Effects of Unconventional Gas Development on Groundwater: A Call for Total Dissolved Gas Pressure Field Measurements

Roy, James W.; Ryan, M. Cathryn

doi:10.1111/gwat.12065

Cited by 18 publications

(19 citation statements)

References 15 publications

(28 reference statements)

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“…Throughout the world the occurrence of freshwater aquifers adjacent to unconventional-gas production is common (Osborn et al, 2011;Moore, 2012;Roy and Ryan, 2013;Vidic et al, 2013;Vengosh et al, 2014;Moritz et al, 2015). We have previously shown that there may be local natural connectivity between the WCM and the CRAA (Iverach et al, 2015 ], δ 13 C-CH 4 , δ 13 C-DIC, δ 13 C-DOC and δ 2 H-H 2 O), as well as characterisation of microbiological communities present, can inform the discussion surrounding the occurrence of CH 4 and its potential for upward migration in the groundwater of the CRAA.…”

Section: Introductionmentioning

confidence: 99%

Biogeochemical constraints on the origin of methane in an alluvial aquifer: evidence for the upward migration of methane from underlying coal measures

et al. 2017

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Abstract. Geochemical and microbiological indicators of methane (CH 4 ) production, oxidation and migration processes in groundwater are important to understand when attributing sources of gas. The processes controlling the natural occurrence of CH 4 in groundwater must be understood, especially when considering the potential impacts of the global expansion of coal seam gas (CSG) production on groundwater quality and quantity. We use geochemical and microbiological data, along with measurements of CH 4 isotopic composition (δ 13 C-CH 4 ), to determine the processes acting upon CH 4 in a freshwater alluvial aquifer that directly overlies coal measures targeted for CSG production in Australia. Measurements of CH 4 indicate that there is biogenic CH 4 in the aquifer; however, microbial data indicate that there are no methanogenic archaea in the groundwater. In addition, geochemical data, particularly the isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC), as well as the concentration of SO 2− 4 , indicate limited potential for methanogenesis in situ. Microbial community analysis also shows that aerobic oxidation of CH 4 occurs in the alluvial aquifer. The combination of microbiological and geochemical indicators suggests that the most likely source of CH 4 , where it was present in the freshwater aquifer, is the upward migration of CH 4 from the underlying coal measures.

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Section: Introductionmentioning

confidence: 99%

Biogeochemical constraints on the origin of methane in an alluvial aquifer: evidence for the upward migration of methane from underlying coal measures

et al. 2017

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“…Debates about the impact of gas production can hinge on claims about CH 4 leaks and emission, but methodologies to fingerprint gas sources are as yet weak. The production of unconventional gas typically requires the joint extraction of very large quantities of groundwater per day, which can affect groundwater levels in neighbouring aquifers 1 2 . Another environmental concern is the impact of gas migration on shallow groundwater resources 1 2 3 4 5 .…”

mentioning

confidence: 99%

“…The production of unconventional gas typically requires the joint extraction of very large quantities of groundwater per day, which can affect groundwater levels in neighbouring aquifers 1 2 . Another environmental concern is the impact of gas migration on shallow groundwater resources 1 2 3 4 5 . Recent studies around shale gas production sites in the USA report elevated CH 4 in aquifers up to two kilometres away from the production wells 6 7 .…”

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confidence: 99%

“…More recent studies have argued that this may not be a result of shale gas production 8 9 . Although research is largely associated with shale gas developments in the USA 1 2 3 4 5 6 7 8 9 similar issues associated with aquifer hydraulic connectivity also accompany CSG developments worldwide. It is clear that a methodology to quantify potential impacts of unconventional gas production needs to be developed, as well as an understanding of existing pathways of hydraulic connectivity, prior to significant gas production.…”

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confidence: 99%

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Assessing Connectivity Between an Overlying Aquifer and a Coal Seam Gas Resource Using Methane Isotopes, Dissolved Organic Carbon and Tritium

Iverach

Cendón

Hankin

et al. 2015

Sci Rep

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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 (δ13C-CH4), groundwater tritium (3H) 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 δ13C-CH4 versus CH4 concentration, in association with DOC concentration and 3H 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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“…In the case of gas‐saturation, this P critical can be assumed as the in situ hydrostatic pressure of the groundwater, which is directly measurable or can be estimated from relevant hydrological information. Even in the case of gas‐unsaturation, P critical could be obtained using a total dissolved gas pressure probe (e.g., Roy and Ryan , ). When P critical is incorrectly assumed, the atmospheric sampling method derives erroneous dissolved gas concentrations, as observed here for CH 4 (aq) concentrations at gas‐unsaturated locations (Figure ).…”

Section: Resultsmentioning

confidence: 99%

A Proposed Method to Estimate In Situ Dissolved Gas Concentrations in Gas‐Saturated Groundwater

Tamamura¹,

Miyakawa

Aramaki

et al. 2017

Groundwater

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Gas-saturated groundwater forms bubbles when brought to atmospheric pressure, preventing precise determination of its in situ dissolved gas concentrations. To overcome this problem, a modeling approach called the atmospheric sampling method is suggested here to recover the in situ dissolved gas concentrations of groundwater collected ex situ under atmospheric conditions at the Horonobe Underground Research Laboratory, Japan. The results from this method were compared with results measured at the same locations using two special techniques, the sealed sampler and pre-evacuated vial methods, that have been developed to collect groundwater under its in situ conditions. In gas-saturated groundwater cases, dissolved methane and inorganic carbon concentrations derived using the atmospheric sampling method were mostly within ±4 and ±10%, respectively, of values from the sealed sampler and pre-evacuated vial methods. In gas-unsaturated groundwater, however, the atmospheric sampling method overestimated the in situ dissolved methane concentrations, because the groundwater pressure at which bubbles appear (P critical ) was overestimated. The atmospheric sampling method is recommended for use where gas-saturated groundwater can be collected only ex situ under atmospheric conditions.

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Effects of Unconventional Gas Development on Groundwater: A Call for Total Dissolved Gas Pressure Field Measurements

Cited by 18 publications

References 15 publications

Biogeochemical constraints on the origin of methane in an alluvial aquifer: evidence for the upward migration of methane from underlying coal measures

Biogeochemical constraints on the origin of methane in an alluvial aquifer: evidence for the upward migration of methane from underlying coal measures

Assessing Connectivity Between an Overlying Aquifer and a Coal Seam Gas Resource Using Methane Isotopes, Dissolved Organic Carbon and Tritium

A Proposed Method to Estimate In Situ Dissolved Gas Concentrations in Gas‐Saturated Groundwater

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