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TitleAssessment of potential impacts of shale gas development on surficial aquifers
AuthorRivard, C; Lavoie, D; Lefebvre, R; Séjourné, S; Bordeleau, G; Duchesne, M J
SourceNew Brunswick Exploration, Mining and Petroleum conference program and abstracts volume; 2014 p. 84
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20140194
PublisherNew Brunswick Department of Mines and Energy
MeetingNew Brunswick 2014 Exploration, Mining and Petroleum conference; Fredericton; CA; November 2-4, 2014
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
Subjectshydrogeology; fossil fuels; shales; gas; aquifers; groundwater; groundwater resources; groundwater regimes; Horn River basin; Montney shales; Mesozoic; Triassic; Paleozoic; Devonian
ProgramEnvironmental Geoscience, Shale Gas - groundwater
AbstractShale gas has more than doubled the natural gas resource base of Canada (5,000 TCF of gas in place). Currently, natural gas and associated liquids are produced from Devonian shales in the Horn River basin and from the Triassic Montney shales (British Columbia). Other shales with gas potential are being evaluated, including the Lower Carboniferous Frederick Brook Shale in New Brunswick. However, hydrocarbon exploration and production may involve risks to groundwater quality and these need to be assessed. Hydraulic fracturing has been used to stimulate production in conventional oil and gas reservoirs for more than 60 years. However, recent multi-stage fracturing in horizontal wells uses greater amounts of water and chemicals, as well as higher pressure than in conventional reservoirs. In order to minimize environmental risks and, in particular, groundwater contamination, it is essential to evaluate exploration and production conditions. These groundwater-related risks are primarily associated to engineering issues, including the casing integrity and surface activities such as transport, storage and treatment of fracturing and flowback fluids. Concerns have also been raised with respect to groundwater contamination that could result from potential fracture interconnections between the shale unit and surficial aquifers. A report of the Canadian Council of Academia on potential environmental impacts of shale gas identified groundwater as a theme where new geoscience knowledge is critically needed. A methodology is being developed at the Geological Survey of Canada to evaluate the likelihood of natural pathways linking target shales to surficial aquifers. This study is carried out using existing hydrogeological, geological, and exploration data such as deep seismic lines, borehole geophysics, water-well log data and rock geochemistry, as well as new fieldwork and lab work to complement existing information. New work includes shallow subsurface seismic surveys, outcrop fracture mapping, shallow drilling and borehole geophysics, core sample tests, hydraulic testing, and groundwater and soil sampling for hydrocarbon concentration and isotopic fingerprinting. This research also includes assessment of geomechanical properties through laboratory tests and well-log analyses, as well as hydrogeological modelling to study the system behaviour and potential effects of fracturing on fluid migration. This study will allow the development of tools for the identification of zones having the least constraints for shale gas production and zones where it might be necessary to modify industry's current practices in order to minimize potential impacts to groundwater resources. The methodology could serve as a basis for the development of a regulatory framework within the context of responsible energy development.
Summary(Plain Language Summary, not published)
Risks of groundwater contamination from shale gas exploration and development have been indentified as an issue to evaluate in a recent report release by the Canadian Council of Academia. The GSC has initiated, in 2012, a research project aimed at developing a research protocol to evaluate the presence of potential natural pathways connecting the deep shale to the shallow groundwater. The organizing committee of the 2014 New Brunswick Exploration, Mining and Petroleum conference has invited us to present the actual results of our research activities in southern Quebec