Assessing Methane in Shallow Groundwater in Unconventional Oil and Gas Play Areas, Eastern Kentucky

Zhu, Junfeng; Parris, Thomas M.; Taylor, C. James; Webb, Steven E.; Davidson, Bart; Smath, Richard A.; Richardson, Stephen D.; Molofsky, Lisa J.; Kromann, Jenna S.; Smith, Alexander Thomas T.

doi:10.1111/gwat.12583

Cited by 6 publications

(10 citation statements)

References 27 publications

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“…As in other studies (e.g. Molofsky et al, 2016;Zhu et al, 2017), this dependency on redox conditions is illustrated by the near mutual 6 157 Synthesis | exclusivity of dissolved sulphate and methane in almost all samples, particularly those with short well screen lengths.…”

Section: Origin and Distribution Of Groundwater Methane In The Netherlandssupporting

confidence: 79%

“…Although subject to differences in sampling bias and dataset size, methane concentrations in groundwater in the Netherlands appear to be relatively high compared to the values obtained in similar international studies (Figure 2). In this study, methane concentrations >1 mg/l occur in 32.5% of samples, a number that is only exceeded by a study conducted in Eastern Kentucky (Zhu et al, 2017). This is evidence of the pervasive presence of dissolved methane in Dutch groundwater, that is presumably related to the equally pervasive presence of degradable organic matter in much of the Cenozoic sedimentary system that hosts freshwater circulation.…”

Section: Origin and Distribution Of Groundwater Methane In The Netherlandsmentioning

confidence: 49%

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Origin, fate and detection of methane leaking from the deep subsurface into groundwater and soil

Schout¹

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Oil and gas development can cause unintended connectivity between the deep subsurface and shallow aquifers. Methane leaking through such connections can result in groundwater contamination, greenhouse gas emissions, and can constitute an explosion hazard. When leaking methane enters into groundwater and soil systems it is subject to a number of processes that can retain it, degrade it, and alter its molecular and isotopic signature. This signature is used for environmental fingerprinting of methane origin, and can be further changed by mixing of leaking methane with naturally occurring biogenic sources. Together, the combination of those processes makes detection of leakage through surficial flux measurements or groundwater sampling challenging.In this work, the fate of methane leaking from oil and gas reservoirs into the environment was studied using a combination of scientific approaches, including groundwater sampling and analysis of dissolved gasses and isotopic tracers, soil gas flux measurements, and multiphase numerical modelling. Additionally, the occurrence of methane leakage at legacy gas wells in the Netherlands was investigated, together with a characterization of the natural distribution and origin of methane in groundwater in the Netherlands. Based on this combined hydrogeochemical investigation, the study provides further insight into the risks of methane leakage, and the processes that control its migration through the subsurface. ContentsChapter 1 | Introduction 1.1 | Methane leaking from the deep subsurface into groundwater and soil 1.2 | Methane geochemistry 1.3 | Construction and abandonment of oil and gas wells 1.4 | Well failure and methane leakage 1.5 | History of oil and gas production in the Netherlands 1.6 | NWO shale gas and water research program 1.7 | Research aims and thesis outline Chapter 2 | Controls on groundwater methane occurrence and origin from shallow aquifers to deep formation waters in the Netherlands 2.1 | Introduction 2.2 | Hydrogeology of the Netherlands 2.3 | Methods 2.4 | Results and discussion 2.5 | Conclusions Chapter 3 | Occurrence and fate of methane leakage from cut and buried abandoned gas wells in the Netherlands 3.1 | Introduction 3.2 | Materials and Methods 3.3 | Results 3.4 | Discussion 3.5 | Conclusions Chapter 4 | The impact of an historic underground gas well blowout on the current methane chemistry in a shallow groundwater system 4.1 | Introduction 4.2 | Hydrogeological setting 4.3 | Methods 4.4 | Results and discussion 4.5 | Conclusions Chapter 5 | Impact of groundwater flow on methane gas migration and retention in unconsolidated aquifers 5.1 | Introduction 5.2 | Material and Methods 5.3 | Results 5.4 | Discussion 5.5 | Conclusions Chapter 6 | Synthesis 6.1 | Introduction 6.2 | Summary of main findings 6.3 | Origin and distribution of groundwater methane in the Netherlands 6.4 | Fate and detection of methane leaking from the deep subsurface 6.5 | The risks of methane leakage in the Dutch context Summary Samenvatting List of Publications Dankwoord Curri...

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Section: Origin and Distribution Of Groundwater Methane In The Netherlandssupporting

confidence: 79%

Section: Origin and Distribution Of Groundwater Methane In The Netherlandsmentioning

confidence: 49%

Origin, fate and detection of methane leaking from the deep subsurface into groundwater and soil

Schout¹

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“…Dissolved methane in drinking water is not considered a public health hazard, and it may also occur naturally in groundwater as the result of thermogenic and microbial processes (Nicot et al 2017;Moortgat et al 2018;Zhu et al 2018). Its presence in groundwater may change pH and redox conditions, causing either the release or the depletion of some trace metals depending on site conditions (Schwartz 2015;Cahill et al 2017;Darvari et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of a Methane Leakage from a Geothermal Well into a Shallow Aquifer

D'Aniello¹,

Fabbricino

Ducci

et al. 2019

Groundwater

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The potential environmental impacts on subsurface water resources induced by unconventional gas production are still under debate. Solving the controversy regarding the potential adverse effects of gas leakages on groundwater resources is therefore crucial. In this work, an interesting real-world case is presented in order to give further insight into methane multiphase and transport behavior in the shallow subsurface, often disregarded compared to the behavior in the deep subsurface. Multiphase flow and solute transport simulations were performed to assess the vulnerability of an existing shallow unconfined aquifer with respect to a hypothetical methane leakage resulting from a well integrity failure of a former deep geothermal well. The analysis showed that migration of gaseous methane through the aquifer under examination can be extremely fast (of the order of a few minutes), occurring predominantly vertically upwards, close to the well. By contrast, dissolved methane migration is largely affected by the groundwater flow field and occurs over larger time scales (of the order of months/years), covering a greater distance from the well. Overall, the real concern for this site in case of gas leakages is the risk of explosion in the close vicinity of the well. Predicted maximum gaseous fluxes (0.89 to 22.60 m 3 /d) are comparable to those reported for leaking wells, and maximum dissolved methane concentrations may overcome risk mitigation thresholds (7 to 10 mg/L) in a few years. Therefore, surface and subsurface monitoring before decommissioning is strongly advised to ensure the safety of the site.

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“…In particular, there has been much discussion on the potential role of hydraulic fracturing, and opinion is divided on whether or not this poses a significant risk (Howarth et al 2011;O'Malley et al 2016;Darrah 2018). There are many recent case studies investigating the sources of methane in groundwater aquifers near shale plays (Molofsky et al 2016;Zhang and Soeder 2016;Nicot et al 2017aNicot et al , 2017bZhu et al 2018). 57, No.…”

Section: Introductionmentioning

confidence: 99%

“…Such reviews tend to focus on one region or country and they are mostly qualitative in nature. There are many recent case studies investigating the sources of methane in groundwater aquifers near shale plays (Molofsky et al 2016;Zhang and Soeder 2016;Nicot et al 2017aNicot et al , 2017bZhu et al 2018). There are also important case studies emerging that are beginning to link contamination in specific areas to unconventional gas activities (e.g.…”

Section: Introductionmentioning

confidence: 99%

Towards Quantifying the Likelihood of Water Resource Impacts from Unconventional Gas Development

2018

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Gas production from unconventional reservoirs has led to widespread environmental concerns. Despite several excellent reviews of various potential impacts to water resources from unconventional gas production, no study has systematically and quantitatively assessed the potential for these impacts to occur. We use empirical evidence and numerical and analytical models to quantify the likelihood of surface water and groundwater contamination, and shallow aquifer depletion from unconventional gas developments. These likelihoods are not intended to be exact. They provide a starting point for comparing the probabilities of adverse impacts between types of water resources and pathways. This analysis provides much needed insight into what are "probable" rather than simply "possible" impacts. The results suggest that the most likely water resource impacts are surface water and groundwater contamination from spills at the well pad, which can be as high as 1 in 10 and 1 in 100 for each gas well, respectively. For wells that are hydraulically fractured, the likelihood of contamination due to inter-aquifer leakage is 1 in 10 or lower (dependent on the separation distance between the production formation and the aquifer). For gas-bearing formations that were initially over-pressurized, the potential for contamination from inter-aquifer leakage after production ceases could be as high as 1 in 400 where the separation between gas formation and shallow aquifer is 500 m, but will be much lower for greater separation distances (more characteristic of shale gas).

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Assessing Methane in Shallow Groundwater in Unconventional Oil and Gas Play Areas, Eastern Kentucky

Cited by 6 publications

References 27 publications

Origin, fate and detection of methane leaking from the deep subsurface into groundwater and soil

Origin, fate and detection of methane leaking from the deep subsurface into groundwater and soil

Numerical Investigation of a Methane Leakage from a Geothermal Well into a Shallow Aquifer

Towards Quantifying the Likelihood of Water Resource Impacts from Unconventional Gas Development

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