Modeling Foam Flooding in Varied Dimensions: The Transport of CO2 Soluble Surfactant for Foam Mobility Control

CO₂ flood is one of the most successful and promising enhanced oil recovery technologies. However the displacement is limited by viscous fingering, gravity segregation and reservoir heterogeneity. Foaming the CO₂ and brine with a tailored surfactant can simultaneously address these three problems. In this study, we use a texture-implicit local-equilibrium model called STARS to investigate the effect of partition coefficient for CO₂ soluble surfactants on foam transport in both 1-D and 2-D porous media. We inject these surfactants with the CO₂ phase to enhance the injectivity of Surfactant-Alternating-Gas (SAG) process and to improve the sweep efficiency of foam process. All test results, from different cases studied, have demonstrated that when surfactant partitions approximately equally between gaseous phase and aqueous phase, foam favors oil displacement in terms of apparent viscosity (1-D), foam propagation speed (1-D), mobility reduction factor (2-D) and sweep efficiency (2-D).