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Regional-Scale Distribution of Helium Isotopes in Aquifers: How Informative Are They as Groundwater Tracers and Chronometers? WATER 2022. [DOI: 10.3390/w14121940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
This study presents an almost entirely unpublished dataset of 121 samples of groundwater analyzed for helium concentration and its isotopic ratio (3He/4He) in two adjacent watersheds of the St. Lawrence Lowlands, in a region with intensive agricultural activities in the southern Québec Province, Eastern Canada. Most of the samples were collected in the regional bedrock fractured aquifer hosted in mid-Ordovician siliciclastic shales, on a total surface of 7500 km2. Even with this low-density sampling, and in a heterogeneous and fractured aquifer, the helium isotopes bring precious information on the recharge conditions and on chemical evolution of water. The helium spatial interpolation does not show a clear isotopic gradient through the basin. However, it shows progressive enrichment of radiogenic 4He in the confined part of the aquifer. The atmospheric and/or tritiogenic-rich helium occurs at the recharge in the Appalachians and in the middle of the plain, where impermeable cover is limited, and local infiltration of meteoric freshwater reaches the bedrock aquifer. The relation between the total dissolved solids (TDS) and 3He/4He ratios remains elusive. However, on discriminating the samples with the dominant chemistry of water, a clear trend is observed with 3He/4He ratio, suggesting that radiogenic 4He accumulates together with dissolved solids and with increasing time (indicated by progressively older 14C ages). Finally, the noble gas temperatures (NGTs) obtained from concentrations of the other noble gases (Ne, Ar, Kr and Xe) brings constraints on the earlier recharge conditions during the Holocene. Particularly, the NGTs showed that the studied aquifers were continuously replenished, even under ice-sheet cover in the last 10,000 years.
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Guerrero-Useda ME. Contaminación físico química en zonas de fracking. REVISTA POLITÉCNICA 2021. [DOI: 10.33571/rpolitec.v17n34a5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A pesar del consenso científico hacia la necesidad de limitar el calentamiento global, la urgencia por la provisión autónoma de recursos energéticos ha llevado a muchos Estados a autorizar proyectos que aplican técnicas no convencionales de extracción de combustibles fósiles, como es el caso de la perforación horizontal y la fracturación hidráulica de esquisto de gran volumen. Aunque son pocos los estudios que presentan evidencias concluyentes, estas técnicas son acusadas de acarrear peligros al ambiente y la salud de las personas que trabajan y habitan zonas de fracking, de tal manera que los Estados están ante la disyuntiva de extender algunos años la autonomía energética exprimiendo hasta el final sus reversas de gas natural y petróleo, o buscar algún equilibrio con el planeta moviéndose hacia fuentes energéticas más sostenibles. A partir de la revisión de trabajos que presentan evidencias de contaminación física y química y otros impactos al ambiente en zonas donde se ha desarrollado la técnica del fracking, se presenta un panorama de riesgos para las personas que habitan cerca de plataformas de extracción y los peligros de desarrollar proyectos de fracking en zonas climáticas tropicales.
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Rosecrans CZ, Landon MK, McMahon PB, Gillespie JM, Kulongoski JT, Stephens MJ, Hunt AG, Shimabukuro DH, Davis TA. Groundwater Quality of Aquifers Overlying the Oxnard Oil Field, Ventura County, California. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 771:144822. [PMID: 33736165 DOI: 10.1016/j.scitotenv.2020.144822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 12/18/2020] [Accepted: 12/20/2020] [Indexed: 06/12/2023]
Abstract
Groundwater samples collected from irrigation, monitoring, and municipal supply wells near the Oxnard Oil Field were analyzed for chemical and isotopic tracers to evaluate if thermogenic gas or water from hydrocarbon-bearing formations have mixed with surrounding groundwater. New and historical data show no evidence of water from hydrocarbon-bearing formations in groundwater overlying the field. However, thermogenic gas mixed with microbial methane was detected in 5 wells at concentrations ranging from 0.011-9.1 mg/L. The presence of these gases at concentrations <10 mg/L do not indicate degraded water quality posing a known health risk. Analysis of carbon isotopes (δ13C-CH4) and hydrogen isotopes (δ2H-CH4) of methane and ratios of methane to heavier hydrocarbon gases were used to differentiate sources of methane between a) microbial, b) thermogenic or c) mixed sources. Results indicate that microbial-sourced methane is widespread in the study area, and concentrations overlap with those from thermogenic sources. The highest concentrations of thermogenic gas were observed in proximity to relatively high density of oil wells, large injection volumes of water disposal and cyclic steam, shallow oil development, and hydrocarbon shows in sediments overlying the producing oil reservoirs. Depths of water wells containing thermogenic gas were within approximately 200 m of the top of the Vaca Tar Sand production zone (approximately 600 m below land surface). Due to the limited sampling density, the source and pathways of thermogenic gas detected in groundwater could not be conclusively determined. Thermogenic gas detected in the absence of co-occurring water from hydrocarbon-bearing formations may result from natural gas migration over geologic time from the Vaca Tar Sand or deeper formations, hydrocarbon shows in sediments overlying producing zones, and/or gas leaking from oil-field infrastructure. Denser sampling of groundwater, potential end-members, and pressure monitoring could help better distinguish pathways of thermogenic gases.
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4
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Zhong C, Zolfaghari A, Hou D, Goss GG, Lanoil BD, Gehman J, Tsang DCW, He Y, Alessi DS. Comparison of the Hydraulic Fracturing Water Cycle in China and North America: A Critical Review. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:7167-7185. [PMID: 33970611 DOI: 10.1021/acs.est.0c06119] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
There is considerable debate about the sustainability of the hydraulic fracturing (HF) water cycle in North America. Recently, this debate has expanded to China, where HF activities continue to grow. Here, we provide a critical review of the HF water cycle in China, including water withdrawal practices and flowback and produced water (FPW) management and their environmental impacts, with a comprehensive comparison to the U.S. and Canada (North America). Water stress in arid regions, as well as water management challenges, FPW contamination of aquatic and soil systems, and induced seismicity are all impacts of the HF water cycle in China, the U.S., and Canada. In light of experience gained in North America, standardized practices for analyzing and reporting FPW chemistry and microbiology in China are needed to inform its efficient and safe treatment, discharge and reuse, and identification of potential contaminants. Additionally, conducting ecotoxicological studies is an essential next step to fully reveal the impacts of accidental FPW releases into aquatic and soil ecosystems in China. From a policy perspective, the development of China's unconventional resources lags behind North America's in terms of overall regulation, especially with regard to water withdrawal, FPW management, and routine monitoring. Our study suggests that common environmental risks exist within the world's two largest HF regions, and practices used in North America may help prevent or mitigate adverse effects in China.
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Affiliation(s)
- Cheng Zhong
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
- School of Environment, Tsinghua University, Beijing, China
| | - Ashkan Zolfaghari
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Deyi Hou
- School of Environment, Tsinghua University, Beijing, China
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Brian D Lanoil
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Joel Gehman
- Department of Strategy, Entrepreneurship and Management, University of Alberta, Edmonton, Alberta, Canada
| | - Daniel C W Tsang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Yuhe He
- School of Energy and Environment and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Kowloon, Hong Kong, China
| | - Daniel S Alessi
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
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5
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Wilson MP, Worrall F, Davies RJ, Hart A. A dynamic baseline for dissolved methane in English groundwater. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 711:134854. [PMID: 31818574 DOI: 10.1016/j.scitotenv.2019.134854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 10/03/2019] [Accepted: 10/04/2019] [Indexed: 06/10/2023]
Abstract
Elevated dissolved methane (CH4) concentrations in groundwater are an environmental concern associated with hydraulic fracturing for shale gas. Therefore, determining dissolved CH4 baselines is important for detecting and understanding any potential environmental impacts. Such baselines should change in time and space to reflect ongoing environmental change and should be able to predict the probability that a change in dissolved CH4 concentration has occurred. We considered four dissolved CH4 concentration datasets of English groundwater using a Bayesian approach: two national datasets and two local datasets from shale gas exploration sites. The most sensitive national dataset (the previously published British Geological Survey CH4 baseline) was used as a strong prior for a larger (2153 measurements compared to 439) but less sensitive (detection limit 1000 times higher) Environment Agency dataset. The use of the strong prior over a weak prior improved the precision of the Environment Agency dataset by 75%. The expected mean dissolved CH4 concentration in English groundwater based on the Bayesian approach is 0.24 mg/l, with a 95% credible interval of 0.11 to 0.45 mg/l, and a Weibull distribution of W(0.35 ± 0.01, 0.34 ± 0.16). This result indicates the amount of CH4 degassing from English groundwater to the atmosphere equates to between 0.7 and 3.1 kt CH4/year, with an expected value of 1.65 kt CH4/year and a greenhouse gas warming potential of 40.3 kt CO2eq/year. The two local monitoring datasets from shale gas exploration sites, in combination with the national datasets, show that dissolved CH4 concentrations in English groundwater are generally low, but locations with concentrations greater than or equal to the widely used risk action level of 10.0 mg/l do exist. Statistical analyses of groundwater redox conditions at these locations suggest that it may be possible to identify other locations with dissolved CH4 concentrations ≥10.0 mg/l using redox parameters such as Fe concentration.
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Affiliation(s)
- M P Wilson
- Department of Earth Sciences, Durham University, Science Labs, Durham DH1 3LE, UK.
| | - F Worrall
- Department of Earth Sciences, Durham University, Science Labs, Durham DH1 3LE, UK
| | - R J Davies
- School of Natural and Environmental Sciences, Newcastle University, Newcastle NE1 7RU, UK
| | - A Hart
- Environment Agency, Research Assessment and Evaluation, Sapphire East, Streetsbrook Road, Solihull B91 1QT, UK
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6
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Iverach CP, Cendón DI, Beckmann S, Hankin SI, Manefield M, Kelly BFJ. Constraining source attribution of methane in an alluvial aquifer with multiple recharge pathways. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 703:134927. [PMID: 31767334 DOI: 10.1016/j.scitotenv.2019.134927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 10/08/2019] [Accepted: 10/09/2019] [Indexed: 06/10/2023]
Abstract
Identifying the source of methane (CH4) in groundwater is often complicated due to various production, degradation and migration pathways, particularly in settings where there are multiple groundwater recharge pathways. This study demonstrates the ability to constrain the origin of CH4 within an alluvial aquifer that could be sourced from in situ microbiological production or underlying formations at depth. To characterise the hydrochemical and microbiological processes active within the alluvium, previously reported hydrochemical data (major ion chemistry and isotopic tracers (3H, 14C, 36Cl)) were interpreted in the context of CH4 and carbon dioxide (CO2) isotopic chemistry, and the microbial community composition in the groundwater. The rate of observed oxidation of CH4 within the aquifer was then characterised using a Rayleigh fractionation model. The stratification of the hydrochemical facies and microbiological community populations is interpreted to be a result of the gradational mixing of water from river leakage and floodwater recharge with water from basal artesian inflow. Within the aquifer there is a low abundance of methanogenic archaea indicating that there is limited biological potential for microbial CH4 production. Our results show that the resulting interconnection between hydrochemistry and microbial community composition affects the occurrence and oxidation of CH4 within the alluvial aquifer, constraining the source of CH4 in the groundwater to the geological formations beneath the alluvium.
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Affiliation(s)
- Charlotte P Iverach
- School of Biological, Earth and Environmental Sciences, UNSW Sydney, NSW 2052, Australia; Connected Waters Initiative Research Centre, UNSW Sydney, NSW 2052, Australia; Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights, NSW 2234, Australia
| | - Dioni I Cendón
- Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights, NSW 2234, Australia; Connected Waters Initiative Research Centre, UNSW Sydney, NSW 2052, Australia
| | - Sabrina Beckmann
- College of Earth, Ocean and Environment, University of Delaware, 700 Pilottown Road, 19958 Lewes, USA
| | - Stuart I Hankin
- Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights, NSW 2234, Australia
| | - Mike Manefield
- School of Civil and Environmental Engineering, School of Chemical Engineering, UNSW Sydney, NSW 2052, Australia
| | - Bryce F J Kelly
- School of Biological, Earth and Environmental Sciences, UNSW Sydney, NSW 2052, Australia; Connected Waters Initiative Research Centre, UNSW Sydney, NSW 2052, Australia.
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Humez P, Osselin F, Wilson LJ, Nightingale M, Kloppmann W, Mayer B. A Probabilistic Approach for Predicting Methane Occurrence in Groundwater. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:12914-12922. [PMID: 31610659 DOI: 10.1021/acs.est.9b03981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Aqueous geochemistry datasets from regional groundwater monitoring programs can be a major asset for environmental baseline assessment (EBA) in regions with development of natural gases from unconventional hydrocarbon resources. However, they usually do not include crucial parameters for EBA in areas of shale gas development such as methane concentrations. A logistic regression (LR) model was developed to predict the probability of methane occurrence in aquifers in Alberta (Canada). The model was calibrated and tested using geochemistry data including methane concentrations from two groundwater monitoring programs. The LR model correctly predicts methane occurrence in 89.8% (n = 234 samples) and 88.1% (n = 532 samples) of groundwater samples from each monitoring program. Methane concentrations strongly depend on the occurrence of electron donors such as sulfate and to a lesser extent on well depth and the total dissolved solids of groundwater. The model was then applied to a province-wide public health groundwater monitoring program (n = 52,849 samples) providing aqueous geochemistry data but no methane concentrations. This approach allowed the prediction of methane occurrence in regions where no groundwater gas data are available, thereby increasing the resolution of EBA in areas of shale gas development by using basic hydrochemical parameters measured in high-density groundwater monitoring programs.
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Affiliation(s)
- Pauline Humez
- Applied Geochemistry Group, Department of Geoscience , University of Calgary , 2500 University Dr. NW , Calgary , Alberta T2N 1N4 , Canada
| | - Florian Osselin
- Applied Geochemistry Group, Department of Geoscience , University of Calgary , 2500 University Dr. NW , Calgary , Alberta T2N 1N4 , Canada
- ISTO, Institut des Sciences de la Terre d'Orléans , 1A Rue de la Ferollerie , 45100 Orléans , France
| | - Leah J Wilson
- Applied Geochemistry Group, Department of Geoscience , University of Calgary , 2500 University Dr. NW , Calgary , Alberta T2N 1N4 , Canada
| | - Michael Nightingale
- Applied Geochemistry Group, Department of Geoscience , University of Calgary , 2500 University Dr. NW , Calgary , Alberta T2N 1N4 , Canada
| | - Wolfram Kloppmann
- French Geological Survey (BRGM) , 3 Avenue Claude Guillemin , 45100 Orléans , France
| | - Bernhard Mayer
- Applied Geochemistry Group, Department of Geoscience , University of Calgary , 2500 University Dr. NW , Calgary , Alberta T2N 1N4 , Canada
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Loveless SE, Lewis MA, Bloomfield JP, Davey I, Ward RS, Hart A, Stuart ME. A method for screening groundwater vulnerability from subsurface hydrocarbon extraction practices. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 249:109349. [PMID: 31434049 DOI: 10.1016/j.jenvman.2019.109349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 07/12/2019] [Accepted: 07/31/2019] [Indexed: 05/12/2023]
Abstract
This paper describes a new screening method for assessing groundwater vulnerability to pollution from hydrocarbon exploitation in the subsurface. The method can be used for various hydrocarbon energy sources, including conventional oil and gas, shale gas and oil, coal bed methane and underground coal gasification. Intrinsic vulnerability of potential receptors is assessed at any particular location by identifying possible geological pathways for contaminant transport. This is followed by an assessment of specific vulnerability which takes into account the nature of the subsurface hydrocarbon activity and driving heads. A confidence rating is attached to each parameter in the assessment to provide an indication of the confidence in the screening. Risk categories and associated confidence ratings are designed to aid in environmental decision making, regulation and management, highlighting where additional information is required. The method is demonstrated for conventional gas and proposed shale gas operations in northern England but can be adapted for use in any geological or hydrogeological setting and for other subsurface activities.
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Affiliation(s)
- S E Loveless
- British Geological Survey, MacLean Building, Wallingford, Oxfordshire, UK.
| | - M A Lewis
- British Geological Survey, MacLean Building, Wallingford, Oxfordshire, UK
| | - J P Bloomfield
- British Geological Survey, MacLean Building, Wallingford, Oxfordshire, UK
| | - I Davey
- Environment Agency, Horizon House, Bristol, UK
| | - R S Ward
- British Geological Survey, MacLean Building, Wallingford, Oxfordshire, UK
| | - A Hart
- Environment Agency, Horizon House, Bristol, UK
| | - M E Stuart
- British Geological Survey, MacLean Building, Wallingford, Oxfordshire, UK
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9
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Loomer DB, MacQuarrie KTB, Al TA. Using permutational and multivariate statistics to understand inorganic well water chemistry and the occurrence of methane in groundwater, southeastern New Brunswick, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 675:667-678. [PMID: 31039501 DOI: 10.1016/j.scitotenv.2019.04.256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 03/28/2019] [Accepted: 04/16/2019] [Indexed: 06/09/2023]
Abstract
Concerns over possible impacts from the rapid expansion of unconventional oil and natural gas (ONG) resource development prompted a regional domestic well sampling program focusing on the Carboniferous Maritimes Basin bedrock in southeastern New Brunswick, Canada. This work applies recent developments in robust multivariate statistical methods to overcome issues with highly non-Gaussian data and support the development of a conceptual model for the regional groundwater chemistry and the occurrence of methane. Principal component analysis reveals that the redox-sensitive species, DO, NO3, Fe, Mn, methane, As and U are the most important parameters that differentiate the samples. Permutation-based MANOVA and ANOVA testing revealed that geology was more important than geographic location and topography in influencing groundwater composition. The statistical inferences are supported by chemistry trends observed in relation to road de-icing salt and other saline sources. However, source differentiation between Carboniferous brines, entrapped post-glacial marine water and modern seawater cannot be made. Furthermore, Cl:Br ratios lower than those of seawater or regional brines suggest an origin related to the diagenesis of organic-rich sediment and that the groundwater may be influenced by local low permeability units. Combined spatial, statistical and chemical analysis shows that, while trace or low levels of methane, <1 mg/L, are found ubiquitously throughout the Maritimes Basin, elevated concentrations, >1 mg/L, are associated with the Horton Group, consistent with it being the host and inferred source of ONG resources in the province. The highest methane concentrations (14-29 mg/L) were detected in the region with a complex history of cycles of uplift and erosion which, in some locations, resulted in the juxtaposition at the surface of the Horton Group with several other groups of the Maritimes Basin. It is thought that proximity to the Horton Group can lead to naturally high methane concentrations in non-ONG-bearing units.
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Affiliation(s)
- Diana B Loomer
- Dept. of Civil Engineering, University of New Brunswick, PO Box 4400, Fredericton, NB E3B 5A3, Canada.
| | - Kerry T B MacQuarrie
- Dept. of Civil Engineering, University of New Brunswick, PO Box 4400, Fredericton, NB E3B 5A3, Canada
| | - Tom A Al
- Dept. of Earth and Environmental Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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McIntosh JC, Hendry MJ, Ballentine C, Haszeldine RS, Mayer B, Etiope G, Elsner M, Darrah TH, Prinzhofer A, Osborn S, Stalker L, Kuloyo O, Lu ZT, Martini A, Lollar BS. A Critical Review of State-of-the-Art and Emerging Approaches to Identify Fracking-Derived Gases and Associated Contaminants in Aquifers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:1063-1077. [PMID: 30585065 DOI: 10.1021/acs.est.8b05807] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
High-volume, hydraulic fracturing (HVHF) is widely applied for natural gas and oil production from shales, coals, or tight sandstone formations in the United States, Canada, and Australia, and is being widely considered by other countries with similar unconventional energy resources. Secure retention of fluids (natural gas, saline formation waters, oil, HVHF fluids) during and after well stimulation is important to prevent unintended environmental contamination, and release of greenhouse gases to the atmosphere. Here, we critically review state-of-the-art techniques and promising new approaches for identifying oil and gas production from unconventional reservoirs to resolve whether they are the source of fugitive methane and associated contaminants into shallow aquifers. We highlight future research needs and propose a phased program, from generic baseline to highly specific analyses, to inform HVHF and unconventional oil and gas production and impact assessment studies. These approaches may also be applied to broader subsurface exploration and development issues (e.g., groundwater resources), or new frontiers of low-carbon energy alternatives (e.g., subsurface H2 storage, nuclear waste isolation, geologic CO2 sequestration).
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Affiliation(s)
- J C McIntosh
- Department of Hydrology and Atmospheric Sciences , University of Arizona , Tucson , Arizona 85721 , United States
| | - M J Hendry
- Department of Geological Sciences , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5E2 , Canada
| | - C Ballentine
- Department of Earth Sciences , University of Oxford , Oxford OX1 3AN United Kingdom
| | - R S Haszeldine
- School of GeoSciences , University of Edinburgh , Edinburgh EH9 3FE United Kingdom
| | - B Mayer
- Department of Geoscience , University of Calgary , Calgary , Alberta T2N 1N4 , Canada
| | - G Etiope
- Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma 2, Italy, and Faculty of Environmental Science and Engineering , Babes-Bolyai University , Cluj-Napoca , Romania
| | - M Elsner
- Chair of Analytical Chemistry and Water Chemistry , Technical University of Munich , Munich , Germany
| | - T H Darrah
- Divisions of Solid Earth Dynamics and Water, Climate and the Environment, School of Earth Sciences , Ohio State University , Columbus , Ohio 43210 , United States
| | | | - S Osborn
- Department of Geological Sciences , California State Polytechnic University , Pomona , California 91768 , United States
| | - L Stalker
- CSIRO Energy , Kensington , Western Australia 6151 , Australia
| | - O Kuloyo
- Department of Geoscience , University of Calgary , Calgary , Alberta T2N 1N4 , Canada
| | - Z-T Lu
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Quantum Information and Quantum Physics , University of Science and Technology of China , Hefei 230026 , China
| | - A Martini
- Department of Geology , Amherst College , Amherst , Massachusetts 01002 , United States
| | - B Sherwood Lollar
- Department of Earth Sciences , University of Toronto , Toronto , Ontario M5S 3B1 , Canada
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11
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Schimmelmann A, Ensminger SA, Drobniak A, Mastalerz M, Etiope G, Jacobi RD, Frankenberg C. Natural geological seepage of hydrocarbon gas in the Appalachian Basin and Midwest USA in relation to shale tectonic fracturing and past industrial hydrocarbon production. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 644:982-993. [PMID: 30743895 DOI: 10.1016/j.scitotenv.2018.06.374] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 06/17/2018] [Accepted: 06/29/2018] [Indexed: 05/02/2023]
Abstract
Geological hydrocarbon gas seepage is a major global source of atmospheric methane, ethane and propane as greenhouse gases and photochemical pollutants. Natural gas seepage is generally related to faults and associated fracture intensification domains that provide conduits for natural gas from reservoir rocks to migrate upward and enter the atmosphere. In this study, we compare the case of intense gas seepage stemming directly from source rocks, mostly organic-rich fractured black shales in western New York State (NYS) versus areas with rare seepage in the more southern regions of the Appalachian Basin and the Midwest USA. In addition to thermogenic methane, western NYS shale gas seeps emit ethane and propane with C2+3 gas concentrations reaching up to 35 vol%. Fractures in NYS developed, reactivated and maintained permeability for gas as a result of Quaternary glaciation and post-glacial basin uplift. In contrast, the Appalachian regions farther south and the southern Midwest regions experienced less glacial loading and unloading than in NYS, resulting in less recent natural fracturing, as witnessed by the rarity of seepage on surface outcrops and in caves overlying gas-bearing shales and coals. The historical literature suggests that early western NYS drilling and production of oil and gas diminished shale gas pressure and resulted in declining gas seepage rates. Our survey documented 12 active western NYS natural gas seeps, whereas >32 seeps have been reported or documented since the 17th century. Preliminary tests showed that SCIAMACHY satellite data did not detect atmospheric methane anomalies over western NYS seeps.
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Affiliation(s)
- Arndt Schimmelmann
- Department of Earth and Atmospheric Sciences, Indiana University, 1001 E 10th Street, Bloomington, IN 47405-1405, USA.
| | - Scott A Ensminger
- Western New York Waterfall Survey, 784 Meadow Drive, North Tonawanda, NY 14120, USA
| | - Agnieszka Drobniak
- Indiana Geological and Water Survey, Indiana University, 611 N. Walnut Grove Avenue, Bloomington, IN 47405-2208, USA.
| | - Maria Mastalerz
- Indiana Geological and Water Survey, Indiana University, 611 N. Walnut Grove Avenue, Bloomington, IN 47405-2208, USA.
| | - Giuseppe Etiope
- Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma 2, Via V. Murata 605, 00143 Roma, Italy; Faculty of Environmental Science and Engineering, Babes Bolyai University, Cluj-Napoca, Romania.
| | - Robert D Jacobi
- Department of Geology, University at Buffalo, 411 Cooke Hall, Buffalo, NY 14260, USA.
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12
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Wang ZP, Zhang L, Wang B, Hou LY, Xiao CW, Zhang XM, Han XG. Dissolved methane in groundwater of domestic wells and its potential emissions in arid and semi-arid regions of Inner Mongolia, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 626:1193-1199. [PMID: 29898526 DOI: 10.1016/j.scitotenv.2018.01.205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 01/19/2018] [Accepted: 01/20/2018] [Indexed: 06/08/2023]
Abstract
Methane (CH4) is widely present in groundwater. Dissolved CH4 in groundwater is less understood when compared with that in wetlands. In this study, the concentrations and origin of dissolved CH4 in groundwater were investigated and the potential importance of groundwater CH4 emissions in arid and semi-arid regions of Inner Mongolia was discussed. Groundwater was extracted from domestic wells using a submersible pump or manual power and was analyzed for CH4 concentrations, δ13C-CH4, and physico-chemical variables. The results show that the concentrations of dissolved CH4 in groundwater had large spatial variability, ranging from 0 to 0.10 mg L-1 with a mean of 0.01 mg L-1 in Xilingol and from 0 to 8.99 mg L-1 with a mean of 1.44 mg L-1 in Xingan-Tongliao. Substantial CH4 concentrations of about 2.5-5.5 mg L-1 were found in central areas of Xingan-Tongliao in the winter and the summer. The δ13C-CH4 of about -85‰ was highly depleted while CH4 concentration was significantly negatively correlated with SO42- concentration, indicating that dissolved CH4 in groundwater was microbial in origin. This study suggests that groundwater as a source of CH4 might have great implications in arid and semi-arid regions worldwide and should deserve more research.
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Affiliation(s)
- Zhi-Ping Wang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing 100093, China.
| | - Lin Zhang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing 100093, China
| | - Bin Wang
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA
| | - Long-Yu Hou
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing 100093, China
| | - Chun-Wang Xiao
- College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China
| | - Xi-Mei Zhang
- Key Laboratory of Dryland Agriculture, MOA, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Xing-Guo Han
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing 100093, China; Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China; University of Chinese Academy of Sciences, Yuquanlu, Beijing 100049, China
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13
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Claire Botner E, Townsend-Small A, Nash DB, Xu X, Schimmelmann A, Miller JH. Monitoring concentration and isotopic composition of methane in groundwater in the Utica Shale hydraulic fracturing region of Ohio. ENVIRONMENTAL MONITORING AND ASSESSMENT 2018; 190:322. [PMID: 29721622 DOI: 10.1007/s10661-018-6696-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 04/18/2018] [Indexed: 05/12/2023]
Abstract
Degradation of groundwater quality is a primary public concern in rural hydraulic fracturing areas. Previous studies have shown that natural gas methane (CH4) is present in groundwater near shale gas wells in the Marcellus Shale of Pennsylvania, but did not have pre-drilling baseline measurements. Here, we present the results of a free public water testing program in the Utica Shale of Ohio, where we measured CH4 concentration, CH4 stable isotopic composition, and pH and conductivity along temporal and spatial gradients of hydraulic fracturing activity. Dissolved CH4 ranged from 0.2 μg/L to 25 mg/L, and stable isotopic measurements indicated a predominantly biogenic carbonate reduction CH4 source. Radiocarbon dating of CH4 in combination with stable isotopic analysis of CH4 in three samples indicated that fossil C substrates are the source of CH4 in groundwater, with one 14C date indicative of modern biogenic carbonate reduction. We found no relationship between CH4 concentration or source in groundwater and proximity to active gas well sites. No significant changes in CH4 concentration, CH4 isotopic composition, pH, or conductivity in water wells were observed during the study period. These data indicate that high levels of biogenic CH4 can be present in groundwater wells independent of hydraulic fracturing activity and affirm the need for isotopic or other fingerprinting techniques for CH4 source identification. Continued monitoring of private drinking water wells is critical to ensure that groundwater quality is not altered as hydraulic fracturing activity continues in the region. Graphical abstract A shale gas well in rural Appalachian Ohio. Photo credit: Claire Botner.
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Affiliation(s)
- E Claire Botner
- Department of Geology, University of Cincinnati, 500 Geology-Physics Building, Cincinnati, OH, 45221-0013, USA
| | - Amy Townsend-Small
- Department of Geology, University of Cincinnati, 500 Geology-Physics Building, Cincinnati, OH, 45221-0013, USA.
| | - David B Nash
- Department of Geology, University of Cincinnati, 500 Geology-Physics Building, Cincinnati, OH, 45221-0013, USA
| | - Xiaomei Xu
- Department of Earth System Science, University of California, Irvine, Irvine, CA, 92697-4675, USA
| | - Arndt Schimmelmann
- Department of Earth and Atmospheric Sciences, Indiana University, 1001 East 10th Street, Bloomington, IN, 47405-1405, USA
| | - Joshua H Miller
- Department of Geology, University of Cincinnati, 500 Geology-Physics Building, Cincinnati, OH, 45221-0013, USA
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14
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Loveless SE, Bloomfield JP, Ward RS, Hart AJ, Davey IR, Lewis MA. Characterising the vertical separation of shale-gas source rocks and aquifers across England and Wales (UK). HYDROGEOLOGY JOURNAL 2018; 26:1975-1987. [PMID: 30956542 PMCID: PMC6417439 DOI: 10.1007/s10040-018-1737-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 01/23/2018] [Indexed: 05/26/2023]
Abstract
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.
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Affiliation(s)
- Sian E. Loveless
- British Geological Survey, Maclean Building, Crowmarsh Gifford, Oxon OX10 8BB UK
| | - John P. Bloomfield
- British Geological Survey, Maclean Building, Crowmarsh Gifford, Oxon OX10 8BB UK
| | - Robert S. Ward
- British Geological Survey, Maclean Building, Crowmarsh Gifford, Oxon OX10 8BB UK
| | - Alwyn J. Hart
- Environment Agency, Horizon House, Deanery Road, Bristol, BS1 5AH UK
| | - Ian R. Davey
- Environment Agency, Horizon House, Deanery Road, Bristol, BS1 5AH UK
| | - Melinda A. Lewis
- British Geological Survey, Maclean Building, Crowmarsh Gifford, Oxon OX10 8BB UK
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15
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Rivard C, Bordeleau G, Lavoie D, Lefebvre R, Malet X. Can groundwater sampling techniques used in monitoring wells influence methane concentrations and isotopes? ENVIRONMENTAL MONITORING AND ASSESSMENT 2018; 190:191. [PMID: 29508059 DOI: 10.1007/s10661-018-6532-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 02/07/2018] [Indexed: 06/08/2023]
Abstract
Methane concentrations and isotopic composition in groundwater are the focus of a growing number of studies. However, concerns are often expressed regarding the integrity of samples, as methane is very volatile and may partially exsolve during sample lifting in the well and transfer to sampling containers. While issues concerning bottle-filling techniques have already been documented, this paper documents a comparison of methane concentration and isotopic composition obtained with three devices commonly used to retrieve water samples from dedicated observation wells. This work lies within the framework of a larger project carried out in the Saint-Édouard area (southern Québec, Canada), whose objective was to assess the risk to shallow groundwater quality related to potential shale gas exploitation. The selected sampling devices, which were tested on ten wells during three sampling campaigns, consist of an impeller pump, a bladder pump, and disposable sampling bags (HydraSleeve). The sampling bags were used both before and after pumping, to verify the appropriateness of a no-purge approach, compared to the low-flow approach involving pumping until stabilization of field physicochemical parameters. Results show that methane concentrations obtained with the selected sampling techniques are usually similar and that there is no systematic bias related to a specific technique. Nonetheless, concentrations can sometimes vary quite significantly (up to 3.5 times) for a given well and sampling event. Methane isotopic composition obtained with all sampling techniques is very similar, except in some cases where sampling bags were used before pumping (no-purge approach), in wells where multiple groundwater sources enter the borehole.
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Affiliation(s)
- Christine Rivard
- Geological Survey of Canada, Natural Resources Canada, 490 rue de la Couronne, Quebec City, QC, G1K 9A9, Canada.
| | - Geneviève Bordeleau
- Geological Survey of Canada, Natural Resources Canada, 490 rue de la Couronne, Quebec City, QC, G1K 9A9, Canada
| | - Denis Lavoie
- Geological Survey of Canada, Natural Resources Canada, 490 rue de la Couronne, Quebec City, QC, G1K 9A9, Canada
| | - René Lefebvre
- Institut national de la recherche scientifique - Centre Eau Terre Environnement, 490 rue de la Couronne, Quebec City, QC, G1K 9A9, Canada
| | - Xavier Malet
- Geological Survey of Canada, Natural Resources Canada, 490 rue de la Couronne, Quebec City, QC, G1K 9A9, Canada
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16
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Eymold WK, Swana K, Moore MT, Whyte CJ, Harkness JS, Talma S, Murray R, Moortgat JB, Miller J, Vengosh A, Darrah TH. Hydrocarbon-Rich Groundwater above Shale-Gas Formations: A Karoo Basin Case Study. GROUND WATER 2018; 56:204-224. [PMID: 29409148 DOI: 10.1111/gwat.12637] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 12/27/2017] [Indexed: 06/07/2023]
Abstract
Horizontal drilling and hydraulic fracturing have enhanced unconventional hydrocarbon recovery but raised environmental concerns related to water quality. Because most basins targeted for shale-gas development in the USA have histories of both active and legacy petroleum extraction, confusion about the hydrogeological context of naturally occurring methane in shallow aquifers overlying shales remains. The Karoo Basin, located in South Africa, provides a near-pristine setting to evaluate these processes, without a history of conventional or unconventional energy extraction. We conducted a comprehensive pre-industrial evaluation of water quality and gas geochemistry in 22 groundwater samples across the Karoo Basin, including dissolved ions, water isotopes, hydrocarbon molecular and isotopic composition, and noble gases. Methane-rich samples were associated with high-salinity, NaCl-type groundwater and elevated levels of ethane, 4 He, and other noble gases produced by radioactive decay. This endmember displayed less negative δ13 C-CH4 and evidence of mixing between thermogenic natural gases and hydrogenotrophic methane. Atmospheric noble gases in the methane-rich samples record a history of fractionation during gas-phase migration from source rocks to shallow aquifers. Conversely, methane-poor samples have a paucity of ethane and 4 He, near saturation levels of atmospheric noble gases, and more negative δ13 C-CH4 ; methane in these samples is biogenic and produced by a mixture of hydrogenotrophic and acetoclastic sources. These geochemical observations are consistent with other basins targeted for unconventional energy extraction in the USA and contribute to a growing data base of naturally occurring methane in shallow aquifers globally, which provide a framework for evaluating environmental concerns related to unconventional energy development (e.g., stray gas).
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Affiliation(s)
- William K Eymold
- School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210
| | - Kelley Swana
- Department of Earth Sciences, Stellenbosch University, Private Bag XI, Matieland, 7602, South Africa
| | - Myles T Moore
- School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210
| | - Colin J Whyte
- School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210
| | - Jennifer S Harkness
- School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210
| | - Siep Talma
- Natural Resources and the Environment, CSIR Pretoria, P.O. Box 395, Pretoria, 0001, South Africa
| | - Ricky Murray
- Groundwater Africa, 38 Disa Ave., Kommetjie, 7975, South Africa
| | - Joachim B Moortgat
- School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210
| | - Jodie Miller
- Department of Earth Sciences, Stellenbosch University, Private Bag XI, Matieland, 7602, South Africa
| | - Avner Vengosh
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC 27708
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17
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Kreuzer RL, Darrah TH, Grove BS, Moore MT, Warner NR, Eymold WK, Whyte CJ, Mitra G, Jackson RB, Vengosh A, Poreda RJ. Structural and Hydrogeological Controls on Hydrocarbon and Brine Migration into Drinking Water Aquifers in Southern New York. GROUND WATER 2018; 56:225-244. [PMID: 29409144 DOI: 10.1111/gwat.12638] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 12/28/2017] [Indexed: 05/12/2023]
Abstract
Environmental concerns regarding the potential for drinking water contamination in shallow aquifers have accompanied unconventional energy development in the northern Appalachian Basin. These activities have also raised several critical questions about the hydrogeological parameters that control the naturally occurring presence and migration of hydrocarbon gases in shallow aquifers within petroliferous basins. To interrogate these factors, we analyzed the noble gas, dissolved ion, and hydrocarbon gas (molecular and isotopic composition) geochemistry of 98 groundwater samples from south-central New York. All samples were collected ≫1km from unconventional drilling activities and sample locations were intentionally targeted based on their proximity to various types of documented fault systems. In agreement with studies from other petroliferous basins, our results show significant correlations between elevated levels of radiogenic [4 He], thermogenic [CH4 ], and dissolved ions (e.g., Cl, Br, Sr, Ba). In combination, our data suggest that faults have facilitated the transport of exogenous hydrocarbon-rich brines from Devonian source rocks into overlying Upper Devonian aquifer lithologies over geologic time. These data conflict with previous reports, which conclude that hydrodynamic focusing regulates the occurrence of methane and salt in shallow aquifers and leads to elevated levels of these species in restricted flow zones within valley bottoms. Instead, our data suggest that faults in Paleozoic rocks play a fundamental role in gas and brine transport from depth, regulate the distribution of their occurrence in shallow aquifers, and influence the geochemistry of shallow groundwater in this petroliferous basin.
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Affiliation(s)
- Rebecca L Kreuzer
- Department of Earth and Environmental Sciences, University of Rochester, 227 Hutchison Hall, Rochester, NY 14627
| | | | - Benjamin S Grove
- Divisions of Solid Earth Dynamics and Water, Climate and the Environment, School of Earth Sciences, The Ohio State University, 125 South Oval Mall, Columbus, OH 43210
| | - Myles T Moore
- Divisions of Solid Earth Dynamics and Water, Climate and the Environment, School of Earth Sciences, The Ohio State University, 125 South Oval Mall, Columbus, OH 43210
| | - Nathaniel R Warner
- Department of Civil and Environmental Engineering, Pennsylvania State University, Sackett Building, 212 East College Avenue University Park, PA 16802
| | - William K Eymold
- Divisions of Solid Earth Dynamics and Water, Climate and the Environment, School of Earth Sciences, The Ohio State University, 125 South Oval Mall, Columbus, OH 43210
| | - Colin J Whyte
- Divisions of Solid Earth Dynamics and Water, Climate and the Environment, School of Earth Sciences, The Ohio State University, 125 South Oval Mall, Columbus, OH 43210
| | - Gautam Mitra
- Department of Earth and Environmental Sciences, University of Rochester, 227 Hutchison Hall, Rochester, NY 14627
| | - Robert B Jackson
- School of Earth, Energy, and Environmental Sciences, Woods Institute for the Environment, and Precourt Institute for Energy, Stanford University, Y2E2 Building Stanford, CA 94305
| | - Avner Vengosh
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, 205 Old Chemistry Building Durham, NC 27708
| | - Robert J Poreda
- Department of Earth and Environmental Sciences, University of Rochester, 227 Hutchison Hall, Rochester, NY 14627
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18
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Moortgat J, Schwartz FW, Darrah TH. Numerical Modeling of Methane Leakage from a Faulty Natural Gas Well into Fractured Tight Formations. GROUND WATER 2018; 56:163-175. [PMID: 29361650 DOI: 10.1111/gwat.12630] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 12/11/2017] [Indexed: 06/07/2023]
Abstract
Horizontal drilling and hydraulic fracturing have enabled hydrocarbon recovery from unconventional reservoirs, but led to natural gas contamination of shallow groundwaters. We describe and apply numerical models of gas-phase migration associated with leaking natural gas wells. Three leakage scenarios are simulated: (1) high-pressure natural gas pulse released into a fractured aquifer; (2) continuous slow leakage into a tilted fractured formation; and (3) continuous slow leakage into an unfractured aquifer with fluvial channels, to facilitate a generalized evaluation of natural gas transport from faulty natural gas wells. High-pressure pulses of gas leakage into sparsely fractured media are needed to produce the extensive and rapid lateral spreading of free gas previously observed in field studies. Transport in fractures explains how methane can travel vastly different distances and directions laterally away from a leaking well, which leads to variable levels of methane contamination in nearby groundwater wells. Lower rates of methane leakage (≤1 Mcf/day) produce shorter length scales of gas transport than determined by the high-pressure scenario or field studies, unless aquifers have low vertical permeabilities (≤1 millidarcy) and fractures and bedding planes have sufficient tilt (∼10°) to allow a lateral buoyancy component. Similarly, in fractured rock aquifers or where permeability is controlled by channelized fluvial deposits, lateral flow is not sufficiently developed to explain fast-developing gas contamination (0-3 months) or large length scales (∼1 km) documented in field studies. Thus, current efforts to evaluate the frequency, mechanism, and impacts of natural gas leakage from faulty natural gas wells likely underestimate contributions from small-volume, low-pressure leakage events.
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Affiliation(s)
| | | | - Thomas H Darrah
- School of Earth Sciences, The Ohio State University, Columbus, OH, 43210
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19
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Origin of methane-rich natural gas at the West Pacific convergent plate boundary. Sci Rep 2017; 7:15646. [PMID: 29142325 PMCID: PMC5688071 DOI: 10.1038/s41598-017-15959-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 11/06/2017] [Indexed: 11/25/2022] Open
Abstract
Methane emission from the geosphere is generally characterized by a radiocarbon-free signature and might preserve information on the deep carbon cycle on Earth. Here we report a clear relationship between the origin of methane-rich natural gases and the geodynamic setting of the West Pacific convergent plate boundary. Natural gases in the frontal arc basin (South Kanto gas fields, Northeast Japan) show a typical microbial signature with light carbon isotopes, high CH4/C2H6 and CH4/3He ratios. In the Akita-Niigata region – which corresponds to the slope stretching from the volcanic-arc to the back-arc –a thermogenic signature characterize the gases, with prevalence of heavy carbon isotopes, low CH4/C2H6 and CH4/3He ratios. Natural gases from mud volcanoes in South Taiwan at the collision zone show heavy carbon isotopes, middle CH4/C2H6 ratios and low CH4/3He ratios. On the other hand, those from the Tokara Islands situated on the volcanic front of Southwest Japan show the heaviest carbon isotopes, middle CH4/C2H6 ratios and the lowest CH4/3He ratios. The observed geochemical signatures of natural gases are clearly explained by a mixing of microbial, thermogenic and abiotic methane. An increasing contribution of abiotic methane towards more tectonically active regions of the plate boundary is suggested.
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20
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Nicot JP, Larson T, Darvari R, Mickler P, Slotten M, Aldridge J, Uhlman K, Costley R. Controls on Methane Occurrences in Shallow Aquifers Overlying the Haynesville Shale Gas Field, East Texas. GROUND WATER 2017; 55:443-454. [PMID: 28102897 DOI: 10.1111/gwat.12500] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/14/2016] [Indexed: 06/06/2023]
Abstract
Understanding the source of dissolved methane in drinking-water aquifers is critical for assessing potential contributions from hydraulic fracturing in shale plays. Shallow groundwater in the Texas portion of the Haynesville Shale area (13,000 km2 ) was sampled (70 samples) for methane and other dissolved light alkanes. Most samples were derived from the fresh water bearing Wilcox formations and show little methane except in a localized cluster of 12 water wells (17% of total) in a approximately 30 × 30 km2 area in Southern Panola County with dissolved methane concentrations less than 10 mg/L. This zone of elevated methane is spatially associated with the termination of an active fault system affecting the entire sedimentary section, including the Haynesville Shale at a depth more than 3.5 km, and with shallow lignite seams of Lower Wilcox age at a depth of 100 to 230 m. The lignite spatial extension overlaps with the cluster. Gas wetness and methane isotope compositions suggest a mixed microbial and thermogenic origin with contribution from lignite beds and from deep thermogenic reservoirs that produce condensate in most of the cluster area. The pathway for methane from the lignite and deeper reservoirs is then provided by the fault system.
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Affiliation(s)
- Jean-Philippe Nicot
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
| | - Toti Larson
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
- Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, 2305 Speedway, Austin, TX
| | - Roxana Darvari
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
| | - Patrick Mickler
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
| | | | | | - Kristine Uhlman
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
| | - Ruth Costley
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
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21
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Nicot JP, Mickler P, Larson T, Clara Castro M, Darvari R, Uhlman K, Costley R. Methane Occurrences in Aquifers Overlying the Barnett Shale Play with a Focus on Parker County, Texas. GROUND WATER 2017; 55:469-481. [PMID: 28248422 DOI: 10.1111/gwat.12508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Revised: 01/24/2017] [Accepted: 01/28/2017] [Indexed: 06/06/2023]
Abstract
Clusters of elevated methane concentrations in aquifers overlying the Barnett Shale play have been the focus of recent national attention as they relate to impacts of hydraulic fracturing. The objective of this study was to assess the spatial extent of high dissolved methane previously observed on the western edge of the play (Parker County) and to evaluate its most likely source. A total of 509 well water samples from 12 counties (14,500 km2 ) were analyzed for methane, major ions, and carbon isotopes. Most samples were collected from the regional Trinity Aquifer and show only low levels of dissolved methane (85% of 457 unique locations <0.1 mg/L). Methane, when present is primarily thermogenic (δ13 C 10th and 90th percentiles of -57.54 and -39.00‰ and C1/C2+C3 ratio 10th, 50th, and 90th percentiles of 5, 15, and 42). High methane concentrations (>20 mg/L) are limited to a few spatial clusters. The Parker County cluster area includes historical vertical oil and gas wells producing from relatively shallow formations and recent horizontal wells producing from the Barnett Shale (depth of ∼1500 m). Lack of correlation with distance to Barnett Shale horizontal wells, with distance to conventional wells, and with well density suggests a natural origin of the dissolved methane. Known commercial very shallow gas accumulations (<200 m in places) and historical instances of water wells reaching gas pockets point to the underlying Strawn Group of Paleozoic age as the main natural source of the dissolved gas.
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Affiliation(s)
- Jean-Philippe Nicot
- Bureau of Economic Geology, The University of Texas at Austin, Austin, TX, 78758-4445
| | - Patrick Mickler
- Bureau of Economic Geology, The University of Texas at Austin, Austin, TX, 78758-4445
| | - Toti Larson
- Bureau of Economic Geology, The University of Texas at Austin, Austin, TX, 78758-4445
- Department of Geological Sciences, The University of Texas at Austin, Austin, TX, 78712-1692
| | - M Clara Castro
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, 48109-1005
| | - Roxana Darvari
- Bureau of Economic Geology, The University of Texas at Austin, Austin, TX, 78758-4445
| | - Kristine Uhlman
- Bureau of Economic Geology, The University of Texas at Austin, Austin, TX, 78758-4445
| | - Ruth Costley
- Bureau of Economic Geology, The University of Texas at Austin, Austin, TX, 78758-4445
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22
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Nicot JP, Larson T, Darvari R, Mickler P, Uhlman K, Costley R. Controls on Methane Occurrences in Aquifers Overlying the Eagle Ford Shale Play, South Texas. GROUND WATER 2017; 55:455-468. [PMID: 28252808 DOI: 10.1111/gwat.12506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 01/22/2017] [Indexed: 06/06/2023]
Abstract
Assessing natural vs. anthropogenic sources of methane in drinking water aquifers is a critical issue in areas of shale oil and gas production. The objective of this study was to determine controls on methane occurrences in aquifers in the Eagle Ford Shale play footprint. A total of 110 water wells were tested for dissolved light alkanes, isotopes of methane, and major ions, mostly in the eastern section of the play. Multiple aquifers were sampled with approximately 47 samples from the Carrizo-Wilcox Aquifer (250-1200 m depth range) and Queen City-Sparta Aquifer (150-900 m depth range) and 63 samples from other shallow aquifers but mostly from the Catahoula Formation (depth <150 m). Besides three shallow wells with unambiguously microbial methane, only deeper wells show significant dissolved methane (22 samples >1 mg/L, 10 samples >10 mg/L). No dissolved methane samples exhibit thermogenic characteristics that would link them unequivocally to oil and gas sourced from the Eagle Ford Shale. In particular, the well water samples contain very little or no ethane and propane (C1/C2+C3 molar ratio >453), unlike what would be expected in an oil province, but they also display relatively heavier δ13 Cmethane (>-55‰) and δDmethane (>-180‰). Samples from the deeper Carrizo and Queen City aquifers are consistent with microbial methane sourced from syndepositional organic matter mixed with thermogenic methane input, most likely originating from deeper oil reservoirs and migrating through fault zones. Active oxidation of methane pushes δ13 Cmethane and δDmethane toward heavier values, whereas the thermogenic gas component is enriched with methane owing to a long migration path resulting in a higher C1/C2+C3 ratio than in the local reservoirs.
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Affiliation(s)
- Jean-Philippe Nicot
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
| | - Toti Larson
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
- Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, 2305 Speedway, Austin, TX
| | - Roxana Darvari
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
| | - Patrick Mickler
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
| | - Kristine Uhlman
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
| | - Ruth Costley
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, 10100 Burnet Road, Austin, TX
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23
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Boothroyd IM, Almond S, Worrall F, Davies RJ. Assessing the fugitive emission of CH 4 via migration along fault zones - Comparing potential shale gas basins to non-shale basins in the UK. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 580:412-424. [PMID: 27914640 DOI: 10.1016/j.scitotenv.2016.09.052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/22/2016] [Accepted: 09/07/2016] [Indexed: 06/06/2023]
Abstract
This study considered whether faults bounding hydrocarbon-bearing basins could be conduits for methane release to the atmosphere. Five basin bounding faults in the UK were considered: two which bounded potential shale gas basins; two faults that bounded coal basins; and one that bounded a basin with no known hydrocarbon deposits. In each basin, two mobile methane surveys were conducted, one along the surface expression of the basin bounding fault and one along a line of similar length but not intersecting the fault. All survey data was corrected for wind direction, the ambient CH4 concentration and the distance to the possible source. The survey design allowed for Analysis of Variance and this showed that there was a significant difference between the fault and control survey lines though a significant flux from the fault was not found in all basins and there was no apparent link to the presence, or absence, of hydrocarbons. As such, shale basins did not have a significantly different CH4 flux to non-shale hydrocarbon basins and non-hydrocarbon basins. These results could have implications for CH4 emissions from faults both in the UK and globally. Including all the corrected fault data, we estimate faults have an emissions factor of 11.5±6.3tCH4/km/yr, while the most conservative estimate of the flux from faults is 0.7±0.3tCH4/km/yr. The use of isotopes meant that at least one site of thermogenic flux from a fault could be identified. However, the total length of faults that penetrate through-basins and go from the surface to hydrocarbon reservoirs at depth in the UK is not known; as such, the emissions factor could not be multiplied by an activity level to estimate a total UK CH4 flux.
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Affiliation(s)
- I M Boothroyd
- Department of Earth Sciences, Durham University, Science Labs, Durham DH1 3LE, UK.
| | - S Almond
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle NE1 7RU, UK
| | - F Worrall
- Department of Earth Sciences, Durham University, Science Labs, Durham DH1 3LE, UK
| | - R J Davies
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle NE1 7RU, UK
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24
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Wen T, Castro MC, Nicot JP, Hall CM, Larson T, Mickler P, Darvari R. Methane Sources and Migration Mechanisms in Shallow Groundwaters in Parker and Hood Counties, Texas-A Heavy Noble Gas Analysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:12012-12021. [PMID: 27680396 DOI: 10.1021/acs.est.6b01494] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This study places constraints on the source and transport mechanisms of methane found in groundwater within the Barnett Shale footprint in Texas using dissolved noble gases, with particular emphasis on 84Kr and 132Xe. Dissolved methane concentrations are positively correlated with crustal 4He, 21Ne, and 40Ar and suggest that noble gases and methane originate from common sedimentary strata, likely the Strawn Group. In contrast to most samples, four water wells with the highest dissolved methane concentrations unequivocally show strong depletion of all atmospheric noble gases (20Ne, 36Ar, 84Kr, 132Xe) with respect to air-saturated water (ASW). This is consistent with predicted noble gas concentrations in a water phase in contact with a gas phase with initial ASW composition at 18 °C-25 °C and it suggests an in situ, highly localized gas source. All of these four water wells tap into the Strawn Group and it is likely that small gas accumulations known to be present in the shallow subsurface were reached. Additionally, lack of correlation of 84Kr/36Ar and 132Xe/36Ar fractionation levels along with 4He/20Ne with distance to the nearest gas production wells does not support the notion that methane present in these groundwaters migrated from nearby production wells either conventional or using hydraulic fracturing techniques.
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Affiliation(s)
- Tao Wen
- University of Michigan , Department of Earth and Environmental Sciences, Ann Arbor, Michigan 48109-1005, United States
| | - M Clara Castro
- University of Michigan , Department of Earth and Environmental Sciences, Ann Arbor, Michigan 48109-1005, United States
| | - Jean-Philippe Nicot
- University of Texas at Austin , Bureau of Economic Geology, Austin, Texas 78713-8924, United States
| | - Chris M Hall
- University of Michigan , Department of Earth and Environmental Sciences, Ann Arbor, Michigan 48109-1005, United States
| | - Toti Larson
- University of Texas at Austin , Bureau of Economic Geology, Austin, Texas 78713-8924, United States
| | - Patrick Mickler
- University of Texas at Austin , Bureau of Economic Geology, Austin, Texas 78713-8924, United States
| | - Roxana Darvari
- University of Texas at Austin , Bureau of Economic Geology, Austin, Texas 78713-8924, United States
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25
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Pinti DL, Gelinas Y, Moritz AM, Larocque M, Sano Y. Anthropogenic and natural methane emissions from a shale gas exploration area of Quebec, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 566-567:1329-1338. [PMID: 27267724 DOI: 10.1016/j.scitotenv.2016.05.193] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 05/16/2016] [Accepted: 05/26/2016] [Indexed: 06/06/2023]
Abstract
The increasing number of studies on the determination of natural methane in groundwater of shale gas prospection areas offers a unique opportunity for refining the quantification of natural methane emissions. Here methane emissions, computed from four potential sources, are reported for an area of ca. 16,500km(2) of the St. Lawrence Lowlands, Quebec (Canada), where Utica shales are targeted by the petroleum industry. Methane emissions can be caused by 1) groundwater degassing as a result of groundwater abstraction for domestic and municipal uses; 2) groundwater discharge along rivers; 3) migration to the surface by (macro- and micro-) diffuse seepage; 4) degassing of hydraulic fracturing fluids during first phases of drilling. Methane emissions related to groundwater discharge to rivers (2.47×10(-4) to 9.35×10(-3)Tgyr(-1)) surpass those of diffuse seepage (4.13×10(-6) to 7.14×10(-5)Tgyr(-1)) and groundwater abstraction (6.35×10(-6) to 2.49×10(-4)Tgyr(-1)). The methane emission from the degassing of flowback waters during drilling of the Utica shale over a 10- to 20-year horizon is estimated from 2.55×10(-3) to 1.62×10(-2)Tgyr(-1). These emissions are from one third to sixty-six times the methane emissions from groundwater discharge to rivers. This study shows that different methane emission sources need to be considered in environmental assessments of methane exploitation projects to better understand their impacts.
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Affiliation(s)
- Daniele L Pinti
- GEOTOP and Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, CP 8888, Succ. Centre-Ville, Montréal, QC H3C 1P8, Canada.
| | - Yves Gelinas
- GEOTOP and Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. West, Montreal, QC H4B 1R6, Canada
| | - Anja M Moritz
- GEOTOP and Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. West, Montreal, QC H4B 1R6, Canada
| | - Marie Larocque
- GEOTOP and Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, CP 8888, Succ. Centre-Ville, Montréal, QC H3C 1P8, Canada
| | - Yuji Sano
- Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba 277-8564, Japan; Department of Geosciences, National Taiwan University, Roosevelt Road, Taipei 106, Taiwan
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26
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Annevelink MPJA, Meesters JAJ, Hendriks AJ. Environmental contamination due to shale gas development. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 550:431-438. [PMID: 26845179 DOI: 10.1016/j.scitotenv.2016.01.131] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 01/21/2016] [Accepted: 01/21/2016] [Indexed: 06/05/2023]
Abstract
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.
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Affiliation(s)
- M P J A Annevelink
- Department of Environmental Science, Institute for Water and Wetland Research (IWWR), Radboud University (RU), Nijmegen, The Netherlands
| | - J A J Meesters
- Department of Environmental Science, Institute for Water and Wetland Research (IWWR), Radboud University (RU), Nijmegen, The Netherlands
| | - A J Hendriks
- Department of Environmental Science, Institute for Water and Wetland Research (IWWR), Radboud University (RU), Nijmegen, The Netherlands.
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27
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Burton TG, Rifai HS, Hildenbrand ZL, Carlton DD, Fontenot BE, Schug KA. Elucidating hydraulic fracturing impacts on groundwater quality using a regional geospatial statistical modeling approach. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 545-546:114-26. [PMID: 26745299 DOI: 10.1016/j.scitotenv.2015.12.084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 12/17/2015] [Accepted: 12/18/2015] [Indexed: 05/10/2023]
Abstract
Hydraulic fracturing operations have been viewed as the cause of certain environmental issues including groundwater contamination. The potential for hydraulic fracturing to induce contaminant pathways in groundwater is not well understood since gas wells are completed while isolating the water table and the gas-bearing reservoirs lay thousands of feet below the water table. Recent studies have attributed ground water contamination to poor well construction and leaks in the wellbore annulus due to ruptured wellbore casings. In this paper, a geospatial model of the Barnett Shale region was created using ArcGIS. The model was used for spatial analysis of groundwater quality data in order to determine if regional variations in groundwater quality, as indicated by various groundwater constituent concentrations, may be associated with the presence of hydraulically fractured gas wells in the region. The Barnett Shale reservoir pressure, completions data, and fracture treatment data were evaluated as predictors of groundwater quality change. Results indicated that elevated concentrations of certain groundwater constituents are likely related to natural gas production in the study area and that beryllium, in this formation, could be used as an indicator variable for evaluating fracturing impacts on regional groundwater quality. Results also indicated that gas well density and formation pressures correlate to change in regional water quality whereas proximity to gas wells, by itself, does not. The results also provided indirect evidence supporting the possibility that micro annular fissures serve as a pathway transporting fluids and chemicals from the fractured wellbore to the overlying groundwater aquifers.
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Affiliation(s)
- Taylour G Burton
- Civil and Environmental Engineering, University of Houston, W455 Engineering Bldg. 2, Houston, TX 77204-4003, United States.
| | - Hanadi S Rifai
- Civil and Environmental Engineering, University of Houston, N138 Engineering Bldg. 1, Houston, TX 77204-4003, United States.
| | - Zacariah L Hildenbrand
- Inform Environmental, LLC, Dallas, TX 75206, United States; Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019, United States.
| | - Doug D Carlton
- Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019, United States; Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX, United States.
| | - Brian E Fontenot
- Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019, United States.
| | - Kevin A Schug
- Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019, United States; Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX, United States.
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28
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Humez P, Mayer B, Ing J, Nightingale M, Becker V, Kingston A, Akbilgic O, Taylor S. Occurrence and origin of methane in groundwater in Alberta (Canada): Gas geochemical and isotopic approaches. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 541:1253-1268. [PMID: 26476065 DOI: 10.1016/j.scitotenv.2015.09.055] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 09/11/2015] [Accepted: 09/12/2015] [Indexed: 06/05/2023]
Abstract
To assess potential future impacts on shallow aquifers by leakage of natural gas from unconventional energy resource development it is essential to establish a reliable baseline. Occurrence of methane in shallow groundwater in Alberta between 2006 and 2014 was assessed and was ubiquitous in 186 sampled monitoring wells. Free and dissolved gas sampling and measurement approaches yielded comparable results with low methane concentrations in shallow groundwater, but in 28 samples from 21 wells methane exceeded 10mg/L in dissolved gas and 300,000 ppmv in free gas. Methane concentrations in free and dissolved gas samples were found to increase with well depth and were especially elevated in groundwater obtained from aquifers containing coal seams and shale units. Carbon isotope ratios of methane averaged -69.7 ± 11.1‰ (n=63) in free gas and -65.6 ± 8.9‰ (n=26) in dissolved gas. δ(13)C values were not found to vary with well depth or lithology indicating that methane in Alberta groundwater was derived from a similar source. The low δ(13)C values in concert with average δ(2)HCH4 values of -289 ± 44‰ (n=45) suggest that most methane was of biogenic origin predominantly generated via CO2 reduction. This interpretation is confirmed by dryness parameters typically >500 due to only small amounts of ethane and a lack of propane in most samples. Comparison with mud gas profile carbon isotope data revealed that methane in the investigated shallow groundwater in Alberta is isotopically similar to hydrocarbon gases found in 100-250 meter depths in the WCSB and is currently not sourced from thermogenic hydrocarbon occurrences in deeper portions of the basin. The chemical and isotopic data for methane gas samples obtained from Alberta groundwater provide an excellent baseline against which potential future impact of deeper stray gases on shallow aquifers can be assessed.
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Affiliation(s)
- P Humez
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
| | - B Mayer
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - J Ing
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - M Nightingale
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - V Becker
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - A Kingston
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - O Akbilgic
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada; UTHSC-ORNL Center for Biomedical Informatics, 910 Madison Avenue, Memphis, TN, 38104, USA
| | - S Taylor
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
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29
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Assessing Connectivity Between an Overlying Aquifer and a Coal Seam Gas Resource Using Methane Isotopes, Dissolved Organic Carbon and Tritium. Sci Rep 2015; 5:15996. [PMID: 26530701 PMCID: PMC4632156 DOI: 10.1038/srep15996] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/07/2015] [Indexed: 11/09/2022] Open
Abstract
Coal seam gas (CSG) production can have an impact on groundwater quality and quantity in adjacent or overlying aquifers. To assess this impact we need to determine the background groundwater chemistry and to map geological pathways of hydraulic connectivity between aquifers. In south-east Queensland (Qld), Australia, a globally important CSG exploration and production province, we mapped hydraulic connectivity between the Walloon Coal Measures (WCM, the target formation for gas production) and the overlying Condamine River Alluvial Aquifer (CRAA), using groundwater methane (CH4) concentration and isotopic composition (δ(13)C-CH4), groundwater tritium ((3)H) and dissolved organic carbon (DOC) concentration. A continuous mobile CH4 survey adjacent to CSG developments was used to determine the source signature of CH4 derived from the WCM. Trends in groundwater δ(13)C-CH4 versus CH4 concentration, in association with DOC concentration and (3)H analysis, identify locations where CH4 in the groundwater of the CRAA most likely originates from the WCM. The methodology is widely applicable in unconventional gas development regions worldwide for providing an early indicator of geological pathways of hydraulic connectivity.
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