TY - JOUR
T1 - El efecto de un bombeo regional a largo plazo sobre la hidroquímica y el contenido de gas disuelto en un acuífero no desarrollado que es portador de shale gas en el sudoeste de Ontario, Canada
AU - Hamilton, Stewart M.
AU - Grasby, Stephen E.
AU - McIntosh, Jennifer C.
AU - Osborn, Stephen G.
N1 - Funding Information:
The authors would like to thank the 24 students who have diligently worked on field data collection for the Ambient Groundwater Program to date and, in particular, Candace Freckelton for helping to supervise them for 5 out of the 7 years the program has been in existence. Fieldwork was carried out and fully funded by the Ontario Geological Survey, as was geochemical analytical work. The Geological Survey of Canada funded and provided stable isotope analysis for waters and isotopic and compositional analysis of gas samples. Aspects of this work were partly the subjects of a number of graduate and undergraduate theses including those of Kathryn Mellor, Edward Matheson, Hanna Burke and Candace Freckelton. Hamilton would like to thank his colleagues Frank Brunton and Derek Armstrong for their insight and many discussions on the Paleozoic geology of southwestern Ontario. McIntosh would like to acknowledge funding from the United States Geological Survey, New York State Energy Research Development Authority, NSF (EAR-0635685) and the American Chemical Society–Petroleum Research Fund (No. 45284-G2).
Publisher Copyright:
© 2015, The Author(s).
PY - 2015/6/18
Y1 - 2015/6/18
N2 - Baseline groundwater geochemical mapping of inorganic and isotopic parameters across 44,000 km2 of southwestern Ontario (Canada) has delineated a discreet zone of natural gas in the bedrock aquifer coincident with an 8,000-km2 exposure of Middle Devonian shale. This study describes the ambient geochemical conditions in these shales in the context of other strata, including Ordovician shales, and discusses shale-related natural and anthropogenic processes contributing to hydrogeochemical conditions in the aquifer. The three Devonian shales—the Kettle Point Formation (Antrim equivalent), Hamilton Group and Marcellus Formation—have higher DOC, DIC, HCO3, CO2(aq), pH and iodide, and much higher CH4(aq). The two Ordovician shales—the Queenston and Georgian-Bay/Blue Mountain Formations—are higher in Ca, Mg, SO4 and H2S. In the Devonian shale region, isotopic zones of Pleistocene-aged groundwater have halved in size since first identified in the 1980s; potentiometric data implicate regional groundwater extraction in the shrinkage. Isotopically younger waters invading the aquifer show rapid increases in CH4(aq), pH and iodide with depth and rapid decrease in oxidized carbon species including CO2, HCO3 and DIC, suggesting contemporary methanogenesis. Pumping in the Devonian shale contact aquifer may stimulate methanogenesis by lowering TDS, removing products and replacing reactants, including bicarbonate, derived from overlying glacial sedimentary aquifers.
AB - Baseline groundwater geochemical mapping of inorganic and isotopic parameters across 44,000 km2 of southwestern Ontario (Canada) has delineated a discreet zone of natural gas in the bedrock aquifer coincident with an 8,000-km2 exposure of Middle Devonian shale. This study describes the ambient geochemical conditions in these shales in the context of other strata, including Ordovician shales, and discusses shale-related natural and anthropogenic processes contributing to hydrogeochemical conditions in the aquifer. The three Devonian shales—the Kettle Point Formation (Antrim equivalent), Hamilton Group and Marcellus Formation—have higher DOC, DIC, HCO3, CO2(aq), pH and iodide, and much higher CH4(aq). The two Ordovician shales—the Queenston and Georgian-Bay/Blue Mountain Formations—are higher in Ca, Mg, SO4 and H2S. In the Devonian shale region, isotopic zones of Pleistocene-aged groundwater have halved in size since first identified in the 1980s; potentiometric data implicate regional groundwater extraction in the shrinkage. Isotopically younger waters invading the aquifer show rapid increases in CH4(aq), pH and iodide with depth and rapid decrease in oxidized carbon species including CO2, HCO3 and DIC, suggesting contemporary methanogenesis. Pumping in the Devonian shale contact aquifer may stimulate methanogenesis by lowering TDS, removing products and replacing reactants, including bicarbonate, derived from overlying glacial sedimentary aquifers.
KW - Canada
KW - Hydrochemistry
KW - Methane
KW - Shale gas
KW - Water supply
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U2 - 10.1007/s10040-014-1229-7
DO - 10.1007/s10040-014-1229-7
M3 - Article
AN - SCOPUS:84939944571
VL - 23
SP - 719
EP - 739
JO - Hydrogeology Journal
JF - Hydrogeology Journal
SN - 1431-2174
IS - 4
ER -