Geothermal energy potential of sedimentary formations in the Athabasca region, northeast Alberta, Canada

Abstract

The Athabasca region, located in the northeast of Alberta, Canada, hosts many ongoing projects of bitumen extraction from oil sands and Devonian carbonate and siliciclastic reservoirs, which require a vast amount of thermal energy. Geothermal energy as a green renewable source of heat can help to reduce the amount of fossil fuels used to provide the required thermal energy for these projects and consequently decrease the greenhouse gas emission. To assess the geothermal development potential in this region, an integrated regional-scale 3D model was constructed with geologic and geophysical data (approximately 7000 formation tops and approximately 800 km seismic 2D profiles). Incorporation of 2D seismic profiles that filled in the gaps between sparse geologic tops particularly for deeper formations adds to structural details of the modeled formations. The temperature and porosity fields were simulated using the sequential Gaussian simulation approach within the modeled sedimentary formations. Based on spatial distribution, thickness, formation porosity and permeability analysis, five Paleozoic formations of Keg River, Waterways, Cooking Lake, Leduc, and Grosmont were identified as potential aquifers for geothermal development. These aquifers have enough coverage and thickness in the area and possess a high amount of thermal energy content. Because the sedimentary basin in the Athabasca region is quite shallow (less than 1400 m), these aquifers are all recognized as low enthalpy geothermal reservoirs with maximum of 40°C temperature and hence direct heating applications are not feasible. Use of industrial-scale heat-pump technologies that have long been used in northern Europe with high coefficients of performance would be recommended for heat extraction from these reservoirs.