In this study, five different simulated oils were obtained, and their viscosities and interfacial tension between simulated oil and surfactant aqueous solution were measured. The core displacement experiments were carried out to explore the effect of oil properties on oil recovery in dilute surfactant flooding. Single-core experimental results indicated that a relatively low oil/water interfacial tension level might have a bigger contribution to improve oil recovery, despite a favorable mobility control being of importance. Parallel cores experimental results illustrated that the higher the permeability contrast, the lower the oil/water interfacial tension that was required to mobilize the low-permeability core. [ABSTRACT FROM AUTHOR]