(590e) Wettability Alteration of Carbonate Rock By Gemini Surfactants

The two most important EOR mechanism for oil-wet carbonate rock are IFT reduction and wettability alteration. By altering rock surface from oil-wet to water-wet, the resulting positive capillary pressure can help imbibe water and displace oil from rock matrix. Researchers have studied the wettability alteration of materials covering surfactants, nanofluids, alkalis, salts, and so on. This study focuses on the wettability alteration performance of gemini surfactants in different salinity condition and their EOR potential when used alone and when combined with other materials. Rock samples were treated with surfactant solutions at different concentration and salinity, in ambient and reservoir conditions. The contact angle before and after treatment were measured. Differences in contact angle values reflect the wettability alteration performance. Results show that all tested gemini surfactants could strongly alter the wettability of carbonate samples from oil-wet to water-wet. Real-time contact angle study under reservoir condition revealed that the oil drop decreased in diameter while increased in height, indicating a higher tendency to be removed from rock surface. This study shows the outstanding wettability alteration performance of gemini surfactants, suggesting possible applications in oil-wet carbonate formations with high salinity. Besides, this study suggests that in low permeability formations, wettability alteration contributes more to oil recovery than IFT reduction.