Interfacial tension and phase behavior of surfactant-brine–oil system

The phase behavior of surfactant-brine–oil system is the key factor in interpreting the performance of oil recovery by microemulsion process. Due to the well established relationship between the microemulsion phase behavior and interfacial tension (IFT), it is common in the industry to screen surfactants and their formulations for low IFT through oil–water phase behavior tests. In the present work, the aqueous phases containing different ethoxylated secondary alcoholic surfactants and electrolyte (NaCl) were contacted with synthetic oil systematically to study of their phase behavior and interfacial tension for higher degree of solubilization, which is desirable for enhanced oil recovery.