REGIONAL-SCALE CHARACTERIZATION OF SALINE AQUIFERS IN THE INDUSTRIAL HEARTLAND OF ALBERTA, CANADA

Alberta is world-renowned for its earth resources and a regulatory framework that focuses on their responsible development, while ensuring public safety, environmental protection, and resource conservation.

The Alberta Geological Survey (AGS) is undertaking regional mapping of saline aquifers in the deep subsurface below the Alberta Industrial Heartland, centred near Edmonton. The goal of this project is to map the major saline aquifers from the Precambrian crystalline basement to the lowermost aquifer of the Cretaceous Colorado Group in order to assess their potential for future water production or storage, geothermal energy, and their intrinsic capacity to safely store liquid or gaseous wastes, like CO₂, over long periods of time.

The initial phase of this evaluation involves the geological and geochemical characterization of two stratigraphic units, one clastic and one carbonate, within the study area. The procedures developed for these two units will act as templates for subsequent strata. The Cretaceous Ellerslie Member clastics infill lows on a pre-Cretaceous erosional surface resulting in its juxtaposition with Devonian, Carboniferous, and Jurassic aquifers at an angular disconformity within the study area. The Devonian Nisku Formation was deposited as an extensive shallow-water carbonate shelf following a period of carbonate platform and reef growth and inter-reef basin infill that formed the well-known Leduc Formation oil reservoirs.

Projects injecting CO₂ into deep saline aquifers and/or injecting CO₂ for enhanced oil recovery (EOR) within depleting oil reservoirs are being proposed within the study area. The AGS saline aquifer mapping project will characterize the injection zones as well as overlying and intervening strata at a regional scale. The study will produce characterizations of the geological framework, mineralogy, porosity and permeability distribution, pore space connectivity, pressure, temperature, and water geochemistry.

Water samples from producing oil and gas wells are being collected to characterize the hydrogeochemistry and identify indicators of cross-formational flow.