LAUSR

Abstract Many studies have been performed in the field of smart water injection and its combination with chemical methods to improve oil recovery. However, there has been less previous evidence for the efficiency of a mixture of cationic and nonionic surfactants combined with smart water for enhanced oil recovery in carbonate reservoirs. Therefore, in the current study, we aimed to investigate the effects of such a combination to enhance oil recovery from a fractured carbonate reservoir. Phase behavior experiments, IFT, and contact angle measurements were performed to design the optimal solution for EOR experiments. Then, through a series of flooding experiments, imbibition tests and simulations, and dimensionless analysis, the efficiency of the designed smart water-surfactant solution was examined. The results demonstrate a strong synergy between low salinity water and surfactant for recovering oil from carbonate reservoirs, as their optimal combination could recover up to 51.1% and 41.25% of the original oil-in-place in the core flood and imbibition experiments, respectively.