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Mechanisms leading to potential impacts of shale gas development on groundwater quality
Author(s) -
Lefebvre René
Publication year - 2016
Publication title -
wiley interdisciplinary reviews: water
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.413
H-Index - 24
ISSN - 2049-1948
DOI - 10.1002/wat2.1188
Subject(s) - groundwater , casing , hydraulic fracturing , aquifer , petroleum engineering , directional drilling , oil shale , drilling fluid , unconventional oil , drilling , environmental science , geology , surface water , natural gas , contamination , environmental engineering , waste management , geotechnical engineering , engineering , mechanical engineering , paleontology , ecology , biology
The development of shale gas resources was made possible by the combination of horizontal drilling and high‐volume hydraulic fracturing (fracking). Environmental concerns have been raised relative to shale gas production, especially potential impacts on groundwater. Fluids related to unconventional oil and gas (O&G) operations contain chemical compounds that can impact groundwater quality. Such impacts can occur due to (1) the infiltration of surface contaminant releases, (2) failures of the integrity of O&G wells, and (3) upward fluid migration from a shale/tight reservoir along preferential paths that can be natural (faults or fracture zone) or man‐made (O&G wells). Surface releases represent the most probable mechanism leading to groundwater contamination. Improvements in O&G drilling operations under stringent regulations can minimize this risk. Experts identify O&G well integrity as the most challenging issue that may lead to groundwater contamination. Failure of casing and cement can lead to upward fluid flow within or outside O&G wells, especially of methane. Integrity failures leading to fluid migration to shallow fresh water aquifers or to the surface are well understood and can be detected and repaired, but this can be complex and costly. A few regulators now impose groundwater monitoring to detect impacts from integrity failures. Occurrences of communication with existing O&G wells from fracking operations have also led some regulators to impose rules aiming to avoid such potential fluid migration paths. There is an ongoing scientific debate regarding the potential for fluids to migrate upward from exploited shale gas units to aquifers through natural preferential paths. WIREs Water 2017, 4:e1188. doi: 10.1002/wat2.1188 This article is categorized under: Engineering Water > Sustainable Engineering of Water Science of Water > Water Quality