Modeling of low-salinity waterflood with temperature-dependent geochemical reactions for heavy oil carbonate reservoirs

Abstract

Enhancing oil mobility and drainage by thermal process in heavy oil reservoirs has been well understood for increased oil recovery. Carbonate reservoirs naturally tend to have high residual oil saturation due to wettability and heterogeneity. Combined with thermal process, low-salinity waterflood (LSWF) has become a promising EOR candidate for heavy oil carbonate reservoirs. The LSWF is cost-effective over tertiary EOR and has been reported to reduce residual oil saturation. The LSWF effect inherently involves thermal sensitivity because wettability modification effect behind LSWF mechanism is attributed to temperature-dependent geochemical reactions in oil-brinemineral system. Spatial and temporal variations of temperature in the reservoir provide various levels of mineral dissolution, aqueous reaction, and ion exchange determining various levels of wettability modification as well as oil mobility. In consideration of thermal effect on geochemical reactions, this study has investigated the feasibility of thermal LSWF in heavy oil reservoir. Sensitivity study has captured the uncertainty when the process has been deployed in a thermally-conductive reservoir.