METHODOLOGY FOR SALINE AQUIFER MAPPING IN THE CONTEXT OF PREVIOUS WORK ON UNDERSTANDING REGIONAL HYDROGEOLOGY IN THE WESTERN CANADA SEDIMENTARY BASIN

Studies of regional groundwater flow have been undertaken in the Western Canada Sedimentary Basin (WCSB) for over 50 years. Understanding the regional hydrogeology of the Alberta and Williston basins is essential as they contain many natural resources that are impacted by basin-scale flow systems. A diverse range of resources such as fresh water, saline water, potash and hydrocarbons are present within the rocks of these basins. There have been many studies on regional hydrogeology in the WCSB focusing on assessing and exploiting these economic resources. However, many of them have used different stratigraphic and hydrostratigraphic frameworks resulting in several nomenclature issues making it difficult to interpret the work across study areas and provincial/international borders. More recently, detailed hydrogeology has been sought after to better characterize deep saline aquifers and depleted oil reservoirs for CO­₂ storage, emphasizing the need for further regional hydrogeology investigations in order to evaluate the proposed uses of the subsurface.

The assessment of deep saline aquifers for their potential geothermal energy, future water production and suitability to safely store liquid or gaseous wastes, must involve detailed saline aquifer mapping. Hydrogeology studies recently completed in the Alberta and Williston basins have focused on further subdividing the stratigraphy and associated rock and hydraulic data into laterally continuous and permeable aquifers resulting in mappable hydrostratigraphic units. This work has found that significantly different water chemistry and flow regimes can exist within and between aquifers at a regional-scale that might not have been revealed using previous aquifer delineation for the given area. The Alberta Geological Survey is undertaking regional mapping of saline aquifers in the Industrial Heartland area (east-central Alberta) with the objective of delineating the hydrostratigraphy such that the cumulative effects of continued and competing uses of the pore space can be assessed and regulated. The project is intended to act as a pilot as various techniques are evaluated to develop and refine the methodology for mapping and characterizing saline aquifers and their connected pore space.