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Repository for Oil and Gas Energy Research (ROGER)
The Repository for Oil and Gas Energy Research, or ROGER, is a near-exhaustive collection of bibliographic information, abstracts, and links to many of journal articles that pertain to shale and tight gas development. The goal of this project is to create a single repository for unconventional oil and gas-related research as a resource for academic, scientific, and citizen researchers.
ROGER currently includes 2303 studies.
Last updated: August 31, 2024
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Use keywords or categories (e.g., air quality, climate, health) to identify peer-reviewed studies and view study abstracts.
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Moving beyond forensic monitoring to understand and manage impacts of hydraulic fracturing for oil and gas development
David A. Dzombak, December 2018
Moving beyond forensic monitoring to understand and manage impacts of hydraulic fracturing for oil and gas development
David A. Dzombak (2018). Proceedings of the National Academy of Sciences, 201819171. 10.1073/pnas.1819171116
Abstract:
In PNAS, Woda et al. (1) present the results of a multidimensional investigation of the impacts of several hydraulically fractured shale gas wells on an aquifer and a hydrologically connected stream in a particular area in central Pennsylvania. The stream, Sugar Run, has been impacted by migration of methane into it. Sugar Run has inflow of groundwater from aquifers overlying the Marcellus Shale, which is relatively close to the land surface in the study area (e.g., one shale gas well of primary focus in the study is reported to intersect the Marcellus Shale at a depth of 997 m). Stream samples and groundwater samples were collected upstream and downstream from a location in Sugar Run where intermittent bubbling and groundwater seepage have been observed for at least 4 y since intensive shale gas development began in the study area in 2008. Samples were analyzed for dissolved methane; Na, Ca, Mg, Fe, Mn, SO42−, Cl−, and other inorganic solutes; carbon and strontium isotopes; and noble gases. The authors also obtained and analyzed regional groundwater-quality data and water-quality data for Sugar Run before shale gas development. Analysis of the water-quality data with consideration of regional characteristics and surface and groundwater characteristics before shale gas development led Woda et al. (1) to conclude from multiple lines of evidence that Sugar Run and the aquifer(s) that provide inflow to the stream have been contaminated by “new methane” mobilized by the shale gas development. They propose a water-quality indicator of the presence of recent methane contamination, namely, high sulfate (>6 mg/L) and iron (>0.3 mg/L) in waters with high methane concentrations. The protocol developed by the authors for use of aqueous geochemical conditions to identify impacts associated with new methane will be useful in the Marcellus region and, perhaps, in … [↵][1]1Email: dzombak{at}cmu.edu. [1]: #xref-corresp-1-1
In PNAS, Woda et al. (1) present the results of a multidimensional investigation of the impacts of several hydraulically fractured shale gas wells on an aquifer and a hydrologically connected stream in a particular area in central Pennsylvania. The stream, Sugar Run, has been impacted by migration of methane into it. Sugar Run has inflow of groundwater from aquifers overlying the Marcellus Shale, which is relatively close to the land surface in the study area (e.g., one shale gas well of primary focus in the study is reported to intersect the Marcellus Shale at a depth of 997 m). Stream samples and groundwater samples were collected upstream and downstream from a location in Sugar Run where intermittent bubbling and groundwater seepage have been observed for at least 4 y since intensive shale gas development began in the study area in 2008. Samples were analyzed for dissolved methane; Na, Ca, Mg, Fe, Mn, SO42−, Cl−, and other inorganic solutes; carbon and strontium isotopes; and noble gases. The authors also obtained and analyzed regional groundwater-quality data and water-quality data for Sugar Run before shale gas development. Analysis of the water-quality data with consideration of regional characteristics and surface and groundwater characteristics before shale gas development led Woda et al. (1) to conclude from multiple lines of evidence that Sugar Run and the aquifer(s) that provide inflow to the stream have been contaminated by “new methane” mobilized by the shale gas development. They propose a water-quality indicator of the presence of recent methane contamination, namely, high sulfate (>6 mg/L) and iron (>0.3 mg/L) in waters with high methane concentrations. The protocol developed by the authors for use of aqueous geochemical conditions to identify impacts associated with new methane will be useful in the Marcellus region and, perhaps, in … [↵][1]1Email: dzombak{at}cmu.edu. [1]: #xref-corresp-1-1
The need to protect fresh and brackish groundwater resources during unconventional oil and gas development
DiGiulio et al., June 2018
The need to protect fresh and brackish groundwater resources during unconventional oil and gas development
Dominic C. DiGiulio, Seth B. C. Shonkoff, Robert B. Jackson (2018). Current Opinion in Environmental Science & Health, 1-7. 10.1016/j.coesh.2018.01.002
Abstract:
Freshwater shortages in the United States have led to increased use of treated brackish groundwater for domestic, agricultural, and municipal uses. This increased use highlights the need for protecting groundwater resources, especially during unconventional oil and gas development. We analyzed the criteria that define protected groundwater in 17 oil- and natural-gas-producing states. In general, we find that these criteria are ambiguous and do not protect brackish groundwater to criteria established for Underground Sources of Drinking Water (USDWs) in the United States Environmental Protection Agency's Underground Injection Control Program. This lack of consistent protection, and continuing unconventional oil and gas development in formations containing USDWs, highlights the need for all states to protect groundwater to the same federally defined standard for USDWs to safeguard fresh and brackish groundwater for present and future use.
Freshwater shortages in the United States have led to increased use of treated brackish groundwater for domestic, agricultural, and municipal uses. This increased use highlights the need for protecting groundwater resources, especially during unconventional oil and gas development. We analyzed the criteria that define protected groundwater in 17 oil- and natural-gas-producing states. In general, we find that these criteria are ambiguous and do not protect brackish groundwater to criteria established for Underground Sources of Drinking Water (USDWs) in the United States Environmental Protection Agency's Underground Injection Control Program. This lack of consistent protection, and continuing unconventional oil and gas development in formations containing USDWs, highlights the need for all states to protect groundwater to the same federally defined standard for USDWs to safeguard fresh and brackish groundwater for present and future use.
Potential water resource impacts of hydraulic fracturing from unconventional oil production in the Bakken shale
Shrestha et al., January 2017
Potential water resource impacts of hydraulic fracturing from unconventional oil production in the Bakken shale
Namita Shrestha, Govinda Chilkoor, Joseph Wilder, Venkataramana Gadhamshetty, James J. Stone (2017). Water Research, 1-24. 10.1016/j.watres.2016.11.006
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.
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.
Impact of Hydraulic Fracturing on the Quality of Natural Waters
Cel et al., September 2024
Impact of Hydraulic Fracturing on the Quality of Natural Waters
Wojciech Cel, Justyna Kujawska, Henryk Wasąg (2024). Journal of Ecological Engineering, 63-68. 10.12911/22998993/67852
Abstract:
Poland, due to the estimated shale gas deposits amounting to 346-768 billion m3 has become one of the most attractive regions for shale gas exploration in Europe. Throughout the period 2010-2015, 72 exploratory drillings have been made (as of 4.01.2016) while hydraulic fracturing was carried out...
Poland, due to the estimated shale gas deposits amounting to 346-768 billion m3 has become one of the most attractive regions for shale gas exploration in Europe. Throughout the period 2010-2015, 72 exploratory drillings have been made (as of 4.01.2016) while hydraulic fracturing was carried out...
A review on risk assessment techniques for hydraulic fracturing water and produced water management implemented in onshore unconventional oil and gas production
Torres et al., January 2016
A review on risk assessment techniques for hydraulic fracturing water and produced water management implemented in onshore unconventional oil and gas production
Luisa Torres, Om Prakash Yadav, Eakalak Khan (2016). Science of The Total Environment, 478-493. 10.1016/j.scitotenv.2015.09.030
Abstract:
The objective of this paper is to review different risk assessment techniques applicable to onshore unconventional oil and gas production to determine the risks to water quantity and quality associated with hydraulic fracturing and produced water management. Water resources could be at risk without proper management of water, chemicals, and produced water. Previous risk assessments in the oil and gas industry were performed from an engineering perspective leaving aside important social factors. Different risk assessment methods and techniques are reviewed and summarized to select the most appropriate one to perform a holistic and integrated analysis of risks at every stage of the water life cycle. Constraints to performing risk assessment are identified including gaps in databases, which require more advanced techniques such as modeling. Discussions on each risk associated with water and produced water management, mitigation strategies, and future research direction are presented. Further research on risks in onshore unconventional oil and gas will benefit not only the U.S. but also other countries with shale oil and gas resources.
The objective of this paper is to review different risk assessment techniques applicable to onshore unconventional oil and gas production to determine the risks to water quantity and quality associated with hydraulic fracturing and produced water management. Water resources could be at risk without proper management of water, chemicals, and produced water. Previous risk assessments in the oil and gas industry were performed from an engineering perspective leaving aside important social factors. Different risk assessment methods and techniques are reviewed and summarized to select the most appropriate one to perform a holistic and integrated analysis of risks at every stage of the water life cycle. Constraints to performing risk assessment are identified including gaps in databases, which require more advanced techniques such as modeling. Discussions on each risk associated with water and produced water management, mitigation strategies, and future research direction are presented. Further research on risks in onshore unconventional oil and gas will benefit not only the U.S. but also other countries with shale oil and gas resources.
Impacts of hydraulic fracturing on water quality: a review of literature, regulatory frameworks and an analysis of information gaps
Gagnon et al., November 2015
Impacts of hydraulic fracturing on water quality: a review of literature, regulatory frameworks and an analysis of information gaps
G.A. Gagnon, W. Krkosek, L. Anderson, E. McBean, M. Mohseni, M. Bazri, I. Mauro (2015). Environmental Reviews, 122-131. 10.1139/er-2015-0043
Abstract:
A review of available literature and current governance approaches related to the potential impacts of hydraulic fracturing on water quality (including drinking water) was developed. The paper identifies gaps in literature and (or) current governance approaches that should be addressed to guide decision-makers in the development of appropriate regulatory regimes that will enable assessment of the impacts of hydraulic fracturing on water quality. The lack of credible and comprehensive data are shown to have been a major setback to properly investigate and monitor hydraulic fracturing activities and their potential risks on the environment and water quality. A review of current governance approaches demonstrates that some jurisdictions have implemented baseline and post-operation water quality monitoring requirements; however, there are large variations in site-specific monitoring requirements across Canada and the United States. In light of recent information, a targeted approach is suggested based on risk..., Les auteurs ont conduit une revue incluant la littérature disponible et les approches courantes de gouvernance reliées aux impacts potentiels de la fracturation hydraulique sur la qualité de l’eau, incluant l’eau potable. On identifie des failles dans la littérature et (ou) les approches courantes de gouvernance qui devraient être considérées afin de guider les preneurs de décisions dans le développement de régimes règlementaires appropriés, rendant possible l’évaluation des impacts de la fracturation hydraulique sur la qualité de l’eau. On démontre que le manque de données crédibles et intégratives a constitué un empêchement majeur pour examiner correctement et faire le suivi des activités de fracturation hydraulique et de leur potentiel de risques pour l’environnement et la qualité de l’eau. Cette revue des approches actuelles de gouvernance démontre que certaines juridictions on mis sur pied une ligne de base et l’exigence de faire le suivi de la qualité de l’eau après les opérations; cependant on obse...
A review of available literature and current governance approaches related to the potential impacts of hydraulic fracturing on water quality (including drinking water) was developed. The paper identifies gaps in literature and (or) current governance approaches that should be addressed to guide decision-makers in the development of appropriate regulatory regimes that will enable assessment of the impacts of hydraulic fracturing on water quality. The lack of credible and comprehensive data are shown to have been a major setback to properly investigate and monitor hydraulic fracturing activities and their potential risks on the environment and water quality. A review of current governance approaches demonstrates that some jurisdictions have implemented baseline and post-operation water quality monitoring requirements; however, there are large variations in site-specific monitoring requirements across Canada and the United States. In light of recent information, a targeted approach is suggested based on risk..., Les auteurs ont conduit une revue incluant la littérature disponible et les approches courantes de gouvernance reliées aux impacts potentiels de la fracturation hydraulique sur la qualité de l’eau, incluant l’eau potable. On identifie des failles dans la littérature et (ou) les approches courantes de gouvernance qui devraient être considérées afin de guider les preneurs de décisions dans le développement de régimes règlementaires appropriés, rendant possible l’évaluation des impacts de la fracturation hydraulique sur la qualité de l’eau. On démontre que le manque de données crédibles et intégratives a constitué un empêchement majeur pour examiner correctement et faire le suivi des activités de fracturation hydraulique et de leur potentiel de risques pour l’environnement et la qualité de l’eau. Cette revue des approches actuelles de gouvernance démontre que certaines juridictions on mis sur pied une ligne de base et l’exigence de faire le suivi de la qualité de l’eau après les opérations; cependant on obse...
Hydraulic fracturing fluid migration in the subsurface: A review and expanded modeling results
Birdsell et al., September 2015
Hydraulic fracturing fluid migration in the subsurface: A review and expanded modeling results
Daniel T. Birdsell, Harihar Rajaram, David Dempsey, Hari S. Viswanathan (2015). Water Resources Research, 7159-7188. 10.1002/2015WR017810
Abstract:
Understanding the transport of hydraulic fracturing (HF) fluid that is injected into the deep subsurface for shale gas extraction is important to ensure that shallow drinking water aquifers are not contaminated. Topographically driven flow, overpressured shale reservoirs, permeable pathways such as faults or leaky wellbores, the increased formation pressure due to HF fluid injection, and the density contrast of the HF fluid to the surrounding brine can encourage upward HF fluid migration. In contrast, the very low shale permeability and capillary imbibition of water into partially saturated shale may sequester much of the HF fluid, and well production will remove HF fluid from the subsurface. We review the literature on important aspects of HF fluid migration. Single-phase flow and transport simulations are performed to quantify how much HF fluid is removed via the wellbore with flowback and produced water, how much reaches overlying aquifers, and how much is permanently sequestered by capillary imbibition, which is treated as a sink term based on a semianalytical, one-dimensional solution for two-phase flow. These simulations include all of the important aspects of HF fluid migration identified in the literature review and are performed in five stages to faithfully represent the typical operation of a hydraulically fractured well. No fracturing fluid reaches the aquifer without a permeable pathway. In the presence of a permeable pathway, 10 times more fracturing fluid reaches the aquifer if well production and capillary imbibition are not included in the model.
Understanding the transport of hydraulic fracturing (HF) fluid that is injected into the deep subsurface for shale gas extraction is important to ensure that shallow drinking water aquifers are not contaminated. Topographically driven flow, overpressured shale reservoirs, permeable pathways such as faults or leaky wellbores, the increased formation pressure due to HF fluid injection, and the density contrast of the HF fluid to the surrounding brine can encourage upward HF fluid migration. In contrast, the very low shale permeability and capillary imbibition of water into partially saturated shale may sequester much of the HF fluid, and well production will remove HF fluid from the subsurface. We review the literature on important aspects of HF fluid migration. Single-phase flow and transport simulations are performed to quantify how much HF fluid is removed via the wellbore with flowback and produced water, how much reaches overlying aquifers, and how much is permanently sequestered by capillary imbibition, which is treated as a sink term based on a semianalytical, one-dimensional solution for two-phase flow. These simulations include all of the important aspects of HF fluid migration identified in the literature review and are performed in five stages to faithfully represent the typical operation of a hydraulically fractured well. No fracturing fluid reaches the aquifer without a permeable pathway. In the presence of a permeable pathway, 10 times more fracturing fluid reaches the aquifer if well production and capillary imbibition are not included in the model.
A review of water and greenhouse gas impacts of unconventional natural gas development in the United States
Arent et al., September 2024
A review of water and greenhouse gas impacts of unconventional natural gas development in the United States
Douglas Arent, Jeffrey Logan, Jordan Macknick, William Boyd, Kenneth III Medlock, Francis O'Sullivan, Jae Edmonds, Leon Clarke, Hillard Huntington, Garvin Heath, Patricia Statwick, Morgan Bazilian (2024). MRS Energy & Sustainability - A Review Journal, . 10.1557/mre.2015.5
Abstract:
ABSTRACT This paper reviews recent developments in the production and use of unconventional natural gas in the United States with a focus on water and greenhouse gas emission implications. If unconventional natural gas in the U.S. is produced responsibly, transported and distributed with little leakage, and incorporated into integrated energy systems that are designed for future resiliency, it could play a significant role in realizing a more sustainable energy future; however, the increased use of natural gas as a substitute for more carbon intensive fuels will alone not substantially alter world carbon dioxide concentration projections. This paper reviews recent developments in the production and use of unconventional natural gas in the United States with a focus on environmental impacts. Specifically, we focus on water management and greenhouse gas emission implications. If unconventional natural gas in the United States is produced responsibly, transported and distributed with little leakage, and incorporated into integrated energy systems that are designed for future resiliency, it could play a significant role in realizing a more sustainable energy future. The cutting-edge of industry water management practices gives a picture of how this transition is unfolding, although much opportunity remains to minimize water use and related environmental impacts. The role of natural gas to mitigate climate forcing is less clear. While natural gas has low CO2 emissions upon direct use, methane leakage and long term climate effects lead to the conclusion that increased use of natural gas as a substitute for more carbon intensive fuels will not substantially alter world carbon dioxide concentration projections, and that other zero or low carbon energy sources will be needed to limit GHG concentrations. We conclude with some possible avenues for further work.
ABSTRACT This paper reviews recent developments in the production and use of unconventional natural gas in the United States with a focus on water and greenhouse gas emission implications. If unconventional natural gas in the U.S. is produced responsibly, transported and distributed with little leakage, and incorporated into integrated energy systems that are designed for future resiliency, it could play a significant role in realizing a more sustainable energy future; however, the increased use of natural gas as a substitute for more carbon intensive fuels will alone not substantially alter world carbon dioxide concentration projections. This paper reviews recent developments in the production and use of unconventional natural gas in the United States with a focus on environmental impacts. Specifically, we focus on water management and greenhouse gas emission implications. If unconventional natural gas in the United States is produced responsibly, transported and distributed with little leakage, and incorporated into integrated energy systems that are designed for future resiliency, it could play a significant role in realizing a more sustainable energy future. The cutting-edge of industry water management practices gives a picture of how this transition is unfolding, although much opportunity remains to minimize water use and related environmental impacts. The role of natural gas to mitigate climate forcing is less clear. While natural gas has low CO2 emissions upon direct use, methane leakage and long term climate effects lead to the conclusion that increased use of natural gas as a substitute for more carbon intensive fuels will not substantially alter world carbon dioxide concentration projections, and that other zero or low carbon energy sources will be needed to limit GHG concentrations. We conclude with some possible avenues for further work.
Use of stable isotopes to identify sources of methane in Appalachian Basin shallow groundwaters: a review
J. Alexandra Hakala, July 2014
Use of stable isotopes to identify sources of methane in Appalachian Basin shallow groundwaters: a review
J. Alexandra Hakala (2014). Environmental Science: Processes & Impacts, . 10.1039/C4EM00140K
Abstract:
Development of unconventional shale gas reservoirs in the Appalachian Basin has raised questions regarding the potential for these activities to affect shallow groundwater resources. Geochemical indicators, such as stable carbon and hydrogen isotopes of methane, stable carbon isotopes of ethane, and hydrocarbon ratios, have been used to evaluate methane sources however their utility is complicated by influences from multiple physical (e.g., mixing) and geochemical (e.g., redox) processes. Baseline sampling of shallow aquifers prior to development, and measurement of additional geochemical indicators within samples from across the Appalachian Basin, may aid in identifying natural causes for dissolved methane in shallow groundwater versus development-induced pathways.
Development of unconventional shale gas reservoirs in the Appalachian Basin has raised questions regarding the potential for these activities to affect shallow groundwater resources. Geochemical indicators, such as stable carbon and hydrogen isotopes of methane, stable carbon isotopes of ethane, and hydrocarbon ratios, have been used to evaluate methane sources however their utility is complicated by influences from multiple physical (e.g., mixing) and geochemical (e.g., redox) processes. Baseline sampling of shallow aquifers prior to development, and measurement of additional geochemical indicators within samples from across the Appalachian Basin, may aid in identifying natural causes for dissolved methane in shallow groundwater versus development-induced pathways.
Evolving shale gas management: water resource risks, impacts, and lessons learned
Brian G. Rahm and Susan J. Riha, March 2014
Evolving shale gas management: water resource risks, impacts, and lessons learned
Brian G. Rahm and Susan J. Riha (2014). Environmental Science: Processes & Impacts, . 10.1039/C4EM00018H
Abstract:
Unconventional shale gas development promises to significantly alter energy portfolios and economies around the world. It also poses a variety of environmental risks, particularly with respect to the management of water resources. We review current scientific understanding of risks associated with the following: water withdrawals for hydraulic fracturing; wastewater treatment, discharge and disposal; methane and fluid migration in the subsurface; and spills and erosion at the surface. Some of these risks are relatively unique to shale gas development, while others are variations of risks that we already face from a variety of industries and activities. All of these risks depend largely on the pace and scale of development that occurs within a particular region. We focus on the United States, where the shale gas boom has been on-going for several years, paying particular attention to the Marcellus Shale, where a majority of peer-reviewed study has taken place. Governments, regulatory agencies, industry, and other stakeholders are challenged with responding to these risks, and we discuss policies and practices that have been adopted or considered by these various groups. Adaptive Management, a structured framework for addressing complex environmental issues, is discussed as a way to reduce polarization of important discussions on risk, and to more formally engage science in policy-making, along with other economic, social and value considerations. Data suggests that some risks can be substantially reduced through policy and best practice, but also that significant uncertainty persists regarding other risks. We suggest that monitoring and data collection related to water resource risks be established as part of planning for shale gas development before activity begins, and that resources are allocated to provide for appropriate oversight at various levels of governance.
Unconventional shale gas development promises to significantly alter energy portfolios and economies around the world. It also poses a variety of environmental risks, particularly with respect to the management of water resources. We review current scientific understanding of risks associated with the following: water withdrawals for hydraulic fracturing; wastewater treatment, discharge and disposal; methane and fluid migration in the subsurface; and spills and erosion at the surface. Some of these risks are relatively unique to shale gas development, while others are variations of risks that we already face from a variety of industries and activities. All of these risks depend largely on the pace and scale of development that occurs within a particular region. We focus on the United States, where the shale gas boom has been on-going for several years, paying particular attention to the Marcellus Shale, where a majority of peer-reviewed study has taken place. Governments, regulatory agencies, industry, and other stakeholders are challenged with responding to these risks, and we discuss policies and practices that have been adopted or considered by these various groups. Adaptive Management, a structured framework for addressing complex environmental issues, is discussed as a way to reduce polarization of important discussions on risk, and to more formally engage science in policy-making, along with other economic, social and value considerations. Data suggests that some risks can be substantially reduced through policy and best practice, but also that significant uncertainty persists regarding other risks. We suggest that monitoring and data collection related to water resource risks be established as part of planning for shale gas development before activity begins, and that resources are allocated to provide for appropriate oversight at various levels of governance.
A Critical Review of the Risks to Water Resources from Unconventional Shale Gas Development and Hydraulic Fracturing in the United States
Vengosh et al., March 2014
A Critical Review of the Risks to Water Resources from Unconventional Shale Gas Development and Hydraulic Fracturing in the United States
Avner Vengosh, Robert B. Jackson, Nathaniel Warner, Thomas H. Darrah, Andrew Kondash (2014). Environmental Science & Technology, . 10.1021/es405118y
Abstract:
The rapid rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded the extraction of hydrocarbon resources in the U.S. The rise of shale gas development has triggered an intense public debate regarding the potential environmental and human health effects from hydraulic fracturing. This paper provides a critical review of the potential risks that shale gas operations pose to water resources, with an emphasis on case studies mostly from the U.S. Four potential risks for water resources are identified: (1) the contamination of shallow aquifers with fugitive hydrocarbon gases (i.e., stray gas contamination), which can also potentially lead to the salinization of shallow groundwater through leaking natural gas wells and subsurface flow; (2) the contamination of surface water and shallow groundwater from spills, leaks, and/or the disposal of inadequately treated shale gas wastewater; (3) the accumulation of toxic and radioactive elements in soil or stream sediments near disposal or spill sites; and (4) the overextraction of water resources for high-volume hydraulic fracturing that could induce water shortages or conflicts with other water users, particularly in water-scarce areas. Analysis of published data (through January 2014) reveals evidence for stray gas contamination, surface water impacts in areas of intensive shale gas development, and the accumulation of radium isotopes in some disposal and spill sites. The direct contamination of shallow groundwater from hydraulic fracturing fluids and deep formation waters by hydraulic fracturing itself, however, remains controversial.
The rapid rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded the extraction of hydrocarbon resources in the U.S. The rise of shale gas development has triggered an intense public debate regarding the potential environmental and human health effects from hydraulic fracturing. This paper provides a critical review of the potential risks that shale gas operations pose to water resources, with an emphasis on case studies mostly from the U.S. Four potential risks for water resources are identified: (1) the contamination of shallow aquifers with fugitive hydrocarbon gases (i.e., stray gas contamination), which can also potentially lead to the salinization of shallow groundwater through leaking natural gas wells and subsurface flow; (2) the contamination of surface water and shallow groundwater from spills, leaks, and/or the disposal of inadequately treated shale gas wastewater; (3) the accumulation of toxic and radioactive elements in soil or stream sediments near disposal or spill sites; and (4) the overextraction of water resources for high-volume hydraulic fracturing that could induce water shortages or conflicts with other water users, particularly in water-scarce areas. Analysis of published data (through January 2014) reveals evidence for stray gas contamination, surface water impacts in areas of intensive shale gas development, and the accumulation of radium isotopes in some disposal and spill sites. The direct contamination of shallow groundwater from hydraulic fracturing fluids and deep formation waters by hydraulic fracturing itself, however, remains controversial.
Impact of Shale Gas Development on Regional Water Quality
Vidic et al., May 2013
Impact of Shale Gas Development on Regional Water Quality
R. D. Vidic, S. L. Brantley, J. M. Vandenbossche, D. Yoxtheimer, J. D. Abad (2013). Science, 1235009. 10.1126/science.1235009
Abstract:
Structured Abstract Background Natural gas has recently emerged as a relatively clean energy source that offers the opportunity for a number of regions around the world to reduce their reliance on energy imports. It can also serve as a transition fuel that will allow for the shift from coal to renewable energy resources while helping to reduce the emissions of CO2, criteria pollutants, and mercury by the power sector. Horizontal drilling and hydraulic fracturing make the extraction of tightly bound natural gas from shale formations economically feasible. These technologies are not free from environmental risks, however, especially those related to regional water quality, such as gas migration, contaminant transport through induced and natural fractures, wastewater discharge, and accidental spills. The focus of this Review is on the current understanding of these environmental issues.
Drilling multiple horizontal wells from a single well pad allows access to as much as 1 square mile of shale that is located more than a mile below. [Image courtesy of Range Resources Appalachia]
Advances The most common problem with well construction is a faulty seal that is emplaced to prevent gas migration into shallow groundwater. The incidence rate of seal problems in unconventional gas wells is relatively low (1 to 3%), but there is a substantial controversy whether the methane detected in private groundwater wells in the area where drilling for unconventional gas is ongoing was caused by well drilling or natural processes. It is difficult to resolve this issue because many areas have long had sources of methane unrelated to hydraulic fracturing, and pre-drilling baseline data are often unavailable. Water management for unconventional shale gas extraction is one of the key issues that will dominate environmental debate surrounding the gas industry. Reuse of produced water for hydraulic fracturing is currently addressing the concerns regarding the vast quantities of contaminants that are brought to the surface. As these well fields mature and the opportunities for wastewater reuse diminish, the need to find alternative management strategies for this wastewater will likely intensify.
Outlook Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help effectively manage water-quality risks associated with unconventional gas industry today and in the future. Confidentiality requirements dictated by legal investigations combined with the expedited rate of development and the limited funding for research are major impediments to peer-reviewed research into environmental impacts. Now is the time to work on these environmental issues to avoid an adverse environmental legacy similar to that from abandoned coal mine discharges in Pennsylvania.
Fracturing Hydrology?
Hydraulic fracturing, widely known as "fracking," is a relatively inexpensive way to tap into what were previously inaccessible natural gas resources. Vidic et al. (p. 826) review the current status of shale gas development and discuss the possible threats to water resources. In one of the hotbeds of fracking activity, the Marcellus Shale in the eastern United States, there is little evidence that additives have directly entered groundwater supplies, but the risk remains. Ensuring access to monitoring data is an important first step toward addressing any public and environmental health concerns.
Unconventional natural gas resources offer an opportunity to access a relatively clean fossil fuel that could potentially lead to energy independence for some countries. Horizontal drilling and hydraulic fracturing make the extraction of tightly bound natural gas from shale formations economically feasible. These technologies are not free from environmental risks, however, especially those related to regional water quality, such as gas migration, contaminant transport through induced and natural fractures, wastewater discharge, and accidental spills. We review the current understanding of environmental issues associated with unconventional gas extraction. Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help manage these water-quality risks today and in the future.
Structured Abstract Background Natural gas has recently emerged as a relatively clean energy source that offers the opportunity for a number of regions around the world to reduce their reliance on energy imports. It can also serve as a transition fuel that will allow for the shift from coal to renewable energy resources while helping to reduce the emissions of CO2, criteria pollutants, and mercury by the power sector. Horizontal drilling and hydraulic fracturing make the extraction of tightly bound natural gas from shale formations economically feasible. These technologies are not free from environmental risks, however, especially those related to regional water quality, such as gas migration, contaminant transport through induced and natural fractures, wastewater discharge, and accidental spills. The focus of this Review is on the current understanding of these environmental issues.
Drilling multiple horizontal wells from a single well pad allows access to as much as 1 square mile of shale that is located more than a mile below. [Image courtesy of Range Resources Appalachia]
Advances The most common problem with well construction is a faulty seal that is emplaced to prevent gas migration into shallow groundwater. The incidence rate of seal problems in unconventional gas wells is relatively low (1 to 3%), but there is a substantial controversy whether the methane detected in private groundwater wells in the area where drilling for unconventional gas is ongoing was caused by well drilling or natural processes. It is difficult to resolve this issue because many areas have long had sources of methane unrelated to hydraulic fracturing, and pre-drilling baseline data are often unavailable. Water management for unconventional shale gas extraction is one of the key issues that will dominate environmental debate surrounding the gas industry. Reuse of produced water for hydraulic fracturing is currently addressing the concerns regarding the vast quantities of contaminants that are brought to the surface. As these well fields mature and the opportunities for wastewater reuse diminish, the need to find alternative management strategies for this wastewater will likely intensify.
Outlook Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help effectively manage water-quality risks associated with unconventional gas industry today and in the future. Confidentiality requirements dictated by legal investigations combined with the expedited rate of development and the limited funding for research are major impediments to peer-reviewed research into environmental impacts. Now is the time to work on these environmental issues to avoid an adverse environmental legacy similar to that from abandoned coal mine discharges in Pennsylvania.
Fracturing Hydrology?
Hydraulic fracturing, widely known as "fracking," is a relatively inexpensive way to tap into what were previously inaccessible natural gas resources. Vidic et al. (p. 826) review the current status of shale gas development and discuss the possible threats to water resources. In one of the hotbeds of fracking activity, the Marcellus Shale in the eastern United States, there is little evidence that additives have directly entered groundwater supplies, but the risk remains. Ensuring access to monitoring data is an important first step toward addressing any public and environmental health concerns.
Unconventional natural gas resources offer an opportunity to access a relatively clean fossil fuel that could potentially lead to energy independence for some countries. Horizontal drilling and hydraulic fracturing make the extraction of tightly bound natural gas from shale formations economically feasible. These technologies are not free from environmental risks, however, especially those related to regional water quality, such as gas migration, contaminant transport through induced and natural fractures, wastewater discharge, and accidental spills. We review the current understanding of environmental issues associated with unconventional gas extraction. Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help manage these water-quality risks today and in the future.
A review of environmental impacts of salts from produced waters on aquatic resources
Aïda M. Farag and David D. Harper, September 2024
A review of environmental impacts of salts from produced waters on aquatic resources
Aïda M. Farag and David D. Harper (2024). International Journal of Coal Geology, . 10.1016/j.coal.2013.12.006
Abstract:
Salts are frequently a major constituent of waste waters produced during oil and gas production. These produced waters or brines must be treated and/or disposed and provide a daily challenge for operators and resource managers. Some elements of salts are regulated with water quality criteria established for the protection of aquatic wildlife, e.g. chloride (Cl−), which has an acute standard of 860 mg/L and a chronic standard of 230 mg/L. However, data for establishing such standards has only recently been studied for other components of produced water, such as bicarbonate (HCO3−), which has acute median lethal concentrations (LC50s) ranging from 699 to > 8000 mg/L and effects on chronic toxicity from 430 to 657 mg/L. While Cl− is an ion of considerable importance in multiple geographical regions, knowledge about the effects of hardness (calcium and magnesium) on its toxicity and about mechanisms of toxicity is not well understood. A multiple-approach design that combines studies of both individuals and populations, conducted both in the laboratory and the field, was used to study toxic effects of bicarbonate (as NaHCO3). This approach allowed interpretations about mechanisms related to growth effects at the individual level that could affect populations in the wild. However, additional mechanistic data for HCO3−, related to the interactions of calcium (Ca2 +) precipitation at the microenvironment of the gill would dramatically increase the scientific knowledge base about how NaHCO3 might affect aquatic life. Studies of the effects of mixtures of multiple salts present in produced waters and more chronic effect studies would give a better picture of the overall potential toxicity of these ions. Organic constituents in hydraulic fracturing fluids, flowback waters, etc. are a concern because of their carcinogenic properties and this paper is not meant to minimize the importance of maintaining vigilance with respect to potential organic contamination.
Salts are frequently a major constituent of waste waters produced during oil and gas production. These produced waters or brines must be treated and/or disposed and provide a daily challenge for operators and resource managers. Some elements of salts are regulated with water quality criteria established for the protection of aquatic wildlife, e.g. chloride (Cl−), which has an acute standard of 860 mg/L and a chronic standard of 230 mg/L. However, data for establishing such standards has only recently been studied for other components of produced water, such as bicarbonate (HCO3−), which has acute median lethal concentrations (LC50s) ranging from 699 to > 8000 mg/L and effects on chronic toxicity from 430 to 657 mg/L. While Cl− is an ion of considerable importance in multiple geographical regions, knowledge about the effects of hardness (calcium and magnesium) on its toxicity and about mechanisms of toxicity is not well understood. A multiple-approach design that combines studies of both individuals and populations, conducted both in the laboratory and the field, was used to study toxic effects of bicarbonate (as NaHCO3). This approach allowed interpretations about mechanisms related to growth effects at the individual level that could affect populations in the wild. However, additional mechanistic data for HCO3−, related to the interactions of calcium (Ca2 +) precipitation at the microenvironment of the gill would dramatically increase the scientific knowledge base about how NaHCO3 might affect aquatic life. Studies of the effects of mixtures of multiple salts present in produced waters and more chronic effect studies would give a better picture of the overall potential toxicity of these ions. Organic constituents in hydraulic fracturing fluids, flowback waters, etc. are a concern because of their carcinogenic properties and this paper is not meant to minimize the importance of maintaining vigilance with respect to potential organic contamination.