Abstract
Surfactant flooding which reduces the interfacial tension between oil and water is one of the promising enhanced oil recovery (EOR) methods. We should improve the efficiency of this scheme to reduce the cost. In present study, we proposed gas injection before the surfactant injection to improve the efficiency. The pore-scale mechanisms of surfactant flooding were visualized by means of X-ray tomography. The oil recovery increases with gas injection preceding surfactant especially for oil wet porous media.
