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TitleAssessing baseline near-surface bedrock and groundwater geochemical data prior to shale gas exploration and development - the case of the Utica Shale, Quebec, Canada
AuthorLavoie, DORCID logo; Mort, A; Haeri Ardakani, OORCID logo; Sanei, HORCID logo; Bordeleau, G; Rivard, CORCID logo; Aznar, J C
SourceGoldschmidt 2014, abstracts; 1370, 2014 p. 1 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20130388
MeetingGoldschmidt 2014; Sacramento, CA; US; June 8-13, 2014
Mediapaper; on-line; digital
File formatpdf
NTS21L; 31H; 31I
AreaSt. Lawrence Platform
Lat/Long WENS -75.0000 -71.0000 46.7500 45.0000
Subjectsfossil fuels; hydrogeology; geochemistry; environmental geology; Nature and Environment; Science and Technology; hydrocarbons; hydrocarbon potential; groundwater; groundwater resources; groundwater pollution; groundwater geochemistry; environmental analysis; environmental studies; environmental impacts; Utica Shale
ProgramGeoscience for New Energy Supply (GNES)
ProgramEnvironmental Geoscience Shale Gas - groundwater
Released2014 06 01
AbstractIn eastern Canada, the Utica Shale is a potential shale gas producer. In 2010, exploration came to a halt pending an environmental review. The Geological Survey of Canada has initiated a bedrock and groundwater-focussed pilot research project near Quebec City. Twenty-five private water wells were sampled and 4 shallow (50 m) wells were drilled, cored and sampled for water chemistry and rock organic geochemistry. In addition, 250 sites were sampled for pore-space radon and hydrocarbons in soils.
The shallow bedrock geology is dominated by Upper Ordovician shales and sandstones. Rock-Eval and organic matter reflectance results suggest that thermal maturity increases southerly from oil to condensate windows. GC and GC-MS analyses of core extracts document the presence of low but detectable concentrations of C1 to C20 hydrocarbons.
Most water samples have significant concentrations of dissolved hydrocarbons including mostly methane, as well as ethane and propane in a few wells. The presence of dissolved hydrocarbons in groundwater is fairly well established in southern Quebec, although their source (biogenic versus thermogenic) remains ambiguous. The presence of dissolved propane indicates that some of the hydrocarbons are thermogenic in origin. Gas wetness and isotopic ratios (d13C, d2H) of methane suggest mixed thermogenic and biogenic origin. Areas with elevated radon, methane, ethane and butane in soils are associated with the tectonized Appalachian deformation front, a sector with high concentrations of hydrocarbons dissolved in groundwater.
Summary(Plain Language Summary, not published)
This abstract will present preliminary geochemical data in groundwater, soils and bedrock that were gathered up to now in this project (Environmental Geoscience and Geoscience for New Energy Supply programs). One of the goals of the study is to identify the source of gas present in groundwater in the St. Edouard de Lotbinière (65 km SW of Quebec City). Some preliminary ideas are considered but without certitude so far. This will be explained in the presentation

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