eprintid: 1719 rev_number: 12 eprint_status: archive userid: 6 dir: disk0/00/00/17/19 datestamp: 2016-09-15 11:12:38 lastmod: 2017-02-08 12:21:35 status_changed: 2016-09-15 11:12:38 type: article metadata_visibility: show creators_name: Jackson, R.E. creators_name: Gorody, A.W. creators_name: Mayer, B. creators_name: Roy, J.W. creators_name: Ryan, M.C. creators_name: Van Stempvoort, D.R. corp_creators: Universal Geoscience Consulting, Houston corp_creators: Universal Geoscience Consulting, Houston corp_creators: Department of Geoscience, University of Calgary,Canada; corp_creators: National Water Research Institute, Environment Canada, corp_creators: Department of Geoscience, University of Calgary, Canada corp_creators: National Water Research Institute, Environment Canada title: Groundwater Protection and Unconventional Gas Extraction: The Critical Need for Field-Based Hydrogeological Research subjects: O subjects: SHC subjects: SHU divisions: SHEER full_text_status: none abstract: Unconventional natural gas extraction from tight sandstones, shales, and some coal-beds is typically accomplished by horizontal drilling and hydraulic fracturing that is necessary for economic development of these new hydrocarbon resources. Concerns have been raised regarding the potential for contamination of shallow groundwater by stray gases, formation waters, and fracturing chemicals associated with unconventional gas exploration. A lack of sound scientific hydrogeological field observations and a scarcity of published peer-reviewed articles on the effects of both conventional and unconventional oil and gas activities on shallow groundwater make it difficult to address these issues. Here, we discuss several case studies related to both conventional and unconventional oil and gas activities illustrating how under some circumstances stray or fugitive gas from deep gas-rich formations has migrated from the subsurface into shallow aquifers and how it has affected groundwater quality. Examples include impacts of uncemented well annuli in areas of historic drilling operations, effects related to poor cement bonding in both new and old hydrocarbon wells, and ineffective cementing practices. We also summarize studies describing how structural features influence the role of natural and induced fractures as contaminant fluid migration pathways. On the basis of these studies, we identify two areas where field-focused research is urgently needed to fill current science gaps related to unconventional gas extraction: (1) baseline geochemical mapping (with time series sampling from a sufficient network of groundwater monitoring wells) and (2) field testing of potential mechanisms and pathways by which hydrocarbon gases, reservoir fluids, and fracturing chemicals might potentially invade and contaminate useable groundwater. date: 2013-06 date_type: published publication: Groundwater volume: 51 number: 4 publisher: Wiley pagerange: 488-510 id_number: doi:10.1111/gwat.12074 issn: 0017-467X official_url: http://doi.org/10.1111/gwat.12074 access_IS-EPOS: limited owner: Publisher citation: Jackson, R.E. and Gorody, A.W. and Mayer, B. and Roy, J.W. and Ryan, M.C. and Van Stempvoort, D.R. (2013) Groundwater Protection and Unconventional Gas Extraction: The Critical Need for Field-Based Hydrogeological Research. Groundwater, 51 (4). pp. 488-510. DOI: https://doi.org/10.1111/gwat.12074