https://hdl.handle.net/10388/14976

Woroniuk, Blake W (2023) Hydrogeology of the intermediate zone between deeper anthropogenic activities and shallow aquifers in Saskatchewan, USASK Harvest - Theses and Dissertations, https://hdl.handle.net/10388/14976

Large volumes of often saline formation water are both produced from and injected into sedimentary basins as a by-product of oil and gas production. In Saskatchewan the prominent disposal zone is the Mannville Group and despite this, the distribution and interactions of these waters have not been studied in detail, and the effects of long-term water injection on reservoir pressures and groundwater quality remain uncertain. Even where injection and production volumes are equal at the basin scale, local changes in hydraulic head can occur due to the distribution of production and injection wells. The changes in hydraulic head caused by this injection of fluids are important in understanding the potential to act as a driver of saline fluid flow, possibly leading to contamination of overlying potable groundwater resources where high permeability pathways or leaky abandoned wells are present. Across the Western Canada Sedimentary Basin's (WCSBs) Mannville Group, approximately 250,000,000 m3 of excess water has been injected into the Group. This study evaluates the effects of injection wells on deep groundwater resources by examining wells within the Intermediate Zone of the WCSB. Hydraulic head maps were created for each aquifer within the Intermediate Zone, as well as maps of the difference between aquifer hydraulic heads. By comparing maps detailing the difference in hydraulic head, it was possible to locate areas where there is the potential for waters to migrate upwards through natural pathways or leaky wells. The potential for significant upward migration through natural pathways was deemed low due to the presence of low permeability shales in the Intermediate Zone of the study area, but leaky wells pose a bigger problem. As the leaky well becomes further away from the injection well this problem is not as severe but still poses a problem for freshwater aquifers.

https://harvest.usask.ca/bitstreams/3a5a600f-212c-417d-91ce-d28c53f43f3c/download