Experimental Investigation of Imbibition Process in a Hybrid Low Salinity- Surfactant EOR Method

More than 60% of the world’s discovered oil reservoirs are stored in carbonate rocks. In most cases, oil-wetness of these formation has led to low recovery factor in the water-flooding process. Due to the negative effect of capillary forces, injected water cannot easily penetrate the oil-wet matrices and push oil to leave the matrix. Wettability alteration of the rock in relatively oil-wet formations has been considered as an approach to improve oil recovery. There are various methods for changing the wettability of reservoirs, among them, surfactants and low salinity waters are mentioned. Both of these methods have been studied in a wide variety of separate studies. In this study, the effect of hybrid low salinity surfactant was investigated. For this purpose, samples of oil and reservoir rock were prepared from one of the Iranian south oil reservoirs and their characteristics have been measured. Then, imbibition experiments of formation brine, low salinity water and low salinity water in the presence of AOT surfactants have been done. Results showed an improvement in the oil recovery in the low salinity surfactant formulation. The anionic surfactant in the low salinity environment has resulted in the recovery of 56% of crude oil C1 and 37% of crude oil C2.