastern part of the basin. TOC values (1-6%) classify the Karoo black shales as promising shale gas resources, especially with regard to the high thermal maturity (Ro >3). The recently drilled deep boreholes in the southern and south-western Karoo Basin, the first since the

A Tale of Two Regions: Landscape Ecological Planning for Shale Gas Energy Futures

NASA Astrophysics Data System (ADS)

Murtha, T., Jr.; Schroth, O.; Orland, B.; Goldberg, L.; Mazurczyk, T.

2015-12-01

As we increasingly embrace deep shale gas deposits to meet global energy demands new and dispersed local and regional policy and planning challenges emerge. Even in regions with long histories of energy extraction, such as coal, shale gas and the infrastructure needed to produce the gas and transport it to market offers uniquely complex transformations in land use and landcover not previously experienced. These transformations are fast paced, dispersed and can overwhelm local and regional planning and regulatory processes. Coupled to these transformations is a structural confounding factor. While extraction and testing are carried out locally, regulation and decision-making is multilayered, often influenced by national and international factors. Using a geodesign framework, this paper applies a set of geospatial landscape ecological planning tools in two shale gas settings. First, we describe and detail a series of ongoing studies and tools that we have developed for communities in the Marcellus Shale region of the eastern United States, specifically the northern tier of Pennsylvania. Second, we apply a subset of these tools to potential gas development areas of the Fylde region in Lancashire, United Kingdom. For the past five years we have tested, applied and refined a set of place based and data driven geospatial models for forecasting, envisioning, analyzing and evaluating shale gas activities in northern Pennsylvania. These models are continuously compared to important landscape ecological planning challenges and priorities in the region, e.g. visual and cultural resource preservation. Adapting and applying these tools to a different landscape allow us to not only isolate and define important regulatory and policy exigencies in each specific setting, but also to develop and refine these models for broader application. As we continue to explore increasingly complex energy solutions globally, we need an equally complex comparative set of landscape ecological

Multiscale model reduction for shale gas transport in poroelastic fractured media

NASA Astrophysics Data System (ADS)

Akkutlu, I. Yucel; Efendiev, Yalchin; Vasilyeva, Maria; Wang, Yuhe

2018-01-01

Inherently coupled flow and geomechanics processes in fractured shale media have implications for shale gas production. The system involves highly complex geo-textures comprised of a heterogeneous anisotropic fracture network spatially embedded in an ultra-tight matrix. In addition, nonlinearities due to viscous flow, diffusion, and desorption in the matrix and high velocity gas flow in the fractures complicates the transport. In this paper, we develop a multiscale model reduction approach to couple gas flow and geomechanics in fractured shale media. A Discrete Fracture Model (DFM) is used to treat the complex network of fractures on a fine grid. The coupled flow and geomechanics equations are solved using a fixed stress-splitting scheme by solving the pressure equation using a continuous Galerkin method and the displacement equation using an interior penalty discontinuous Galerkin method. We develop a coarse grid approximation and coupling using the Generalized Multiscale Finite Element Method (GMsFEM). GMsFEM constructs the multiscale basis functions in a systematic way to capture the fracture networks and their interactions with the shale matrix. Numerical results and an error analysis is provided showing that the proposed approach accurately captures the coupled process using a few multiscale basis functions, i.e. a small fraction of the degrees of freedom of the fine-scale problem.

Evidence of magma recharge at Colli Albani (Italy), the volcanic district at the gates of Rome, from geodesy and gas geochemistry

NASA Astrophysics Data System (ADS)

Trasatti, E.; Marra, F.; Polcari, M.; Etiope, G.; Ciotoli, G.; Darrah, T.; Tedesco, D.; Stramondo, S.; Florindo, F.; Ventura, G.

2017-12-01

Colli Albani (Italy) is an alkali-potassic volcanic district located about 20 km SE of Rome (3 M inhabitants) and lastly erupted 36 ka ago. Since the modern volcanic activity at Colli Albani seems not particularly intense, scientists have interpreted this volcano to be quiescent. Therefore, unlike other Italian volcanoes, the area has not undergone extensive monitoring. However, a seismic swarm during 1989-1990 has been related to a local uplift of ca. 30 cm since the 1950's along a line crossing the western side of the volcano, giving rise to a debate about its possible interpretation in terms of unrest. Furthermore, recent geological investigations indicate a coupling of eruption history, uplift history, and changes in the regional stress field, pointing to the conclusion that Colli Albani is in unrest. Here, we investigate the deformation processes and the gas geochemistry (He, CO2 and their isotopic ratios). From the analysis of about 20 years of InSAR data (1992-2010), we retrieve a puzzling deformation field at Colli Albani, consisting of long-term, constant rate, uplift of its western and southern flanks, and by coeval intra-caldera subsidence. This deformation setting cannot be related to a single cause, but reflects the interaction between different and spatially independent dynamic processes. Furthermore, we obtain information on the nature of the sources from the isotopic composition of the discharging CO2 and helium, showing that the Colli Albani dynamics are the result of decoupling between magma intrusion along pre-existing tectonic faults and caldera subsidence. In order to design a comprehensive geophysical model inclusive of all the above reported peculiarities, we consider potential sources related to magma/fluid migration or accumulation processes at depth through the main tectonic structures active at CA, by means of a numerical model. In summary, we demonstrate that despite the present-day phase of caldera deflation, the magmatic system at

Numerical Modeling of Gas and Water Flow in Shale Gas Formations with a Focus on the Fate of Hydraulic Fracturing Fluid.

PubMed

Edwards, Ryan W J; Doster, Florian; Celia, Michael A; Bandilla, Karl W

2017-12-05

Hydraulic fracturing in shale gas formations involves the injection of large volumes of aqueous fluid deep underground. Only a small proportion of the injected water volume is typically recovered, raising concerns that the remaining water may migrate upward and potentially contaminate groundwater aquifers. We implement a numerical model of two-phase water and gas flow in a shale gas formation to test the hypothesis that the remaining water is imbibed into the shale rock by capillary forces and retained there indefinitely. The model includes the essential physics of the system and uses the simplest justifiable geometrical structure. We apply the model to simulate wells from a specific well pad in the Horn River Basin, British Columbia, where there is sufficient available data to build and test the model. Our simulations match the water and gas production data from the wells remarkably closely and show that all the injected water can be accounted for within the shale system, with most imbibed into the shale rock matrix and retained there for the long term.

Process for oil shale retorting

DOEpatents

Jones, John B.; Kunchal, S. Kumar

1981-10-27

Particulate oil shale is subjected to a pyrolysis with a hot, non-oxygenous gas in a pyrolysis vessel, with the products of the pyrolysis of the shale contained kerogen being withdrawn as an entrained mist of shale oil droplets in a gas for a separation of the liquid from the gas. Hot retorted shale withdrawn from the pyrolysis vessel is treated in a separate container with an oxygenous gas so as to provide combustion of residual carbon retained on the shale, producing a high temperature gas for the production of some steam and for heating the non-oxygenous gas used in the oil shale retorting process in the first vessel. The net energy recovery includes essentially complete recovery of the organic hydrocarbon material in the oil shale as a liquid shale oil, a high BTU gas, and high temperature steam.

A Theoretical Investigation of Radial Lateral Wells with Shockwave Completion in Shale Gas Reservoirs

NASA Astrophysics Data System (ADS)

Shan, Jia

As its role in satisfying the energy demand of the U.S. and as a clean fuel has become more significant than ever, the shale gas production in the U.S. has gained increasing momentum over recent years. Thus, effective and environmentally friendly methods to extract shale gas are critical. Hydraulic fracturing has been proven to be efficient in the production of shale gas. However, environmental issues such as underground water contamination and high usage of water make this technology controversial. A potential technology to eliminate the environmental issues concerning water usage and contamination is to use blast fracturing, which uses explosives to create fractures. It can be further aided by HEGF and multi-pulse pressure loading technology, which causes less crushing effect near the wellbore and induces longer fractures. Radial drilling is another relatively new technology that can bypass damage zones due to drilling and create a larger drainage area through drilling horizontal wellbores. Blast fracturing and radial drilling both have the advantage of cost saving. The successful combination of blast fracturing and radial drilling has a great potential for improving U.S. shale gas production. An analytical productivity model was built in this study, considering linear flow from the reservoir rock to the fracture face, to analyze factors affecting shale gas production from radial lateral wells with shockwave completion. Based on the model analyses, the number of fractures per lateral is concluded to be the most effective factor controlling the productivity index of blast-fractured radial lateral wells. This model can be used for feasibility studies of replacing hydraulic fracturing by blast fracturing in shale gas well completions. Prediction of fracture geometry is recommended for future studies.

Evolving shale gas management: water resource risks, impacts, and lessons learned.

PubMed

Rahm, Brian G; Riha, Susan J

2014-05-01

Unconventional shale gas development promises to significantly alter energy portfolios and economies around the world. It also poses a variety of environmental risks, particularly with respect to the management of water resources. We review current scientific understanding of risks associated with the following: water withdrawals for hydraulic fracturing; wastewater treatment, discharge and disposal; methane and fluid migration in the subsurface; and spills and erosion at the surface. Some of these risks are relatively unique to shale gas development, while others are variations of risks that we already face from a variety of industries and activities. All of these risks depend largely on the pace and scale of development that occurs within a particular region. We focus on the United States, where the shale gas boom has been on-going for several years, paying particular attention to the Marcellus Shale, where a majority of peer-reviewed study has taken place. Governments, regulatory agencies, industry, and other stakeholders are challenged with responding to these risks, and we discuss policies and practices that have been adopted or considered by these various groups. Adaptive Management, a structured framework for addressing complex environmental issues, is discussed as a way to reduce polarization of important discussions on risk, and to more formally engage science in policy-making, along with other economic, social and value considerations. Data suggests that some risks can be substantially reduced through policy and best practice, but also that significant uncertainty persists regarding other risks. We suggest that monitoring and data collection related to water resource risks be established as part of planning for shale gas development before activity begins, and that resources are allocated to provide for appropriate oversight at various levels of governance.

Implications of shale gas exploitation for UK climate change targets under a production-based accounting system.

NASA Astrophysics Data System (ADS)

Turk, J.; Reay, D.; Haszeldine, S.

2017-12-01

The shale gas boom in the USA has seemingly decreased the greenhouse gas intensity of electricity generation in the USA over the last decade. The United Kingdom is supporting its own shale gas industry to increase its own domestic energy supply. The UK's climate change policy is underpinned by defined national carbon budgets periods. The UK has met Carbon Budget 1 (2008 - 2012) and is likely to meet the second and third carbon budgets (2013 - 2022). There is a projected shortcoming in the fourth carbon budget (2023 - 2027). This shortfall may be increased as the UK pursues a domestic shale gas industry. Under the current production-based GHG accounting system, the UK is incentivized to import natural gas rather than produce it domestically. If the projected gas supply were to be met by UK shale gas, we project additional greenhouse gas emissions which would need to be accommodated during Carbon Budget periods 3 - 6. Additionally, natural gas electricity generation will contribute to sustaining grid electricity emissions during the same time period within the traded European Union emissions cap.

Impact of Shale Gas Development on Water Resources: A Case Study in Northern Poland

NASA Astrophysics Data System (ADS)

Vandecasteele, Ine; Marí Rivero, Inés; Sala, Serenella; Baranzelli, Claudia; Barranco, Ricardo; Batelaan, Okke; Lavalle, Carlo

2015-06-01

Shale gas is currently being explored in Europe as an alternative energy source to conventional oil and gas. There is, however, increasing concern about the potential environmental impacts of shale gas extraction by hydraulic fracturing (fracking). In this study, we focussed on the potential impacts on regional water resources within the Baltic Basin in Poland, both in terms of quantity and quality. The future development of the shale play was modeled for the time period 2015-2030 using the LUISA modeling framework. We formulated two scenarios which took into account the large range in technology and resource requirements, as well as two additional scenarios based on the current legislation and the potential restrictions which could be put in place. According to these scenarios, between 0.03 and 0.86 % of the total water withdrawals for all sectors could be attributed to shale gas exploitation within the study area. A screening-level assessment of the potential impact of the chemicals commonly used in fracking was carried out and showed that due to their wide range of physicochemical properties, these chemicals may pose additional pressure on freshwater ecosystems. The legislation put in place also influenced the resulting environmental impacts of shale gas extraction. Especially important are the protection of vulnerable ground and surface water resources and the promotion of more water-efficient technologies.

Impact of shale gas development on water resources: a case study in northern poland.

PubMed

Vandecasteele, Ine; Marí Rivero, Inés; Sala, Serenella; Baranzelli, Claudia; Barranco, Ricardo; Batelaan, Okke; Lavalle, Carlo

2015-06-01

Shale gas is currently being explored in Europe as an alternative energy source to conventional oil and gas. There is, however, increasing concern about the potential environmental impacts of shale gas extraction by hydraulic fracturing (fracking). In this study, we focussed on the potential impacts on regional water resources within the Baltic Basin in Poland, both in terms of quantity and quality. The future development of the shale play was modeled for the time period 2015-2030 using the LUISA modeling framework. We formulated two scenarios which took into account the large range in technology and resource requirements, as well as two additional scenarios based on the current legislation and the potential restrictions which could be put in place. According to these scenarios, between 0.03 and 0.86% of the total water withdrawals for all sectors could be attributed to shale gas exploitation within the study area. A screening-level assessment of the potential impact of the chemicals commonly used in fracking was carried out and showed that due to their wide range of physicochemical properties, these chemicals may pose additional pressure on freshwater ecosystems. The legislation put in place also influenced the resulting environmental impacts of shale gas extraction. Especially important are the protection of vulnerable ground and surface water resources and the promotion of more water-efficient technologies.

Construction of Shale Gas Well

NASA Astrophysics Data System (ADS)

Sapińska-Śliwa, Aneta; Wiśniowski, Rafał; Skrzypaszek, Krzysztof

2018-03-01

The paper describes shale gas borehole axes trajectories (vertical, horizontal, multilateral). The methodology of trajectory design in a two-and three-dimensional space has been developed. The selection of the profile type of the trajectory axes of the directional borehole depends on the technical and technological possibilities of its implementation and the results of a comprehensive economic analysis of the availability and development of the field. The work assumes the possibility of a multivariate design of trajectories depending on the accepted (available or imposed) input data.

Experimental investigation on the coupled effect of effective stress and gas slippage on the permeability of shale

PubMed Central

Yang, Diansen; Wang, Wei; Chen, Weizhong; Wang, Shugang; Wang, Xiaoqiong

2017-01-01

Permeability is one of the most important parameters to evaluate gas production in shale reservoirs. Because shale permeability is extremely low, gas is often used in the laboratory to measure permeability. However, the measured apparent gas permeability is higher than the intrinsic permeability due to the gas slippage effect, which could be even more dominant for materials with nanopores. Increasing gas pressure during tests reduces gas slippage effect, but it also decreases the effective stress which in turn influences the permeability. The coupled effect of gas slippage and effective stress on shale permeability remains unclear. Here we perform laboratory experiments on Longmaxi shale specimens to explore the coupled effect. We use the pressure transient method to measure permeability under different stress and pressure conditions. Our results reveal that the apparent measured permeability is controlled by these two competing effects. With increasing gas pressure, there exists a pressure threshold at which the dominant effect on permeability switches from gas slippage to effective stress. Based on the Klinkenberg model, we propose a new conceptual model that incorporates both competing effects. Combining microstructure analysis, we further discuss the roles of stress, gas pressure and water contents on gas permeability of shale. PMID:28304395

Safe Management of Waste Generated during Shale Gas Operations

NASA Astrophysics Data System (ADS)

Kukulska-Zając, Ewa; Król, Anna; Holewa-Rataj, Jadwiga

2017-04-01

Exploration and exploitation of hydrocarbon deposits, regardless of their type, are connected with the generation of waste, which may have various environmental effects. Such wastes may pose a serious risk to the surrounding environment and public health because they usually contain numerous potentially toxic chemicals. Waste associated with exploration and exploitation of unconventional hydrocarbon deposits is composed of a mixture of organic and inorganic materials, the qualitative and quantitative composition of which changes widely over time, depending on numerous factors. As a result the proper characteristic of this type of waste is very important. Information gained from detailed chemical analyses of drilling chemicals, drilling wastes, and flowback water can be used to manage shale gas-related wastes more appropriately, to develop treatment methods, to store the waste, and assess the potential environmental and health risk. The following paper will focus mainly on the results of research carried out on waste samples coming from the unconventional hydrogen exploration sites. Additionally, regulatory frameworks applicable to the management of wastes produced during this type of works will be discussed. The scope of research concerning physicochemical parameters for this type of wastes will also be presented. The presented results were obtained during M4ShaleGas project realization. The M4ShaleGas project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 640715.

On the possibility of magnetic nano-markers use for hydraulic fracturing in shale gas mining

NASA Astrophysics Data System (ADS)

Zawadzki, Jaroslaw; Bogacki, Jan

2016-04-01

Recently shale gas production became essential for the global economy, thanks to fast advances in shale fracturing technology. Shale gas extraction can be achieved by drilling techniques coupled with hydraulic fracturing. Further increasing of shale gas production is possible by improving the efficiency of hydraulic fracturing and assessing the spatial distribution of fractures in shale deposits. The latter can be achieved by adding magnetic markers to fracturing fluid or directly to proppant, which keeps the fracture pathways open. After that, the range of hydraulic fracturing can be assessed by measurement of vertical and horizontal component of earth's magnetic field before and after fracturing. The difference in these components caused by the presence of magnetic marker particles may allow to delineate spatial distribution of fractures. Due to the fact, that subterranean geological formations may contain minerals with significant magnetic properties, it is important to provide to the markers excellent magnetic properties which should be also, independent of harsh chemical and geological conditions. On the other hand it is of great significance to produce magnetic markers at an affordable price because of the large quantities of fracturing fluids or proppants used during shale fracturing. Examining the properties of nano-materials, it was found, that they possess clearly superior magnetic properties, as compared to the same structure but having a larger particle size. It should be then possible, to use lower amount of magnetic marker, to obtain the same effect. Although a research on properties of new magnetic nano-materials is very intensive, cheap magnetic nano-materials are not yet produced on a scale appropriate for shale gas mining. In this work we overview, in detail, geological, technological and economic aspects of using magnetic nano-markers in shale gas mining. Acknowledgment This work was supported by the NCBiR under Grant "Electromagnetic method to

The optimized log interpretation method and sweet-spot prediction of gas-bearing shale reservoirs

NASA Astrophysics Data System (ADS)

Tan, Maojin; Bai, Ze; Xu, Jingjing

2017-04-01

Shale gas is one of the most important unconventional oil and gas resources, and its lithology and reservoir type are both different from conventional reservoirs [1,2]. "Where are shale reservoirs" "How to determine the hydrocarbon potential" "How to evaluate the reservoir quality", these are some key problems in front of geophysicists. These are sweet spots prediction and quantitative evaluation. As we known, sweet spots of organic shale include geological sweet spot and engineering sweet spot. Geophysical well logging can provide a lot of in-site formation information along the borehole, and all parameters describing the sweet spots of organic shale are attained by geophysical log interpretation[2]. Based on geological and petrophysical characteristics of gas shale, the log response characteristics of gas shales are summarized. Geological sweet spot includes hydrocarbon potential, porosity, fracture, water saturation and total gas content, which can be calculated by using wireline logs[3]. Firstly, the based-logging hydrocarbon potential evaluation is carried out, and the RBF neural network method is developed to estimate the total organic carbon content (TOC), which was proved more effective and suitable than empirical formula and ΔlogR methods [4]. Next, the optimized log interpretation is achieved by using model-searching, and the mineral concentrations of kerogen, clay, feldspar and pyrite and porosity are calculated. On the other hand, engineering sweet spot of shale refers to the rock physical properties and rock mechanism parameters. Some elastic properties including volume module, shear modulus and Poisson's ratio are correspondingly determined from log interpretation, and the brittleness index (BI), effective stress and pore pressure are also estimated. BI is one of the most important engineering sweet spot parameters. A large number of instances show that the summarized log responses can accurately identify the gas-bearing shale, and the proposed RBF

Evaluation of impact of shale gas operations in the Barnett Shale region on volatile organic compounds in air and potential human health risks.

PubMed

Bunch, A G; Perry, C S; Abraham, L; Wikoff, D S; Tachovsky, J A; Hixon, J G; Urban, J D; Harris, M A; Haws, L C

2014-01-15

Shale gas exploration and production (E&P) has experienced substantial growth across the U.S. over the last decade. The Barnett Shale, in north-central Texas, contains one of the largest, most active onshore gas fields in North America, stretching across 5000 square miles and having an estimated 15,870 producing wells as of 2011. Given that these operations may occur in relatively close proximity to populated/urban areas, concerns have been expressed about potential impacts on human health. In response to these concerns, the Texas Commission on Environmental Quality established an extensive air monitoring network in the region. This network provides a unique data set for evaluating the potential impact of shale gas E&P activities on human health. As such, the objective of this study was to evaluate community-wide exposures to volatile organic compounds (VOCs) in the Barnett Shale region. In this current study, more than 4.6 million data points (representing data from seven monitors at six locations, up to 105 VOCs/monitor, and periods of record dating back to 2000) were evaluated. Measured air concentrations were compared to federal and state health-based air comparison values (HBACVs) to assess potential acute and chronic health effects. None of the measured VOC concentrations exceeded applicable acute HBACVs. Only one chemical (1,2-dibromoethane) exceeded its applicable chronic HBACV, but it is not known to be associated with shale gas production activities. Annual average concentrations were also evaluated in deterministic and probabilistic risk assessments and all risks/hazards were below levels of concern. The analyses demonstrate that, for the extensive number of VOCs measured, shale gas production activities have not resulted in community-wide exposures to those VOCs at levels that would pose a health concern. With the high density of active wells in this region, these findings may be useful for understanding potential health risks in other shale play

Atmospheric emission characterization of Marcellus shale natural gas development sites.

PubMed

Goetz, J Douglas; Floerchinger, Cody; Fortner, Edward C; Wormhoudt, Joda; Massoli, Paola; Knighton, W Berk; Herndon, Scott C; Kolb, Charles E; Knipping, Eladio; Shaw, Stephanie L; DeCarlo, Peter F

2015-06-02

Limited direct measurements of criteria pollutants emissions and precursors, as well as natural gas constituents, from Marcellus shale gas development activities contribute to uncertainty about their atmospheric impact. Real-time measurements were made with the Aerodyne Research Inc. Mobile Laboratory to characterize emission rates of atmospheric pollutants. Sites investigated include production well pads, a well pad with a drill rig, a well completion, and compressor stations. Tracer release ratio methods were used to estimate emission rates. A first-order correction factor was developed to account for errors introduced by fenceline tracer release. In contrast to observations from other shale plays, elevated volatile organic compounds, other than CH4 and C2H6, were generally not observed at the investigated sites. Elevated submicrometer particle mass concentrations were also generally not observed. Emission rates from compressor stations ranged from 0.006 to 0.162 tons per day (tpd) for NOx, 0.029 to 0.426 tpd for CO, and 67.9 to 371 tpd for CO2. CH4 and C2H6 emission rates from compressor stations ranged from 0.411 to 4.936 tpd and 0.023 to 0.062 tpd, respectively. Although limited in sample size, this study provides emission rate estimates for some processes in a newly developed natural gas resource and contributes valuable comparisons to other shale gas studies.

Surface water geochemical and isotopic variations in an area of accelerating Marcellus Shale gas development.

PubMed

Pelak, Adam J; Sharma, Shikha

2014-12-01

Water samples were collected from 50 streams in an area of accelerating shale gas development in the eastern U.S.A. The geochemical/isotopic characteristics show no correlation with the five categories of Marcellus Shale production. The sub-watersheds with the greatest density of Marcellus Shale development have also undergone extensive coal mining. Hence, geochemical/isotopic compositions were used to understand sources of salinity and effects of coal mining and shale gas development in the area. The data indicates that while some streams appear to be impacted by mine drainage; none appear to have received sustained contribution from deep brines or produced waters associated with shale gas production. However, it is important to note that our interpretations are based on one time synoptic base flow sampling of a few sampling stations and hence do account potential intermittent changes in chemistry that may result from major/minor spills or specific mine discharges on the surface water chemistry. Copyright © 2014 Elsevier Ltd. All rights reserved.

Permitting program with best management practices for shale gas wells to safeguard public health.

PubMed

Centner, Terence J; Petetin, Ludivine

2015-11-01

The development of shale gas resources in the United States has been controversial as governments have been tardy in devising sufficient safeguards to protect both people and the environment. Alleged health and environmental damages suggest that other countries around the world that decide to develop their shale gas resources can learn from these problems and take further actions to prevent situations resulting in the release of harmful pollutants. Looking at U.S. federal regulations governing large animal operations under the permitting provisions of the Clean Water Act, the idea of a permitting program is proposed to respond to the risks of pollution by shale gas development activities. Governments can require permits before allowing the drilling of a new gas well. Each permit would include fluids and air emissions reduction plans containing best management practices to minimize risks and releases of pollutants. The public availability of permits and permit applications, as occurs for water pollution under various U.S. permitting programs, would assist governments in protecting public health. The permitting proposals provide governments a means for providing further assurances that shale gas development projects will not adversely affect people and the environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Increased traffic accident rates associated with shale gas drilling in Pennsylvania.

PubMed

Graham, Jove; Irving, Jennifer; Tang, Xiaoqin; Sellers, Stephen; Crisp, Joshua; Horwitz, Daniel; Muehlenbachs, Lucija; Krupnick, Alan; Carey, David

2015-01-01

We examined the association between shale gas drilling and motor vehicle accident rates in Pennsylvania. Using publicly available data on all reported vehicle crashes in Pennsylvania, we compared accident rates in counties with and without shale gas drilling, in periods with and without intermittent drilling (using data from 2005 to 2012). Counties with drilling were matched to non-drilling counties with similar population and traffic in the pre-drilling period. Heavily drilled counties in the north experienced 15-23% higher vehicle crash rates in 2010-2012 and 61-65% higher heavy truck crash rates in 2011-2012 than control counties. We estimated 5-23% increases in crash rates when comparing months with drilling and months without, but did not find significant effects on fatalities and major injury crashes. Heavily drilled counties in the southwest showed 45-47% higher rates of fatal and major injury crashes in 2012 than control counties, but monthly comparisons of drilling activity showed no significant differences associated with drilling. Vehicle accidents have measurably increased in conjunction with shale gas drilling. Copyright © 2014. Published by Elsevier Ltd.

An assessment of the potential for the development of the shale gas industry in countries outside of North America.

PubMed

Le, Minh-Thong

2018-02-01

The revolution of shale gas in the United States (the US) has become a phenomenon at the beginning of the 21st century. It has been significantly influencing the United States' economy and the global gas market. Like America, other countries have also been searching for shale gas. However, the conditions for developing this resource are very different among regions and nations. On the other hand, there are also many doubts, debates and even strong oppositions to the development of shale gas because of the complicated issues that arise regarding its extraction, and also due to the fact that its impacts are not fully known. Therefore, at present, the development of shale gas is still a big question for regions, countries that have potential and desires to exploit such resources. Although it is difficult to identify all necessary or sufficient conditions to develop shale gas, the experiences of the United States could be instructive for other countries. In this article, the potential development of shale gas in China and Europe is analyzed, which relies on the fundamental conditions considered as important factors for the success of the shale gas industry in the US. Through these analyses and we demonstrate the difficulty of developing this resource outside North America.

Review of the scientific evidence to support environmental risk assessment of shale gas development in the UK.

PubMed

Prpich, George; Coulon, Frédéric; Anthony, Edward J

2016-09-01

Interest in the development of shale gas resources using hydraulic fracturing techniques is increasing worldwide despite concerns about the environmental risks associated with this activity. In the United Kingdom (UK), early attempts to hydraulically fracture a shale gas well resulted in a seismic event that led to the suspension of all hydraulic fracturing operations. In response to this occurrence, UK regulators have requested that future shale gas operations that use hydraulic fracturing should be accompanied by a high-level environmental risk assessment (ERA). Completion of an ERA can demonstrate competency, communicate understanding, and ultimately build trust that environmental risks are being managed properly, however, this assessment requires a scientific evidence base. In this paper we discuss how the ERA became a preferred assessment technique to understand the risks related to shale gas development in the UK, and how it can be used to communicate information between stakeholders. We also provide a review of the evidence base that describes the environmental risks related to shale gas operations, which could be used to support an ERA. Finally, we conclude with an update of the current environmental risks associated with shale gas development in the UK and present recommendations for further research. Copyright © 2015 Elsevier B.V. All rights reserved.

Desalination and reuse of high-salinity shale gas produced water: drivers, technologies, and future directions.

PubMed

Shaffer, Devin L; Arias Chavez, Laura H; Ben-Sasson, Moshe; Romero-Vargas Castrillón, Santiago; Yip, Ngai Yin; Elimelech, Menachem

2013-09-03

In the rapidly developing shale gas industry, managing produced water is a major challenge for maintaining the profitability of shale gas extraction while protecting public health and the environment. We review the current state of practice for produced water management across the United States and discuss the interrelated regulatory, infrastructure, and economic drivers for produced water reuse. Within this framework, we examine the Marcellus shale play, a region in the eastern United States where produced water is currently reused without desalination. In the Marcellus region, and in other shale plays worldwide with similar constraints, contraction of current reuse opportunities within the shale gas industry and growing restrictions on produced water disposal will provide strong incentives for produced water desalination for reuse outside the industry. The most challenging scenarios for the selection of desalination for reuse over other management strategies will be those involving high-salinity produced water, which must be desalinated with thermal separation processes. We explore desalination technologies for treatment of high-salinity shale gas produced water, and we critically review mechanical vapor compression (MVC), membrane distillation (MD), and forward osmosis (FO) as the technologies best suited for desalination of high-salinity produced water for reuse outside the shale gas industry. The advantages and challenges of applying MVC, MD, and FO technologies to produced water desalination are discussed, and directions for future research and development are identified. We find that desalination for reuse of produced water is technically feasible and can be economically relevant. However, because produced water management is primarily an economic decision, expanding desalination for reuse is dependent on process and material improvements to reduce capital and operating costs.

Life Cycle Water Consumption and Wastewater Generation Impacts of a Marcellus Shale Gas Well

PubMed Central

2013-01-01

This study estimates the life cycle water consumption and wastewater generation impacts of a Marcellus shale gas well from its construction to end of life. Direct water consumption at the well site was assessed by analysis of data from approximately 500 individual well completion reports collected in 2010 by the Pennsylvania Department of Conservation and Natural Resources. Indirect water consumption for supply chain production at each life cycle stage of the well was estimated using the economic input–output life cycle assessment (EIO-LCA) method. Life cycle direct and indirect water quality pollution impacts were assessed and compared using the tool for the reduction and assessment of chemical and other environmental impacts (TRACI). Wastewater treatment cost was proposed as an additional indicator for water quality pollution impacts from shale gas well wastewater. Four water management scenarios for Marcellus shale well wastewater were assessed: current conditions in Pennsylvania; complete discharge; direct reuse and desalination; and complete desalination. The results show that under the current conditions, an average Marcellus shale gas well consumes 20 000 m3 (with a range from 6700 to 33 000 m3) of freshwater per well over its life cycle excluding final gas utilization, with 65% direct water consumption at the well site and 35% indirect water consumption across the supply chain production. If all flowback and produced water is released into the environment without treatment, direct wastewater from a Marcellus shale gas well is estimated to have 300–3000 kg N-eq eutrophication potential, 900–23 000 kg 2,4D-eq freshwater ecotoxicity potential, 0–370 kg benzene-eq carcinogenic potential, and 2800–71 000 MT toluene-eq noncarcinogenic potential. The potential toxicity of the chemicals in the wastewater from the well site exceeds those associated with supply chain production, except for carcinogenic effects. If all the Marcellus shale well

Life cycle water consumption and wastewater generation impacts of a Marcellus shale gas well.

PubMed

Jiang, Mohan; Hendrickson, Chris T; VanBriesen, Jeanne M

2014-01-01

This study estimates the life cycle water consumption and wastewater generation impacts of a Marcellus shale gas well from its construction to end of life. Direct water consumption at the well site was assessed by analysis of data from approximately 500 individual well completion reports collected in 2010 by the Pennsylvania Department of Conservation and Natural Resources. Indirect water consumption for supply chain production at each life cycle stage of the well was estimated using the economic input-output life cycle assessment (EIO-LCA) method. Life cycle direct and indirect water quality pollution impacts were assessed and compared using the tool for the reduction and assessment of chemical and other environmental impacts (TRACI). Wastewater treatment cost was proposed as an additional indicator for water quality pollution impacts from shale gas well wastewater. Four water management scenarios for Marcellus shale well wastewater were assessed: current conditions in Pennsylvania; complete discharge; direct reuse and desalination; and complete desalination. The results show that under the current conditions, an average Marcellus shale gas well consumes 20,000 m(3) (with a range from 6700 to 33,000 m(3)) of freshwater per well over its life cycle excluding final gas utilization, with 65% direct water consumption at the well site and 35% indirect water consumption across the supply chain production. If all flowback and produced water is released into the environment without treatment, direct wastewater from a Marcellus shale gas well is estimated to have 300-3000 kg N-eq eutrophication potential, 900-23,000 kg 2,4D-eq freshwater ecotoxicity potential, 0-370 kg benzene-eq carcinogenic potential, and 2800-71,000 MT toluene-eq noncarcinogenic potential. The potential toxicity of the chemicals in the wastewater from the well site exceeds those associated with supply chain production, except for carcinogenic effects. If all the Marcellus shale well wastewater is

Baseline groundwater chemistry characterization in an area of future Marcellus shale gas development

NASA Astrophysics Data System (ADS)

Eisenhauer, P.; Zegre, N.; Edwards, P. J.; Strager, M.

2012-12-01

The recent increase in development of the Marcellus shale formation for natural gas in the mid-Atlantic can be attributed to advances in unconventional extraction methods, namely hydraulic fracturing, a process that uses water to pressurize and fracture relatively impermeable shale layers to release natural gas. In West Virginia, the Department of Energy estimates 95 to 105 trillion cubic feet (TCF) of expected ultimately recovery (EUR) of natural gas for this formation. With increased development of the Marcellus shale formation comes concerns for the potential of contamination to groundwater resources that serve as primary potable water sources for many rural communities. However, the impacts of this practice on water resources are poorly understood because of the lack of controlled pre versus post-drilling experiments attributed to the rapid development of this resource. To address the knowledge gaps of the potential impacts of Marcellus shale development on groundwater resources, a pre versus post-drilling study has been initiated by the USFS Fernow Experimental Forest in the Monongahela National Forest. Drilling is expected to start at three locations within the next year. Pre-drilling water samples were collected and analyzed from two groundwater wells, a shallow spring, a nearby lake, and river to characterize background water chemistry and identify potential end-members. Geochemical analysis includes major ions, methane, δ13C-CH4, δ2H-CH4, 226Radium, and δ13C-DIC. In addition, a GIS-based conceptual ground water flow model was developed to identify possible interactions between shallow groundwater and natural gas wells given gas well construction failure. This model is used to guide management decisions regarding groundwater resources in an area of increasing shale gas development.

Lithofacies classification of the Barnett Shale gas reservoir using neural network

NASA Astrophysics Data System (ADS)

Aliouane, Leila; Ouadfeul, Sid-Ali

2017-04-01

Here, we show the contribution of the artificial intelligence such as neural network to predict the lithofacies in the lower Barnett shale gas reservoir. The Multilayer Perceptron (MLP) neural network with Hidden Weight Optimization Algorithm is used. The input is raw well-logs data recorded in a horizontal well drilled in the Lower Barnett shale formation, however the output is the concentration of the Clay and the Quartz calculated using the ELAN model and confirmed with the core rock measurement. After training of the MLP machine weights of connection are calculated, the raw well-logs data of two other horizontal wells drilled in the same reservoir are propagated though the neural machine and an output is calculated. Comparison between the predicted and measured clay and Quartz concentrations in these two horizontal wells shows the ability of neural network to improve shale gas reservoirs characterization.

The capacity of states to govern shale gas development risks.

PubMed

Wiseman, Hannah J

2014-01-01

The development of natural gas and oil from unconventional formations in the United States has grown substantially in recent years and has created governance challenges. In light of this recent growth, and increasing attention to global shale gas resources, the successes and failures of governance efforts in this country serve as important lessons for other nations that have their own unconventional petroleum resources and are beginning to move forward with development, thus calling for a more in-depth examination of the laws governing shale gas development and their implementation. Governance includes both the substance of laws and the activities of entities that implement and influence laws, and in the case of oil and gas, states are primarily responsible for risk governance. Nongovernmental actors and industry also work with states to shape and implement regulations and standards. This Policy Analysis introduces the role of various actors in U.S. shale gas governance, explaining why the states are primarily responsible for risk governance, and explores the capacity of states to conduct governance, examining the content of their laws and the strength of their regulatory entities. The Analysis concludes that states are, to a degree, addressing the changing risks of development. Gaps remain in the substance of regulations, however, and many states appear to lack adequate support or policies for training industry in compliance matters, monitoring activity at sites, prioritizing certain types of regulatory violations that pose the highest risks, enforcing laws, and ensuring that the public is aware of inspections and enforcement and can therefore monitor state activity.

Maximize Liquid Oil Production from Shale Oil and Gas Condensate Reservoirs by Cyclic Gas Injection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng, James; Li, Lei; Yu, Yang

The current technology to produce shale oil reservoirs is the primary depletion using fractured wells (generally horizontal wells). The oil recovery is less than 10%. The prize to enhance oil recovery (EOR) is big. Based on our earlier simulation study, huff-n-puff gas injection has the highest EOR potential. This project was to explore the potential extensively and from broader aspects. The huff-n-puff gas injection was compared with gas flooding, water huff-n-puff and waterflooding. The potential to mitigate liquid blockage was also studied and the gas huff-n-puff method was compared with other solvent methods. Field pilot tests were initiated but terminatedmore » owing to the low oil price and the operator’s budget cut. To meet the original project objectives, efforts were made to review existing and relevant field projects in shale and tight reservoirs. The fundamental flow in nanopores was also studied.« less

Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development

PubMed Central

Llewellyn, Garth T.; Dorman, Frank; Westland, J. L.; Yoxtheimer, D.; Grieve, Paul; Sowers, Todd; Humston-Fulmer, E.; Brantley, Susan L.

2015-01-01

High-volume hydraulic fracturing (HVHF) has revolutionized the oil and gas industry worldwide but has been accompanied by highly controversial incidents of reported water contamination. For example, groundwater contamination by stray natural gas and spillage of brine and other gas drilling-related fluids is known to occur. However, contamination of shallow potable aquifers by HVHF at depth has never been fully documented. We investigated a case where Marcellus Shale gas wells in Pennsylvania caused inundation of natural gas and foam in initially potable groundwater used by several households. With comprehensive 2D gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS), an unresolved complex mixture of organic compounds was identified in the aquifer. Similar signatures were also observed in flowback from Marcellus Shale gas wells. A compound identified in flowback, 2-n-Butoxyethanol, was also positively identified in one of the foaming drinking water wells at nanogram-per-liter concentrations. The most likely explanation of the incident is that stray natural gas and drilling or HF compounds were driven ∼1–3 km along shallow to intermediate depth fractures to the aquifer used as a potable water source. Part of the problem may have been wastewaters from a pit leak reported at the nearest gas well pad—the only nearby pad where wells were hydraulically fractured before the contamination incident. If samples of drilling, pit, and HVHF fluids had been available, GCxGC-TOFMS might have fingerprinted the contamination source. Such evaluations would contribute significantly to better management practices as the shale gas industry expands worldwide. PMID:25941400

Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development.

PubMed

Llewellyn, Garth T; Dorman, Frank; Westland, J L; Yoxtheimer, D; Grieve, Paul; Sowers, Todd; Humston-Fulmer, E; Brantley, Susan L

2015-05-19

High-volume hydraulic fracturing (HVHF) has revolutionized the oil and gas industry worldwide but has been accompanied by highly controversial incidents of reported water contamination. For example, groundwater contamination by stray natural gas and spillage of brine and other gas drilling-related fluids is known to occur. However, contamination of shallow potable aquifers by HVHF at depth has never been fully documented. We investigated a case where Marcellus Shale gas wells in Pennsylvania caused inundation of natural gas and foam in initially potable groundwater used by several households. With comprehensive 2D gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS), an unresolved complex mixture of organic compounds was identified in the aquifer. Similar signatures were also observed in flowback from Marcellus Shale gas wells. A compound identified in flowback, 2-n-Butoxyethanol, was also positively identified in one of the foaming drinking water wells at nanogram-per-liter concentrations. The most likely explanation of the incident is that stray natural gas and drilling or HF compounds were driven ∼ 1-3 km along shallow to intermediate depth fractures to the aquifer used as a potable water source. Part of the problem may have been wastewaters from a pit leak reported at the nearest gas well pad-the only nearby pad where wells were hydraulically fractured before the contamination incident. If samples of drilling, pit, and HVHF fluids had been available, GCxGC-TOFMS might have fingerprinted the contamination source. Such evaluations would contribute significantly to better management practices as the shale gas industry expands worldwide.

Lung Cancer Risk from Radon in Marcellus Shale Gas in Northeast U.S. Homes.

PubMed

Mitchell, Austin L; Griffin, W Michael; Casman, Elizabeth A

2016-11-01

The amount of radon in natural gas varies with its source. Little has been published about the radon from shale gas to date, making estimates of its impact on radon-induced lung cancer speculative. We measured radon in natural gas pipelines carrying gas from the Marcellus Shale in Pennsylvania and West Virginia. Radon concentrations ranged from 1,520 to 2,750 Bq/m 3 (41-74 pCi/L), and the throughput-weighted average was 1,983 Bq/m 3 (54 pCi/L). Potential radon exposure due to the use of Marcellus Shale gas for cooking and space heating using vent-free heaters or gas ranges in northeastern U.S. homes and apartments was assessed. Though the measured radon concentrations are higher than what has been previously reported, it is unlikely that exposure from natural gas cooking would exceed 1.2 Bq/m 3 (<1% of the U.S. Environmental Protection Agency's action level). Using worst-case assumptions, we estimate the excess lifetime (70 years) lung cancer risk associated with cooking to be 1.8×10 -4 (interval spanning 95% of simulation results: 8.5×10 -5 , 3.4×10 -4 ). The risk profile for supplemental heating with unvented gas appliances is similar. Individuals using unvented gas appliances to provide primary heating may face lifetime risks as high as 3.9×10 -3 . Under current housing stock and gas consumption assumptions, expected levels of residential radon exposure due to unvented combustion of Marcellus Shale natural gas in the Northeast United States do not result in a detectable change in the lung cancer death rates. © 2016 Society for Risk Analysis.

The Impact of a Potential Shale Gas Development in Germany and the United Kingdom on Local and Regional Air Quality

NASA Astrophysics Data System (ADS)

Weger, L.; Lupascu, A.; Cremonese, L.; Butler, T. M.

2017-12-01

Numerous countries in Europe that possess domestic shale gas reserves are considering exploiting this unconventional gas resource as part of their energy transition agenda. While natural gas generates less CO2 emissions upon combustion compared to coal or oil, making it attractive as a bridge in the transition from fossil fuels to renewables, production of shale gas leads to emissions of CH4 and air pollutants such as NOx, VOCs and PM. These gases in turn influence the climate as well as air quality. In this study, we investigate the impact of a potential shale gas development in Germany and the United Kingdom on local and regional air quality. This work builds on our previous study in which we constructed emissions scenarios based on shale gas utilization in these counties. In order to explore the influence of shale gas production on air quality, we investigate emissions predicted from our shale gas scenarios with the Weather Research and Forecasting model with chemistry (WRF-Chem) model. In order to do this, we first design a model set-up over Europe and evaluate its performance for the meteorological and chemical parameters. Subsequently we add shale gas emissions fluxes based on the scenarios over the area of the grid in which the shale gas activities are predicted to occur. Finally, we model these emissions and analyze the impact on air quality on both a local and regional scale. The aims of this work are to predict the range of adverse effects on air quality, highlight the importance of emissions control strategies in reducing air pollution, to promote further discussion, and to provide policy makers with information for decision making on a potential shale gas development in the two study countries.

Assessment of Appalachian basin oil and gas resources: Devonian gas shales of the Devonian Shale-Middle and Upper Paleozoic Total Petroleum System: Chapter G.9 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

USGS Publications Warehouse

Milici, Robert C.; Swezey, Christopher S.; Ruppert, Leslie F.; Ryder, Robert T.

2014-01-01

This report presents the results of a U.S. Geological Survey (USGS) assessment of the technically recoverable undiscovered natural gas resources in Devonian shale in the Appalachian Basin Petroleum Province of the eastern United States. These results are part of the USGS assessment in 2002 of the technically recoverable undiscovered oil and gas resources of the province. This report does not use the results of a 2011 USGS assessment of the Devonian Marcellus Shale because the area considered in the 2011 assessment is much greater than the area of the Marcellus Shale described in this report. The USGS assessment in 2002 was based on the identification of six total petroleum systems, which include strata that range in age from Cambrian to Pennsylvanian. The Devonian gas shales described in this report are within the Devonian Shale-Middle and Upper Paleozoic Total Petroleum System, which extends generally from New York to Tennessee. This total petroleum system is divided into ten assessment units (plays), four of which are classified as conventional and six as continuous. The Devonian shales described in this report make up four of these continuous assessment units. The assessment results are reported as fully risked fractiles (F95, F50, F5, and the mean); the fractiles indicate the probability of recovery of the assessment amount. The products reported are oil, gas, and natural gas liquids. The mean estimates for technically recoverable undiscovered hydrocarbons in the four gas shale assessment units are 12,195.53 billion cubic feet (12.20 trillion cubic feet) of gas and 158.91 million barrels of natural gas liquids

The importance of public health agency independence: Marcellus shale gas drilling in Pennsylvania.

PubMed

Goldstein, Bernard D

2014-02-01

Public health often deals with inconvenient truths. These are best communicated and acted on when public health agencies are independent of the organizations or individuals for whom the truths are inconvenient. The importance of public health independence is exemplified by the lack of involvement of the Pennsylvania Department of Health in responding to health concerns about shale gas drilling. Pennsylvania Department of Health involvement has been forestalled by the state governor, who has intensely supported shale gas development.

Gas production in the Barnett Shale obeys a simple scaling theory

PubMed Central

Patzek, Tad W.; Male, Frank; Marder, Michael

2013-01-01

Natural gas from tight shale formations will provide the United States with a major source of energy over the next several decades. Estimates of gas production from these formations have mainly relied on formulas designed for wells with a different geometry. We consider the simplest model of gas production consistent with the basic physics and geometry of the extraction process. In principle, solutions of the model depend upon many parameters, but in practice and within a given gas field, all but two can be fixed at typical values, leading to a nonlinear diffusion problem we solve exactly with a scaling curve. The scaling curve production rate declines as 1 over the square root of time early on, and it later declines exponentially. This simple model provides a surprisingly accurate description of gas extraction from 8,294 wells in the United States’ oldest shale play, the Barnett Shale. There is good agreement with the scaling theory for 2,057 horizontal wells in which production started to decline exponentially in less than 10 y. The remaining 6,237 horizontal wells in our analysis are too young for us to predict when exponential decline will set in, but the model can nevertheless be used to establish lower and upper bounds on well lifetime. Finally, we obtain upper and lower bounds on the gas that will be produced by the wells in our sample, individually and in total. The estimated ultimate recovery from our sample of 8,294 wells is between 10 and 20 trillion standard cubic feet. PMID:24248376

Gas production in the Barnett Shale obeys a simple scaling theory.

PubMed

Patzek, Tad W; Male, Frank; Marder, Michael

2013-12-03

Natural gas from tight shale formations will provide the United States with a major source of energy over the next several decades. Estimates of gas production from these formations have mainly relied on formulas designed for wells with a different geometry. We consider the simplest model of gas production consistent with the basic physics and geometry of the extraction process. In principle, solutions of the model depend upon many parameters, but in practice and within a given gas field, all but two can be fixed at typical values, leading to a nonlinear diffusion problem we solve exactly with a scaling curve. The scaling curve production rate declines as 1 over the square root of time early on, and it later declines exponentially. This simple model provides a surprisingly accurate description of gas extraction from 8,294 wells in the United States' oldest shale play, the Barnett Shale. There is good agreement with the scaling theory for 2,057 horizontal wells in which production started to decline exponentially in less than 10 y. The remaining 6,237 horizontal wells in our analysis are too young for us to predict when exponential decline will set in, but the model can nevertheless be used to establish lower and upper bounds on well lifetime. Finally, we obtain upper and lower bounds on the gas that will be produced by the wells in our sample, individually and in total. The estimated ultimate recovery from our sample of 8,294 wells is between 10 and 20 trillion standard cubic feet.

Reservoir characteristics of coal-shale sedimentary sequence in coal-bearing strata and their implications for the accumulation of unconventional gas

NASA Astrophysics Data System (ADS)

Wang, Yang; Zhu, Yanming; Liu, Yu; Chen, Shangbin

2018-04-01

Shale gas and coalbed methane (CBM) are both considered unconventional natural gas and are becoming increasingly important energy resources. In coal-bearing strata, coal and shale are vertically adjacent as coal and shale are continuously deposited. Research on the reservoir characteristics of coal-shale sedimentary sequences is important for CBM and coal-bearing shale gas exploration. In this study, a total of 71 samples were collected, including coal samples (total organic carbon (TOC) content >40%), carbonaceous shale samples (TOC content: 6%-10%), and shale samples (TOC content <6%). Combining techniques of field emission scanning electron microscopy (FE-SEM), x-ray diffraction, high-pressure mercury intrusion porosimetry, and methane adsorption, experiments were employed to characterize unconventional gas reservoirs in coal-bearing strata. The results indicate that in the coal-shale sedimentary sequence, the proportion of shale is the highest at 74% and that of carbonaceous shale and coal are 14% and 12%, respectively. The porosity of all measured samples demonstrates a good positive relationship with TOC content. Clay and quartz also have a great effect on the porosity of shale samples. According to the FE-SEM image technique, nanoscale pores in the organic matter of coal samples are much more developed compared with shale samples. For shales with low TOC, inorganic minerals provide more pores than organic matter. In addition, TOC content has a positive relationship with methane adsorption capacity, and the adsorption capacity of coal samples is more sensitive than the shale samples to temperature.

Drought Resilience of Water Supplies for Shale Gas Extraction and Related Power Generation in Texas

NASA Astrophysics Data System (ADS)

Reedy, R. C.; Scanlon, B. R.; Nicot, J. P.; Uhlman, K.

2014-12-01

There is considerable concern about water availability to support energy production in Texas, particularly considering that many of the shale plays are in semiarid areas of Texas and the state experienced the most extreme drought on record in 2011. The Eagle Ford shale play provides an excellent case study. Hydraulic fracturing water use for shale gas extraction in the play totaled ~ 12 billion gallons (bgal) in 2012, representing ~7 - 10% of total water use in the 16 county play area. The dominant source of water is groundwater which is not highly vulnerable to drought from a recharge perspective because water is primarily stored in the confined portion of aquifers that were recharged thousands of years ago. Water supply drought vulnerability results primarily from increased water use for irrigation. Irrigation water use in the Eagle Ford play was 30 billion gallons higher in the 2011 drought year relative to 2010. Recent trends toward increased use of brackish groundwater for shale gas extraction in the Eagle Ford also reduce pressure on fresh water resources. Evaluating the impacts of natural gas development on water resources should consider the use of natural gas in power generation, which now represents 50% of power generation in Texas. Water consumed in extracting the natural gas required for power generation is equivalent to ~7% of the water consumed in cooling these power plants in the state. However, natural gas production from shale plays can be overall beneficial in terms of water resources in the state because natural gas combined cycle power generation decreases water consumption by ~60% relative to traditional coal, nuclear, and natural gas plants that use steam turbine generation. This reduced water consumption enhances drought resilience of power generation in the state. In addition, natural gas combined cycle plants provide peaking capacity that complements increasing renewable wind generation which has no cooling water requirement. However, water

Study on fracturing flowback fluid treatment technology for shale gas in Yangzhou

NASA Astrophysics Data System (ADS)

Shi, Shengwei; Du, Jiajia; Kang, Dingyu; Chen, Xinjian; Qu, Chengtun; Yu, Tao

2018-02-01

Shale gas fracturing flowback fluid has the characteristics of high viscosity, large displacement, complex components and difficult to deal with. Therefore, it is of great significance for environmental protection to treat and reuse it. In this paper, Yangzhou shale gas is taken as an object to study the treatment of shale gas fracturing flowback fluid. The results shown that the viscosity of the fracturing flowback fluid before treatment was 16.75mPa·s, and when the pH was adjusted to 3.5, with Cerium(III) sulfate and ferrous sulfate as catalyst and the dosage were 60mg/L and 120 mg/L respectively, and hydrogen peroxide dosage was 0.5%, the viscosity of fracturing folwback fluid was reduced from 16.75mPa·s to 1.97mPa·s After the oxidation treatment, adjusting pH to 7.5, and treating it with inorganic flocculant and organic flocculant, the water quality met the reinjection requirement of the average air permeability of less than or equal to 0.01 μm2.

Upscaling pore pressure-dependent gas permeability in shales

NASA Astrophysics Data System (ADS)

Ghanbarian, Behzad; Javadpour, Farzam

2017-04-01

Upscaling pore pressure dependence of shale gas permeability is of great importance and interest in the investigation of gas production in unconventional reservoirs. In this study, we apply the Effective Medium Approximation, an upscaling technique from statistical physics, and modify the Doyen model for unconventional rocks. We develop an upscaling model to estimate the pore pressure-dependent gas permeability from pore throat size distribution, pore connectivity, tortuosity, porosity, and gas characteristics. We compare our adapted model with six data sets: three experiments, one pore-network model, and two lattice-Boltzmann simulations. Results showed that the proposed model estimated the gas permeability within a factor of 3 of the measurements/simulations in all data sets except the Eagle Ford experiment for which we discuss plausible sources of discrepancies.

Shale Gas Implications for C2-C3 Olefin Production: Incumbent and Future Technology.

PubMed

Stangland, Eric E

2018-06-07

Substantial natural gas liquids recovery from tight shale formations has produced a significant boon for the US chemical industry. As fracking technology improves, shale liquids may represent the same for other geographies. As with any major industry disruption, the advent of shale resources permits both the chemical industry and the community an excellent opportunity to have open, foundational discussions on how both public and private institutions should research, develop, and utilize these resources most sustainably. This review summarizes current chemical industry processes that use ethane and propane from shale gas liquids to produce the two primary chemical olefins of the industry: ethylene and propylene. It also discusses simplified techno-economics related to olefins production from an industry perspective, attempting to provide a mutually beneficial context in which to discuss the next generation of sustainable olefin process development.

An Image-based Micro-continuum Pore-scale Model for Gas Transport in Organic-rich Shale

NASA Astrophysics Data System (ADS)

Guo, B.; Tchelepi, H.

2017-12-01

Gas production from unconventional source rocks, such as ultra-tight shales, has increased significantly over the past decade. However, due to the extremely small pores ( 1-100 nm) and the strong material heterogeneity, gas flow in shale is still not well understood and poses challenges for predictive field-scale simulations. In recent years, digital rock analysis has been applied to understand shale gas transport at the pore-scale. An issue with rock images (e.g. FIB-SEM, nano-/micro-CT images) is the so-called "cutoff length", i.e., pores and heterogeneities below the resolution cannot be resolved, which leads to two length scales (resolved features and unresolved sub-resolution features) that are challenging for flow simulations. Here we develop a micro-continuum model, modified from the classic Darcy-Brinkman-Stokes framework, that can naturally couple the resolved pores and the unresolved nano-porous regions. In the resolved pores, gas flow is modeled with Stokes equation. In the unresolved regions where the pore sizes are below the image resolution, we develop an apparent permeability model considering non-Darcy flow at the nanoscale including slip flow, Knudsen diffusion, adsorption/desorption, surface diffusion, and real gas effect. The end result is a micro-continuum pore-scale model that can simulate gas transport in 3D reconstructed shale images. The model has been implemented in the open-source simulation platform OpenFOAM. In this paper, we present case studies to demonstrate the applicability of the model, where we use 3D segmented FIB-SEM and nano-CT shale images that include four material constituents: organic matter, clay, granular mineral, and pore. In addition to the pore structure and the distribution of the material constituents, we populate the model with experimental measurements (e.g. size distribution of the sub-resolution pores from nitrogen adsorption) and parameters from the literature and identify the relative importance of different

Shale Gas Geomechanics for Development and Performance of Unconventional Reservoirs

NASA Astrophysics Data System (ADS)

Domonik, Andrzej; Łukaszewski, Paweł; Wilczyński, Przemysław; Dziedzic, Artur; Łukasiak, Dominik; Bobrowska, Alicja

2017-04-01

Mechanical properties of individual shale formations are predominantly determined by their lithology, which reflects sedimentary facies distribution, and subsequent diagenetic and tectonic alterations. Shale rocks may exhibit complex elasto-viscoplastic deformation mechanisms depending on the rate of deformation and the amount of clay minerals, also bearing implications for subcritical crack growth and heterogeneous fracture network development. Thus, geomechanics for unconventional resources differs from conventional reservoirs due to inelastic matrix behavior, stress sensitivity, rock anisotropy and low matrix permeability. Effective horizontal drilling and hydraulic fracturing technologies are required to obtain and maintain high performance. Success of these techniques strongly depends on the geomechanical investigations of shales. An inelastic behavior of shales draws increasing attention of investigators [1], due to its role in stress relaxation between fracturing phases. A strong mechanical anisotropy in the vertical plane and a lower and more variable one in the horizontal plane are characteristic for shale rocks. The horizontal anisotropy plays an important role in determining the direction and effectiveness of propagation of technological hydraulic fractures. Non-standard rock mechanics laboratory experiments are being applied in order to obtain the mechanical properties of shales that have not been previously studied in Poland. Novel laboratory investigations were carried out to assess the creep parameters and to determine time-dependent viscoplastic deformation of shale samples, which can provide a limiting factor to tectonic stresses and control stress change caused by hydraulic fracturing. The study was supported by grant no.: 13-03-00-501-90-472946 "An integrated geomechanical investigation to enhance gas extraction from the Pomeranian shale formations", funded by the National Centre for Research and Development (NCBiR). References: Ch. Chang M. D

Unfinished business in the regulation of shale gas production in the United States.

PubMed

Centner, Terence J; O'Connell, Laura Kathryn

2014-04-01

With increased drilling for natural gas, toxic chemicals used to fracture wells have been introduced into the environment accompanied by allegations of injuries. This article evaluates laws and regulations governing shale gas production to disclose ideas for offering further protection to people and the environment. The aim of the study is to offer state governments ideas for addressing contractual obligations of drilling operators, discerning health risks, disclosing toxic chemicals, and reporting sufficient information to detect problems and enforce regulations. The discussion suggests opportunities for state regulators to become more supportive of public health through greater oversight of shale gas extraction. Copyright © 2014 Elsevier B.V. All rights reserved.

Applying probabilistic well-performance parameters to assessments of shale-gas resources

USGS Publications Warehouse

Charpentier, Ronald R.; Cook, Troy

2010-01-01

In assessing continuous oil and gas resources, such as shale gas, it is important to describe not only the ultimately producible volumes, but also the expected well performance. This description is critical to any cost analysis or production scheduling. A probabilistic approach facilitates (1) the inclusion of variability in well performance within a continuous accumulation, and (2) the use of data from developed accumulations as analogs for the assessment of undeveloped accumulations. In assessing continuous oil and gas resources of the United States, the U.S. Geological Survey analyzed production data from many shale-gas accumulations. Analyses of four of these accumulations (the Barnett, Woodford, Fayetteville, and Haynesville shales) are presented here as examples of the variability of well performance. For example, the distribution of initial monthly production rates for Barnett vertical wells shows a noticeable change with time, first increasing because of improved completion practices, then decreasing from a combination of decreased reservoir pressure (in infill wells) and drilling in less productive areas. Within a partially developed accumulation, historical production data from that accumulation can be used to estimate production characteristics of undrilled areas. An understanding of the probabilistic relations between variables, such as between initial production and decline rates, can improve estimates of ultimate production. Time trends or spatial trends in production data can be clarified by plots and maps. The data can also be divided into subsets depending on well-drilling or well-completion techniques, such as vertical in relation to horizontal wells. For hypothetical or lightly developed accumulations, one can either make comparisons to a specific well-developed accumulation or to the entire range of available developed accumulations. Comparison of the distributions of initial monthly production rates of the four shale-gas accumulations that were

Assessment and longitudinal analysis of health impacts and stressors perceived to result from unconventional shale gas development in the Marcellus Shale region.

PubMed

Ferrar, Kyle J; Kriesky, Jill; Christen, Charles L; Marshall, Lynne P; Malone, Samantha L; Sharma, Ravi K; Michanowicz, Drew R; Goldstein, Bernard D

2013-01-01

Concerns for health and social impacts have arisen as a result of Marcellus Shale unconventional natural gas development. Our goal was to document the self-reported health impacts and mental and physical health stressors perceived to result from Marcellus Shale development. Two sets of interviews were conducted with a convenience sample of community members living proximal to Marcellus Shale development, session 1 March-September 2010 (n = 33) and session 2 January-April 2012 (n = 20). Symptoms of health impacts and sources of psychological stress were coded. Symptom and stressor counts were quantified for each interview. The counts for each participant were compared longitudinally. Participants attributed 59 unique health impacts and 13 stressors to Marcellus Shale development. Stress was the most frequently-reported symptom. Over time, perceived health impacts increased (P = 0·042), while stressors remained constant (P = 0·855). Exposure-based epidemiological studies are needed to address identified health impacts and those that may develop as unconventional natural gas extraction continues. Many of the stressors can be addressed immediately.

Assessment of undiscovered oil and gas resources of the Mississippian Sunbury shale and Devonian–Mississippian Chattanooga shale in the Appalachian Basin Province, 2016

USGS Publications Warehouse

Higley, Debra K.; Rouse, William A.; Enomoto, Catherine B.; Trippi, Michael H.; Klett, Timothy R.; Mercier, Tracey J.; Brownfield, Michael E.; Tennyson, Marilyn E.; Drake, Ronald M.; Finn, Thomas M.; Gianoutsos, Nicholas J.; Pearson, Ofori N.; Doolan, Colin A.; Le, Phuong A.; Schenk, Christopher J.

2016-11-08

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered, technically recoverable continuous resources that total 464 million barrels of oil and 4.08 trillion cubic feet of gas in the Lower Mississippian Sunbury Shale and Middle Devonian–Lower Mississippian Chattanooga Shale of the Appalachian Basin Province.

Direct Imaging of Shale Gas Leaks Using Passive Thermal Infrared Hyperspectral Imaging

NASA Astrophysics Data System (ADS)

Marcotte, F.; Chamberland, M.; Morton, V.; Gagnon, M. A.

2017-12-01

Natural gas is an energy resource in great demand worldwide. There are many types of gas fields including shale formations which are common especially in the St-Lawrence Valley (Qc). Regardless of its origin, methane (CH4) is the major component of natural gas. Methane gas is odorless, colorless and highly flammable. It is also an important greenhouse gas. Therefore, dealing efficiently with methane emanations and/or leaks is an important and challenging issue for both safety and environmental considerations. In this regard, passive remote sensing represents an interesting approach since it allows characterization of large areas from a safe location. The high propensity of methane contributing to global warming is mainly because it is a highly infrared-active molecule. For this reason, thermal infrared remote sensing represents one of the best approaches for methane investigations. In order to illustrate the potential of passive thermal infrared hyperspectral imaging for research on natural gas, imaging was carried out on a shale gas leak that unexpectedly happen during a geological survey near Hospital Enfant-Jésus (Québec City) in December 2014. Methane was selectively identified in the scene by its unique infrared signature. The estimated gas column density near the leak source was on the order of 65 000 ppm×m. It was estimated that the methane content in the shale gas is on the order of 6-7 %, which is in good agreement with previous geological surveys carried out in this area. Such leaks represent a very serious situation because such a methane concentration lies within the methane lower/upper explosion limits (LEL-UEL, 5-15 %). The results show how this novel technique could be used for research work dealing with methane gas.

The potential for spills and leaks of contaminated liquids from shale gas developments.

PubMed

Clancy, S A; Worrall, F; Davies, R J; Gluyas, J G

2018-06-01

Rapid growth of hydraulic fracturing for shale gas within the USA and the possibility of shale developments within Europe has created public concern about the risks of spills and leaks associated with the industry. Reports from the Texas Railroad Commission (1999 to 2015) and the Colorado Oil and Gas Commission (2009 to 2015) were used to examine spill rates from oil and gas well pads. Pollution incident records for England and road transport incident data for the UK were examined as an analogue for potential offsite spills associated with transport for a developing shale industry. The Texas and Colorado spill data shows that the spill rate on the well pads has increased over the recorded time period. The most common spill cause was equipment failure. Within Colorado 33% of the spills recorded were found during well pad remediation and random site inspections. Based on data from the Texas Railroad Commission, a UK shale industry developing well pads with 10 lateral wells would likely experience a spill for every 16 well pads developed. The same well pad development scenario is estimated to require at least 2856 tanker movements over two years per well pad. Considering this tanker movement estimate with incident and spill frequency data from UK milk tankers, a UK shale industry would likely experience an incident on the road for every 12 well pads developed and a road spill for every 19 well pads developed. Consequently, should a UK shale industry be developed it is important that appropriate mitigation strategies are in place to minimise the risk of spills associated with well pad activities and fluid transportation movements. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Comparative Human Toxicity Impact of Electricity Produced from Shale Gas and Coal.

PubMed

Chen, Lu; Miller, Shelie A; Ellis, Brian R

2017-11-07

The human toxicity impact (HTI) of electricity produced from shale gas is lower than the HTI of electricity produced from coal, with 90% confidence using a Monte Carlo Analysis. Two different impact assessment methods estimate the HTI of shale gas electricity to be 1-2 orders of magnitude less than the HTI of coal electricity (0.016-0.024 DALY/GWh versus 0.69-1.7 DALY/GWh). Further, an implausible shale gas scenario where all fracturing fluid and untreated produced water is discharged directly to surface water throughout the lifetime of a well also has a lower HTI than coal electricity. Particulate matter dominates the HTI for both systems, representing a much larger contribution to the overall toxicity burden than VOCs or any aquatic emission. Aquatic emissions can become larger contributors to the HTI when waste products are inadequately disposed or there are significant infrastructure or equipment failures. Large uncertainty and lack of exposure data prevent a full risk assessment; however, the results of this analysis provide a comparison of relative toxicity, which can be used to identify target areas for improvement and assess potential trade-offs with other environmental impacts.

Assessment of undiscovered oil and gas resources of the Devonian Marcellus Shale of the Appalachian Basin Province

USGS Publications Warehouse

Coleman, James L.; Milici, Robert C.; Cook, Troy A.; Charpentier, Ronald R.; Kirshbaum, Mark; Klett, Timothy R.; Pollastro, Richard M.; Schenk, Christopher J.

2011-01-01

Using a geology-based assessment methodology, the U.S. Geological Survey (USGS) estimated a mean undiscovered natural gas resource of 84,198 billion cubic feet and a mean undiscovered natural gas liquids resource of 3,379 million barrels in the Devonian Marcellus Shale within the Appalachian Basin Province. All this resource occurs in continuous accumulations. In 2011, the USGS completed an assessment of the undiscovered oil and gas potential of the Devonian Marcellus Shale within the Appalachian Basin Province of the eastern United States. The Appalachian Basin Province includes parts of Alabama, Georgia, Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. The assessment of the Marcellus Shale is based on the geologic elements of this formation's total petroleum system (TPS) as recognized in the characteristics of the TPS as a petroleum source rock (source rock richness, thermal maturation, petroleum generation, and migration) as well as a reservoir rock (stratigraphic position and content and petrophysical properties). Together, these components confirm the Marcellus Shale as a continuous petroleum accumulation. Using the geologic framework, the USGS defined one TPS and three assessment units (AUs) within this TPS and quantitatively estimated the undiscovered oil and gas resources within the three AUs. For the purposes of this assessment, the Marcellus Shale is considered to be that Middle Devonian interval that consists primarily of shale and lesser amounts of bentonite, limestone, and siltstone occurring between the underlying Middle Devonian Onondaga Limestone (or its stratigraphic equivalents, the Needmore Shale and Huntersville Chert) and the overlying Middle Devonian Mahantango Formation (or its stratigraphic equivalents, the upper Millboro Shale and middle Hamilton Group).

The costs of avoiding environmental impacts from shale-gas surface infrastructure.

PubMed

Milt, Austin W; Gagnolet, Tamara D; Armsworth, Paul R

2016-12-01

Growing energy demand has increased the need to manage conflicts between energy production and the environment. As an example, shale-gas extraction requires substantial surface infrastructure, which fragments habitats, erodes soils, degrades freshwater systems, and displaces rare species. Strategic planning of shale-gas infrastructure can reduce trade-offs between economic and environmental objectives, but the specific nature of these trade-offs is not known. We estimated the cost of avoiding impacts from land-use change on forests, wetlands, rare species, and streams from shale-energy development within leaseholds. We created software for optimally siting shale-gas surface infrastructure to minimize its environmental impacts at reasonable construction cost. We visually assessed sites before infrastructure optimization to test whether such inspection could be used to predict whether impacts could be avoided at the site. On average, up to 38% of aggregate environmental impacts of infrastructure could be avoided for 20% greater development costs by spatially optimizing infrastructure. However, we found trade-offs between environmental impacts and costs among sites. In visual inspections, we often distinguished between sites that could be developed to avoid impacts at relatively low cost (29%) and those that could not (20%). Reductions in a metric of aggregate environmental impact could be largely attributed to potential displacement of rare species, sedimentation, and forest fragmentation. Planners and regulators can estimate and use heterogeneous trade-offs among development sites to create industry-wide improvements in environmental performance and do so at reasonable costs by, for example, leveraging low-cost avoidance of impacts at some sites to offset others. This could require substantial effort, but the results and software we provide can facilitate the process. © 2016 Society for Conservation Biology.

Modeling of Gas Production from Shale Reservoirs Considering Multiple Transport Mechanisms.

PubMed

Guo, Chaohua; Wei, Mingzhen; Liu, Hong

2015-01-01

Gas transport in unconventional shale strata is a multi-mechanism-coupling process that is different from the process observed in conventional reservoirs. In micro fractures which are inborn or induced by hydraulic stimulation, viscous flow dominates. And gas surface diffusion and gas desorption should be further considered in organic nano pores. Also, the Klinkenberg effect should be considered when dealing with the gas transport problem. In addition, following two factors can play significant roles under certain circumstances but have not received enough attention in previous models. During pressure depletion, gas viscosity will change with Knudsen number; and pore radius will increase when the adsorption gas desorbs from the pore wall. In this paper, a comprehensive mathematical model that incorporates all known mechanisms for simulating gas flow in shale strata is presented. The objective of this study was to provide a more accurate reservoir model for simulation based on the flow mechanisms in the pore scale and formation geometry. Complex mechanisms, including viscous flow, Knudsen diffusion, slip flow, and desorption, are optionally integrated into different continua in the model. Sensitivity analysis was conducted to evaluate the effect of different mechanisms on the gas production. The results showed that adsorption and gas viscosity change will have a great impact on gas production. Ignoring one of following scenarios, such as adsorption, gas permeability change, gas viscosity change, or pore radius change, will underestimate gas production.

Modeling of Gas Production from Shale Reservoirs Considering Multiple Transport Mechanisms

PubMed Central

Guo, Chaohua; Wei, Mingzhen; Liu, Hong

2015-01-01

Gas transport in unconventional shale strata is a multi-mechanism-coupling process that is different from the process observed in conventional reservoirs. In micro fractures which are inborn or induced by hydraulic stimulation, viscous flow dominates. And gas surface diffusion and gas desorption should be further considered in organic nano pores. Also, the Klinkenberg effect should be considered when dealing with the gas transport problem. In addition, following two factors can play significant roles under certain circumstances but have not received enough attention in previous models. During pressure depletion, gas viscosity will change with Knudsen number; and pore radius will increase when the adsorption gas desorbs from the pore wall. In this paper, a comprehensive mathematical model that incorporates all known mechanisms for simulating gas flow in shale strata is presented. The objective of this study was to provide a more accurate reservoir model for simulation based on the flow mechanisms in the pore scale and formation geometry. Complex mechanisms, including viscous flow, Knudsen diffusion, slip flow, and desorption, are optionally integrated into different continua in the model. Sensitivity analysis was conducted to evaluate the effect of different mechanisms on the gas production. The results showed that adsorption and gas viscosity change will have a great impact on gas production. Ignoring one of following scenarios, such as adsorption, gas permeability change, gas viscosity change, or pore radius change, will underestimate gas production. PMID:26657698

Effect of depletion rate on solution gas drive in shale

NASA Astrophysics Data System (ADS)

Zhang, Mingshan; Sang, Qian; Gong, Houjian; Li, Yajun; Dong, Mingzhe

2018-01-01

Solution gas drive process has been studied extensively in sand rocks and heavy oil reservoirs for a long time. Oil recovery is affected by several factors, such as depletion rate, initial GOR (gas oil ratio), oil viscosity, and temperature and so on. Before the solution gas drive tests, elastic drive without dissolved gas was carried out as a reference, which shows a limited oil recovery. Solution gas drive experiments were conducted in shale to study oil recovery with various depletion rates. Results show that oil recovery increases with the decrease of depletion rates because of the low permeability and desorption of methane.

USA-France: Confronting two perspectives on shale gas

NASA Astrophysics Data System (ADS)

Gautier, C.; Fellous, J.

2013-12-01

Exploiting shale gas and oil can be seen from very different perspectives, whether you live in the US where it is a decade long reality shaping the country's energy landscape or in France, where it is banned by law since 2011. Beyond this situation, the overall legal framework that regulates (or not) environmental and water protection, the use of chemicals, land ownership and the exploitation of underground mineral resources, the attribution of licenses for exploration and exploitation, etc. in Europe (and particularly in France, the only European country with Bulgaria where hydraulic fracturation is strictly forbidden) and in the US is at complete variance. This presentation will discuss subsequent attitudes vis-à-vis exploration, exploitation, scientific research on shale gas and fracking, and public activism that has arisen as a result of environmental, socioeconomic and human concerns. It will compare and contrast the different views and look at lessons that can be learned from those differences. This work is building upon the experience of the authors who have studied the issues relating to energy, water, population and climate and their connections, as seen from both sides of the Atlantic.

Impacts of Marcellus Shale Natural Gas Production on Regional Air Quality

NASA Astrophysics Data System (ADS)

Swarthout, R.; Russo, R. S.; Zhou, Y.; Mitchell, B.; Miller, B.; Lipsky, E. M.; Sive, B. C.

2012-12-01

Natural gas is a clean burning alternative to other fossil fuels, producing lower carbon dioxide (CO2) emissions during combustion. Gas deposits located within shale rock or tight sand formations are difficult to access using conventional drilling techniques. However, horizontal drilling coupled with hydraulic fracturing is now widely used to enhance natural gas extraction. Potential environmental impacts of these practices are currently being assessed because of the rapid expansion of natural gas production in the U.S. Natural gas production has contributed to the deterioration of air quality in several regions, such as in Wyoming and Utah, that were near or downwind of natural gas basins. We conducted a field campaign in southwestern Pennsylvania on 16-18 June 2012 to investigate the impact of gas production operations in the Marcellus Shale on regional air quality. A total of 235 whole air samples were collected in 2-liter electropolished stainless- steel canisters throughout southwestern Pennsylvania in a regular grid pattern that covered an area of approximately 8500 square km. Day and night samples were collected at each grid point and additional samples were collected near active wells, flaring wells, fluid retention reservoirs, transmission pipelines, and a processing plant to assess the influence of different stages of the gas production operation on emissions. The samples were analyzed at Appalachian State University for methane (CH4), CO2, C2-C10 nonmethane hydrocarbons (NMHCs), C1-C2 halocarbons, C1-C5 alkyl nitrates and selected reduced sulfur compounds. In-situ measurements of ozone (O3), CH4, CO2, nitric oxide (NO), total reactive nitrogen (NOy), formaldehyde (HCHO), and a range of volatile organic compounds (VOCs) were carried out at an upwind site and a site near active gas wells using a mobile lab. Emissions associated with gas production were observed throughout the study region. Elevated mixing ratios of CH4 and CO2 were observed in the

First-principles calculation of adsorption of shale gas on CaCO3 (100) surfaces.

PubMed

Luo, Qiang; Pan, Yikun; Guo, Ping; Wang, Zhouhua; Wei, Na; Sun, Pengfei; Liu, Yuxiao

2017-06-16

To demonstrate the adsorption strength of shale gas to calcium carbonate in shale matrix, the adsorption of shale gas on CaCO3 (100) surfaces was studied using the first-principles method, which is based on the density functional theory (DFT). The structures and electronic properties of CH4, C2H6, CO2 and N2 molecules were calculated by the generalized gradient approximation (GGA), for a coverage of 1 monolayer (ML). Under the same conditions, the density of states (DOS) of CaCO3 (100) surfaces before and after the adsorption of shale gas molecules at high-symmetry adsorption sites were compared. The results showed that the adsorption energies of CH4, C2H6, CO2 and N2 on CaCO3 (100) surfaces were between 0.2683 eV and -0.7388 eV. When a CH4 molecule was adsorbed at a hollow site and its 2 hydrogen atoms were parallel to the long diagonal (H3) on the CaCO3 (100) surface, it had the most stable adsorption, and the adsorption energy was only -0.4160 eV. The change of adsorption energy of CH4 was no more than 0.0535 eV. Compared with the DOS distribution of CH4 before adsorption, it shifted to the left overall after adsorption. At the same time, the partial density of states (PDOS) curves of CaCO3 (100) surfaces before and after adsorption basically overlapped. This work showed that the adsorption effect of shale gas on calcium carbonate is very weak, and the adsorption is physisorption at the molecular level.

Atmospheric hydrocarbon emissions and concentrations in the barnett shale natural gas production region.

PubMed

Zavala-Araiza, Daniel; Sullivan, David W; Allen, David T

2014-05-06

Hourly ambient hydrocarbon concentration data were collected, in the Barnett Shale Natural Gas Production Region, using automated gas chromatography (auto-GC), for the period from April 2010 to December 2011. Data for three sites were compared: a site in the geographical center of the natural gas production region (Eagle Mountain Lake (EML)); a rural/suburban site at the periphery of the production region (Flower Mound Shiloh), and an urban site (Hinton). The dominant hydrocarbon species observed in the Barnett Shale region were light alkanes. Analyses of daily, monthly, and hourly patterns showed little variation in relative composition. Observed concentrations were compared to concentrations predicted using a dispersion model (AERMOD) and a spatially resolved inventory of volatile organic compounds (VOC) emissions from natural gas production (Barnett Shale Special Emissions Inventory) prepared by the Texas Commission on Environmental Quality (TCEQ), and other emissions information. The predicted concentrations of VOC due to natural gas production were 0-40% lower than background corrected measurements, after accounting for potential under-estimation of certain emission categories. Hourly and daily variations in observed, background corrected concentrations were primarily explained by variability in meteorology, suggesting that episodic emission events had little impact on hourly averaged concentrations. Total emissions for VOC from natural gas production sources are estimated to be approximately 25,300 tons/yr, when accounting for potential under-estimation of certain emission categories. This region produced, in 2011, approximately 5 bcf/d of natural gas (100 Gg/d) for a VOC to natural gas production ratio (mass basis) of 0.0006.

Direct Measure of the Dense Methane Phase in Gas Shale Organic Porosity by Neutron Scattering

DOE PAGES

Eberle, Aaron P. R.; King, Hubert E.; Ravikovitch, Peter I.; ...

2016-08-30

Here, we report the first direct measurements of methane density in shale gas using small-angle neutron scattering. At a constant pressure, the density of methane in the inorganic pores is similar to the gas bulk density of the system conditions. Conversely, the methane density is 2.1 ± 0.2 times greater in the organic mesopores. Furthermore, classical density functional theory calculations show that this excess density in the organic pores persists to elevated temperatures, typical of shale gas reservoir conditions, providing new insight into the hydrocarbon storage mechanisms within these reservoirs.

Numerical solution of fractured horizontal wells in shale gas reservoirs considering multiple transport mechanisms

NASA Astrophysics Data System (ADS)

Zhao, Yu-long; Tang, Xu-chuan; Zhang, Lie-hui; Tang, Hong-ming; Tao, Zheng-Wu

2018-06-01

The multiscale pore size and specific gas storage mechanism in organic-rich shale gas reservoirs make gas transport in such reservoirs complicated. Therefore, a model that fully incorporates all transport mechanisms and employs an accurate numerical method is urgently needed to simulate the gas production process. In this paper, a unified model of apparent permeability was first developed, which took into account multiple influential factors including slip flow, Knudsen diffusion (KD), surface diffusion, effects of the adsorbed layer, permeability stress sensitivity, and ad-/desorption phenomena. Subsequently, a comprehensive mathematical model, which included the model of apparent permeability, was derived to describe gas production behaviors. Thereafter, on the basis of unstructured perpendicular bisection grids and finite volume method, a fully implicit numerical simulator was developed using Matlab software. The validation and application of the new model were confirmed using a field case reported in the literature. Finally, the impacts of related influencing factors on gas production were analyzed. The results showed that KD resulted in a negligible impact on gas production in the proposed model. The smaller the pore size was, the more obvious the effects of the adsorbed layer on the well production rate would be. Permeability stress sensitivity had a slight effect on well cumulative production in shale gas reservoirs. Adsorbed gas made a major contribution to the later flow period of the well; the greater the adsorbed gas content, the greater the well production rate would be. This paper can improve the understanding of gas production in shale gas reservoirs for petroleum engineers.

Mississippian Barnett Shale, Fort Worth basin, north-central Texas: Gas-shale play with multi-trillion cubic foot potential

USGS Publications Warehouse

Montgomery, S.L.; Jarvie, D.M.; Bowker, K.A.; Pollastro, R.M.

2005-01-01

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. The most actively drilled area is Newark East field, currently the largest gas field in Texas. Newark East is 400 mi2 (1036 km2) in extent, with more than 2340 producing wells and about 2.7 tcf of booked gas reserves. Cumulative gas production from Barnett Shale wells through 2003 was about 0.8 tcf. Wells in Newark East field typically produce from depths of 7500 ft (2285 m) at rates ranging from 0.5 to more than 4 mmcf/day. Estimated ultimate recoveries per well range from 0.75 to as high as 7.0 bcf. Efforts to extend the current Barnett play beyond the field limits have encountered several challenges, including westward and northward increases in oil saturation and the absence of lithologic barriers to induced fracture growth. Patterns of oil and gas occurrence in the Barnett, in conjunction with maturation and burial-history data, indicate a complex, multiphased thermal evolution, with episodic expulsion of hydrocarbons and secondary cracking of primary oils to gas in portions of the basin where paleotemperatures were especially elevated. These and other data imply a large-potential Barnett resource for the basin as a whole (possibly > 200 tcf gas in place). Recent assessment by the U.S. Geological Survey suggests a mean volume of 26.2 tcf of undiscovered, technically recoverable gas in the central Fort Worth basin. Recovery of a significant portion of

Solar heated oil shale pyrolysis process

NASA Technical Reports Server (NTRS)

Qader, S. A. (Inventor)

1985-01-01

An improved system for recovery of a liquid hydrocarbon fuel from oil shale is presented. The oil shale pyrolysis system is composed of a retort reactor for receiving a bed of oil shale particules which are heated to pyrolyis temperature by means of a recycled solar heated gas stream. The gas stream is separated from the recovered shale oil and a portion of the gas stream is rapidly heated to pyrolysis temperature by passing it through an efficient solar heater. Steam, oxygen, air or other oxidizing gases can be injected into the recycle gas before or after the recycle gas is heated to pyrolysis temperature and thus raise the temperature before it enters the retort reactor. The use of solar thermal heat to preheat the recycle gas and optionally the steam before introducing it into the bed of shale, increases the yield of shale oil.

Characterization of fractures and flow zones in a contaminated shale at the Watervliet Arsenal, Albany County, New York

USGS Publications Warehouse

Williams, John H.; Paillet, Frederick L.

2002-01-01

Flow zones in a fractured shale in and near a plume of volatile organic compounds at the Watervliet Arsenal in Albany County, N. Y. were characterized through the integrated analysis of geophysical logs and single- and cross-hole flow tests. Information on the fracture-flow network at the site was needed to design an effective groundwater monitoring system, estimate offsite contaminant migration, and evaluate potential containment and remedial actions.Four newly drilled coreholes and four older monitoring wells were logged and tested to define the distribution and orientation of fractures that intersected a combined total of 500 feet of open hole. Analysis of borehole-wall image logs obtained with acoustic and optical televiewers indicated 79 subhorizontal to steeply dipping fractures with a wide range of dip directions. Analysis of fluid resistivity, temperature, and heat-pulse and electromagnetic flowmeter logs obtained under ambient and short-term stressed conditions identified 14 flow zones, which consist of one to several fractures and whose estimated transmissivity values range from 0.1 to more than 250 feet squared per day.Cross-hole flow tests, which were used to characterize the hydraulic connection between fracture-flow zones intersected by the boreholes, entailed (1) injection into or extraction from boreholes that penetrated a single fracture-flow zone or whose zones were isolated by an inflatable packer, and (2) measurement of the transient response of water levels and flow in surrounding boreholes. Results indicate a wellconnected fracture network with an estimated transmissivity of 80 to 250 feet squared per day that extends for at least 200 feet across the site. This interconnected fracture-flow network greatly affects the hydrology of the site and has important implications for contaminant monitoring and remedial actions.

Regional variation in water-related impacts of shale gas development and implications for emerging international plays.

PubMed

Mauter, Meagan S; Alvarez, Pedro J J; Burton, Allen; Cafaro, Diego C; Chen, Wei; Gregory, Kelvin B; Jiang, Guibin; Li, Qilin; Pittock, Jamie; Reible, Danny; Schnoor, Jerald L

2014-01-01

The unconventional fossil fuel industry is expected to expand dramatically in coming decades as conventional reserves wane. Minimizing the environmental impacts of this energy transition requires a contextualized understanding of the unique regional issues that shale gas development poses. This manuscript highlights the variation in regional water issues associated with shale gas development in the U.S. and the approaches of various states in mitigating these impacts. The manuscript also explores opportunities for emerging international shale plays to leverage the diverse experiences of U.S. states in formulating development strategies that minimize water-related impacts within their environmental, cultural, and political ecosystem.

U.S. Geological Survey Georgia Water Science Center and Albany Water, Gas, and Light Commission Cooperative Water Program-Summary of Activities, July 2005 through June 2006

USGS Publications Warehouse

Gordon, Debbie W.

2006-01-01

The U.S. Geological Survey (USGS) has been working with the Albany Water, Gas, and Light Commission to monitor ground-water quality and availability since 1977. This report presents the findings for July 2005 through June 2006 and summarizes the ground-water and surface-water conditions for 2005. Water levels in 14 wells were continuously monitored in Dougherty County, Georgia. Water levels in 12 of those wells were above normal, one was normal, and one was below normal. Ground-water samples collected from the Upper Floridan aquifer indicate that nitrate levels have increased in 13 wells and decreased in two wells from a year earlier. A sample also was collected from the Flint River. A trilinear diagram showing the percent composition of selected major cations and anions indicates that the ground-water quality of the Upper Floridan aquifer at the Albany wellfield is distinctly different from the water quality of the Flint River. To improve the understanding of the ground-water flow system and nitrate movement in the Upper Floridan aquifer, the USGS is developing a ground-water flow model in the southwest Albany area, Georgia.

Groundwater Conditions and Studies in the Albany Area of Dougherty County, Georgia, 2008

USGS Publications Warehouse

Gordon, Debbie W.

2009-01-01

The U.S. Geological Survey has been working cooperatively with the Albany Water, Gas, and Light Commission to monitor groundwater quality and availability since 1977. This report presents an overview of groundwater conditions and studies in the Albany area of Dougherty County, Georgia, during 2008. Historical data also are presented for comparison with 2008 data. Ongoing monitoring activities include continuous water-level recording in 24 wells and periodic water-level measurements in 5 wells. During 2008, water levels in 10 of the continuous-recording wells were below normal, corresponding to lower than average rainfall. Groundwater samples collected from 25 wells in the Upper Floridan aquifer indicate that nitrate levels during 2008 were similar to values from 2007, with a maximum of 12.5 milligrams per liter at one well. Water samples collected from the Flint River and wells at the Albany well field were analyzed and plotted on a trilinear diagram to show the percent composition of selected major cations and anions. Groundwater constituents (major cations and anions) of the Upper Floridan aquifer at the Albany well field remain distinctly different from those in the water of the Flint River. To improve the understanding of the groundwater-flow system and nitrate movement in the Upper Floridan aquifer, the U.S. Geological Survey is developing a groundwater-flow model in the Albany area of southwestern Georgia. The model is being calibrated to simulate periods of dry (October 1999) hydrologic conditions. Preliminary results of particle tracking indicate that water flows to the well field from the northwest.

Impact of shale gas development on regional water quality.

PubMed

Vidic, R D; Brantley, S L; Vandenbossche, J M; Yoxtheimer, D; Abad, J D

2013-05-17

Unconventional natural gas resources offer an opportunity to access a relatively clean fossil fuel that could potentially lead to energy independence for some countries. Horizontal drilling and hydraulic fracturing make the extraction of tightly bound natural gas from shale formations economically feasible. These technologies are not free from environmental risks, however, especially those related to regional water quality, such as gas migration, contaminant transport through induced and natural fractures, wastewater discharge, and accidental spills. We review the current understanding of environmental issues associated with unconventional gas extraction. Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help manage these water-quality risks today and in the future.

Ground-Water Conditions and Studies in the Albany Area of Dougherty County, Georgia, 2007

USGS Publications Warehouse

Gordon, Debbie W.

2008-01-01

The U.S. Geological Survey (USGS) has been working with the Albany Water, Gas, and Light Commission to monitor ground-water quality and availability since 1977. This report presents an overview of ground-water conditions and studies in the Albany area of Dougherty County, Georgia, during 2007. Historical data are also presented for comparison with 2007 data. Ongoing monitoring activities include continuous water-level recording in 24 wells and monthly water-level measurements in 5 wells. During 2007, water levels in 21 of the continuous-recording wells were below normal, corresponding to lower than average rainfall. Ground-water samples collected from the Upper Floridan aquifer indicate that nitrate levels have decreased or remained about the same since 2006. Water samples were collected from the Flint River and wells at the Albany wellfield, and data were plotted on a trilinear diagram to show the percent composition of selected major cations and anions. Ground-water constituents (major cations and anions) of the Upper Floridan aquifer at the Albany wellfield are distinctly different from those in the water of the Flint River. To improve the understanding of the ground-water flow system and nitrate movement in the Upper Floridan aquifer, the USGS is developing a ground-water flow model in the southwestern Albany area of Georgia. The model is being calibrated to simulate periods of dry (October 1999) and relatively wet (March 2001) hydrologic conditions. Preliminary water-level simulations indicate a generally good fit to measured water levels.

Physical and chemical characterization of Devonian gas shale. Quarterly status report, October 1-December 31, 1978

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zielinski, R.E.; Nance, S.W.

On shale samples from the WV-6 (Monongalia County, West Virginia) well, mean total gas yield was 80.4 ft/sup 3//ton. Mean hydrocarbon gas yield was 5.7 ft/sup 3//ton, 7% of total yield. Methane was the major hydrocarbon component and carbon dioxide the major nonhydrocarbon component. Oil yield was negligible. Clay minerals and organic matter were the dominant phases of the shale. Illite averages 76% of the total clay mineral content. This is detrital illite. Permeation of methane, parallel to the bedding direction for select samples from WV-5 (Mason County, West Virginia) well ranges from 10/sup -4/ to 10/sup -12/ darcys. Themore » permeability of these shales is affected by orgaic carbon content, density, particle orientation, depositional facies, etc. Preliminary studies of Devonian shale methane sorption rates suggest that these rates may be affected by shale porosity, as well as absorption and adsorption processes. An experimental system was designed to effectively simulate sorption of methane at natural reservoir conditions. The bulk density and color of select shales from Illinois, Appalachian and Michigan Basins suggest a general trend of decreasing density with increasing organic content. Black and grayish black shales have organic contents which normally exceed 1.0 wt %. Medium dark gray and gray shales generally have organic contents less than 1.0 wt %.« less

Effects of Hydraulic Frac Fluids on Subsurface Microbial Communities in Gas Shales

NASA Astrophysics Data System (ADS)

Jiménez, Núria; Krüger, Martin

2014-05-01

Shale gas is being considered as a complementary energy resource to coal or other fossil fuels. The exploitation of unconventional gas reservoirs requires the use of advanced drilling techniques and hydraulic stimulation (fracking). During fracking operations, large amounts of fluids (fresh water, proppants and chemical additives) are injected at high pressures into the formations, to produce fractures and fissures, and thus to release gas from the source rock into the wellbore. The injected fluids partly remain in the formation, while about 20 to 40% of the originally injected fluid flows back to the surface, together with formation waters, sometimes containing dissolved hydrocarbons, high salt concentrations, etc. The overall production operation will likely affect and be affected by subsurface microbial communities associated to the shale formations. On the one hand microbial activity (like growth, biofilm formation) can cause unwanted processes like corrosion, clogging, etc. On the other hand, the introduction of frac fluids could either enhance microbial growth or cause toxicity to the shale-associated microbial communities. To investigate the potential impacts of changing environmental reservoir conditions, like temperature, salinity, oxgen content and pH, as well as the introduction of frac or geogenic chemicals on subsurface microbial communities, laboratory experiments under in situ conditions (i.e. high temperatures and pressures) are being conducted. Enrichment cultures with samples from several subsurface environments (e.g. shale and coal deposits, gas reservoirs, geothermal fluids) have been set up using a variety of carbon sources, including hydrocarbons and typical frac chemicals. Classical microbiological and molecular analysis are used to determine changes in the microbial abundance, community structure and function after the exposure to different single frac chemicals, "artificial" frac fluids or production waters. On the other hand, potential

EIA responds to Nature article on shale gas projections

EIA Publications

2014-01-01

EIA has responded to a December 4, 2014 Nature article on projections of shale gas production made by EIA and by the Bureau of Economic Geology of the University of Texas at Austin (BEG/UT) with a letter to the editors of Nature. BEG/UT has also responded to the article in their own letter to the editor.

U.S. shale gas trends - economic and global implications

NASA Astrophysics Data System (ADS)

Murphy, T.

2016-09-01

Natural gas from shale has moved the U.S., and North America more broadly, to become one of the largest producers of the commodity worldwide. Large technological gains have allowed reservoirs of unconventional hydrocarbons to become commercially viable to extract and market. The addition of this growing supply into the global marketplace, has upended longstanding trading patterns, and created new economic outcomes worth noting. This paper will discuss the recent trends of shale energy development in the U.S., the impact it is having on domestic and international markets, and the implications as the world shifts to a new low carbon energy paradigm. It will cover changes in workforce, midstream build out, power generation trends, petrochemicals, and emerging LNG export capacities.

New Isotopic Tracers for Shale Gas and Hydraulic Fracturing Fluids

EPA Pesticide Factsheets

The combined application of geochemistry, stable isotopes (δ18O, δ2H), strontium isotopes (87Sr/86Sr), boron isotopes (δ11B), and radium isotopes (228Ra/226Ra) provides a unique methodology for tracing and monitoring shale gas and fracking fluids in the environment.

Hydraulic fracturing in shales: the spark that created an oil and gas boom

NASA Astrophysics Data System (ADS)

Olson, J. E.

2017-12-01

In the oil and gas business, one of the valued properties of a shale was its lack of flow capacity (its sealing integrity) and its propensity to provide mechanical barriers to hydraulic fracture height growth when exploiting oil and gas bearing sandstones. The other important property was the high organic content that made shale a potential source rock for oil and gas, commodities which migrated elsewhere to be produced. Technological advancements in horizontal drilling and hydraulic fracturing have turned this perspective on its head, making shale (or other ultra-low permeability rocks that are described with this catch-all term) the most prized reservoir rock in US onshore operations. Field and laboratory results have changed our view of how hydraulic fracturing works, suggesting heterogeneities like bedding planes and natural fractures can cause significant complexity in hydraulic fracture growth, resulting in induced networks of fractures whose details are controlled by factors including in situ stress contrasts, ductility contrasts in the stratigraphy, the orientation and strength of pre-existing natural fractures, injection fluid viscosity, perforation cluster spacing and effective mechanical layer thickness. The stress shadowing and stress relief concepts that structural geologists have long used to explain joint spacing and orthogonal fracture pattern development in stratified sequences are key to understanding optimal injection point spacing and promotion of more uniform length development in induced hydraulic fractures. Also, fracture interaction criterion to interpret abutting vs crossing natural fracture relationships in natural fracture systems are key to modeling hydraulic fracture propagation within natural fractured reservoirs such as shale. Scaled physical experiments provide constraints on models where the physics is uncertain. Numerous interesting technical questions remain to be answered, and the field is particularly appealing in that better

Determination of maximal amount of minor gases adsorbed in a shale sample by headspace gas chromatography.

PubMed

Zhang, Chun-Yun; Hu, Hui-Chao; Chai, Xin-Sheng; Pan, Lei; Xiao, Xian-Ming

2014-02-07

In this paper, we present a novel method for determining the maximal amount of ethane, a minor gas species, adsorbed in a shale sample. The method is based on the time-dependent release of ethane from shale samples measured by headspace gas chromatography (HS-GC). The study includes a mathematical model for fitting the experimental data, calculating the maximal amount gas adsorbed, and predicting results at other temperatures. The method is a more efficient alternative to the isothermal adsorption method that is in widespread use today. Copyright © 2013 Elsevier B.V. All rights reserved.

A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

PubMed Central

Yang, Ruiyue; Huang, Zhongwei; Yu, Wei; Li, Gensheng; Ren, Wenxi; Zuo, Lihua; Tan, Xiaosi; Sepehrnoori, Kamy; Tian, Shouceng; Sheng, Mao

2016-01-01

A complex fracture network is generally generated during the hydraulic fracturing treatment in shale gas reservoirs. Numerous efforts have been made to model the flow behavior of such fracture networks. However, it is still challenging to predict the impacts of various gas transport mechanisms on well performance with arbitrary fracture geometry in a computationally efficient manner. We develop a robust and comprehensive model for real gas transport in shales with complex non-planar fracture network. Contributions of gas transport mechanisms and fracture complexity to well productivity and rate transient behavior are systematically analyzed. The major findings are: simple planar fracture can overestimate gas production than non-planar fracture due to less fracture interference. A “hump” that occurs in the transition period and formation linear flow with a slope less than 1/2 can infer the appearance of natural fractures. The sharpness of the “hump” can indicate the complexity and irregularity of the fracture networks. Gas flow mechanisms can extend the transition flow period. The gas desorption could make the “hump” more profound. The Knudsen diffusion and slippage effect play a dominant role in the later production time. Maximizing the fracture complexity through generating large connected networks is an effective way to increase shale gas production. PMID:27819349

A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks.

PubMed

Yang, Ruiyue; Huang, Zhongwei; Yu, Wei; Li, Gensheng; Ren, Wenxi; Zuo, Lihua; Tan, Xiaosi; Sepehrnoori, Kamy; Tian, Shouceng; Sheng, Mao

2016-11-07

A complex fracture network is generally generated during the hydraulic fracturing treatment in shale gas reservoirs. Numerous efforts have been made to model the flow behavior of such fracture networks. However, it is still challenging to predict the impacts of various gas transport mechanisms on well performance with arbitrary fracture geometry in a computationally efficient manner. We develop a robust and comprehensive model for real gas transport in shales with complex non-planar fracture network. Contributions of gas transport mechanisms and fracture complexity to well productivity and rate transient behavior are systematically analyzed. The major findings are: simple planar fracture can overestimate gas production than non-planar fracture due to less fracture interference. A "hump" that occurs in the transition period and formation linear flow with a slope less than 1/2 can infer the appearance of natural fractures. The sharpness of the "hump" can indicate the complexity and irregularity of the fracture networks. Gas flow mechanisms can extend the transition flow period. The gas desorption could make the "hump" more profound. The Knudsen diffusion and slippage effect play a dominant role in the later production time. Maximizing the fracture complexity through generating large connected networks is an effective way to increase shale gas production.

Shale gas impacts on groundwater resources: insights from monitoring a fracking site in Poland

NASA Astrophysics Data System (ADS)

Montcoudiol, Nelly; Isherwood, Catherine; Gunning, Andrew; Kelly, Thomas; Younger, Paul

2017-04-01

Exploitation of shale gas by hydraulic fracturing (fracking) is highly controversial and concerns have been raised regarding induced risks from this technique. The SHEER project, an EU Horizon 2020-funded project, is looking into developing best practice to understand, prevent and mitigate the potential short- and long-term environmental impacts and risks from shale gas exploration and exploitation. Three major potential impacts were identified: groundwater contamination, air pollution and induced seismicity. This presentation will deal with the hydrogeological aspect. As part of the SHEER project, four monitoring wells were installed at a shale gas exploration site in Northern Poland. They intercept the main drinking water aquifer located in Quaternary sediments. Baseline monitoring was carried out from mid-December 2015 to beginning of June 2016. Fracking operations occurred in two horizontal wells, in two stages, in June and July 2016. The monitoring has continued after fracking was completed, with site visits every 4-6 weeks. Collected data include measurements of groundwater level, conductivity and temperature at 15-minute intervals, frequent sampling for laboratory analyses and field measurements of groundwater physico-chemical parameters. Groundwater samples are analysed for a range of constituents including dissolved gases and isotopes. The presentation will focus on the interpretation of baseline monitoring data. The insights gained into the behaviour of the Quaternary aquifer will allow a greater perspective to be place on the initial project understanding draw from previous studies. Short-term impacts will also be discussed in comparison with the baseline monitoring results. The presentation will conclude with discussion of challenges regarding monitoring of shale gas fracking sites.

Assessment of undiscovered oil and gas resources of the Ordovician Utica Shale of the Appalachian Basin Province, 2012

USGS Publications Warehouse

Kirschbaum, Mark A.; Schenk, Christopher J.; Cook, Troy A.; Ryder, Robert T.; Charpentier, Ronald R.; Klett, Timothy R.; Gaswirth, Stephanie B.; Tennyson, Marilyn E.; Whidden, Katherine J.

2012-01-01

The U.S. Geological Survey assessed unconventional oil and gas resources of the Upper Ordovician Utica Shale and adjacent units in the Appalachian Basin Province. The assessment covers parts of Maryland, New York, Ohio, Pennsylvania, Virginia, and West Virginia. The geologic concept is that black shale of the Utica Shale and adjacent units generated hydrocarbons from Type II organic material in areas that are thermally mature for oil and gas. The source rocks generated petroleum that migrated into adjacent units, but also retained significant hydrocarbons within the matrix and adsorbed to organic matter of the shale. These are potentially technically recoverable resources that can be exploited by using horizontal drilling combined with hydraulic fracturing techniques.

The U.S. Shale Oil and Gas Resource - a Multi-Scale Analysis of Productivity

NASA Astrophysics Data System (ADS)

O'sullivan, F.

2014-12-01

Over the past decade, the large-scale production of natural gas, and more recently oil, from U.S. shale formations has had a transformative impact on the energy industry. The emergence of shale oil and gas as recoverable resources has altered perceptions regarding both the future abundance and cost of hydrocarbons, and has shifted the balance of global energy geopolitics. However, despite the excitement, shale is a resource in its nascency, and many challenges surrounding its exploitation remain. One of the most significant of these is the dramatic variation in resource productivity across multiple length scales, which is a feature of all of today's shale plays. This paper will describe the results of work that has looked to characterize the spatial and temporal variations in the productivity of the contemporary shale resource. Analysis will be presented that shows there is a strong stochastic element to observed shale well productivity in all the major plays. It will be shown that the nature of this stochasticity is consistent regardless of specific play being considered. A characterization of this stochasticity will be proposed. As a parallel to the discussion of productivity, the paper will also address the issue of "learning" in shale development. It will be shown that "creaming" trends are observable and that although "absolute" well productivity levels have increased, "specific" productivity levels (i.e. considering well and stimulation size) have actually falling markedly in many plays. The paper will also show that among individual operators' well ensembles, normalized well-to-well performance distributions are almost identical, and have remained consistent year-to-year. This result suggests little if any systematic learning regarding the effective management of well-to-well performance variability has taken place. The paper will conclude with an articulation of how the productivity characteristics of the shale resource are impacting on the resources

Effect of organic-matter type and thermal maturity on methane adsorption in shale-gas systems

USGS Publications Warehouse

Zhang, Tongwei; Ellis, Geoffrey S.; Ruppel, Stephen C.; Milliken, Kitty; Yang, Rongsheng

2012-01-01

A series of methane (CH4) adsorption experiments on bulk organic rich shales and their isolated kerogens were conducted at 35 °C, 50 °C and 65 °C and CH4 pressure of up to 15 MPa under dry conditions. Samples from the Eocene Green River Formation, Devonian–Mississippian Woodford Shale and Upper Cretaceous Cameo coal were studied to examine how differences in organic matter type affect natural gas adsorption. Vitrinite reflectance values of these samples ranged from 0.56–0.58 %Ro. In addition, thermal maturity effects were determined on three Mississippian Barnett Shale samples with measured vitrinite reflectance values of 0.58, 0.81 and 2.01 %Ro. For all bulk and isolated kerogen samples, the total amount of methane adsorbed was directly proportional to the total organic carbon (TOC) content of the sample and the average maximum amount of gas sorption was 1.36 mmol of methane per gram of TOC. These results indicate that sorption on organic matter plays a critical role in shale-gas storage. Under the experimental conditions, differences in thermal maturity showed no significant effect on the total amount of gas sorbed. Experimental sorption isotherms could be fitted with good accuracy by the Langmuir function by adjusting the Langmuir pressure (PL) and maximum sorption capacity (Γmax). The lowest maturity sample (%Ro = 0.56) displayed a Langmuir pressure (PL) of 5.15 MPa, significantly larger than the 2.33 MPa observed for the highest maturity (%Ro > 2.01) sample at 50 °C. The value of the Langmuir pressure (PL) changes with kerogen type in the following sequence: type I > type II > type III. The thermodynamic parameters of CH4 adsorption on organic rich shales were determined based on the experimental CH4 isotherms. For the adsorption of CH4 on organic rich shales and their isolated kerogen, the heat of adsorption (q) and the standard entropy (Δs0) range from 7.3–28.0 kJ/mol and from −36.2 to −92.2 J/mol/K, respectively.

Geological implications and controls on the determination of water saturation in shale gas reservoirs

NASA Astrophysics Data System (ADS)

Hartigan, David; Lovell, Mike; Davies, Sarah

2014-05-01

A significant challenge to the petrophysical evaluation of shale gas systems can be attributed to the conductivity behaviour of clay minerals and entrained clay bound waters. This is compounded by centimetre to sub-millimetre vertical and lateral heterogeneity in formation composition and structure. Where despite significant variation in formation geological and therefore petrophysical properties, we routinely rely on conventional resistivity methods for the determination of water saturation (Sw), and hence the free gas saturation (Sg) in gas bearing mudstones. The application of resistivity based methods is the subject of continuing debate, and there is often significant uncertainty in both how they are applied and the saturation estimates they produce. This is partly a consequence of the view that "the quantification of the behaviour of shale conductivity....has only limited geological significance" (Rider 1986). As a result, there is a separation between our geological understanding of shale gas systems and the petrophysical rational and methods employed to evaluate them. In response to this uncertainty, many petrophysicists are moving away from the use of more complex 'shaly-sand' based evaluation techniques and returning to traditional Archie methods for answers. The Archie equation requires various parameter inputs such as porosity and saturation exponents (m and n), as well as values for connate fluid resistivity (Rw). Many of these parameters are difficult to determine in shale gas systems, where obtaining a water sample, or carrying out laboratory experiments on recovered core is often technically impractical. Here we assess the geological implications and controls on variations in pseudo Archie parameters across two geological formations, using well data spanning multiple basinal settings for a prominent shale gas play in the northern Gulf of Mexico basin. The results, of numerical analysis and systematic modification of parameter values to minimise the

Monitoring environmental effects of shale gas exploitation at Wysin in Poland.

NASA Astrophysics Data System (ADS)

Lasocki, Stanislaw; Mirek, Janusz; Bialon, Wojciech; Cielesta, Szymon; Lasak, Mateusz; Cesca, Simone; Lopez Comino, Jose Angel; Dahm, Torsten; Scarpa, Roberto; Gunning, Andrew; Montcoudiol, Nelly; Isherwood, Catherine; Jaroslawski, Janusz; Guzikowski, Jakub

2017-04-01

Environmental effects of shale gas exploration and exploitation are extensively studied in the framework of "Shale Gas Exploration and Exploitation Induced Risks" project (SHEER, H2020-LCE 16-2014-1). One of the main component of this study is on-site monitoring of the effects at Wysin shale-gas play of Polish Oil and Gas Company in Poland. This includes monitoring of seismicity and water and air quality. Surface seismic monitoring network consists of 6 surface broadband (BB) seismometers and 25 surface short-period (SP) seismometers The SPs are assembled into three small aperture arrays with 9, 8 and 8 stations, respectively, distributed in a triangle geometry at a distance of about 2-4 km from the hydrofracturing rig. Each array is complemented with one BB station. The three remaining BBs are located up to about 5 km from the rig. In addition 3 borehole broadband seismometers are located in three shallow boreholes. The groundwater monitoring makes use of four wells, which reach a main underground water reservoir. Three complementary datasets are collected: continuous monitoring of borehole data, laboratory analyses of water samples and field monitoring of water quality parameters. The continuous monitoring makes use of down-hole probes, which have been installed in each borehole. The probes record absolute pressure, temperature and electrical conductivity. In addition, a barometric probe has been installed above ground to record atmospheric pressure in order to allow conversion of absolute pressure to a water level. After collection, water samples are sent to an accredited laboratory for analysis. The field monitoring is undertaken during the sampling visits. Whilst the borehole is being purged, physico-chemical parameters are monitored using a multi-parameter probe. This measures and records temperature, specific conductivity, pH, dissolved oxygen and oxidation-reduction potential within the water. Hydrocarbon gas content within the water is below detection

Combuston method of oil shale retorting

DOEpatents

Jones, Jr., John B.; Reeves, Adam A.

1977-08-16

A gravity flow, vertical bed of crushed oil shale having a two level injection of air and a three level injection of non-oxygenous gas and an internal combustion of at least residual carbon on the retorted shale. The injection of air and gas is carefully controlled in relation to the mass flow rate of the shale to control the temperature of pyrolysis zone, producing a maximum conversion of the organic content of the shale to a liquid shale oil. The parameters of the operation provides an economical and highly efficient shale oil production.

Experimental and Model Studies on Loading Path-Dependent and Nonlinear Gas Flow Behavior in Shale Fractures

NASA Astrophysics Data System (ADS)

Li, Honglian; Lu, Yiyu; Zhou, Lei; Tang, Jiren; Han, Shuaibin; Ao, Xiang

2018-01-01

Interest in shale gas as an energy source is growing worldwide. Because the rock's natural fracture system can contribute to gas production, it is important to understand the flow behavior of natural fractures in shale. Previous studies on the flow characteristics in shale fractures were limited and did not consider the effect of nonlinearity. To understand the basic mechanics of the gas flow behavior in shale fractures, laboratory investigations with consideration of the fluid pressure gradient, the confining stress, the loading history and the fracture geometry were conducted in this paper. Izbash's equation was used to analyze the nonlinearity of the flow. The results show that the behavior of the friction factors is similar to that shown in flow tests in smooth and rough pipes. The increase of the confining stress and the irreversible damage to the shale decreased the hydraulic aperture and increased the relative roughness. Thus, turbulent flow could appear at a low Reynolds number, resulting in a significant pressure loss. The limits of the cubic law and the existing correction factor for transmissivity are discussed. It is found that the previous friction models overestimate the friction factor in the laminar regime and underestimate the friction factor in the turbulent regime. For this reason, a new friction model based on a linear combination of the Reynolds number and the relative roughness was developed.

Shale Gas Development and Brook Trout: Scaling Best Management Practices to Anticipate Cumulative Effects

USGS Publications Warehouse

Smith, David; Snyder, Craig D.; Hitt, Nathaniel P.; Young, John A.; Faulkner, Stephen P.

2012-01-01

Shale gas development may involve trade-offs between energy development and benefits provided by natural ecosystems. However, current best management practices (BMPs) focus on mitigating localized ecological degradation. We review evidence for cumulative effects of natural gas development on brook trout (Salvelinus fontinalis) and conclude that BMPs should account for potential watershed-scale effects in addition to localized influences. The challenge is to develop BMPs in the face of uncertainty in the predicted response of brook trout to landscape-scale disturbance caused by gas extraction. We propose a decision-analysis approach to formulating BMPs in the specific case of relatively undisturbed watersheds where there is consensus to maintain brook trout populations during gas development. The decision analysis was informed by existing empirical models that describe brook trout occupancy responses to landscape disturbance and set bounds on the uncertainty in the predicted responses to shale gas development. The decision analysis showed that a high efficiency of gas development (e.g., 1 well pad per square mile and 7 acres per pad) was critical to achieving a win-win solution characterized by maintaining brook trout and maximizing extraction of available gas. This finding was invariant to uncertainty in predicted response of brook trout to watershed-level disturbance. However, as the efficiency of gas development decreased, the optimal BMP depended on the predicted response, and there was considerable potential value in discriminating among predictive models through adaptive management or research. The proposed decision-analysis framework provides an opportunity to anticipate the cumulative effects of shale gas development, account for uncertainty, and inform management decisions at the appropriate spatial scales.

Spatial and Temporal Characteristics of Historical Oil and Gas Wells in Pennsylvania: Implications for New Shale Gas Resources.

PubMed

Dilmore, Robert M; Sams, James I; Glosser, Deborah; Carter, Kristin M; Bain, Daniel J

2015-10-20

Recent large-scale development of oil and gas from low-permeability unconventional formations (e.g., shales, tight sands, and coal seams) has raised concern about potential environmental impacts. If left improperly sealed, legacy oil and gas wells colocated with that new development represent a potential pathway for unwanted migration of fluids (brine, drilling and stimulation fluids, oil, and gas). Uncertainty in the number, location, and abandonment state of legacy wells hinders environmental assessment of exploration and production activity. The objective of this study is to apply publicly available information on Pennsylvania oil and gas wells to better understand their potential to serve as pathways for unwanted fluid migration. This study presents a synthesis of historical reports and digital well records to provide insights into spatial and temporal trends in oil and gas development. Areas with a higher density of wells abandoned prior to the mid-20th century, when more modern well-sealing requirements took effect in Pennsylvania, and areas where conventional oil and gas production penetrated to or through intervals that may be affected by new Marcellus shale development are identified. This information may help to address questions of environmental risk related to new extraction activities.

Zero Discharge Water Management for Horizontal Shale Gas Well Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paul Ziemkiewicz; Jennifer Hause; Raymond Lovett

Hydraulic fracturing technology (fracking), coupled with horizontal drilling, has facilitated exploitation of huge natural gas (gas) reserves in the Devonian-age Marcellus Shale Formation (Marcellus) of the Appalachian Basin. The most-efficient technique for stimulating Marcellus gas production involves hydraulic fracturing (injection of a water-based fluid and sand mixture) along a horizontal well bore to create a series of hydraulic fractures in the Marcellus. The hydraulic fractures free the shale-trapped gas, allowing it to flow to the well bore where it is conveyed to pipelines for transport and distribution. The hydraulic fracturing process has two significant effects on the local environment. First,more » water withdrawals from local sources compete with the water requirements of ecosystems, domestic and recreational users, and/or agricultural and industrial uses. Second, when the injection phase is over, 10 to 30% of the injected water returns to the surface. This water consists of flowback, which occurs between the completion of fracturing and gas production, and produced water, which occurs during gas production. Collectively referred to as returned frac water (RFW), it is highly saline with varying amounts of organic contamination. It can be disposed of, either by injection into an approved underground injection well, or treated to remove contaminants so that the water meets the requirements of either surface release or recycle use. Depending on the characteristics of the RFW and the availability of satisfactory disposal alternatives, disposal can impose serious costs to the operator. In any case, large quantities of water must be transported to and from well locations, contributing to wear and tear on local roadways that were not designed to handle the heavy loads and increased traffic. The search for a way to mitigate the situation and improve the overall efficiency of shale gas production suggested a treatment method that would allow RFW to be used

Organic compounds in produced waters from shale gas wells.

PubMed

Maguire-Boyle, Samuel J; Barron, Andrew R

2014-01-01

A detailed analysis is reported of the organic composition of produced water samples from typical shale gas wells in the Marcellus (PA), Eagle Ford (TX), and Barnett (NM) formations. The quality of shale gas produced (and frac flowback) waters is a current environmental concern and disposal problem for producers. Re-use of produced water for hydraulic fracturing is being encouraged; however, knowledge of the organic impurities is important in determining the method of treatment. The metal content was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Mineral elements are expected depending on the reservoir geology and salts used in hydraulic fracturing; however, significant levels of other transition metals and heavier main group elements are observed. The presence of scaling elements (Ca and Ba) is related to the pH of the water rather than total dissolved solids (TDS). Using gas chromatography mass spectrometry (GC/MS) analysis of the chloroform extracts of the produced water samples, a plethora of organic compounds were identified. In each water sample, the majority of organics are saturated (aliphatic), and only a small fraction comes under aromatic, resin, and asphaltene categories. Unlike coalbed methane produced water it appears that shale oil/gas produced water does not contain significant quantities of polyaromatic hydrocarbons reducing the potential health hazard. Marcellus and Barnett produced waters contain predominantly C6-C16 hydrocarbons, while the Eagle Ford produced water shows the highest concentration in the C17-C30 range. The structures of the saturated hydrocarbons identified generally follows the trend of linear > branched > cyclic. Heterocyclic compounds are identified with the largest fraction being fatty alcohols, esters, and ethers. However, the presence of various fatty acid phthalate esters in the Barnett and Marcellus produced waters can be related to their use in drilling fluids and breaker additives

Numerical modeling of fracking fluid and methane migration through fault zones in shale gas reservoirs

NASA Astrophysics Data System (ADS)

Taherdangkoo, Reza; Tatomir, Alexandru; Sauter, Martin

2017-04-01

Hydraulic fracturing operation in shale gas reservoir has gained growing interest over the last few years. Groundwater contamination is one of the most important environmental concerns that have emerged surrounding shale gas development (Reagan et al., 2015). The potential impacts of hydraulic fracturing could be studied through the possible pathways for subsurface migration of contaminants towards overlying aquifers (Kissinger et al., 2013; Myers, 2012). The intent of this study is to investigate, by means of numerical simulation, two failure scenarios which are based on the presence of a fault zone that penetrates the full thickness of overburden and connect shale gas reservoir to aquifer. Scenario 1 addresses the potential transport of fracturing fluid from the shale into the subsurface. This scenario was modeled with COMSOL Multiphysics software. Scenario 2 deals with the leakage of methane from the reservoir into the overburden. The numerical modeling of this scenario was implemented in DuMux (free and open-source software), discrete fracture model (DFM) simulator (Tatomir, 2012). The modeling results are used to evaluate the influence of several important parameters (reservoir pressure, aquifer-reservoir separation thickness, fault zone inclination, porosity, permeability, etc.) that could affect the fluid transport through the fault zone. Furthermore, we determined the main transport mechanisms and circumstances in which would allow frack fluid or methane migrate through the fault zone into geological layers. The results show that presence of a conductive fault could reduce the contaminant travel time and a significant contaminant leakage, under certain hydraulic conditions, is most likely to occur. Bibliography Kissinger, A., Helmig, R., Ebigbo, A., Class, H., Lange, T., Sauter, M., Heitfeld, M., Klünker, J., Jahnke, W., 2013. Hydraulic fracturing in unconventional gas reservoirs: risks in the geological system, part 2. Environ Earth Sci 70, 3855

Evolution of water chemistry during Marcellus Shale gas development: A case study in West Virginia.

PubMed

Ziemkiewicz, Paul F; Thomas He, Y

2015-09-01

Hydraulic fracturing (HF) has been used with horizontal drilling to extract gas and natural gas liquids from source rock such as the Marcellus Shale in the Appalachian Basin. Horizontal drilling and HF generates large volumes of waste water known as flowback. While inorganic ion chemistry has been well characterized, and the general increase in concentration through the flowback is widely recognized, the literature contains little information relative to organic compounds and radionuclides. This study examined the chemical evolution of liquid process and waste streams (including makeup water, HF fluids, and flowback) in four Marcellus Shale gas well sites in north central West Virginia. Concentrations of organic and inorganic constituents and radioactive isotopes were measured to determine changes in waste water chemistry during shale gas development. We found that additives used in fracturing fluid may contribute to some of the constituents (e.g., Fe) found in flowback, but they appear to play a minor role. Time sequence samples collected during flowback indicated increasing concentrations of organic, inorganic and radioactive constituents. Nearly all constituents were found in much higher concentrations in flowback water than in injected HF fluids suggesting that the bulk of constituents originate in the Marcellus Shale formation rather than in the formulation of the injected HF fluids. Liquid wastes such as flowback and produced water, are largely recycled for subsequent fracturing operations. These practices limit environmental exposure to flowback. Copyright © 2015 Elsevier Ltd. All rights reserved.

Experimental Determination of P-V-T-X Properties and Adsorption Kinetics in the CO2-CH4 System under Shale Gas Reservoir Conditions

NASA Astrophysics Data System (ADS)

Xiong, Y.; Wang, Y.

2014-12-01

Shale gas production via hydrofracturing has profoundly changed the energy portfolio in the USA and other parts of the world. Under the shale gas reservior conditions, CO2 and H2O, either in residence or being injected during hydrofracturing or both, co-exist with CH4. One important feature characteristic of shale is the presence of nanometer-scale (1-100 nm) pores in shale or mudstone. The interactions among CH4, CO2 and H2O in those nano-sized pores directly impact shale gas storage and gas release from the shale matrix. Therefore, a fundamental understanding of interactions among CH4, CO2 and H2O in nanopore confinement would provide guidance in addressing a number of problems such as rapid decline in production after a few years and low recovery rates. We are systematically investigating the P-V-T-X properties and adsorption kinetics in the CH4-CO2-H2O system under the reservior conditions. We have designed and constructed a unique high temperature and pressure experimental system that can measure both of the P-V-T-X properties and adsorption kinetics sequentially. We measure the P-V-T-X properties of CH4-CO2 mixtures with CH4 up to 95 vol. %, and adsorption kinetics of various materials, under the conditions relevant to shale gas reservoir. We use three types of materials: (I) model materials, (II) single solid phases separated from shale samples, and (III) crushed shale samples from both the known shale gas producing formations and the shale gas barren formations. The model materials are well characterized in terms of pore sizes. Therefore, the results associated with the model material serve as benchmarks for our model development. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. This research is supported by a Geoscience Foundation LDRD.

Prediction of shale prospectivity from seismically-derived reservoir and completion qualities: Application to a shale-gas field, Horn River Basin, Canada

NASA Astrophysics Data System (ADS)

Mo, Cheol Hoon; Lee, Gwang H.; Jeoung, Taek Ju; Ko, Kyung Nam; Kim, Ki Soo; Park, Kyung-sick; Shin, Chang Hoon

2018-04-01

Prospective shale plays require a combination of good reservoir and completion qualities. Total organic carbon (TOC) is an important reservoir quality and brittleness is the most critical condition for completion quality. We analyzed seismically-derived brittleness and TOC to investigate the prospectivity of the Horn River Group shale (the Muskwa, Otter Park, Evie shales) of a shale-gas field in the western Horn River Basin, British Columbia, Canada. We used the λρ-μρ brittleness template, constructed from the mineralogy-based brittleness index (MBI) and elastic logs from two wells, to convert the λρ and μρ volumes from prestack seismic inversion to the volume for the brittleness petrotypes (most brittle, intermediate, and least brittle). The probability maps of the most brittle petrotype for the three shales were generated from Bayesian classification, based on the λρ-μρ template. The relationship between TOC and P-wave and S-wave velocity ratio (VP/VS) at the wells allowed the conversion of the VP/VS volume from prestack inversion to the TOC volume, which in turn was used to construct the TOC maps for the three shales. Increased TOC is correlated with high brittleness, contrasting with the commonly-held understanding. Therefore, the prospectivity of the shales in the study area can be represented by high brittleness and increased TOC. We propose a shale prospectivity index (SPI), computed by the arithmetic average of the normalized probability of the most brittle petrotype and the normalized TOC. The higher SPI corresponds to higher production rates in the Muskwa and Evie shales. The areas of the highest SPI have not been fully tested. The future drilling should be focused on these areas to increase the economic viability of the field.

Ecological risks of shale oil and gas development to wildlife, aquatic resources and their habitats

USGS Publications Warehouse

Brittingham, Margaret C.; Maloney, Kelly O.; Farag, Aïda M.; Harper, David D.; Bowen, Zachary H.

2014-01-01

Technological advances in hydraulic fracturing and horizontal drilling have led to the exploration and exploitation of shale oil and gas both nationally and internationally. Extensive development of shale resources has occurred within the United States over the past decade, yet full build out is not expected to occur for years. Moreover, countries across the globe have large shale resources and are beginning to explore extraction of these resources. Extraction of shale resources is a multistep process that includes site identification, well pad and infrastructure development, well drilling, high-volume hydraulic fracturing and production; each with its own propensity to affect associated ecosystems. Some potential effects, for example from well pad, road and pipeline development, will likely be similar to other anthropogenic activities like conventional gas drilling, land clearing, exurban and agricultural development and surface mining (e.g., habitat fragmentation and sedimentation). Therefore, we can use the large body of literature available on the ecological effects of these activities to estimate potential effects from shale development on nearby ecosystems. However, other effects, such as accidental release of wastewaters, are novel to the shale gas extraction process making it harder to predict potential outcomes. Here, we review current knowledge of the effects of high-volume hydraulic fracturing coupled with horizontal drilling on terrestrial and aquatic ecosystems in the contiguous United States, an area that includes 20 shale plays many of which have experienced extensive development over the past decade. We conclude that species and habitats most at risk are ones where there is an extensive overlap between a species range or habitat type and one of the shale plays (leading to high vulnerability) coupled with intrinsic characteristics such as limited range, small population size, specialized habitat requirements, and high sensitivity to disturbance

Ecological risks of shale oil and gas development to wildlife, aquatic resources and their habitats.

PubMed

Brittingham, Margaret C; Maloney, Kelly O; Farag, Aïda M; Harper, David D; Bowen, Zachary H

2014-10-07

Technological advances in hydraulic fracturing and horizontal drilling have led to the exploration and exploitation of shale oil and gas both nationally and internationally. Extensive development of shale resources has occurred within the United States over the past decade, yet full build out is not expected to occur for years. Moreover, countries across the globe have large shale resources and are beginning to explore extraction of these resources. Extraction of shale resources is a multistep process that includes site identification, well pad and infrastructure development, well drilling, high-volume hydraulic fracturing and production; each with its own propensity to affect associated ecosystems. Some potential effects, for example from well pad, road and pipeline development, will likely be similar to other anthropogenic activities like conventional gas drilling, land clearing, exurban and agricultural development and surface mining (e.g., habitat fragmentation and sedimentation). Therefore, we can use the large body of literature available on the ecological effects of these activities to estimate potential effects from shale development on nearby ecosystems. However, other effects, such as accidental release of wastewaters, are novel to the shale gas extraction process making it harder to predict potential outcomes. Here, we review current knowledge of the effects of high-volume hydraulic fracturing coupled with horizontal drilling on terrestrial and aquatic ecosystems in the contiguous United States, an area that includes 20 shale plays many of which have experienced extensive development over the past decade. We conclude that species and habitats most at risk are ones where there is an extensive overlap between a species range or habitat type and one of the shale plays (leading to high vulnerability) coupled with intrinsic characteristics such as limited range, small population size, specialized habitat requirements, and high sensitivity to disturbance

Capillary pressure – saturation relationships for gas shales measured using a water activity meter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donnelly, B.; Perfect, E.; McKay, L. D.

Hydraulic fracturing of gas shale formations involves pumping a large volume of fracking fluid into a hydrocarbon reservoir to fracture the rock and thus increase its permeability. The majority of the fracking fluid introduced is never recovered and the fate of this lost fluid, often called “leak off,” has become the source of much debate. Information on the capillary pressure – saturation relationship for each wetting phase is needed to simulate leak off using numerical reservoir models. The petroleum industry commonly employs air – water capillary pressure – saturation curves to predict these relationships for mixed wet reservoirs. Traditional methodsmore » of measuring this curve are unsuitable for gas shales due to high capillary pressures associated with the small pores present. Still, a possible alternative method is the water activity meter which is used widely in the soil sciences for such measurements. However, its application to lithified material has been limited. Here, this study utilized a water activity meter to measure air – water capillary pressures (ranging from 1.3 to 219.6 MPa) at several water saturation levels in both the wetting and drying directions. Water contents were measured gravimetrically. Seven types of gas producing shale with different porosities (2.5–13.6%) and total organic carbon contents (0.4–13.5%) were investigated. Nonlinear regression was used to fit the resulting capillary pressure – water saturation data pairs for each shale type to the Brooks and Corey equation. Data for six of the seven shale types investigated were successfully fitted (median R 2 = 0.93), indicating this may be a viable method for parameterizing capillary pressure – saturation relationships for inclusion in numerical reservoir models. As expected, the different shale types had statistically different Brooks and Corey parameters. However, there were no significant differences between the Brooks and Corey parameters for the wetting

Capillary pressure – saturation relationships for gas shales measured using a water activity meter

DOE PAGES

Donnelly, B.; Perfect, E.; McKay, L. D.; ...

2016-05-10

Hydraulic fracturing of gas shale formations involves pumping a large volume of fracking fluid into a hydrocarbon reservoir to fracture the rock and thus increase its permeability. The majority of the fracking fluid introduced is never recovered and the fate of this lost fluid, often called “leak off,” has become the source of much debate. Information on the capillary pressure – saturation relationship for each wetting phase is needed to simulate leak off using numerical reservoir models. The petroleum industry commonly employs air – water capillary pressure – saturation curves to predict these relationships for mixed wet reservoirs. Traditional methodsmore » of measuring this curve are unsuitable for gas shales due to high capillary pressures associated with the small pores present. Still, a possible alternative method is the water activity meter which is used widely in the soil sciences for such measurements. However, its application to lithified material has been limited. Here, this study utilized a water activity meter to measure air – water capillary pressures (ranging from 1.3 to 219.6 MPa) at several water saturation levels in both the wetting and drying directions. Water contents were measured gravimetrically. Seven types of gas producing shale with different porosities (2.5–13.6%) and total organic carbon contents (0.4–13.5%) were investigated. Nonlinear regression was used to fit the resulting capillary pressure – water saturation data pairs for each shale type to the Brooks and Corey equation. Data for six of the seven shale types investigated were successfully fitted (median R 2 = 0.93), indicating this may be a viable method for parameterizing capillary pressure – saturation relationships for inclusion in numerical reservoir models. As expected, the different shale types had statistically different Brooks and Corey parameters. However, there were no significant differences between the Brooks and Corey parameters for the wetting

CO 2 utilization and storage in shale gas reservoirs: Experimental results and economic impacts

DOE PAGES

Schaef, Herbert T.; Davidson, Casie L.; Owen, Antionette Toni; ...

2014-12-31

Natural gas is considered a cleaner and lower-emission fuel than coal, and its high abundance from advanced drilling techniques has positioned natural gas as a major alternative energy source for the U.S. However, each ton of CO 2 emitted from any type of fossil fuel combustion will continue to increase global atmospheric concentrations. One unique approach to reducing anthropogenic CO 2 emissions involves coupling CO 2 based enhanced gas recovery (EGR) operations in depleted shale gas reservoirs with long-term CO 2 storage operations. In this paper, we report unique findings about the interactions between important shale minerals and sorbing gasesmore » (CH 4 and CO 2) and associated economic consequences. Where enhanced condensation of CO 2 followed by desorption on clay surface is observed under supercritical conditions, a linear sorption profile emerges for CH 4. Volumetric changes to montmorillonites occur during exposure to CO 2. Theory-based simulations identify interactions with interlayer cations as energetically favorable for CO 2 intercalation. Thus, experimental evidence suggests CH 4 does not occupy the interlayer and has only the propensity for surface adsorption. Mixed CH 4:CO 2 gas systems, where CH 4 concentrations prevail, indicate preferential CO 2 sorption as determined by in situ infrared spectroscopy and X-ray diffraction techniques. Collectively, these laboratory studies combined with a cost-based economic analysis provide a basis for identifying favorable CO 2-EOR opportunities in previously fractured shale gas reservoirs approaching final stages of primary gas production. Moreover, utilization of site-specific laboratory measurements in reservoir simulators provides insight into optimum injection strategies for maximizing CH 4/CO 2 exchange rates to obtain peak natural gas production.« less

Stream measurements locate thermogenic methane fluxes in groundwater discharge in an area of shale-gas development.

PubMed

Heilweil, Victor M; Grieve, Paul L; Hynek, Scott A; Brantley, Susan L; Solomon, D Kip; Risser, Dennis W

2015-04-07

The environmental impacts of shale-gas development on water resources, including methane migration to shallow groundwater, have been difficult to assess. Monitoring around gas wells is generally limited to domestic water-supply wells, which often are not situated along predominant groundwater flow paths. A new concept is tested here: combining stream hydrocarbon and noble-gas measurements with reach mass-balance modeling to estimate thermogenic methane concentrations and fluxes in groundwater discharging to streams and to constrain methane sources. In the Marcellus Formation shale-gas play of northern Pennsylvania (U.S.A.), we sampled methane in 15 streams as a reconnaissance tool to locate methane-laden groundwater discharge: concentrations up to 69 μg L(-1) were observed, with four streams ≥ 5 μg L(-1). Geochemical analyses of water from one stream with high methane (Sugar Run, Lycoming County) were consistent with Middle Devonian gases. After sampling was completed, we learned of a state regulator investigation of stray-gas migration from a nearby Marcellus Formation gas well. Modeling indicates a groundwater thermogenic methane flux of about 0.5 kg d(-1) discharging into Sugar Run, possibly from this fugitive gas source. Since flow paths often coalesce into gaining streams, stream methane monitoring provides the first watershed-scale method to assess groundwater contamination from shale-gas development.

Undiscovered petroleum resources for the Woodford Shale and Thirteen Finger Limestone-Atoka Shale assessment units, Anadarko Basin

USGS Publications Warehouse

Higley, Debra K.

2011-01-01

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 three continuous (unconventional) assessment units (AU). Mean undiscovered resources for the (1) Devonian Woodford Shale Gas AU are about 16 trillion cubic feet of gas (TCFG) and 192 million barrels of natural gas liquids (MMBNGL), (2) Woodford Shale Oil AU are 393 million barrels of oil (MMBO), 2 TCFG, and 59 MMBNGL, and (3) Pennsylvanian Thirteen Finger Limestone-Atoka Shale Gas AU are 6.8 TCFG and 82 MMBNGL. The continuous gas AUs are mature for gas generation within the deep basin of Oklahoma and Texas. Gas generation from the Woodford Shale source rock started about 335 Ma, and from the Thirteen Finger Limestone-Atoka Shale AU about 300 Ma. Maturation results are based on vitrinite reflectance data, and on 1D and 4D petroleum system models that calculated vitrinite reflectance (Ro), and Rock-Eval and hydrous pyrolysis transformation (HP) ratios through time for petroleum source rocks. The Woodford Shale Gas AU boundary and sweet spot were defined mainly on (1) isopach thickness from well-log analysis and published sources; (2) estimated ultimate recoverable production from existing, mainly horizontal, wells; and (3) levels of thermal maturation. Measured and modeled Ro ranges from about 1.2% to 5% in the AU, which represents marginally mature to overmature for gas generation. The sweet spot included most of the Woodford that was deposited within eroded channels in the unconformably underlying Hunton Group. The Thirteen Finger Limestone-Atoka Shale Gas AU has no known production in the deep basin. This AU boundary is based primarily on the gas generation window, and on thickness and distribution of organic-rich facies from these mainly thin shale and limestone beds. Estimates of organic richness were based on well-log signatures and published data.

Deliberating the perceived risks, benefits, and societal implications of shale gas and oil extraction by hydraulic fracturing in the US and UK

NASA Astrophysics Data System (ADS)

Thomas, Merryn; Partridge, Tristan; Harthorn, Barbara Herr; Pidgeon, Nick

2017-04-01

Shale gas and oil production in the US has increased rapidly in the past decade, while interest in prospective development has also arisen in the UK. In both countries, shale resources and the method of their extraction (hydraulic fracturing, or 'fracking') have been met with opposition amid concerns about impacts on water, greenhouse gas emissions, and health effects. Here we report the findings of a qualitative, cross-national deliberation study of public perceptions of shale development in UK and US locations not yet subject to extensive shale development. When presented with a carefully calibrated range of risks and benefits, participants' discourse focused on risks or doubts about benefits, and potential impacts were viewed as inequitably distributed. Participants drew on direct, place-based experiences as well as national contexts in deliberating shale development. These findings suggest that shale gas development already evokes a similar 'signature' of risk across the US and UK.

Total petroleum system assessment of undiscovered resources in the giant Barnett Shale continuous (unconventional) gas accumulation, Fort Worth Basin, Texas

USGS Publications Warehouse

Pollastro, R.M.

2007-01-01

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

Estimating emissions of toxic hydrocarbons from natural gas production sites in the Barnett Shale region

NASA Astrophysics Data System (ADS)

Marrero, J. E.; Townsend-Small, A.; Lyon, D. R.; Tsai, T.; Meinardi, S.; Blake, D. R.

2015-12-01

Throughout the past decade, shale gas operations have moved closer to urban centers and densely populated areas, contributing to growing public concerns regarding exposure to hazardous air pollutants (HAPs). These HAPs include gases like hexane, 1,3-butadiene and BTEX compounds, which can cause minor health effects from short-term exposure or possibly cancer due to prolonged exposure. During the Barnett Shale Coordinated Campaign in October, 2013, ground-based whole air samples revealed enhancements in several of these toxic volatile organic compounds (VOCs) downwind of natural gas well pads and compressor stations. Two methods were used to estimate the emission rate of several HAPs in the Barnett Shale. The first method utilized CH4 flux measurements derived from the Picarro Mobile Flux Plane (MFP) and taken concurrently with whole air samples, while the second used a CH4 emissions inventory developed for the Barnett Shale region. From these two approaches, the regional emission estimate for benzene (C6H6) ranged from 48 ± 16 to 84 ± 26 kg C6H6 hr-1. A significant regional source of atmospheric benzene is evident, despite measurement uncertainty and limited number of samples. The extent to which these emission rates equate to a larger public health risk is unclear, but is of particular interest as natural gas productions continues to expand.

Modeling of Methane Migration in Shallow Aquifers from Shale Gas Well Drilling.

PubMed

Zhang, Liwei; Soeder, Daniel J

2016-05-01

The vertical portion of a shale gas well, known as the "tophole" is often drilled using an air-hammer bit that may introduce pressures as high as 2400 kPa (350 psi) into groundwater while penetrating shallow aquifers. A 3-D TOUGH2 model was used to simulate the flow of groundwater under the high hydraulic heads that may be imposed by such trapped compressed air, based on an observed case in West Virginia (USA) in 2012. The model realizations show that high-pressure air trapped in aquifers may cause groundwater to surge away from the drill site at observable velocities. If dissolved methane is present within the aquifer, the methane can be entrained and transported to a maximum distance of 10.6 m per day. Results from this study suggest that one cause of the reported increase in methane concentrations in groundwater near shale gas production wells may be the transport of pre-existing methane via groundwater surges induced by air drilling, not necessarily direct natural gas leakage from the unconventional gas reservoir. The primary transport mechanisms are advective transport of dissolved methane with water flow, and diffusive transport of dissolved methane. © 2015, National Ground Water Association.

Estimation of brittleness indices for pay zone determination in a shale-gas reservoir by using elastic properties obtained from micromechanics

NASA Astrophysics Data System (ADS)

Lizcano-Hernández, Edgar G.; Nicolás-López, Rubén; Valdiviezo-Mijangos, Oscar C.; Meléndez-Martínez, Jaime

2018-04-01

The brittleness indices (BI) of gas-shales are computed by using their effective mechanical properties obtained from micromechanical self-consistent modeling with the purpose of assisting in the identification of the more-brittle regions in shale-gas reservoirs, i.e., the so-called ‘pay zone’. The obtained BI are plotted in lambda-rho versus mu-rho λ ρ -μ ρ and Young’s modulus versus Poisson’s ratio E-ν ternary diagrams along with the estimated elastic properties from log data of three productive shale-gas wells where the pay zone is already known. A quantitative comparison between the obtained BI and the well log data allows for the delimitation of regions where BI values could indicate the best reservoir target in regions with the highest shale-gas exploitation potential. Therefore, a range of values for elastic properties and brittleness indexes that can be used as a data source to support the well placement procedure is obtained.

Characterizing the Noble Gas Isotopic Composition of the Barnett Shale and Strawn Group and Constraining the Source of Stray Gas in the Trinity Aquifer, North-Central Texas.

PubMed

Wen, Tao; Castro, M Clara; Nicot, Jean-Philippe; Hall, Chris M; Pinti, Daniele L; Mickler, Patrick; Darvari, Roxana; Larson, Toti

2017-06-06

This study presents the complete set of stable noble gases for Barnett Shale and Strawn Group production gas together with stray flowing gas in the Trinity Aquifer, Texas. It places new constraints on the source of this stray gas and further shows that Barnett and Strawn gas have distinct crustal and atmospheric noble gas signatures, allowing clear identification of these two sources. Like stray gas, Strawn gas is significantly more enriched in crustal 4 He*, 21 Ne*, and 40 Ar* than Barnett gas. The similarity of Strawn and stray gas crustal noble gas signatures suggests that the Strawn is the source of stray gas in the Trinity Aquifer. Atmospheric 22 Ne/ 36 Ar ratios of stray gas mimic also that of Strawn, further reinforcing the notion that the source of stray gas in this aquifer is the Strawn. While noble gas signatures of Strawn and stray gas are consistent with a single-stage water degassing model, a two-stage oil modified groundwater exsolution fractionation model is required to explain the light atmospheric noble gas signature of Barnett Shale production gas. These distinct Strawn and Barnett noble gas signatures are likely the reflection of distinct evolution histories with Strawn gas being possibly older than that of Barnett Shale.

An evaluation of water quality in private drinking water wells near natural gas extraction sites in the Barnett Shale formation.

PubMed

Fontenot, Brian E; Hunt, Laura R; Hildenbrand, Zacariah L; Carlton, Doug D; Oka, Hyppolite; Walton, Jayme L; Hopkins, Dan; Osorio, Alexandra; Bjorndal, Bryan; Hu, Qinhong H; Schug, Kevin A

2013-09-03

Natural gas has become a leading source of alternative energy with the advent of techniques to economically extract gas reserves from deep shale formations. Here, we present an assessment of private well water quality in aquifers overlying the Barnett Shale formation of North Texas. We evaluated samples from 100 private drinking water wells using analytical chemistry techniques. Analyses revealed that arsenic, selenium, strontium and total dissolved solids (TDS) exceeded the Environmental Protection Agency's Drinking Water Maximum Contaminant Limit (MCL) in some samples from private water wells located within 3 km of active natural gas wells. Lower levels of arsenic, selenium, strontium, and barium were detected at reference sites outside the Barnett Shale region as well as sites within the Barnett Shale region located more than 3 km from active natural gas wells. Methanol and ethanol were also detected in 29% of samples. Samples exceeding MCL levels were randomly distributed within areas of active natural gas extraction, and the spatial patterns in our data suggest that elevated constituent levels could be due to a variety of factors including mobilization of natural constituents, hydrogeochemical changes from lowering of the water table, or industrial accidents such as faulty gas well casings.

Beyond Consultation: First Nations and the Governance of Shale Gas in British Columbia

NASA Astrophysics Data System (ADS)

Garvie, Kathryn Henderson

As the province of British Columbia seeks to rapidly develop an extensive natural gas industry, it faces a number of challenges. One of these is that of ensuring that development does not disproportionately impact some of the province's most marginalized communities: the First Nations on whose land extraction will take place. This is particularly crucial given that environmental problems are often caused by unjust and inequitable social conditions that must be rectified before sustainable development can be advanced. This research investigates how the BC Oil and Gas Commission's consultation process addresses, and could be improved to better address Treaty 8 First Nations' concerns regarding shale gas development within their traditional territories. Interviews were conducted with four Treaty 8 First Nations, the Treaty 8 Tribal Association, and provincial government and industry staff. Additionally, participant observation was conducted with the Fort Nelson First Nation Lands and Resources Department. Findings indicate that like many other resource consultation processes in British Columbia, the oil and gas consultation process is unable to meaningfully address First Nations' concerns and values due to fundamental procedural problems, including the permit-by-permit approach and the exclusion of First Nations from the point of decision-making. Considering the government's failure to regulate the shale gas industry in a way that protects ecological, social and cultural resilience, we argue that new governance mechanisms are needed that reallocate authority to First Nations and incorporate proposals for early engagement, long-term planning and cumulative impact assessment and monitoring. Additionally, considering the exceptional power differential between government, industry and First Nations, we argue that challenging industry's social license to operate is an important strategy for First Nations working to gain greater influence over development within their

Shale Gas Development Requires Bipartisan Path Forward, U.S. Senator Wyden Urges

NASA Astrophysics Data System (ADS)

Showstack, Randy

2013-08-01

"How do we work in a bipartisan way to lock in the lead that the country has with respect to natural gas and win all the gold that we want in the economic Olympic games?" That is a question U.S. Sen. Ron Wyden (D-Oreg.) posed during his keynote address at a 25 July forum in Washington, D. C., on the future of shale gas development.

Organoporosity Evaluation of Shale: A Case Study of the Lower Silurian Longmaxi Shale in Southeast Chongqing, China

PubMed Central

Chen, Fangwen; Lu, Shuangfang; Ding, Xue

2014-01-01

The organopores play an important role in determining total volume of hydrocarbons in shale gas reservoir. The Lower Silurian Longmaxi Shale in southeast Chongqing was selected as a case to confirm the contribution of organopores (microscale and nanoscale pores within organic matters in shale) formed by hydrocarbon generation to total volume of hydrocarbons in shale gas reservoir. Using the material balance principle combined with chemical kinetics methods, an evaluation model of organoporosity for shale gas reservoirs was established. The results indicate that there are four important model parameters to consider when evaluating organoporosity in shale: the original organic carbon (w(TOC0)), the original hydrogen index (I H0), the transformation ratio of generated hydrocarbon (F(R o)), and the organopore correction coefficient (C). The organoporosity of the Lower Silurian Longmaxi Shale in the Py1 well is from 0.20 to 2.76%, and the average value is 1.25%. The organoporosity variation trends and the residual organic carbon of Longmaxi Shale are consistent in section. The residual organic carbon is indicative of the relative levels of organoporosity, while the samples are in the same shale reservoirs with similar buried depths. PMID:25184155

Shale gas development effects on the songbird community in a central Appalachian forest

USGS Publications Warehouse

Farwell, Laura S.; Wood, Petra; Sheehan, James; George, Gregory A.

2016-01-01

In the last decade, unconventional drilling for natural gas from the Marcellus-Utica shale has increased exponentially in the central Appalachians. This heavily forested region contains important breeding habitat for many neotropical migratory songbirds, including several species of conservation concern. Our goal was to examine effects of unconventional gas development on forest habitat and breeding songbirds at a predominantly forested site from 2008 to 2015. Construction of gas well pads and infrastructure (e.g., roads, pipelines) contributed to an overall 4.5% loss in forest cover at the site, a 12.4% loss in core forest, and a 51.7% increase in forest edge density. We evaluated the relationship between land-cover metrics and species richness within three avian guilds: forest-interior, early-successional, and synanthropic, in addition to abundances of 21 focal species. Land-cover impacts were evaluated at two spatial extents: a point-level within 100-m and 500-m buffers of each avian survey station, and a landscape-level across the study area (4326 ha). Although we observed variability in species-specific responses, we found distinct trends in long-term response among the three avian guilds. Forest-interior guild richness declined at all points across the site and at points impacted within 100 m by shale gas but did not change at unimpacted points. Early-successional and synanthropic guild richness increased at all points and at impacted points. Our results suggest that shale gas development has the potential to fragment regional forests and alter avian communities, and that efforts to minimize new development in core forests will reduce negative impacts to forest dependent species.

A critical review of the risks to water resources from unconventional shale gas development and hydraulic fracturing in the United States.

PubMed

Vengosh, Avner; Jackson, Robert B; Warner, Nathaniel; Darrah, Thomas H; Kondash, Andrew

2014-01-01

The rapid rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded the extraction of hydrocarbon resources in the U.S. The rise of shale gas development has triggered an intense public debate regarding the potential environmental and human health effects from hydraulic fracturing. This paper provides a critical review of the potential risks that shale gas operations pose to water resources, with an emphasis on case studies mostly from the U.S. Four potential risks for water resources are identified: (1) the contamination of shallow aquifers with fugitive hydrocarbon gases (i.e., stray gas contamination), which can also potentially lead to the salinization of shallow groundwater through leaking natural gas wells and subsurface flow; (2) the contamination of surface water and shallow groundwater from spills, leaks, and/or the disposal of inadequately treated shale gas wastewater; (3) the accumulation of toxic and radioactive elements in soil or stream sediments near disposal or spill sites; and (4) the overextraction of water resources for high-volume hydraulic fracturing that could induce water shortages or conflicts with other water users, particularly in water-scarce areas. Analysis of published data (through January 2014) reveals evidence for stray gas contamination, surface water impacts in areas of intensive shale gas development, and the accumulation of radium isotopes in some disposal and spill sites. The direct contamination of shallow groundwater from hydraulic fracturing fluids and deep formation waters by hydraulic fracturing itself, however, remains controversial.

Removal of calcium and magnesium ions from shale gas flowback water by chemically activated zeolite.

PubMed

Chang, Haiqing; Liu, Teng; He, Qiping; Li, Duo; Crittenden, John; Liu, Baicang

2017-07-01

Shale gas has become a new sweet spot of global oil and gas exploration, and the large amount of flowback water produced during shale gas extraction is attracting increased attention. Internal recycling of flowback water for future hydraulic fracturing is currently the most effective, and it is necessary to decrease the content of divalent cations for eliminating scaling and maintaining effectiveness of friction reducer. Zeolite has been widely used as a sorbent to remove cations from wastewater. This work was carried out to investigate the effects of zeolite type, zeolite form, activation chemical, activation condition, and sorption condition on removal of Ca 2+ and Mg 2+ from shale gas flowback water. Results showed that low removal of Ca 2+ and Mg 2+ was found for raw zeolite 4A and zeolite 13X, and the efficiency of the mixture of both zeolites was slightly higher. Compared with the raw zeolites, the zeolites after activation using NaOH and NaCl greatly improved the sorption performance, and there was no significant difference between dynamic activation and static activation. Dynamic sorption outperformed static sorption, the difference exceeding 40% and 7-70% for removal of Ca 2+ and Mg 2+ , respectively. Moreover, powdered zeolites outperformed granulated zeolites in divalent cation removal.

CBD Fare-Free Transit Service in Albany, New York

DOT National Transportation Integrated Search

1981-12-01

The report presents an evaluation of the impacts associated with the implementation of fare-free transit service in the Central Business District (CBD) of Albany, New York. The Albany demonstration began in November 1978; fares were eliminated for tr...

Environmental security control of resource utilization of shale gas' drilling cuttings containing heavy metals.

PubMed

Wang, Chao-Qiang; Lin, Xiao-Yan; Zhang, Chun; Mei, Xu-Dong

2017-09-01

The overall objective of this research project was to investigate the heavy metals environmental security control of resource utilization of shale gas' drilling cuttings. To achieve this objective, we got through theoretical calculation and testing, ultimately and preliminarily determine the content of heavy metals pollutants, and compared with related standards at domestically and abroad. The results indicated that using the second Fike's law, the theoretical model of the release amount of heavy metal can be made, and the groundwater environmental risk as main point compared with soil. This study can play a role of standard guidance on environmental security control of drilling cuttings resource utilization by the exploration and development of shale gas in our country.

Experimental research of gas shale electrical properties by NMR and the combination of imbibition and drainage

NASA Astrophysics Data System (ADS)

Dong, Xu; Sun, Jianmeng; Li, Jun; Gao, Hui; Liu, Xuefeng; Wang, Jinjie

2015-08-01

Gas shale has shown considerable force in gas production worldwide, but little attention has been paid to its electrical properties, which are essential for reservoir evaluation and differentiating absorbed gas and free gas. In this study, experiments are designed to research water saturation establishment methods and electrical properties of gas shale. Nuclear magnetic resonance (NMR) with short echo space (TE) is used to identify water saturation and distribution of saturated pores which contribute to the conductivity. The experimental results indicate that NMR with shorter TE can estimate porosity and fluid distribution better than NMR with longer TE. A full range of water saturation is established by the combination of new-type spontaneous imbibition and semi-permeable plate drainage techniques. Spontaneous imbibition gains water saturation from 0% to near irreducible water saturation, and, semi-permeable plate drainage desaturates from 100% to irreducible water saturation. The RI-Sw curve shows a nonlinear relationship, and can be divided into three parts with different behaviors. The comparative analysis of transverse relaxation time (T2) distribution and RI-Sw curves, indicates that free water, and water trapped by capillarity in the non-clay matrix, differ in terms of electrical conductivity from water absorbed in clay. The new experiments prove the applicability of imbibition, drainage and NMR in investigating electrical properties of gas shale and differentiating fluid distribution which makes contribution to conductivity.

Assessment of Paleozoic shale gas resources in the Sichuan Basin of China, 2015

USGS Publications Warehouse

Potter, Christopher J.; Schenk, Christopher J.; Charpentier, Ronald R.; Gaswirth, Stephanie B.; Klett, Timothy R.; Leathers, Heidi M.; Brownfield, Michael E.; Mercier, Tracey J.; Tennyson, Marilyn E.; Pitman, Janet K.

2015-10-14

Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 23.9 trillion cubic feet of technically recoverable shale gas resources in Paleozoic formations in the Sichuan Basin of China.

Paper 5991: How Much Gas, Condensate, and Oil Will be Produced from Major Shale Plays in the U.S., and Why?

NASA Astrophysics Data System (ADS)

Marder, M. P.; Patzek, T. W.

2014-12-01

A one-dimensional universal model of gas inflow into the hydrofractured horizontal wells (Patzek, et al., PNAS, 110, 2013) was developed for the Barnett shale, and applied to explain historical production and predict future production in 8294 wells there. Subsequently, this model was extended and applied to 3756 wells in the Fayetteville shale, 2199 wells in the Haynesville shale, and 2764 wells in the Marcellus shale. Out of these, 2057, 703, 1515, and 1063 wells in the Barnett, Fayetteville, Haynesville, and Marcellus, respectively, show evidence of pressure interference between consecutive hydrofractures. For the interfering wells, we calculate their EURs and the distributions of effective gas permeability in the reservoir volumes influenced by these wells. For the non-interfering wells we calculate the lower and upper bounds on their EURs. We show that given the available data, a better field-wide prediction of EUR is impossible. The expected EURs vary between 0.4 and 4.3 Bscf in the Barnett, depending on the well quality. In the other shales the expected well EURs are 0.5 - 3.4 Bcf in the Fayetteville, 1.4 - 7.9 Bcf in the Haynesville, and 1 - 9 Bcf in the Marcellus. The respective mean effective gas permeabilities are 400, 1000, 230, and 800 nanodarcy for the same shales, much high than the core values. Work on the Eagle Ford shale is in progress and will be presented in December. In a shale- horizontal well system, we model rectilinear flow of natural gas as dimensionless nonlinear pseudo-pressure diffusion IVBP with gas sorption on the rock and the multiple planar hydrofractures acting as internal sorbing boundaries. After the initial choked flow, wells must decline as the inverse of the square root of time on production, until the gas pressure starts declining at the midplane of a reservoir cell between two consecutive hydrofractures. At this point of time production decline is exponential. The transition between the square-root-of-time and exponential

Time-dependent deformation of gas shales - role of rock framework versus reservoir fluids

NASA Astrophysics Data System (ADS)

Hol, Sander; Zoback, Mark

2013-04-01

Hydraulic fracturing operations are generally performed to achieve a fast, drastic increase of permeability and production rates. Although modeling of the underlying short-term mechanical response has proven successful via conventional geomechanical approaches, predicting long-term behavior is still challenging as the formation interacts physically and chemically with the fluids present in-situ. Recent experimental work has shown that shale samples subjected to a change in effective stress deform in a time-dependent manner ("creep"). Although the magnitude and nature of this behavior is strongly related to the composition and texture of the sample, also the choice of fluid used in the experiments affects the total strain response - strongly adsorbing fluids result in more, recoverable creep. The processes underlying time-dependent deformation of shales under in-situ stresses, and the long-term impact on reservoir performance, are at present poorly understood. In this contribution, we report triaxial mechanical tests, and theoretical/thermodynamic modeling work with the aim to identify and describe the main mechanisms that control time-dependent deformation of gas shales. In particular, we focus on the role of the shale solid framework versus the type and pressure of the present pore fluid. Our experiments were mainly performed on Eagle Ford Shale samples. The samples were subjected to cycles of loading and unloading, first in the dry state, and then again after equilibrating them with (adsorbing) CO2 and (non-adsorbing) He at fluid pressures of 4 MPa. Stresses were chosen close to those persisting under in-situ conditions. The results of our tests demonstrate that likely two main types of deformation mechanisms operate that relate to a) the presence of microfractures as a dominating feature in the solid framework of the shale, and b) the adsorbing potential of fluids present in the nanoscale voids of the shale. To explain the role of adsorption in the observed

Malignant human cell transformation of Marcellus Shale gas drilling flow back water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Yixin; Department of Environmental Medicine, New York University School of Medicine, Tuxedo, NY 10987; Chen, Tingting

The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation are known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these wastewaters, flow back waters from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of these samples was analyzed by inductively coupled plasma mass spectrometry and scanning electron microscopy/energy dispersive X-ray spectroscopy. A cytotoxicity study using colony formation as the endpoint was carriedmore » out to define the LC{sub 50} values of test samples using human bronchial epithelial cells (BEAS-2B). The BEAS-2B cell transformation assay was employed to assess the carcinogenic potential of the samples. Barium and strontium were among the most abundant metals in these samples and the same metals were found to be elevated in BEAS-2B cells after long-term treatment. BEAS-2B cells treated for 6 weeks with flow back waters produced colony formation in soft agar that was concentration dependent. In addition, flow back water-transformed BEAS-2B cells show better migration capability when compared to control cells. This study provides information needed to assess the potential health impact of post-hydraulic fracturing flow back waters from Marcellus Shale natural gas mining. - Highlights: • This is the first report of potential cytotoxicity and transforming activity of Marcellus shale gas mining flow back to mammalian cells. • Barium and Strontium were elevated in flow back water exposed cells. • Flow back water malignantly transformed cells and formed tumor in athymic nude mice. • Flow back transformed cells exhibited altered transcriptome with dysregulated cell migration pathway and adherent junction pathway.« less

Risk and resilience in the shale gas context: a nexus perspective

NASA Astrophysics Data System (ADS)

Rosales, T. Y.; Notte, C. A.; Allen, D. M.; Kirste, D. M.

2014-12-01

The accelerated exploration for and development of unconventional gas plays around the world has raised public concern about potential risks to human health and the environment. In this study, a risk assessment framework specific to shale gas development is proposed. The framework aims to quantify and/or qualify both risk and resilience within a water-energy nexus context, using a comprehensive approach that considers environment, health and policy. The risk assessment framework is intended to be flexible so that it can be used in different regions, but will be tested in North East British Columbia, Canada where shale gas development is rapidly expanding. The main components of risk include hazards, susceptibility and potential consequences, which will be evaluated in space and time using ArcGIS software. The hazards are associated with all phases of shale gas development and include: water, air, and soil contamination; water use (surface and groundwater), and land use disturbance, and their assessment will take into account where they may occur, their frequency, duration and magnitude. Hazard-specific susceptibility maps will be generated based on the physical characteristics of the environment (e.g. soil, geology, hydrology, topography) as well as water source information (e.g. well locations), community footprints, etc. When combined with an evaluation of potential consequences, the resulting set of spatial risk maps can then be used for water resource management, land use planning, and industry permitting. Resilience, which buffers risk, here considers the existing regulatory framework and whether or not existing regulations can mitigate risk by reducing the hazard potential or consequences. The study considers how regulations may fully, partially, or inadequately mitigate the consequences of a given hazard. If development is to continue at its current pace in North East BC, it is imperative that decision-makers recognize the changing risk and resilience

Volatile Organic Compound Emissions from Natural Gas Facilities in the Denver-Julesburg Basin, the Uintah Basin and the Marcellus Shale

NASA Astrophysics Data System (ADS)

Li, X.; Omara, M.; Sullivan, M.; Subramanian, R.; Robinson, A. L.; Presto, A. A.

2015-12-01

Natural gas has been widely considered as a "bridge" fuel in the future. Because of the rapid advancement of horizontal drilling and hydraulic fracturing techniques, the production of crude oil and natural gas in US increased dramatically in recent years; and currently natural gas contributes to about 25% of total US energy consumption. Recent studies suggest that shale gas extraction facilities may emit Volatile Organic Compounds (VOCs), which could contribute to the formation of ozone and affect regional air quality, public health and climate change. In this study we visited 37 natural gas facilities in Denver-Julesburg and Uintah Basins from March to May, 2015. VOCs and methane concentrations were measured downwind of individual facilities with our mobile lab. In total 13 VOCs, including benzene and toluene, were measured by a SRI 8610C Gas Chromatograph. Similar measurements will be conducted in the Marcellus Shale in late August 2015. Preliminary results show that VOC emissions from individual shale gas facilities are variable, which suggests that a single VOC profile may not characterize all natural gas production facilities, though there may be some common characteristics. Measured VOC concentrations will be normalized to concurrently-measured methane emissions, and coupled with methane emission rates measured at these facilities, used to obtain VOC emission factors from natural gas production. This presentation will also compare VOC emission rates from the Marcellus shale with that from the Denver-Julesburg and Uintah basins.

Lattice Boltzmann Simulation of Shale Gas Transport in Organic Nano-Pores

PubMed Central

Zhang, Xiaoling; Xiao, Lizhi; Shan, Xiaowen; Guo, Long

2014-01-01

Permeability is a key parameter for investigating the flow ability of sedimentary rocks. The conventional model for calculating permeability is derived from Darcy's law, which is valid only for continuum flow in porous rocks. We discussed the feasibility of simulating methane transport characteristics in the organic nano-pores of shale through the Lattice Boltzmann method (LBM). As a first attempt, the effects of high Knudsen number and the associated slip flow are considered, whereas the effect of adsorption in the capillary tube is left for future work. Simulation results show that at small Knudsen number, LBM results agree well with Poiseuille's law, and flow rate (flow capacity) is proportional to the square of the pore scale. At higher Knudsen numbers, the relaxation time needs to be corrected. In addition, velocity increases as the slip effect causes non negligible velocities on the pore wall, thereby enhancing the flow rate inside the pore, i.e., the permeability. Therefore, the LBM simulation of gas flow characteristics in organic nano-pores provides an effective way of evaluating the permeability of gas-bearing shale. PMID:24784022

Methane Occurrence in a Drinking Water Aquifer Before and During Natural Gas Production from the Marcellus Shale

NASA Astrophysics Data System (ADS)

Saiers, J. E.; Barth-Naftilan, E.

2017-12-01

More than 4,000 thousand wells have punctured aquifers of Pennsylvania's northern tier to siphon natural gas from the underlying Marcellus Shale. As drilling and hydraulic fracturing ramped up a decade ago, homeowner reports of well water contamination by methane and other contaminants began to emerge. Although made infrequently compared to the number of gas wells drilled, these reports were troubling and motivated our two-year, prospective study of groundwater quality within the Marcellus Shale Play. We installed multi-level sampling wells within a bedrock aquifer of a 25 km2 area that was targeted for shale gas development. These wells were sampled on a monthly basis before, during, and after seven shale gas wells were drilled, hydraulically fractured, and placed into production. The groundwater samples, together with surface water samples collected from nearby streams, were analyzed for hydrocarbons, trace metals, major ions, and the isotopic compositions of methane, ethane, water, strontium, and dissolved inorganic carbon. With regard to methane in particular, concentrations ranged from under 0.1 to over 60 mg/L, generally increased with aquifer depth, and, at some sites, exhibited considerable temporal variability. The isotopic composition of methane and hydrocarbon ratios also spanned a large range, suggesting that methane origins are diverse and, notably, shift on the time scale of this study. We will present inferences on factors governing methane occurrence across our study area by interpreting time-series data on methane concentrations and isotopic composition in context of local hydrologic variation, companion measurements of groundwater chemistry, and the known timing of key stages of natural gas extraction.

Composition of pyrolysis gas from oil shale at various stages of heating

NASA Astrophysics Data System (ADS)

Martemyanov, S. M.; Bukharkin, A. A.; Koryashov, I. A.; Ivanov, A. A.

2017-05-01

Underground, the pyrolytic conversion of an oil shale in the nearest future may become an alternative source of a fuel gas and a synthetic oil. The main scientific problem in designing this technology is to provide a methodology for determination of the optimal mode of heating the subterranean formation. Such a methodology must allow predicting the composition of the pyrolysis products and the energy consumption at a given heating rate of the subterranean formation. The paper describes the results of heating of the oil shale fragments in conditions similar to the underground. The dynamics of composition of the gaseous products of pyrolysis are presented and analyzed.

Gas occurrence property in shales of Tuha basin northwest china

NASA Astrophysics Data System (ADS)

Chen, Jinlong; Huang, Zhilong

2017-04-01

Pore of rock under formation condition must be fulfilled by gas, oil, or water, so the volume of water and gas is equation to porous volume in shale gas. The occurrences states of gas are free gas, solution gas, and absorbed gas. Field analysis is used to obtain total gas content by improved lost gas recover method. Free gas content acquired by pore proportion of gas, which use measured pore volume minus water and oil saturation, convert gas content of standard condition by state equation. Water saturation obtain from core water content, oil saturation obtain from extract carbohydrate. Solution gas need gas solubility in oil and water to calculate solution gas content in standard condition. Absorbed gas, introduce Absorbed Gas Saturation ɛ, which acquire from isothermal adsorption volume vs field analysis gas content in many basins of published paper, need isothermal adsorption and Absorbed Gas Saturation to obtain absorbed gas content. All of the data build connect with logging value by regression equation. The gas content is 0.92-1.53 m3/t from field analysis, evaluate gas content is 1.33 m3/t average, free gas proportion is about 47%, absorbed gas counter for 49%, and solution gas is average 4%.

The economic impact of shale gas development on state and local economies: benefits, costs, and uncertainties.

PubMed

Barth, Jannette M

2013-01-01

It is often assumed that natural gas exploration and development in the Marcellus Shale will bring great economic prosperity to state and local economies. Policymakers need accurate economic information on which to base decisions regarding permitting and regulation of shale gas extraction. This paper provides a summary review of research findings on the economic impacts of extractive industries, with an emphasis on peer-reviewed studies. The conclusions from the studies are varied and imply that further research, on a case-by-case basis, is necessary before definitive conclusions can be made regarding both short- and long-term implications for state and local economies.

The geochemistry of naturally occurring methane and saline groundwater in an area of unconventional shale gas development

NASA Astrophysics Data System (ADS)

Harkness, Jennifer S.; Darrah, Thomas H.; Warner, Nathaniel R.; Whyte, Colin J.; Moore, Myles T.; Millot, Romain; Kloppmann, Wolfram; Jackson, Robert B.; Vengosh, Avner

2017-07-01

Since naturally occurring methane and saline groundwater are nearly ubiquitous in many sedimentary basins, delineating the effects of anthropogenic contamination sources is a major challenge for evaluating the impact of unconventional shale gas development on water quality. This study investigates the geochemical variations of groundwater and surface water before, during, and after hydraulic fracturing and in relation to various geospatial parameters in an area of shale gas development in northwestern West Virginia, United States. To our knowledge, we are the first to report a broadly integrated study of various geochemical techniques designed to distinguish natural from anthropogenic sources of natural gas and salt contaminants both before and after drilling. These measurements include inorganic geochemistry (major cations and anions), stable isotopes of select inorganic constituents including strontium (87Sr/86Sr), boron (δ11B), lithium (δ7Li), and carbon (δ13C-DIC), select hydrocarbon molecular (methane, ethane, propane, butane, and pentane) and isotopic tracers (δ13C-CH4, δ13C-C2H6), tritium (3H), and noble gas elemental and isotopic composition (helium, neon, argon) in 105 drinking-water wells, with repeat testing in 33 of the wells (total samples = 145). In a subset of wells (n = 20), we investigated the variations in water quality before and after the installation of nearby (<1 km) shale-gas wells. Methane occurred above 1 ccSTP/L in 37% of the groundwater samples and in 79% of the samples with elevated salinity (chloride > 50 mg/L). The integrated geochemical data indicate that the saline groundwater originated via naturally occurring processes, presumably from the migration of deeper methane-rich brines that have interacted extensively with coal lithologies. These observations were consistent with the lack of changes in water quality observed in drinking-water wells following the installation of nearby shale-gas wells. In contrast to groundwater

Assessment of freshwater withdrawals and availability for Marcellus shale natural gas development: a case study in Pennsylvania

Treesearch

Patrick C. Eisenhauer; Nicolas P. Zegre; Samuel J. Lamont

2013-01-01

To evaluate surface water withdrawals used for Marcellus shale natural gas development and to assess potential impacts on water yield, a regional water balance model was developed for the Pine Creek watershed, located primarily in Lycoming County, Pennsylvania. Marcellus shale development has increased rapidly in Lycoming County since 2007. We used precipitation,...

Water pollution risk associated with natural gas extraction from the Marcellus Shale.

PubMed

Rozell, Daniel J; Reaven, Sheldon J

2012-08-01

In recent years, shale gas formations have become economically viable through the use of horizontal drilling and hydraulic fracturing. These techniques carry potential environmental risk due to their high water use and substantial risk for water pollution. Using probability bounds analysis, we assessed the likelihood of water contamination from natural gas extraction in the Marcellus Shale. Probability bounds analysis is well suited when data are sparse and parameters highly uncertain. The study model identified five pathways of water contamination: transportation spills, well casing leaks, leaks through fractured rock, drilling site discharge, and wastewater disposal. Probability boxes were generated for each pathway. The potential contamination risk and epistemic uncertainty associated with hydraulic fracturing wastewater disposal was several orders of magnitude larger than the other pathways. Even in a best-case scenario, it was very likely that an individual well would release at least 200 m³ of contaminated fluids. Because the total number of wells in the Marcellus Shale region could range into the tens of thousands, this substantial potential risk suggested that additional steps be taken to reduce the potential for contaminated fluid leaks. To reduce the considerable epistemic uncertainty, more data should be collected on the ability of industrial and municipal wastewater treatment facilities to remove contaminants from used hydraulic fracturing fluid. © 2012 Society for Risk Analysis.

Organic substances in produced and formation water from unconventional natural gas extraction in coal and shale

USGS Publications Warehouse

Orem, William H.; Tatu, Calin A.; Varonka, Matthew S.; Lerch, Harry E.; Bates, Anne L.; Engle, Mark A.; Crosby, Lynn M.; McIntosh, Jennifer

2014-01-01

Organic substances in produced and formation water from coalbed methane (CBM) and gas shale plays from across the USA were examined in this study. Disposal of produced waters from gas extraction in coal and shale is an important environmental issue because of the large volumes of water involved and the variable quality of this water. Organic substances in produced water may be environmentally relevant as pollutants, but have been little studied. Results from five CBM plays and two gas shale plays (including the Marcellus Shale) show a myriad of organic chemicals present in the produced and formation water. Organic compound classes present in produced and formation water in CBM plays include: polycyclic aromatic hydrocarbons (PAHs), heterocyclic compounds, alkyl phenols, aromatic amines, alkyl aromatics (alkyl benzenes, alkyl biphenyls), long-chain fatty acids, and aliphatic hydrocarbons. Concentrations of individual compounds range from < 1 to 100 μg/L, but total PAHs (the dominant compound class for most CBM samples) range from 50 to 100 μg/L. Total dissolved organic carbon (TOC) in CBM produced water is generally in the 1–4 mg/L range. Excursions from this general pattern in produced waters from individual wells arise from contaminants introduced by production activities (oils, grease, adhesives, etc.). Organic substances in produced and formation water from gas shale unimpacted by production chemicals have a similar range of compound classes as CBM produced water, and TOC levels of about 8 mg/L. However, produced water from the Marcellus Shale using hydraulic fracturing has TOC levels as high as 5500 mg/L and a range of added organic chemicals including, solvents, biocides, scale inhibitors, and other organic chemicals at levels of 1000 s of μg/L for individual compounds. Levels of these hydraulic fracturing chemicals and TOC decrease rapidly over the first 20 days of water recovery and some level of residual organic contaminants remain up to 250 days after

Shale characterization on Barito field, Southeast Kalimantan for shale hydrocarbon exploration

NASA Astrophysics Data System (ADS)

Sumotarto, T. A.; Haris, A.; Riyanto, A.; Usman, A.

2017-07-01

Exploration and exploitation in Indonesia now are still focused on conventional hydrocarbon energy than unconventional hydrocarbon energy such as shale gas. Tanjung Formation is a source rock of Barito Basin located in South Kalimantan that potentially as shale hydrocarbon. In this research, integrated methods using geochemical analysis, mineralogy, petrophysical analysis and seismic interpretation has been applied to explore the shale hydrocarbon potential in Barito Field for Tanjung formation. The first step is conducting geochemical and mineralogy analysis to the shale rock sample. Our analysis shows that the organic richness is ranging from 1.26-5.98 wt.% (good to excellent) with the depth of early mature window of 2170 m. The brittleness index is in an average of 0.44-0.56 (less Brittle) and Kerogen type is classified into II/III type that potentially produces oil and gas. The second step is continued by performing petrophysical analysis, which includes Total Organic Carbon (TOC) calculation and brittleness index continuously. The result has been validated with a laboratory measurement that obtained a good correlation. In addition, seismic interpretation based on inverted acoustic impedance is applied to map the distributions of shale hydrocarbon potential. Our interpretation shows that shale hydrocarbon potential is localized in the eastern and southeastern part of the study area.

Eastern gas shales bibliography selected annotations: gas, oil, uranium, etc. Citations in bituminous shales worldwide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, V.S.

1980-06-01

This bibliography contains 2702 citations, most of which are annotated. They are arranged by author in numerical order with a geographical index following the listing. The work is international in scope and covers the early geological literature, continuing through 1979 with a few 1980 citations in Addendum II. Addendum I contains a listing of the reports, well logs and symposiums of the Unconventional Gas Recovery Program (UGR) through August 1979. There is an author-subject index for these publications following the listing. The second part of Addendum I is a listing of the UGR maps which also has a subject-author indexmore » following the map listing. Addendum II includes several important new titles on the Devonian shale as well as a few older citations which were not found until after the bibliography had been numbered and essentially completed. A geographic index for these citations follows this listing.« less

Mineral Reactions in Shale Gas Reservoirs: Barite Scale Formation from Reusing Produced Water As Hydraulic Fracturing Fluid.

PubMed

Paukert Vankeuren, Amelia N; Hakala, J Alexandra; Jarvis, Karl; Moore, Johnathan E

2017-08-15

Hydraulic fracturing for gas production is now ubiquitous in shale plays, but relatively little is known about shale-hydraulic fracturing fluid (HFF) reactions within the reservoir. To investigate reactions during the shut-in period of hydraulic fracturing, experiments were conducted flowing different HFFs through fractured Marcellus shale cores at reservoir temperature and pressure (66 °C, 20 MPa) for one week. Results indicate HFFs with hydrochloric acid cause substantial dissolution of carbonate minerals, as expected, increasing effective fracture volume (fracture volume + near-fracture matrix porosity) by 56-65%. HFFs with reused produced water composition cause precipitation of secondary minerals, particularly barite, decreasing effective fracture volume by 1-3%. Barite precipitation occurs despite the presence of antiscalants in experiments with and without shale contact and is driven in part by addition of dissolved sulfate from the decomposition of persulfate breakers in HFF at reservoir conditions. The overall effect of mineral changes on the reservoir has yet to be quantified, but the significant amount of barite scale formed by HFFs with reused produced water composition could reduce effective fracture volume. Further study is required to extrapolate experimental results to reservoir-scale and to explore the effect that mineral changes from HFF interaction with shale might have on gas production.

Dissolution of cemented fractures in gas bearing shales in the context of CO2 sequestration

NASA Astrophysics Data System (ADS)

Kwiatkowski, Kamil; Szymczak, Piotr

2016-04-01

Carbon dioxide has a stronger binding than methane to the organic matter contained in the matrix of shale rocks [1]. Thus, the injection of CO2 into shale formation may enhance the production rate and total amount of produced methane, and simultaneously permanently store pumped CO2. Carbon dioxide can be injected during the initial fracking stage as CO2 based hydraulic fracturing, and/or later, as a part of enhanced gas recovery (EGR) [2]. Economic and environmental benefits makes CO2 sequestration in shales potentially very for industrial-scale operation [3]. However, the effective process requires large area of fracture-matrix interface, where CO2 and CH4 can be exchanged. Usually natural fractures, existing in shale formation, are preferentially reactivated during hydraulic fracturing, thus they considerably contribute to the flow paths in the resulting fracture system [4]. Unfortunately, very often these natural fractures are sealed by calcite [5]. Consequently the layer of calcite coating surfaces impedes exchange of gases, both CO2 and CH4, between shale matrix and fracture. In this communication we address the question whether carbonic acid, formed when CO2 is mixed with brine, is able to effectively dissolve a calcite layer present in the natural fractures. We investigate numerically fluid flow and dissolution of calcite coating in natural shale fractures, with CO2-brine mixture as a reactive fluid. Moreover, we discuss the differences between slow dissolution (driven by carbonic acid) and fast dissolution (driven by stronger hydrochloric acid) of calcite layer. We compare an impact of the flow rate and geometry of the fracture on the parameters of practical importance: available surface area, morphology of dissolution front, time scale of the dissolution, and the penetration length. We investigate whether the dissolution is sufficiently non-uniform to retain the fracture permeability, even in the absence of the proppant. The sizes of analysed fractures

The Relationship between Marcellus Shale Gas Development in Pennsylvania and Local Perceptions of Risk and Opportunity

ERIC Educational Resources Information Center

Schafft, Kai A.; Borlu, Yetkin; Glenna, Leland

2013-01-01

Recent advances in gas and oil drilling technology have led to dramatic boomtown development in many rural areas that have endured extended periods of economic decline. In Pennsylvania's Marcellus gas fields, the recent development of unconventional shale gas resources has not been without controversy. It has been variously framed as a major…

The Shear Mechanisms of Natural Fractures during the Hydraulic Stimulation of Shale Gas Reservoirs.

PubMed

Zhang, Zhaobin; Li, Xiao

2016-08-23

The shearing of natural fractures is important in the permeability enhancement of shale gas reservoirs during hydraulic fracturing treatment. In this work, the shearing mechanisms of natural fractures are analyzed using a newly proposed numerical model based on the displacement discontinuities method. The fluid-rock coupling system of the model is carefully designed to calculate the shearing of fractures. Both a single fracture and a complex fracture network are used to investigate the shear mechanisms. The investigation based on a single fracture shows that the non-ignorable shearing length of a natural fracture could be formed before the natural fracture is filled by pressurized fluid. Therefore, for the hydraulic fracturing treatment of the naturally fractured shale gas reservoirs, the shear strength of shale is generally more important than the tensile strength. The fluid-rock coupling propagation processes of a complex fracture network are simulated under different crustal stress conditions and the results agree well with those of the single fracture. The propagation processes of complex fracture network show that a smaller crustal stress difference is unfavorable to the shearing of natural fractures, but is favorable to the formation of complex fracture network.

The Shear Mechanisms of Natural Fractures during the Hydraulic Stimulation of Shale Gas Reservoirs

PubMed Central

Zhang, Zhaobin; Li, Xiao

2016-01-01

The shearing of natural fractures is important in the permeability enhancement of shale gas reservoirs during hydraulic fracturing treatment. In this work, the shearing mechanisms of natural fractures are analyzed using a newly proposed numerical model based on the displacement discontinuities method. The fluid-rock coupling system of the model is carefully designed to calculate the shearing of fractures. Both a single fracture and a complex fracture network are used to investigate the shear mechanisms. The investigation based on a single fracture shows that the non-ignorable shearing length of a natural fracture could be formed before the natural fracture is filled by pressurized fluid. Therefore, for the hydraulic fracturing treatment of the naturally fractured shale gas reservoirs, the shear strength of shale is generally more important than the tensile strength. The fluid-rock coupling propagation processes of a complex fracture network are simulated under different crustal stress conditions and the results agree well with those of the single fracture. The propagation processes of complex fracture network show that a smaller crustal stress difference is unfavorable to the shearing of natural fractures, but is favorable to the formation of complex fracture network. PMID:28773834

Organic and inorganic composition and microbiology of produced waters from Pennsylvania shale gas wells

USGS Publications Warehouse

Akob, Denise M.; Cozzarelli, Isabelle M.; Dunlap, Darren S.; Rowan, Elisabeth L.; Lorah, Michelle M.

2015-01-01

Hydraulically fractured shales are becoming an increasingly important source of natural gas production in the United States. This process has been known to create up to 420 gallons of produced water (PW) per day, but the volume varies depending on the formation, and the characteristics of individual hydraulic fracture. PW from hydraulic fracturing of shales are comprised of injected fracturing fluids and natural formation waters in proportions that change over time. Across the state of Pennsylvania, shale gas production is booming; therefore, it is important to assess the variability in PW chemistry and microbiology across this geographical span. We quantified the inorganic and organic chemical composition and microbial communities in PW samples from 13 shale gas wells in north central Pennsylvania. Microbial abundance was generally low (66–9400 cells/mL). Non-volatile dissolved organic carbon (NVDOC) was high (7–31 mg/L) relative to typical shallow groundwater, and the presence of organic acid anions (e.g., acetate, formate, and pyruvate) indicated microbial activity. Volatile organic compounds (VOCs) were detected in four samples (∼1 to 11.7 μg/L): benzene and toluene in the Burket sample, toluene in two Marcellus samples, and tetrachloroethylene (PCE) in one Marcellus sample. VOCs can be either naturally occurring or from industrial activity, making the source of VOCs unclear. Despite the addition of biocides during hydraulic fracturing, H2S-producing, fermenting, and methanogenic bacteria were cultured from PW samples. The presence of culturable bacteria was not associated with salinity or location; although organic compound concentrations and time in production were correlated with microbial activity. Interestingly, we found that unlike the inorganic chemistry, PW organic chemistry and microbial viability were highly variable across the 13 wells sampled, which can have important implications for the reuse and handling of these fluids

RADON BASELINE MONITORING AROUND A POTENTIAL SHALE GAS DEVELOPMENT SITE IN YORKSHIRE, ENGLAND.

PubMed

Daraktchieva, Z; Wasikiewicz, J M; Howarth, C B; Bradley, E J

2017-11-01

The Vale of Pickering in Yorkshire, England has been identified as a potential area for shale gas extraction. Public Health England joined a collaboration led by the British Geological Survey for environmental baseline monitoring near the potential shale gas extraction site following a grant award from UK Government Department for Business, Energy and Industrial Strategy. The analysis of results for the first 6 months of indoor monitoring indicated that the results followed a log-normal distribution. The numbers of homes found to be at or above the Action Level followed the numbers predicted by the radon potential maps. The results from the measurements of outdoor air in this study indicated that the radon concentrations are slightly higher than previously measured but close to the detection limit of the technique. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Indirect heating pyrolysis of oil shale

DOEpatents

Jones, Jr., John B.; Reeves, Adam A.

1978-09-26

Hot, non-oxygenous gas at carefully controlled quantities and at predetermined depths in a bed of lump oil shale provides pyrolysis of the contained kerogen of the oil shale, and cool non-oxygenous gas is passed up through the bed to conserve the heat

Oil shale retort apparatus

DOEpatents

Reeves, Adam A.; Mast, Earl L.; Greaves, Melvin J.

1990-01-01

A retorting apparatus including a vertical kiln and a plurality of tubes for delivering rock to the top of the kiln and removal of processed rock from the bottom of the kiln so that the rock descends through the kiln as a moving bed. Distributors are provided for delivering gas to the kiln to effect heating of the rock and to disturb the rock particles during their descent. The distributors are constructed and disposed to deliver gas uniformly to the kiln and to withstand and overcome adverse conditions resulting from heat and from the descending rock. The rock delivery tubes are geometrically sized, spaced and positioned so as to deliver the shale uniformly into the kiln and form symmetrically disposed generally vertical paths, or "rock chimneys", through the descending shale which offer least resistance to upward flow of gas. When retorting oil shale, a delineated collection chamber near the top of the kiln collects gas and entrained oil mist rising through the kiln.

A Numerical Study of Factors Affecting Fracture-Fluid Cleanup and Produced Gas/Water in Marcellus Shale: Part II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seales, Maxian B.; Dilmore, Robert; Ertekin, Turgay

Horizontal wells combined with successful multi-stage hydraulic fracture treatments are currently the most established method for effectively stimulating and enabling economic development of gas bearing organic-rich shale formations. Fracture cleanup in the Stimulated Reservoir Volume (SRV) is critical to stimulation effectiveness and long-term well performance. However, fluid cleanup is often hampered by formation damage, and post-fracture well performance frequently falls below expectations. A systematic study of the factors that hinder fracture fluid cleanup in shale formations can help optimize fracture treatments and better quantify long term volumes of produced water and gas. Fracture fluid cleanup is a complex process influencedmore » by multi-phase flow through porous media (relative permeability hysteresis, capillary pressure etc.), reservoir rock and fluid properties, fracture fluid properties, proppant placement, fracture treatment parameters, and subsequent flowback and field operations. Changing SRV and fracture conductivity as production progresses further adds to the complexity of this problem. Numerical simulation is the best, and most practical approach to investigate such a complicated blend of mechanisms, parameters, their interactions, and subsequent impact on fracture fluid cleanup and well deliverability. In this paper, a 3-dimensional, 2-phase, dual-porosity model was used to investigate the impact of multiphase flow, proppant crushing, proppant diagenesis, shut-in time, reservoir rock compaction, gas slippage, and gas desorption on fracture fluid cleanup, and well performance in Marcellus shale. The research findings have shed light on the factors that substantially constrains efficient fracture fluid cleanup in gas shales, and provided guidelines for improved fracture treatment designs and water management.« less

A Numerical Study of Factors Affecting Fracture-Fluid Cleanup and Produced Gas/Water in Marcellus Shale: Part II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seales, Maxian B.; Dilmore, Robert; Ertekin, Turgay

Horizontal wells combined with successful multistage-hydraulic-fracture treatments are currently the most-established method for effectively stimulating and enabling economic development of gas-bearing organic-rich shale formations. Fracture cleanup in the stimulated reservoir volume (SRV) is critical to stimulation effectiveness and long-term well performance. But, fluid cleanup is often hampered by formation damage, and post-fracture well performance frequently falls to less than expectations. A systematic study of the factors that hinder fracture-fluid cleanup in shale formations can help optimize fracture treatments and better quantify long-term volumes of produced water and gas. Fracture-fluid cleanup is a complex process influenced by mutliphase flow through porousmore » media (relative permeability hysteresis, capillary pressure), reservoir-rock and -fluid properties, fracture-fluid properties, proppant placement, fracture-treatment parameters, and subsequent flowback and field operations. Changing SRV and fracture conductivity as production progresses further adds to the complexity of this problem. Numerical simulation is the best and most-practical approach to investigate such a complicated blend of mechanisms, parameters, their interactions, and subsequent effect on fracture-fluid cleanup and well deliverability. Here, a 3D, two-phase, dual-porosity model was used to investigate the effect of mutliphase flow, proppant crushing, proppant diagenesis, shut-in time, reservoir-rock compaction, gas slippage, and gas desorption on fracture-fluid cleanup and well performance in Marcellus Shale. Our findings have shed light on the factors that substantially constrain efficient fracture-fluid cleanup in gas shales, and we have provided guidelines for improved fracture-treatment designs and water management.« less

A Numerical Study of Factors Affecting Fracture-Fluid Cleanup and Produced Gas/Water in Marcellus Shale: Part II

DOE PAGES

Seales, Maxian B.; Dilmore, Robert; Ertekin, Turgay; ...

2017-04-01

Horizontal wells combined with successful multistage-hydraulic-fracture treatments are currently the most-established method for effectively stimulating and enabling economic development of gas-bearing organic-rich shale formations. Fracture cleanup in the stimulated reservoir volume (SRV) is critical to stimulation effectiveness and long-term well performance. But, fluid cleanup is often hampered by formation damage, and post-fracture well performance frequently falls to less than expectations. A systematic study of the factors that hinder fracture-fluid cleanup in shale formations can help optimize fracture treatments and better quantify long-term volumes of produced water and gas. Fracture-fluid cleanup is a complex process influenced by mutliphase flow through porousmore » media (relative permeability hysteresis, capillary pressure), reservoir-rock and -fluid properties, fracture-fluid properties, proppant placement, fracture-treatment parameters, and subsequent flowback and field operations. Changing SRV and fracture conductivity as production progresses further adds to the complexity of this problem. Numerical simulation is the best and most-practical approach to investigate such a complicated blend of mechanisms, parameters, their interactions, and subsequent effect on fracture-fluid cleanup and well deliverability. Here, a 3D, two-phase, dual-porosity model was used to investigate the effect of mutliphase flow, proppant crushing, proppant diagenesis, shut-in time, reservoir-rock compaction, gas slippage, and gas desorption on fracture-fluid cleanup and well performance in Marcellus Shale. Our findings have shed light on the factors that substantially constrain efficient fracture-fluid cleanup in gas shales, and we have provided guidelines for improved fracture-treatment designs and water management.« less

World Shale Resource Assessments

EIA Publications

2015-01-01

Four countries: Chad, Kazakhstan, Oman and the United Arab Emirates (UAE) have been added to report “Technically Recoverable Shale Oil and Shale Gas Resources.” The report provides an estimate of shale resources in selected basins around the world. The new chapters cover shale basins from the Sub-Saharan Africa region, represented by Chad; the Caspian region, represented by Kazakhstan; and the Middle East region, represented by Oman and the United Arab Emirates (UAE) and are available as supplemental chapters to the 2013 report.

Water use competition scenarios during the upcoming development of shale gas reserves across the Mexican Eagle Ford play Image already added

NASA Astrophysics Data System (ADS)

Arciniega, S.; Breña-Naranjo, J. A.; Hernaández Espriú, A.; Pedrozo-Acuña, A.

2017-12-01

Mexico has significant shale oil and gas resources mainly contained within the Mexican part of the Eagle Ford play (Mex-EF), in the Burgos Basin located in northern Mexico. Over the last years, concerns about the water use associated to shale gas development using hydraulic fracturing (HF) have been increasing in the United States and Canada. In Mexico, the recent approval of a new energy bill allows the exploration, development and production of shale gas reserves. However, several of the Mexican shale gas resources are located in water-limited environments, such as the Mex-EF. The lack of climate and hydrological gauging stations across this region constrains information about how much freshwater from surface and groundwater sources is available and whether its interannual water availability is sufficient to satisfy the water demand by other users (agricultural, urban) of the region This work projects the water availability across the Mex-EF and its water use derived from the expansion of unconventional gas developments over the next 15 years. Water availability is estimated using a water balance approach, where the irrigation's groundwater withdrawals time series were reconstructed using remote sensing products (vegetation index and hydrological outputs from LSMs) and validated with in situ observed water use at three different irrigation districts of the region. Water use for HF is inferred using type curves of gas production, flowback and produced (FP) water and curves of drilled wells per year from the US experience, mainly from the Texas-EF play. Scenarios that combine freshwater use and FP water use for HF are developed and the spatial distribution of HF well pads is projected using random samples with a range of wells' horizontal length. This proposed methodology can be applied in other shale formations of the world under water stress and it also helps to determine whether water scarcity can be a limiting factor for the shale gas industry over the next

Compaction bands in high temperature/pressure diagenetically altered unconventional shale gas reservoirs

NASA Astrophysics Data System (ADS)

Regenauer-Lieb, K.; Veveakis, M.; Poulet, T.

2014-12-01

Unconventional energy and mineral resources are typically trapped in a low porosity/permeability environment and are difficult to produce. An extreme end-member is the shale gas reservoir in the Cooper Basin (Australia) that is located at 3500-4000 m depth and ambient temperature conditions around 200oC. Shales of lacustrine origin (with high clay content) are diagenetically altered. Diagenesis involves fluid release mineral reactions of the general type Asolid ↔ Bsolid +Cfluid and switches on suddenly in the diagenetic window between 100-200oC. Diagenetic reactions can involve concentrations of smectite, aqueous silica compound, illite, potassium ions, aqueous silica, quartz, feldspar, kerogen, water and gas . In classical petroleum engineering such interlayer water/gas release reactions are considered to cause cementation and significantly reduce porosity and permeability. Yet in contradiction to the expected permeability reduction gas is successfully being produced. We propose that the success is based on the ductile equivalent of classical compaction bands in solid mechanics. The difference being that that the rate of the volumetric compaction is controlled by the diagenetic reactions. Ductile compaction bands are forming high porosity fluid channels rather than low porosity crushed grains in the solid mechanical equivalent. We show that this new type of volumetric instability appears in rate-dependent heterogenous materials as Cnoidal waves. These are nonlinear and exact periodic stationary waves, well known in the shallow water theory of fluid mechanics. Their distance is a direct function of the hydromechanical diffusivities. These instabilities only emerge in low permeability environment where the fluid diffusivity is about an order of magnitude lower than the mechanical loading. The instabilities are expected to be of the type as shown in the image below. The image shows a CT-scan of a laboratory experiment kindly provided by Papamichos (pers

Barnett Shale or Strawn Group: Identifying the Source of Stray Gas through Noble Gases in the Trinity Aquifer, North-Central Texas

NASA Astrophysics Data System (ADS)

Wen, T.; Castro, M. C.; Nicot, J. P.; Hall, C. M.; Pinti, D. L.; Mickler, P. J.; Darvari, R.; Larson, T. E.

2017-12-01

The complete set of stable noble gases (He, Ne, Ar, Kr, Xe) is presented for Barnett Shale and Strawn Group production gas together with that of stray flowing gas present in the Trinity Aquifer, Texas. It places new constraints on the source of this stray gas and further shows that Barnett and Strawn gas have distinct crustal and atmospheric noble gas signatures, allowing clear identification of these two sources. Like Trinity Aquifer stray gas, Strawn gas is significantly more enriched in crustal 4He*, 21Ne*, and 40Ar* than Barnett gas. The similarity of Strawn and stray gas crustal noble gas signatures suggests that the Strawn is the source of stray gas in the Trinity Aquifer. Atmospheric 22Ne/36Ar ratios of stray gas mimic also that of Strawn, further reinforcing the notion that the source of stray gas in this aquifer is the Strawn. While noble gas signatures of Strawn and stray gas are consistent with a single-stage water degassing model, a two-stage oil modified groundwater exsolution fractionation model is required to explain the light atmospheric noble gas signature of Barnett Shale production gas. These distinct Strawn and Barnett noble gas signatures are likely the reflection of distinct evolution histories with Strawn gas being possibly older than that of Barnett Shale.

Impact of emissions from natural gas production facilities on ambient air quality in the Barnett Shale area: a pilot study.

PubMed

Zielinska, Barbara; Campbell, Dave; Samburova, Vera

2014-12-01

Rapid and extensive development of shale gas resources in the Barnett Shale region of Texas in recent years has created concerns about potential environmental impacts on water and air quality. The purpose of this study was to provide a better understanding of the potential contributions of emissions from gas production operations to population exposure to air toxics in the Barnett Shale region. This goal was approached using a combination of chemical characterization of the volatile organic compound (VOC) emissions from active wells, saturation monitoring for gaseous and particulate pollutants in a residential community located near active gas/oil extraction and processing facilities, source apportionment of VOCs measured in the community using the Chemical Mass Balance (CMB) receptor model, and direct measurements of the pollutant gradient downwind of a gas well with high VOC emissions. Overall, the study results indicate that air quality impacts due to individual gas wells and compressor stations are not likely to be discernible beyond a distance of approximately 100 m in the downwind direction. However, source apportionment results indicate a significant contribution to regional VOCs from gas production sources, particularly for lower-molecular-weight alkanes (< C6). Although measured ambient VOC concentrations were well below health-based safe exposure levels, the existence of urban-level mean concentrations of benzene and other mobile source air toxics combined with soot to total carbon ratios that were high for an area with little residential or commercial development may be indicative of the impact of increased heavy-duty vehicle traffic related to gas production. Implications: Rapid and extensive development of shale gas resources in recent years has created concerns about potential environmental impacts on water and air quality. This study focused on directly measuring the ambient air pollutant levels occurring at residential properties located near

A microfluidic investigation of gas exsolution in glass and shale fracture networks

NASA Astrophysics Data System (ADS)

Porter, M. L.; Jimenez-Martinez, J.; Harrison, A.; Currier, R.; Viswanathan, H. S.

2016-12-01

Microfluidic investigations of pore-scale fluid flow and transport phenomena has steadily increased in recent years. In these investigations fluid flow is restricted to two-dimensions allowing for real-time visualization and quantification of complex flow and reactive transport behavior, which is difficult to obtain in other experimental systems. In this work, we describe a unique high pressure (up to 10.3 MPa) and temperature (up to 80 °C) microfluidics experimental system that allows us to investigate fluid flow and transport in geo-material (e.g., shale, Portland cement, etc.) micromodels. The use of geo-material micromodels allows us to better represent fluid-rock interactions including wettability, chemical reactivity, and nano-scale porosity at conditions representative of natural subsurface environments. Here, we present experimental results in fracture systems with applications to hydrocarbon mobility in fractured rocks. Complex fracture network patterns are derived from 3D x-ray tomography images of actual fractures created in shale rock cores. We use both shale and glass micromodels, allowing for a detailed comparison between flow phenomena in the different materials. We discuss results from two-phase gas (CO2 and N2) injection experiments designed to enhance oil recovery. In these experiments gas was injected into micromodels saturated with oil and allowed to soak for approximately 12 hours at elevated pressures. The pressure in the system was then decreased to atmospheric, causing the gas to expand and/or dissolve out of solution, subsequently mobilizing the oil. In addition to the experimental results, we present a relatively simple model designed to quantify the amount of oil mobilized as a function of decreasing system pressure. We will show comparisons between the experiments and model, and discuss the potential use of the model in field-scale reservoir simulations.

Enhanced formation of disinfection byproducts in shale gas wastewater-impacted drinking water supplies.

PubMed

Parker, Kimberly M; Zeng, Teng; Harkness, Jennifer; Vengosh, Avner; Mitch, William A

2014-10-07

The disposal and leaks of hydraulic fracturing wastewater (HFW) to the environment pose human health risks. Since HFW is typically characterized by elevated salinity, concerns have been raised whether the high bromide and iodide in HFW may promote the formation of disinfection byproducts (DBPs) and alter their speciation to more toxic brominated and iodinated analogues. This study evaluated the minimum volume percentage of two Marcellus Shale and one Fayetteville Shale HFWs diluted by fresh water collected from the Ohio and Allegheny Rivers that would generate and/or alter the formation and speciation of DBPs following chlorination, chloramination, and ozonation treatments of the blended solutions. During chlorination, dilutions as low as 0.01% HFW altered the speciation toward formation of brominated and iodinated trihalomethanes (THMs) and brominated haloacetonitriles (HANs), and dilutions as low as 0.03% increased the overall formation of both compound classes. The increase in bromide concentration associated with 0.01-0.03% contribution of Marcellus HFW (a range of 70-200 μg/L for HFW with bromide = 600 mg/L) mimics the increased bromide levels observed in western Pennsylvanian surface waters following the Marcellus Shale gas production boom. Chloramination reduced HAN and regulated THM formation; however, iodinated trihalomethane formation was observed at lower pH. For municipal wastewater-impacted river water, the presence of 0.1% HFW increased the formation of N-nitrosodimethylamine (NDMA) during chloramination, particularly for the high iodide (54 ppm) Fayetteville Shale HFW. Finally, ozonation of 0.01-0.03% HFW-impacted river water resulted in significant increases in bromate formation. The results suggest that total elimination of HFW discharge and/or installation of halide-specific removal techniques in centralized brine treatment facilities may be a better strategy to mitigate impacts on downstream drinking water treatment plants than altering

Primary emissions and secondary formation of volatile organic compounds from natural gas production in five major U.S. shale plays

NASA Astrophysics Data System (ADS)

Gilman, J.; Lerner, B. M.; Warneke, C.; Graus, M.; Lui, R.; Koss, A.; Yuan, B.; Murphy, S. M.; Alvarez, S. L.; Lefer, B. L.; Min, K. E.; Brown, S. S.; Roberts, J. M.; Osthoff, H. D.; Hatch, C. D.; Peischl, J.; Ryerson, T. B.; De Gouw, J. A.

2014-12-01

According to the U.S. Energy and Information Administration (EIA), domestic production of natural gas from shale formations is currently at the highest levels in U.S. history. Shale gas production may also result in the production of natural gas plant liquids (NGPLs) such as ethane and propane as well as natural gas condensate composed of a complex mixture of non-methane hydrocarbons containing more than ~5 carbon atoms (e.g., hexane, cyclohexane, and benzene). The amounts of natural gas liquids and condensate produced depends on the particular reservoir. The source signature of primary emissions of hydrocarbons to the atmosphere within each shale play will therefore depend on the composition of the raw natural gas as well as the industrial processes and equipment used to extract, separate, store, and transport the raw materials. Characterizing the primary emissions of VOCs from natural gas production is critical to assessing the local and regional atmospheric impacts such as the photochemical formation of ozone and secondary formation of organic aerosol. This study utilizes ground-based measurements of a full suite of volatile organic compounds (VOCs) in two western U.S. basins, the Uintah (2012-2014 winter measurements only) and Denver-Julesburg (winter 2011 and summer 2012), and airborne measurements over the Haynesville, Fayetteville, and Marcellus shale basins (summer 2013). By comparing the observed VOC to propane enhancement ratios, we show that each basin has a unique VOC source signature associated with oil and natural gas operations. Of the shale basins studied, the Uintah basin had the largest overall VOC to propane enhancement ratios while the Marcellus had the lowest. For the western basins, we will compare the composition of oxygenated VOCs produced from photochemical oxidation of VOC precursors and contrast the oxygenated VOC mixture to a "typical" summertime urban VOC mixture. The relative roles of alkanes, alkenes, aromatics, and cycloalkanes as

Paleozoic oil/gas shale reservoirs in southern Tunisia: An overview

NASA Astrophysics Data System (ADS)

Soua, Mohamed

2014-12-01

During these last years, considerable attention has been given to unconventional oil and gas shale in northern Africa where the most productive Paleozoic basins are located (e.g. Berkine, Illizi, Kufra, Murzuk, Tindouf, Ahnet, Oued Mya, Mouydir, etc.). In most petroleum systems, which characterize these basins, the Silurian played the main role in hydrocarbon generation with two main 'hot' shale levels distributed in different locations (basins) and their deposition was restricted to the Rhuddanian (Lllandovery: early Silurian) and the Ludlow-Pridoli (late Silurian). A third major hot shale level had been identified in the Frasnian (Upper Devonian). Southern Tunisia is characterized by three main Paleozoic sedimentary basins, which are from North to South, the southern Chotts, Jeffara and Berkine Basin. They are separated by a major roughly E-W trending lower Paleozoic structural high, which encompass the Mehrez-Oued Hamous uplift to the West (Algeria) and the Nefusa uplift to the East (Libya), passing by the Touggourt-Talemzane-PGA-Bou Namcha (TTPB) structure close to southern Tunisia. The forementioned major source rocks in southern Tunisia are defined by hot shales with elevated Gamma ray values often exceeding 1400 API (in Hayatt-1 well), deposited in deep water environments during short lived (c. 2 Ma) periods of anoxia. In the course of this review, thickness, distribution and maturity maps have been established for each hot shale level using data for more than 70 wells located in both Tunisia and Algeria. Mineralogical modeling was achieved using Spectral Gamma Ray data (U, Th, K), SopectroLith logs (to acquire data for Fe, Si and Ti) and Elemental Capture Spectroscopy (ECS). The latter technique provided data for quartz, pyrite, carbonate, clay and Sulfur. In addition to this, the Gamma Ray (GR), Neutron Porosity (ΦN), deep Resistivity (Rt) and Bulk Density (ρb) logs were used to model bulk mineralogy and lithology. Biostratigraphic and complete

The three-zone composite productivity model for a multi-fractured horizontal shale gas well

NASA Astrophysics Data System (ADS)

Qi, Qian; Zhu, Weiyao

2018-02-01

Due to the nano-micro pore structures and the massive multi-stage multi-cluster hydraulic fracturing in shale gas reservoirs, the multi-scale seepage flows are much more complicated than in most other conventional reservoirs, and are crucial for the economic development of shale gas. In this study, a new multi-scale non-linear flow model was established and simplified, based on different diffusion and slip correction coefficients. Due to the fact that different flow laws existed between the fracture network and matrix zone, a three-zone composite model was proposed. Then, according to the conformal transformation combined with the law of equivalent percolation resistance, the productivity equation of a horizontal fractured well, with consideration given to diffusion, slip, desorption, and absorption, was built. Also, an analytic solution was derived, and the interference of the multi-cluster fractures was analyzed. The results indicated that the diffusion of the shale gas was mainly in the transition and Fick diffusion regions. The matrix permeability was found to be influenced by slippage and diffusion, which was determined by the pore pressure and diameter according to the Knudsen number. It was determined that, with the increased half-lengths of the fracture clusters, flow conductivity of the fractures, and permeability of the fracture network, the productivity of the fractured well also increased. Meanwhile, with the increased number of fractures, the distance between the fractures decreased, and the productivity slowly increased due to the mutual interfere of the fractures.

Modeling of fault reactivation and induced seismicity during hydraulic fracturing of shale-gas reservoirs

EPA Science Inventory

We have conducted numerical simulation studies to assess the potential for injection-induced fault reactivation and notable seismic events associated with shale-gas hydraulic fracturing operations. The modeling is generally tuned toward conditions usually encountered in the Marce...

Ground-water quality of the Upper Floridan Aquifer near an abandoned manufactured gas plant in Albany, Georgia

USGS Publications Warehouse

Chapman, M.J.

1993-01-01

Manufactured gas plants produced gas for heating and lighting in the United States from as early as 1816 into the 1960's. By-products including, but not limited to, oil residues and tar, were generated during the gas-manufacturing process. Organic compounds (hydrocarbons) were detected in water in the upper water-bearing zone of the Upper Floridan aquifer near an abandoned manufactured gas plant (MGP) in Albany, Georgia, during an earlier investigation in 1990. Chemical analyses of ground-water samples collected from five existing monitoring wells in 1991 verify the presence of hydrocarbons and metals in the upper water-beating zone of the Upper Floridan aquifer. One well was drilled into the lower water-beating zone of the Upper Floridan aquifer in 1991 for water-quality sampling and water-level monitoring. Analyses of ground water sampled from this well did not show evidence of benzene, toluene, xylene, napthalene, acenaphthlene, or other related compounds detected in the upper water-bearing zone in the study area. Low concentrations of tetrachloroethane, trichloromethane, and l,2-cisdichloroethene were detected in a water sample from the deeper well; however, these compounds were not detected in the upper water-bearing zone in the study area. Inorganic constituent concentrations also were substantially lower in the deeper well. Overall, ground water sampled from the lower water-bearing zone had lower specific conductance and alkalinity; and lower concentrations of dissolved solids, iron, and manganese compared to ground water sampled from the upper water-bearing zone. Water levels for the upper and lower water-bearing zones were similar throughout the study period.

Radon-222 content of natural gas samples from Upper and Middle Devonian sandstone and shale reservoirs in Pennsylvania—preliminary data

USGS Publications Warehouse

Rowan, E.L.; Kraemer, T.F.

2012-01-01

Samples of natural gas were collected as part of a study of formation water chemistry in oil and gas reservoirs in the Appalachian Basin. Nineteen samples (plus two duplicates) were collected from 11 wells producing gas from Upper Devonian sandstones and the Middle Devonian Marcellus Shale in Pennsylvania. The samples were collected from valves located between the wellhead and the gas-water separator. Analyses of the radon content of the gas indicated 222Rn (radon-222) activities ranging from 1 to 79 picocuries per liter (pCi/L) with an overall median of 37 pCi/L. The radon activities of the Upper Devonian sandstone samples overlap to a large degree with the activities of the Marcellus Shale samples.

Mobile measurement of methane and hydrogen sulfide at natural gas production site fence lines in the Texas Barnett Shale.

PubMed

Eapi, Gautam R; Sabnis, Madhu S; Sattler, Melanie L

2014-08-01

Production of natural gas from shale formations is bringing drilling and production operations to regions of the United States that have seen little or no similar activity in the past, which has generated considerable interest in potential environmental impacts. This study focused on the Barnett Shale Fort Worth Basin in Texas, which saw the number of gas-producing wells grow from 726 in 2001 to 15,870 in 2011. This study aimed to measure fence line concentrations of methane and hydrogen sulfide at natural gas production sites (wells, liquid storage tanks, and associated equipment) in the four core counties of the Barnett Shale (Denton, Johnson, Tarrant, and Wise). A mobile measurement survey was conducted in the vicinity of 4788 wells near 401 lease sites, representing 35% of gas production volume, 31% of wells, and 38% of condensate production volume in the four-county core area. Methane and hydrogen sulfide concentrations were measured using a Picarro G2204 cavity ring-down spectrometer (CRDS). Since the research team did not have access to lease site interiors, measurements were made by driving on roads on the exterior of the lease sites. Over 150 hr of data were collected from March to July 2012. During two sets of drive-by measurements, it was found that 66 sites (16.5%) had methane concentrations > 3 parts per million (ppm) just beyond the fence line. Thirty-two lease sites (8.0%) had hydrogen sulfide concentrations > 4.7 parts per billion (ppb) (odor recognition threshold) just beyond the fence line. Measured concentrations generally did not correlate well with site characteristics (natural gas production volume, number of wells, or condensate production). t tests showed that for two counties, methane concentrations for dry sites were higher than those for wet sites. Follow-up study is recommended to provide more information at sites identified with high levels of methane and hydrogen sulfide. Implications: Information regarding air emissions from shale gas

Structural characteristics and its exploration significance of Wufeng-Longmaxi formation in LaiFeng-Xianfeng Shale gas block, Hubei province

NASA Astrophysics Data System (ADS)

Hong, Keyan; Li, Bo; Zhu, Liangliang; Hu, Xiaolan

2017-06-01

Laifeng-Xianfeng Block whose licensee of exploration belongs to China Huadian Corporation, is located in the west of Hubei province, the eastern edge of the Sichuan Basin and close to the eastern Sichuan high steep fold belt. This block is a mountain landform, in which the geology conditions are complicated. Thus, this paper focuses on 11 two-dimension seismic data and one discovery well in this block. By jointing logging to seismic, the bottom interface of shale gas reservoir in Wufeng-Longmaxi Formation are determined precisely and this type of Formation is characterized by low frequency, strong dual phases, stable distribution, and can be traced in the full-region. Finally, the structure style and distribution of target formations are identified, on the basis of which the integrated evaluation of preservation conditions for shale gas syncline structure is carried out, leading to a selection of Lianghekou Syncline for the best exploration area, which lays a foundation for the future exploration and deployment of shale gas.

Characterization of Radium and Radon Isotopes in Hydraulic Fracturing Flowback Fluid and Gas from the Marcellus Shale

NASA Astrophysics Data System (ADS)

Bardsley, A.

2015-12-01

High volume hydraulic fracturing of unconventional deposits has expanded rapidly over the past decade in the US, with much attention focused on the Marcellus Shale gas reservoir in the northeastern US. We use naturally occurring radium isotopes and 222Rn to explore changes in formation characteristics as a result of hydraulic fracturing. Gas and produced waters were analyzed from time series samples collected soon after hydraulic fracturing at three Marcellus Shale well sites in the Appalachian Basin, USA. Analyses of δ18O, Cl- , and 226Ra in flowback fluid are consistent with two end member mixing between injected slick water and formation brine. All three tracers indicate that the ratio of injected water to formation brine declines with time across both time series. Cl- concentration (max ~1.5-2.2 M) and 226Ra activity (max ~165-250 Bq/Kg) in flowback fluid are comparable at all three sites. There are differences evident in the stable isotopic composition (δ18O & δD) of injected slick water across the three sites, but all appear to mix with formation brine of similar isotopic composition. On a plot of water isotopes, δ18O in formation brine-dominated fluid is enriched by ~3-4 permille relative to the Global Meteoric Water Line, indicating oxygen exchange with shale. The ratio of 223Ra/226Ra and 228Ra/226Ra in produced waters is quite low relative to shale samples analyzed. This indicates that most of the 226Ra in the formation brine must be sourced from shale weathering or dissolution rather than emanation due to alpha recoil from the rock surface. During the first week of flowback, ratios of short lived isotopes 223Ra and 224Ra to longer lived radium isotopes change modestly, suggesting rock surface area per unit of produced water volume did not change substantially. For one well, longer term gas samples were collected. The 222Rn/methane ratio in produced gas from this site declines with time and may represent a decrease in the brine to gas ratio in the

The impact of shale gas on the cost and feasibility of meeting climate targets—A global energy system model analysis and an exploration of uncertainties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Few, Sheridan; Gambhir, Ajay; Napp, Tamaryn

There exists considerable uncertainty over both shale and conventional gas resource availability and extraction costs, as well as the fugitive methane emissions associated with shale gas extraction and its possible role in mitigating climate change. This study uses a multi-region energy system model, TIAM (TIMES integrated assessment model), to consider the impact of a range of conventional and shale gas cost and availability assessments on mitigation scenarios aimed at achieving a limit to global warming of below 2 °C in 2100, with a 50% likelihood. When adding shale gas to the global energy mix, the reduction to the global energymore » system cost is relatively small (up to 0.4%), and the mitigation cost increases by 1%–3% under all cost assumptions. The impact of a “dash for shale gas”, of unavailability of carbon capture and storage, of increased barriers to investment in low carbon technologies, and of higher than expected leakage rates, are also considered; and are each found to have the potential to increase the cost and reduce feasibility of meeting global temperature goals. Finally, we conclude that the extraction of shale gas is not likely to significantly reduce the effort required to mitigate climate change under globally coordinated action, but could increase required mitigation effort if not handled sufficiently carefully.« less

The impact of shale gas on the cost and feasibility of meeting climate targets—A global energy system model analysis and an exploration of uncertainties

DOE PAGES

Few, Sheridan; Gambhir, Ajay; Napp, Tamaryn; ...

2017-01-27

There exists considerable uncertainty over both shale and conventional gas resource availability and extraction costs, as well as the fugitive methane emissions associated with shale gas extraction and its possible role in mitigating climate change. This study uses a multi-region energy system model, TIAM (TIMES integrated assessment model), to consider the impact of a range of conventional and shale gas cost and availability assessments on mitigation scenarios aimed at achieving a limit to global warming of below 2 °C in 2100, with a 50% likelihood. When adding shale gas to the global energy mix, the reduction to the global energymore » system cost is relatively small (up to 0.4%), and the mitigation cost increases by 1%–3% under all cost assumptions. The impact of a “dash for shale gas”, of unavailability of carbon capture and storage, of increased barriers to investment in low carbon technologies, and of higher than expected leakage rates, are also considered; and are each found to have the potential to increase the cost and reduce feasibility of meeting global temperature goals. Finally, we conclude that the extraction of shale gas is not likely to significantly reduce the effort required to mitigate climate change under globally coordinated action, but could increase required mitigation effort if not handled sufficiently carefully.« less

Eagle Ford Shale BTEX and NOx concentrations are dominated by oil and gas industry emissions

NASA Astrophysics Data System (ADS)

Schade, G. W.; Roest, G. S.

2017-12-01

US shale oil and gas exploration has been identified as a major source of greenhouse gases and non-methane hydrocarbon (NMHC) emissions to the atmosphere. Here, we present a detailed analysis of 2015 air quality data acquired by the Texas Commission on Environmental Quality (TCEQ) at an air quality monitoring station in Karnes County, TX, central to Texas' Eagle Ford shale area. Data include time series of hourly measured NMHCs, nitrogen oxides (NOx), and hydrogen sulfide (H2S) alongside meteorological measurements. The monitor was located in Karnes City, and thus affected by various anthropogenic emissions, including traffic and oil and gas exploration sources. Highest mixing ratios measured in 2015 included nearly 1 ppm ethane, 0.8 ppm propane, alongside 4 ppb benzene. A least-squares minimization non-negative matrix factorization (NMF) analysis, tested with prior data analyzed using standard PMF-2 software, showed six major emission sources: an evaporative and fugitive source, a flaring source, a traffic source, an oil field source, a diesel source, and an industrial manufacturing source, together accounting for more than 95% of data set variability, and interpreted using NMHC composition and meteorological data. Factor scores strongly suggest that NOx emissions are dominated by flaring and associated sources, such as diesel compressor engines, likely at midstream facilities, while traffic in this rural area is a minor NOx source. The results support, but exceed existing 2012 emission inventories estimating that local traffic emitted seven times fewer NOx than oil and gas exploration sources in the county. Sources of air toxics such as the BTEX compounds are also dominated by oil and gas exploration sources, but are more equally distributed between the associated factors. Benzene abundance is only 20-40% associated with traffic sources, and may thus be 2.5-5 times higher now than prior to the shale boom in this area. Although the monitor was located relatively

76 FR 79271 - Genesee & Wyoming Inc.-Continuance in Control Exemption-Hilton & Albany Railroad, Inc.

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-21

... Inc.--Continuance in Control Exemption-Hilton & Albany Railroad, Inc. AGENCY: Surface Transportation.... (GWI), a noncarrier, to continue in control of Hilton & Albany Railroad, Inc. (HAL), upon HAL's... Railway Company (NSR) and operation of a 55.5-mile rail line between Hilton and Albany, Ga.\\1\\ GWI's...

Combustion heater for oil shale

DOEpatents

Mallon, R.; Walton, O.; Lewis, A.E.; Braun, R.

1983-09-21

A combustion heater for oil shale heats particles of spent oil shale containing unburned char by burning the char. A delayed fall is produced by flowing the shale particles down through a stack of downwardly sloped overlapping baffles alternately extending from opposite sides of a vertical column. The delayed fall and flow reversal occurring in passing from each baffle to the next increase the residence time and increase the contact of the oil shale particles with combustion supporting gas flowed across the column to heat the shale to about 650 to 700/sup 0/C for use as a process heat source.

Combustion heater for oil shale

DOEpatents

Mallon, Richard G.; Walton, Otis R.; Lewis, Arthur E.; Braun, Robert L.

1985-01-01

A combustion heater for oil shale heats particles of spent oil shale containing unburned char by burning the char. A delayed fall is produced by flowing the shale particles down through a stack of downwardly sloped overlapping baffles alternately extending from opposite sides of a vertical column. The delayed fall and flow reversal occurring in passing from each baffle to the next increase the residence time and increase the contact of the oil shale particles with combustion supporting gas flowed across the column to heat the shale to about 650.degree.-700.degree. C. for use as a process heat source.

A new method for calculation of water saturation in shale gas reservoirs using V P -to-V S ratio and porosity

NASA Astrophysics Data System (ADS)

Liu, Kun; Sun, Jianmeng; Zhang, Hongpan; Liu, Haitao; Chen, Xiangyang

2018-02-01

Total water saturation is an important parameter for calculating the free gas content of shale gas reservoirs. Owing to the limitations of the Archie formula and its extended solutions in zones rich in organic or conductive minerals, a new method was proposed to estimate total water saturation according to the relationship between total water saturation, V P -to-V S ratio and total porosity. Firstly, the ranges of the relevant parameters in the viscoelastic BISQ model in shale gas reservoirs were estimated. Then, the effects of relevant parameters on the V P -to-V S ratio were simulated based on the partially saturated viscoelastic BISQ model. These parameters were total water saturation, total porosity, permeability, characteristic squirt-flow length, fluid viscosity and sonic frequency. The simulation results showed that the main factors influencing V P -to-V S ratio were total porosity and total water saturation. When the permeability and the characteristic squirt-flow length changed slightly for a particular shale gas reservoir, their influences could be neglected. Then an empirical equation for total water saturation with respect to total porosity and V P -to-V S ratio was obtained according to the experimental data. Finally, the new method was successfully applied to estimate total water saturation in a sequence formation of shale gas reservoirs. Practical applications have shown good agreement with the results calculated by the Archie model.

Assessment of shale-gas resources of the Karoo Province, South Africa and Lesotho, Africa, 2016

USGS Publications Warehouse

Brownfield, Michael E.; Schenk, Christopher J.; Klett, Timothy R.; Pitman, Janet K.; Tennyson, Marilyn E.; Gaswirth, Stephanie B.; Le, Phuong A.; Leathers-Miller, Heidi M.; Mercier, Tracey J.; Finn, Thomas M.

2016-07-08

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resource of 44.5 trillion cubic feet of shale gas in the Karoo Province of South Africa and Lesotho, Africa.

Linear infrastructure drives habitat conversion and forest fragmentation associated with Marcellus shale gas development in a forested landscape.

PubMed

Langlois, Lillie A; Drohan, Patrick J; Brittingham, Margaret C

2017-07-15

Large, continuous forest provides critical habitat for some species of forest dependent wildlife. The rapid expansion of shale gas development within the northern Appalachians results in direct loss of such habitat at well sites, pipelines, and access roads; however the resulting habitat fragmentation surrounding such areas may be of greater importance. Previous research has suggested that infrastructure supporting gas development is the driver for habitat loss, but knowledge of what specific infrastructure affects habitat is limited by a lack of spatial tracking of infrastructure development in different land uses. We used high-resolution aerial imagery, land cover data, and well point data to quantify shale gas development across four time periods (2010, 2012, 2014, 2016), including: the number of wells permitted, drilled, and producing gas (a measure of pipeline development); land use change; and forest fragmentation on both private and public land. As of April 2016, the majority of shale gas development was located on private land (74% of constructed well pads); however, the number of wells drilled per pad was lower on private compared to public land (3.5 and 5.4, respectively). Loss of core forest was more than double on private than public land (4.3 and 2.0%, respectively), which likely results from better management practices implemented on public land. Pipelines were by far the largest contributor to the fragmentation of core forest due to shale gas development. Forecasting future land use change resulting from gas development suggests that the greatest loss of core forest will occur with pads constructed farthest from pre-existing pipelines (new pipelines must be built to connect pads) and in areas with greater amounts of core forest. To reduce future fragmentation, our results suggest new pads should be placed near pre-existing pipelines and methods to consolidate pipelines with other infrastructure should be used. Without these mitigation practices, we

Laboratory characterization of shale pores

NASA Astrophysics Data System (ADS)

Nur Listiyowati, Lina

2018-02-01

To estimate the potential of shale gas reservoir, one needs to understand the characteristics of pore structures. Characterization of shale gas reservoir microstructure is still a challenge due to ultra-fine grained micro-fabric and micro level heterogeneity of these sedimentary rocks. The sample used in the analysis is a small portion of any reservoir. Thus, each measurement technique has a different result. It raises the question which methods are suitable for characterizing pore shale. The goal of this paper is to summarize some of the microstructure analysis tools of shale rock to get near-real results. The two analyzing pore structure methods are indirect measurement (MIP, He, NMR, LTNA) and direct observation (SEM, TEM, Xray CT). Shale rocks have a high heterogeneity; thus, it needs multiscale quantification techniques to understand their pore structures. To describe the complex pore system of shale, several measurement techniques are needed to characterize the surface area and pore size distribution (LTNA, MIP), shapes, size and distribution of pore (FIB-SEM, TEM, Xray CT), and total porosity (He pycnometer, NMR). The choice of techniques and methods should take into account the purpose of the analysis and also the time and budget.

Applying of the Artificial Neural Networks (ANN) to Identify and Characterize Sweet Spots in Shale Gas Formations

NASA Astrophysics Data System (ADS)

Puskarczyk, Edyta

2018-03-01

The main goal of the study was to enhance and improve information about the Ordovician and Silurian gas-saturated shale formations. Author focused on: firstly, identification of the shale gas formations, especially the sweet spots horizons, secondly, classification and thirdly, the accurate characterization of divisional intervals. Data set comprised of standard well logs from the selected well. Shale formations are represented mainly by claystones, siltstones, and mudstones. The formations are also partially rich in organic matter. During the calculations, information about lithology of stratigraphy weren't taken into account. In the analysis, selforganizing neural network - Kohonen Algorithm (ANN) was used for sweet spots identification. Different networks and different software were tested and the best network was used for application and interpretation. As a results of Kohonen networks, groups corresponding to the gas-bearing intervals were found. The analysis showed diversification between gas-bearing formations and surrounding beds. It is also shown that internal diversification in sweet spots is present. Kohonen algorithm was also used for geological interpretation of well log data and electrofacies prediction. Reliable characteristic into groups shows that Ja Mb and Sa Fm which are usually treated as potential sweet spots only partially have good reservoir conditions. It is concluded that ANN appears to be useful and quick tool for preliminary classification of members and sweet spots identification.

Mobile Measurements of Gas and Particle Emissions from Marcellus Shale Gas Development

NASA Astrophysics Data System (ADS)

DeCarlo, P. F.; Goetz, J. D.; Floerchinger, C. R.; Fortner, E.; Wormhoudt, J.; Knighton, W. B.; Herndon, S.; Kolb, C. E.; Shaw, S. L.; Knipping, E. M.

2013-12-01

Production of natural gas in the Marcellus shale is increasing rapidly due to the vast quantities of natural gas stored in the formation. Transient and long-term activities have associated emissions to the atmosphere of methane, volatile organic compounds, NOx, particulates and other species from gas production and transport infrastructure. In the summer of 2012, a team of researchers from Drexel University and Aerodyne Research deployed the Aerodyne mobile laboratory (AML) and measured in-situ concentrations of gas-phase and aerosol chemical components in the main gas producing regions of Pennsylvania, with the overall goal of understanding the impacts to regional ozone and particulate matter (PM) concentrations. State-of-the-art instruments including quantum cascade laser systems, proton transfer mass spectrometry, tunable diode lasers and a soot particle aerosol mass spectrometer, were used quantify concentrations of pollutants of interest. Chemical species measured include methane, ethane, NO, NO2, CO, CO2, SO2, and many volatile organic compounds, and aerosol size and chemical composition. Tracer-release techniques were employed to link sources with emissions and to quantify emission rates from gas facilities, in order to understand the regional burden of these chemical species from oil and gas development in the Marcellus. Measurements were conducted in two regions of Pennsylvania: the NE region that is predominantly dry gas (95% + methane), and the SW region where wet gas (containing greater than 5% higher hydrocarbons) is found. Regional scale measurements of current levels of air pollutants will be shown and will put into context how further development of the gas resource in one of the largest natural gas fields in the world impacts air quality in a region upwind of the highly urbanized east coast corridor.

History of gas production from Devonian shale in eastern Kentucky

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kemper, J.R.; Frankie, W.T.; Smath, R.A.

More than 10,500 wells that penetrate the Devonian shale have been compiled into a data base covering a 25-county area of eastern Kentucky. This area includes the Big Sandy gas field, the largest in the Appalachian basin, and marginal areas to the southwest, west, and northwest. The development of the Big Sandy gas field began in the 1920s in western Floyd County, Kentucky, and moved concentrically outward through 1970. Since 1971, the trend has been for infill and marginal drilling, and fewer companies have been involved. The resulting outline of the Big Sandy gas field covers most of Letcher, Knott,more » Floyd, Martin, and Pike Counties in Kentucky; it also extends into West Virginia. Outside the Big Sandy gas field, exploration for gas has been inconsistent, with a much higher ratio of dry holes. The results of this study, which was partially supported by the Gas Research Institute (GRI), indicate that certain geologic factors, such as fracture size and spacing, probably determine the distribution of commercial gas reserves as well as the outline of the Big Sandy gas field. Future Big Sandy infill and extension drilling will need to be based on an understanding of these factors.« less

Converting oil shale to liquid fuels: energy inputs and greenhouse gas emissions of the Shell in situ conversion process.