Alkaline-surfactant-alternated-gas/CO2 flooding: Effects of key parameters

This study investigates the critical parameters which influence the residual oil recovery by alkaline-surfactant-alternated-gas/CO2 (ASAG) flooding. A series of lab-scale core flood experiments were carried out with sandstone reservoir cores and Assam crude oil to examine the oil recovery potential by various schemes of ASAG flooding. The coreflood results demonstrated that ASAG flooding recovers higher residual oil (23.06% original oil in place, OOIP) compared to surfactant-alternated-gas (SAG: 18.29% OOIP) and water-alternated-gas (WAG: 8.84% OOIP) flooding processes. Effects of key parameters such as injection volume ratio, tapering, reservoir rock property, number of cycles and injection schemes on oil recovery during ASAG flooding were investigated. These factors affect the performance of ASAG flooding to an extent similar to WAG and SAG flooding.