Impact of Wettability on Residual Oil Saturation and Capillary Desaturation Curves

In this paper we supplement capillary desaturation data in the literature with additional wetting systems. The study is performed on Berea sandstone rock samples prepared with different wetting conditions. The rock wettability is characterized with spontaneous imbibition. Residual oil saturations as a function of capillary and Bond number are measured using flooding and centrifuge techniques, respectively, for a wide range of capillary and Bond numbers. We find a strong interrelation between wettability, residual oil saturation, and critical capillary and Bond numbers. As the system becomes less waterwet the residual oil saturation decreases and the critical capillary and Bond numbers increase. We find that the critical capillary or Bond number for strongly water-wet rock is ~10–5, which is in agreement with data reported in literature. However, for less water-wet rock, the critical capillary or Bond number is higher by at least one order of magnitude. The data presented in this paper indicate that reservoir wettability may significantly impact the design of enhanced oil recovery processes.