A Review on CO 2 Foam for Mobility Control: Enhanced Oil Recovery

Injection of gas is increased nowadays, and among various kinds, the mainly used gas in past 30 years for EOR purpose is CO2. The recovery mechanisms associated with CO2 flooding are oil viscosity reduction, oil swelling, and the phase transition due to miscible displacement. On the other hand, high mobility of CO2 and reservoir heterogeneities are the two major factors that are responsible for poor sweep efficiency. CO2 is having low density, and it results in the gravity override and starts moving toward the top of the reservoir causing an unfavorable mobility ratio. The combination of surfactant with CO2 generates foam which is a promising and cost-effective method in improving the sweep efficiency. The focus of research nowadays is to obtain foam with high stability and low mobility because it is directly related to sweep efficiency. Due to overwhelming interest in foam EOR, some new surfactants have been produced with the objective to meet wide range of reservoir condition and for targeting difficult reservoir design and operating conditions. In this paper, recent experimental research for laboratory screening and evaluation of surfactant is highlighted and the foam mobility in the porous media has been reviewed. The parameters important for the generation of efficient foam for the purpose of EOR have also been reviewed.