Effect of water salinity and rock components on wettability alteration during low-salinity water flooding in carbonate rocks

In this paper, contact angle measurements using crude oil, five carbonate rocks, and six brines were conducted to study the effect of water salinity and rock components on wettability alteration. The results showed that lowering water salinity results in wettability alteration of carbonate surfaces to more water-wet. And there exists an optimal salinity at which the maximum wettability alteration occurs. In addition, the optimal salinity tends to increase as the content of dolomite in the rock decreases gradually. When low-salinity water is kept the same, the lower dolomite content in the carbonate rock, the more water-wet the rock will tend to be.