Improvements on modelling wettability alteration by Engineered water injection: Surface complexation at the oil/brine/rock contact

Several laboratory experiments demonstrated that different water compositions cause rocks to change from oil- to water-wet state. Although it is a consensus that wettability alteration is the main recovery process, modeling the underlying mechanism is still a major challenge. Our main goal is to improve and validate a physically based model to predict contact angles from zeta-potential measurements. We hypothesize that, if rock and oil surface are sufficiently close as consequence of thin water layer, then the charge development of one surface will be affected by the other. We propose a new mass-action formulation for surface complexation modelling that includes the energy interface of two interacting double layers. Currently, surface complexation models consider rock and oil as completely isolated surfaces. Additionally, we develop a method of determining surface complexation equilibrium constants to honor several zeta-potential measurements for different ion concentrations (Na+, Ca2+, Mg2+, SO42− and H+). Finally, we estimate contact angles using disjoining pressure calculations and compare them with experimental ones reported in the literature.