Abstract:
Viscous fingering and early breakthrough are the main problems observed during the water flooding. These problems could be overcome by using foam flooding by coinjection of surfactant solution and nitrogen gas as a mobility control in a porous media to help improve the sweep efficiency. To gain the maximum benefits of foam flooding, ultra-low interfacial tension foam was studied to obtain a foaming system with high sweep efficiency and at the same time high oil solubilization to help mobilize the oil phase from reservoir rock. In this work, mixed surfactant systems between sodium dioctylsulfosuccinate (AOT) and internal olefin sulfonate (IOS) with three different carbon chain lengths were tested through phase behavior studies and interfacial tension measurements without adding alcohol. The optimal type III middle phase microemulsion with ultra-low interfacial tension in the order of 10-3 mN/m could be obtained from the mixed systems of 1:1 surfactant/cosurfactant ratio (AOT:IOS) with a wide range of optimum salinity. Surfactant and foam floodings were conducted by a sand pack glass column at atmospheric pressure and ambient temperature. High oil recovery (>10% OOIP) at the optimum salinity was obtained in both surfactant flooding which Type III microemulsion played a key role in oil solubilization and better sweep efficiency by foam flooding.
