On surface interactions of environmental friendly surfactant/oil/rock/low salinity system: IFT, wettability, and foamability

Abstract

In recent years, natural surfactants have been considered as part of the EOR processes given their non-toxic and environment friendly nature. However, once chosen wisely, surfactants can only reduce the interfacial tension (IFT) and are often unable to alter the surface wettability for a better hydrocarbon production. Low salinity water (LSW) is a good candidate on these occasions, but the interaction of LSW with natural surfactants for wettability alteration has not been deeply understood. In this work, an attempt was made to extract and characterize a natural surfactant which could be used together with LSW for EOR purposes. To do this, a natural surfactant was extracted from Saponin and its physico-chemical properties such as CMC, foamability, and thermal stability were tested. A series of IFT and wettability measurements were then conducted to evaluate the performance of the surfactant as an EOR additive. The results obtained indicated that the extracted surfactant has a high thermal stability and can be fully functional in the temperature of up to 100 °C. It appears that increasing the level of salinity in the solution can improve the efficiency and foamability of the surfactant. It was observed that the extracted surfactant as can reduce the IFT of an air-water system by 78.65% and is capable of favorably altering the surface wettability of sandstone for a better hydrocarbon production once combined with LSW.