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Zhang H, Han X, Wang G, Zhou L, Huang D, Chen X, Zhang F. Hydrogeochemical and isotopic evidences of the underlying produced water intrusion into shallow groundwater in an oil production area, Northwest China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 916:170242. [PMID: 38278275 DOI: 10.1016/j.scitotenv.2024.170242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 12/22/2023] [Accepted: 01/15/2024] [Indexed: 01/28/2024]
Abstract
The extensive use of fossil fuels (e.g., oil) poses a hidden danger to groundwater quality. However, inorganic pollution has received limited attention compared to organic pollution. In this study, the potential contaminant sources to shallow groundwater were investigated using hydrochemical (e.g., major and trace elements) and isotopic (δ2H and δ18O) methods at an oil field, northwest China, with emphasis on the identification of produced water (PW; oil production-related water) intrusion. The results showed that the groundwater samples can be chemically and isotopically classified into two groups: Group A (severely polluted) and B (slightly or non- polluted). The hydrochemical characteristics of Group A were similar to that of PW, with a comparable Na+/Cl- ratio and elevated levels of Na+, Ca2+, Cl-, Br-, Sr, Ba, Li, B and total volatile organic compounds (TVOCs; volatile and semi-volatile) concentration, but lower HCO3- and SO42- contents, and depleted δ2H and δ18O, which was not suitable for drinking. Groundwater salinity sources involve mineral dissolution (silicate, carbonate and evaporite), cation exchange and anaerobic microbial degradation, as well as deep PW intrusion (especially in Group A). The Cl mixing model showed that PW contributed 13.63-27.78 % to Group A, supported by the results of the isotope mixing model based on δ2H and δ18O (24.43-33.29 %). An overall pollution conceptual model involves three modes: fracturing, surface infiltration, and groundwater lateral runoff. This study validates the effectiveness of Na, Cl, Br, Sr, Ba, Li and B as favorable tracers for monitoring PW intrusion.
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Affiliation(s)
- Hongyu Zhang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Xu Han
- Geology Institute of China Chemical Geology and Mine Bureau, Beijing 100028, China
| | - Guangcai Wang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China.
| | - Ling Zhou
- Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, College of Water Sciences, Beijing Normal University, Beijing 100875, China
| | - Dandan Huang
- School of Water Resources & Environment Engineering, East China University of Technology, Nanchang, Jiangxi 330013, China
| | - Xianglong Chen
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Fan Zhang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
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2
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Zhang H, Han X, Wang G, Mao H, Chen X, Zhou L, Huang D, Zhang F, Yan X. Spatial distribution and driving factors of groundwater chemistry and pollution in an oil production region in the Northwest China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 875:162635. [PMID: 36889386 DOI: 10.1016/j.scitotenv.2023.162635] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 02/28/2023] [Accepted: 03/01/2023] [Indexed: 06/18/2023]
Abstract
Concerns have been raised on the deterioration of groundwater quality associated with anthropogenic impacts such as oil extraction and overuse of fertilizers. However, it is still difficult to identify groundwater chemistry/pollution and driving forces in regional scale since both natural and anthropogenic factors are spatially complex. This study, combining self-organizing map (SOM, combined with K-means algorithm) and principal component analysis (PCA), attempted to characterize the spatial variability and driving factors of shallow groundwater hydrochemistry in Yan'an area of Northwest China where diverse land use types (e.g., various oil production sites and agriculture lands) coexist. Based on the major and trace elements (e.g., Ba, Sr, Br, Li) and total petroleum hydrocarbons (TPH), groundwater samples were classified into four clusters with obvious geographical and hydrochemical characteristics by using SOM - K-means clustering: heavily oil-contaminated groundwater (Cluster 1), slightly oil-contaminated groundwater (Cluster 2), least-polluted groundwater (Cluster 3) and NO3- contaminated groundwater (Cluster 4). Noteworthily, Cluster 1, located in a river valley with long-term oil exploitation, had the highest levels of TPH and potentially toxic elements (Ba, Sr). Multivariate analysis combined with ion ratios analysis were used to determine the causes of these clusters. The results revealed that the hydrochemical compositions in Cluster 1 were mainly caused by the oil-related produced water intrusion into the upper aquifer. The elevated NO3- concentrations in Cluster 4 were induced by agricultural activities. Water-rock interactions (e.g., carbonate as well as silicate dissolution and precipitation) also shaped the chemical constituents of groundwater in clusters 2, 3, and 4. In addition, SO42--related processes (redox, precipitation of sulfate minerals) also affected groundwater chemical compositions in Cluster 1. This work provides the insight into the driving factors of groundwater chemistry and pollution which could contribute to groundwater sustainable management and protection in this area and other oil extraction areas.
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Affiliation(s)
- Hongyu Zhang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China
| | - Xu Han
- Geology Institute of China Chemical Geology and Mine Bureau, Beijing 100028, China
| | - Guangcai Wang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
| | - Hairu Mao
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China
| | - Xianglong Chen
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China
| | - Ling Zhou
- Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, College of Water Sciences, Beijing Normal University, Beijing 100875, PR China
| | - Dandan Huang
- School of Water Resources & Environment Engineering, East China University of Technology, Nanchang, Jiangxi 330013, PR China
| | - Fan Zhang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China
| | - Xin Yan
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China
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3
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Shaheen SW, Wen T, Herman A, Brantley SL. Geochemical Evidence of Potential Groundwater Contamination with Human Health Risks Where Hydraulic Fracturing Overlaps with Extensive Legacy Hydrocarbon Extraction. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:10010-10019. [PMID: 35767873 PMCID: PMC9302435 DOI: 10.1021/acs.est.2c00001] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Unconventional oil and gas development (UOGD) sometimes impacts water resources, including incidents of methane (CH4) migration from compromised wells and spills that degrade water with salts, organics, and metals. We hypothesized that contamination may be more common where UOGD overlaps with legacy coal, oil, and gas extraction. We tested this hypothesis on ∼7000 groundwater analyses from the largest U.S. shale gas play (Marcellus), using data mining techniques to explore UOGD contamination frequency. Corroborating the hypothesis, we discovered small, statistically significant regional correlations between groundwater chloride concentrations ([Cl]) and UOGD proximity and density where legacy extraction was extremely dense (southwestern Pennsylvania (SWPA)) but no such correlations where it was minimal (northeastern Pennsylvania). On the other hand, legacy extraction of shallow gas in SWPA may have lessened today's gas leakage, as no regional correlation was detected for [CH4] in SWPA. We identify hotspots where [Cl] and [CH4] increase by 3.6 and 3.0 mg/L, respectively, per UOG well drilled in SWPA. If the [Cl] correlations document contamination via brines leaked from wellbores, impoundments, or spills, we calculate that thallium concentrations could exceed EPA limits in the most densely developed hotspots, thus posing a potential human health risk.
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Affiliation(s)
- Samuel W. Shaheen
- Department
of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tao Wen
- Department
of Earth and Environmental Sciences, Syracuse
University, Syracuse, New York 13244, United States
| | - Alison Herman
- Earth
and Environmental Systems Institute, Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
| | - Susan L. Brantley
- Department
of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Earth
and Environmental Systems Institute, Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
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4
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Gallegos TJ, Doolan C, Caldwell R, Engle MA, Varonka M, Birdwell J, Jolly G, Coplen TB, Oliver T. Insights on Geochemical, Isotopic, and Volumetric Compositions of Produced Water from Hydraulically Fractured Williston Basin Oil Wells. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:10025-10034. [PMID: 34197090 DOI: 10.1021/acs.est.0c06789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Tracing produced water origins from wells hydraulically fractured with freshwater-based fluids is sometimes predicated on assumptions that (1) each geological formation contains compositionally unique brine and (2) produced water from recently hydraulically fractured wells resembles fresher meteoric water more so than produced water from older wells. These assumptions are not valid in Williston Basin oil wells sampled in this study. Although distinct average 228Ra/226Ra ratios were found in water produced from the Bakken and Three Forks Formations, average δ2H, δ18O, specific gravity, and conductivity were similar but exhibited significant variability across five oil fields within each formation. Furthermore, initial produced water ("flowback") was operationally defined based on the presence of glycol ether compounds and water from wells that had produced <56% of the amount of fluids injected and sampled within 160 days of fracturing. Flowback unexpectedly exhibited higher temperature, specific gravity, conductivity, δ2H, and δ18O, but lower oxidation-reduction potential and δ11B, relative to the wells thought to be producing formation brines (from wells with a produced-to-injected water ratio [PIWR] > 0.84 and sampled more than 316 days after fracturing). As such, establishing an overall geochemical and isotopic signature of produced water compositions based solely on chemical similarity to meteoric water and formation without the consideration of well treatments, well completion depth, or lateral location across the basin could be misleading if these signatures are assumed to be applicable across the entire basin. These findings have implications for using produced water compositions to understand the interbasin fluid flow and trace sources of hydraulic fracturing fluids.
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Affiliation(s)
- Tanya J Gallegos
- Geology, Energy and Minerals Science Center, U.S. Geological Survey, Reston, Virginia 20192, United States
| | - Colin Doolan
- Geology, Energy and Minerals Science Center, U.S. Geological Survey, Reston, Virginia 20192, United States
| | - Rodney Caldwell
- Wyoming-Montana Water Science Center, U.S. Geological Survey, Helena, Montana 59601, United States
| | - Mark A Engle
- Geology, Energy and Minerals Science Center, U.S. Geological Survey, Reston, Virginia 20192, United States
- The University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Matthew Varonka
- Geology, Energy and Minerals Science Center, U.S. Geological Survey, Reston, Virginia 20192, United States
| | - Justin Birdwell
- U.S. Geological Survey, Denver, Colorado 80225, United States
| | - Glenn Jolly
- Geology, Energy and Minerals Science Center, U.S. Geological Survey, Reston, Virginia 20192, United States
- U.S. Geological Survey, Water Mission Area, Reston, Virginia 20192, United States
| | - Tyler B Coplen
- Reston Stable Isotope Lab, U.S. Geological Survey, Reston, Virginia 20192, United States
| | - Thomas Oliver
- U.S. Geological Survey, Denver, Colorado 80225, United States
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5
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Bondu R, Kloppmann W, Naumenko-Dèzes MO, Humez P, Mayer B. Potential Impacts of Shale Gas Development on Inorganic Groundwater Chemistry: Implications for Environmental Baseline Assessment in Shallow Aquifers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:9657-9671. [PMID: 34251200 DOI: 10.1021/acs.est.1c01172] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The potential contamination of shallow groundwater with inorganic constituents is a major environmental concern associated with shale gas extraction through hydraulic fracturing. However, the impact of shale gas development on groundwater quality is a highly controversial issue. The only way to reliably assess whether groundwater quality has been impacted by shale gas development is to collect pre-development baseline data against which subsequent changes in groundwater quality can be compared. The objective of this paper is to provide a conceptual and methodological framework for establishing a baseline of inorganic groundwater quality in shale gas areas, which is becoming standard practice as a prerequisite for evaluating shale gas development impacts on shallow aquifers. For this purpose, this paper first reviews the potential sources of inorganic contaminants in shallow groundwater from shale gas areas. Then, it reviews the previous baseline studies of groundwater geochemistry in shale gas areas, showing that a comprehensive baseline assessment includes documenting the natural sources of salinity, potential geogenic contamination, and potential anthropogenic influences from legacy contamination and surface land use activities that are not related to shale gas development. Based on this knowledge, best practices are identified in terms of baseline sampling, selection of inorganic baseline parameters, and definition of threshold levels.
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Affiliation(s)
- Raphaël Bondu
- BRGM (French Geological Survey), 3 Avenue Claude-Guillemin, 45060 Orléans, France
| | - Wolfram Kloppmann
- BRGM (French Geological Survey), 3 Avenue Claude-Guillemin, 45060 Orléans, France
| | | | - Pauline Humez
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Bernhard Mayer
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
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6
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Soeder DJ. Groundwater Quality and Hydraulic Fracturing: Current Understanding and Science Needs. GROUND WATER 2018; 56:852-858. [PMID: 29992548 DOI: 10.1111/gwat.12810] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 06/29/2018] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
Hydraulic fracturing (fracking) is a process used for the stimulation and production of ultra-low permeability shale gas and tight oil resources. Fracking poses two main risks to groundwater quality: (1) stray gas migration and (2) potential contamination from chemical and fluid spills. Risk assessment is complicated by the lack of predrilling baseline measurements, limited access to well sites and industry data, the constant introduction of new chemical additives to frack fluids, and difficulties comparing data sets obtained by different sampling and analytical methods. Specific recommendations to reduce uncertainties and meet science needs for better assessment of groundwater risks include improving data-sharing among researchers, adopting standardized methodologies, collecting predrilling baseline data, installing dedicated monitoring wells, developing shale-specific environmental indicators, and providing greater access to field sites, samples, and industry data to the research community.
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Affiliation(s)
- Daniel J Soeder
- Energy Resources Initiative, Department of Geology and Geological Engineering, South Dakota School of Mines & Technology, 501 East St. Joseph Street, Rapid City, SD 57701-3995
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7
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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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8
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Harkness JS, Swana K, Eymold WK, Miller J, Murray R, Talma S, Whyte CJ, Moore MT, Maletic EL, Vengosh A, Darrah TH. Pre-drill Groundwater Geochemistry in the Karoo Basin, South Africa. GROUND WATER 2018; 56:187-203. [PMID: 29381808 DOI: 10.1111/gwat.12635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 12/19/2017] [Indexed: 06/07/2023]
Abstract
Enhanced production of unconventional hydrocarbons in the United States has driven interest in natural gas development globally, but simultaneously raised concerns regarding water quantity and quality impacts associated with hydrocarbon extraction. We conducted a pre-development assessment of groundwater geochemistry in the critically water-restricted Karoo Basin, South Africa. Twenty-two springs and groundwater samples were analyzed for major dissolved ions, trace elements, water stable isotopes, strontium and boron isotopes, hydrocarbons and helium composition. The data revealed three end-members: a deep, saline groundwater with a sodium-chloride composition, an old, deep freshwater with a sodium-bicarbonate-chloride composition and a shallow, calcium-bicarbonate freshwater. In a few cases, we identified direct mixing of the deep saline water and shallow groundwater. Stable water isotopes indicate that the shallow groundwater was controlled by evaporation in arid conditions, while the saline waters were diluted by apparently fossil meteoric water originated under wetter climatic conditions. These geochemical and isotopic data, in combination with elevated helium levels, suggest that exogenous fluids are the source of the saline groundwater and originated from remnant seawater prior to dilution by old meteoric water combined with further modification by water-rock interactions. Samples with elevated methane concentrations (>14 ccSTP/kg) were strongly associated with the sodium-chloride water located near dolerite intrusions, which likely provide a preferential pathway for vertical migration of deeply sourced hydrocarbon-rich saline waters to the surface. This pre-drill evaluation indicates that the natural migration of methane- and salt-rich waters provides a source of geogenic contamination to shallow aquifers prior to shale gas development in the Karoo Basin.
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Affiliation(s)
- Jennifer S Harkness
- School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC 27708
| | - Kelley Swana
- Department of Earth Sciences, Stellenbosch University, Private Bag XI, Matieland 7602, South Africa
| | - William K Eymold
- 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
| | - Ricky Murray
- Groundwater Africa, 54 Irene Road, Somerset West 7130, South Africa
| | - Siep Talma
- Natural Resources and the Environment, CSIR Pretoria, P.O. Box 395, Pretoria 0001, South Africa
| | - Colin J Whyte
- School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210
| | - Myles T Moore
- School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210
| | - Erica L Maletic
- School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210
| | - Avner Vengosh
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC 27708
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9
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Harkness JS, Darrah TH, Moore MT, Whyte CJ, Mathewson PD, Cook T, Vengosh A. Naturally Occurring versus Anthropogenic Sources of Elevated Molybdenum in Groundwater: Evidence for Geogenic Contamination from Southeast Wisconsin, United States. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:12190-12199. [PMID: 28980802 DOI: 10.1021/acs.est.7b03716] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Molybdenum (Mo) is an essential trace nutrient but has negative health effects at high concentrations. Groundwater typically has low Mo (<2 μg/L), and elevated levels are associated with anthropogenic contamination, although geogenic sources have also been reported. Coal combustion residues (CCRs) are enriched in Mo, and thus present a potential anthropogenic contamination source. Here, we use diagnostic geochemical tracers combined with groundwater residence time indicators to investigate the sources of Mo in drinking-water wells from shallow aquifers in a region of widespread CCR disposal in southeastern Wisconsin. Samples from drinking-water wells were collected in areas near and away from known CCR disposal sites, and analyzed for Mo and inorganic geochemistry indicators, including boron and strontium isotope ratios, along with groundwater tritium-helium and radiogenic 4He in-growth age-dating techniques. Mo concentrations ranged from <1 to 149 μg/L. Concentrations exceeding the U.S. Environmental Protection Agency health advisory of 40 μg/L were found in deeper, older groundwater (mean residence time >300 y). The B (δ11B = 22.9 ± 3.5‰) and Sr (87Sr/86Sr = 0.70923 ± 0.00024) isotope ratios were not consistent with the expected isotope fingerprints of CCRs, but rather mimic the compositions of local lithologies. The isotope signatures combined with mean groundwater residence times of more than 300 years for groundwater with high Mo concentrations support a geogenic source of Mo to the groundwater, rather than CCR-induced contamination. This study demonstrates the utility of a multi-isotope approach to distinguish between fossil fuel-related and natural sources of groundwater contamination.
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Affiliation(s)
- Jennifer S Harkness
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States
- Divisions of Solid Earth Dynamics and Water, Climate and the Environment, School of Earth Sciences, The Ohio State University , Columbus, Ohio 43210, United States
| | - Thomas H Darrah
- Divisions of Solid Earth Dynamics and Water, Climate and the Environment, School of Earth Sciences, The Ohio State University , Columbus, Ohio 43210, United States
| | - Myles T Moore
- Divisions of Solid Earth Dynamics and Water, Climate and the Environment, School of Earth Sciences, The Ohio State University , Columbus, Ohio 43210, United States
| | - Colin J Whyte
- Divisions of Solid Earth Dynamics and Water, Climate and the Environment, School of Earth Sciences, The Ohio State University , Columbus, Ohio 43210, United States
| | - Paul D Mathewson
- Clean Wisconsin, 634 W. Main Street, Suite 300, Madison, Wisconsin 53703, United States
| | - Tyson Cook
- Clean Wisconsin, 634 W. Main Street, Suite 300, Madison, Wisconsin 53703, United States
| | - Avner Vengosh
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States
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10
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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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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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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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McMahon PB, Barlow JRB, Engle MA, Belitz K, Ging PB, Hunt AG, Jurgens BC, Kharaka YK, Tollett RW, Kresse TM. Methane and Benzene in Drinking-Water Wells Overlying the Eagle Ford, Fayetteville, and Haynesville Shale Hydrocarbon Production Areas. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:6727-6734. [PMID: 28562061 DOI: 10.1021/acs.est.7b00746] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Water wells (n = 116) overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas were sampled for chemical, isotopic, and groundwater-age tracers to investigate the occurrence and sources of selected hydrocarbons in groundwater. Methane isotopes and hydrocarbon gas compositions indicate most of the methane in the wells was biogenic and produced by the CO2 reduction pathway, not from thermogenic shale gas. Two samples contained methane from the fermentation pathway that could be associated with hydrocarbon degradation based on their co-occurrence with hydrocarbons such as ethylbenzene and butane. Benzene was detected at low concentrations (<0.15 μg/L), but relatively high frequencies (2.4-13.3% of samples), in the study areas. Eight of nine samples containing benzene had groundwater ages >2500 years, indicating the benzene was from subsurface sources such as natural hydrocarbon migration or leaking hydrocarbon wells. One sample contained benzene that could be from a surface release associated with hydrocarbon production activities based on its age (10 ± 2.4 years) and proximity to hydrocarbon wells. Groundwater travel times inferred from the age-data indicate decades or longer may be needed to fully assess the effects of potential subsurface and surface releases of hydrocarbons on the wells.
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Affiliation(s)
- Peter B McMahon
- U.S. Geological Survey, Colorado Water Science Center, Denver Federal Center, Bldg 53, MS 415, Denver, Colorado 80225, United States
| | - Jeannie R B Barlow
- U.S. Geological Survey, Lower Mississippi-Gulf Water Science Center, 308 South Airport Road, Jackson, Mississippi 39208, United States
| | - Mark A Engle
- U.S. Geological Survey, Eastern Energy Resources Science Center, Department of Geological Sciences, University of Texas at El Paso , El Paso, Texas 79968, United States
| | - Kenneth Belitz
- U.S. Geological Survey, New England Water Science Center, 10 Bearfoot Road, Northboro, Massachusetts 01532, United States
| | - Patricia B Ging
- U.S. Geological Survey, Texas Water Science Center, 1505 Ferguson Lane, Austin, Texas 78754, United States
| | - Andrew G Hunt
- Crustal Geophysics and 17 Geochemistry Science Center, Denver Federal Center, Bldg 95, MS 963, Denver, Colorado 80225, United States
| | - Bryant C Jurgens
- U.S. Geological Survey, California Water Science Center, 6000 J Street, Placer Hall, Sacramento, California 95819, United States
| | - Yousif K Kharaka
- U.S. Geological Survey, National Research Program, 345 Middlefield Road, Menlo Park, California 94025, United States
| | - Roland W Tollett
- U.S. Geological Survey, Lower Mississippi-Gulf Water Science Center, 3095 West California, Ruston, Louisiana 71270, United States
| | - Timothy M Kresse
- U.S. Geological Survey, Lower Mississippi-Gulf Water Science Center, 401 Hardin Road, Little Rock, Arkansas 72211, United States
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Shrestha N, Chilkoor G, Wilder J, Gadhamshetty V, Stone JJ. Potential water resource impacts of hydraulic fracturing from unconventional oil production in the Bakken shale. WATER RESEARCH 2017; 108:1-24. [PMID: 27865434 DOI: 10.1016/j.watres.2016.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/28/2016] [Accepted: 11/01/2016] [Indexed: 05/24/2023]
Abstract
Modern drilling techniques, notably horizontal drilling and hydraulic fracturing, have enabled unconventional oil production (UOP) from the previously inaccessible Bakken Shale Formation located throughout Montana, North Dakota (ND) and the Canadian province of Saskatchewan. The majority of UOP from the Bakken shale occurs in ND, strengthening its oil industry and businesses, job market, and its gross domestic product. However, similar to UOP from other low-permeability shales, UOP from the Bakken shale can result in environmental and human health effects. For example, UOP from the ND Bakken shale generates a voluminous amount of saline wastewater including produced and flowback water that are characterized by unusual levels of total dissolved solids (350 g/L) and elevated levels of toxic and radioactive substances. Currently, 95% of the saline wastewater is piped or trucked onsite prior to disposal into Class II injection wells. Oil and gas wastewater (OGW) spills that occur during transport to injection sites can potentially result in drinking water resource contamination. This study presents a critical review of potential water resource impacts due to deterministic (freshwater withdrawals and produced water management) and probabilistic events (spills due to leaking pipelines and truck accidents) related to UOP from the Bakken shale in ND.
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Affiliation(s)
- Namita Shrestha
- Civil and Environmental Engineering, South Dakota School of Mines and Technology, 501 E. St Joseph Street, Rapid City, SD 57701, USA
| | - Govinda Chilkoor
- Civil and Environmental Engineering, South Dakota School of Mines and Technology, 501 E. St Joseph Street, Rapid City, SD 57701, USA
| | - Joseph Wilder
- Civil and Environmental Engineering, South Dakota School of Mines and Technology, 501 E. St Joseph Street, Rapid City, SD 57701, USA
| | - Venkataramana Gadhamshetty
- Civil and Environmental Engineering, South Dakota School of Mines and Technology, 501 E. St Joseph Street, Rapid City, SD 57701, USA.
| | - James J Stone
- Civil and Environmental Engineering, South Dakota School of Mines and Technology, 501 E. St Joseph Street, Rapid City, SD 57701, USA
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