Quality and Age of Shallow Groundwater in the Bakken Formation Production Area, Williston Basin, Montana and North Dakota

McMahon, Peter B.; Caldwell, Rodney R.; Galloway, Joel M.; Valder, Joshua F.; Hunt, Andrew G.

doi:10.1111/gwat.12296

Cited by 30 publications

(39 citation statements)

References 57 publications

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“…Tritium active waters indicate the presence of post‐1950s (Modern) water (recharged since the early 1950s). Excess 3 He produced by the radioactive decay of 3 H was calculated by in‐growth methods using the measured 3 He/ 4 He and 4 He concentrations and noble‐gas derived amounts of excess air and recharge temperatures (Schlosser et al ; McMahon et al ).…”

Section: Study Area and Methodologymentioning

confidence: 99%

Pre‐drill Groundwater Geochemistry in the Karoo Basin, South Africa

et al. 2018

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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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Section: Study Area and Methodologymentioning

confidence: 99%

Pre‐drill Groundwater Geochemistry in the Karoo Basin, South Africa

et al. 2018

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“…These initial studies were quickly followed by others in Pennsylvania (Heisig and Scott 2013;Baldassare et al 2014;Darrah et al 2014;Wilson 2014;Siegel et al 2015Siegel et al , 2016Christian et al 2016) and elsewhere: Colorado (Li and Carlson 2014;Sherwood et al 2016), Fayetteville in Arkansas (Warner et al 2013), Bakken in North Dakota (McMahon et al 2015), Texas (Nicot et al 2015(Nicot et al , 2017a(Nicot et al , 2017bWen et al 2016), and Canada (Cheung et al 2010;Moritz et al 2015;Humez et al 2016). The source of the dissolved methane is sometimes clear, in particular when it is microbial (Warner et al 2013;McMahon et al 2015) but still the object of conflicting studies when mostly thermogenic, such as in Pennsylvania (Jackson et al 2013a;Molofsky et al 2013;Darrah et al 2014) or Texas (Darrah et al 2014;Wen et al 2016). If dissolved methane of microbial origin is natural in the vast majority of cases, a thermogenic dissolved gas can be naturally present in shallow groundwater or it can be anthropogenic and introduced directly or indirectly during well drilling and completion or natural gas production (Jackson et al 2013b).…”

Section: Introductionmentioning

confidence: 99%

Methane Occurrences in Aquifers Overlying the Barnett Shale Play with a Focus on Parker County, Texas

et al. 2017

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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 km ) 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 (δ 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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“…The now decade-old rapid development of U.S. shale oil and gas plays has renewed discussions about impacts of the oil and gas industry on fresh water resources (Nicot and Scanlon 2012;Jackson et al 2013b;Vidic et al 2013;Soeder et al 2014;Stephens 2015). Several recent studies have investigated the presence of methane in shallow aquifers in the footprint of the Marcellus Shale in the northeastern United States (White and Mathes 2006;Osborn et al 2011;Warner et al 2012;Heisig and Scott 2013;Jackson et al 2013a;Molofsky et al 2013;Darrah et al 2014;Sharma et al 2014;Siegel et al 2015), of the Fayetteville Shale in Arkansas (Warner et al 2013), of the Bakken Play in North Dakota (McMahon et al 2015), of the Niobrara Play in Colorado (Li and Carlson 2014), of the Haynesville Play in East Texas (Nicot et al 2017a), and of the Barnett Shale in North Texas (Darrah et al 2014;Wen et al 2016;Nicot et al 2017b2017b). Other studies have also been performed in Canada (Cheung et al 2010;Moritz et al 2015;Humez et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Controls on Methane Occurrences in Aquifers Overlying the Eagle Ford Shale Play, South Texas

et al. 2017

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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 δ C (>-55‰) and δD (>-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 δ C and δD 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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Quality and Age of Shallow Groundwater in the Bakken Formation Production Area, Williston Basin, Montana and North Dakota

Cited by 30 publications

References 57 publications

Pre‐drill Groundwater Geochemistry in the Karoo Basin, South Africa

Pre‐drill Groundwater Geochemistry in the Karoo Basin, South Africa

Methane Occurrences in Aquifers Overlying the Barnett Shale Play with a Focus on Parker County, Texas

Controls on Methane Occurrences in Aquifers Overlying the Eagle Ford Shale Play, South Texas

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