Wettability alteration and interfacial tension reduction on high salinity of anionic/nonionic surfactant

Surfactants are used in enhanced oil recovery (EOR) methods to decrease interfacial tension at the oil-aqueous interface and to alter the wettability of the reservoir rock. Herein, the effect of salinity on interfacial tension (IFT) reduction and wettability was investigated using a mixture of a nonionic and an anionic surfactant. Brines with varying salinities are being considered in this study. The interfacial property and rock wetting characteristics of the surfactant were examined by measuring the interfacial tension and contact angle (CA), respectively. The IFT at the oil-aqueous interface was shown to decrease considerably under high salinity. Furthermore, CA measurements revealed that a high salinity anionic/nonionic surfactant was successful in altering oil-wet sandstone to a water-wet condition. IFT and contact angle are interrelated to provide significant EOR efficiency. Thus, this anionic/nonionic surfactant provides good properties for EOR applications.