Hydrogeology of a coal-seam gas exploration area, southeastern British Columbia, Canada: Part 2. Modeling potential hydrogeological impacts associated with depressurizing |
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| Authors: | S Harrison J Molson H Abercrombie J Barker |
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| Institution: | (1) 202, 2307 17A St. S.W., Calgary, Alberta T2T 4S3, Canada,;(2) Department of Earth Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada,;(3) Birch Mountain Resources Ltd., 3100, 205 5th Ave. S.W., Calgary, Alberta T2P 2V7, Canada, |
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| Abstract: | A three-dimensional, finite-element flow model was used to assess the hydrogeological effects of depressurizing coalbeds
lying in the Weary Creek exploration block, Elk River valley, southeastern British Columbia, Canada. The simulation results
permit, at an early stage, assessment of the environmental and economic implications of how the flow system may respond to
depressurization.
Estimated reservoir conditions for the coal-seam gas targets lying within the Upper Jurassic–Lower Cretaceous Mist Mountain
Formation indicate that the coalbeds must be depressurized by up to 350 m to attain the critical gas desorption pressure.
The simulations suggest that depressurizing has little effect on groundwater flux to the Elk River. Simulated water production
for three depressurizing wells operating under steady-state, single-phase flow for initial reservoir conditions of 13 and
16.5 cm3/g is 645 m3/d (4,057 barrels/d) and 355 m3/d (2,233 barrels/d), respectively.
Groundwaters collected from monitoring wells have relatively low salinity, ranging from about 250–1,300 mg/L. The groundwater
is supersaturated with respect to Ca–Mg–Fe carbonates (calcite, dolomite, and siderite) and Al-bearing silicates, including
kaolinite and illite. Dissolved trace-metal concentrations are low; only Fe, Cd, Cr, and Zn exceed Canadian water-quality
guidelines for aquatic life. Groundwaters were devoid of the more soluble monocyclic aromatic organic compounds, including
benzene, toluene, ethylbenzene, and polycyclic aromatic compounds, including naphthalene.
Electronic Publication |
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| Keywords: | groundwater/surface-water relations numerical modeling hydrochemistry groundwater protection Canada |
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