Numerical modeling of highly saline wastewater disposal in Northeast British Columbia

Dense, saline wastewater generated during oil and gas activities (hydraulic fracturing and production) is commonly disposed of in deep formations, but the migration of this wastewater after entering the subsurface is poorly understood. This study uses numerical models to simulate wastewater disposal in the Paddy-Cadotte of Northeast British Columbia using both single-well axisymmetric box models and a regional model of the formation in which multiple disposal and water source wells operate. A sensitivity analysis performed on the box models reveals that dispersivity and permeability exert the strongest control on overall wastewater distribution. Models show that wastewater migrates further than predicted using a simple volumetric calculation, and extends further along the base of the formation than the top due to variations in fluid density. Interference between disposal and source wells is observed to influence wastewater migration, while formation dip and regional groundwater flow have no discernible impact.