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TitreBaseline near-surface bedrock and groundwater geochemical data prior to shale gas development - Preliminary data from southern Quebec
AuteurLavoie, D; Mort, A; Haeri Ardakani, O; Sanei, H; Bordeleau, G; Rivard, C; Aznar, J C
SourceL'Association géologique du Canada-L'Association minéralogique du Canada, Réunion annuelle conjointe, Recueil des résumés vol. 37, 2014 p. 154
Année2014
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130415
ÉditeurGeological Association of Canada - Mineralogical Association of Canada
RéunionGerological Association of Canada - Mineralogical Association of Canada annual meeting; Fredericton; CA; mai 21-23, 2014
Documentpublication en série
Lang.anglais
Mediapapier; en ligne; numérique
Formatspdf
ProvinceQuébec
SNRC21L; 31H; 31I
Lat/Long OENS -75.0000 -71.0000 46.7500 45.0000
Sujetsgéologie du substratum rocheux; géochimie des eaux souterraines; eau souterraine; hydrocarbures; capacité de production d'hydrocarbures; méthane; Argile d'Uthica ; Groupe de Lorraine ; combustibles fossiles; géochimie; hydrogéologie; Paléozoïque; Ordovicien
ProgrammeGas de schiste - les eaux souterraines, Géosciences de l'environnement
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
In southern Quebec, from 2006 to 2010, drilling and fracking results have shown that the Upper Ordovician Utica Shale is a potential shale gas producer. In 2010, exploration came to a halt pending an environmental review of all issues related to shale gas exploration and development. The Geological Survey of Canada has initiated a detailed evaluation of shallow and deep sub-surface conditions (geology, hydrogeology, geochemistry, geophysics and geomechanic) at a specific site southwest of Quebec City where one shale gas well targeting the Utica Shale has been drilled and fracked. During the summer and fall of 2013, 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 of the Lorraine Group, the cap rock of the Utica Shale present at roughly 2 km deep in the subsurface. Rock-Eval and organic matter reflectance results from the organic matter rich Lorraine shales 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 (?13C, ?2H) of methane suggest mixed thermogenic and biogenic origin. Areas with elevated radon, methane, ethane and butane in soils are located close of the Appalachians ' St. Lawrence Platform contact, a sector with high concentrations of hydrocarbons dissolved in groundwater.
Résumé(Résumé en langage clair et simple, non publié)
Ce résumé permettra de présenter des données de géochimie préliminaires dans l'eau souterraine, les sols et le roc qui ont été récoltées jusqu'à maintenant dans ce projet (programmes Géoscience Environnementale et Géoscience pour de nouvelles sources énergétiques). Un des objectifs de l'étude est d'identifier l'origine du gaz trouvé un peu partout dans l'eau souterraine de la région d'étude (St-Édouard-de-Lotbnière, à environ 65 km au sud-ouest de Québec). Nous avons des indices, mais nous ne pouvons pas encore déterminer l'origine du gaz des échantillons d'eau avec certitude. C'est ce que nous expliquerons.
GEOSCAN ID293521