Sensitivity Analysis and Prediction of Wettability Alteration Using Response Surface Methodology and PHREEQC

In studying the wettability alteration of oil reservoirs in enhanced oil recovery (EOR) techniques like water injection methods, special attention is paid to the composition of injected water. However, the extent of the impact of other factors, such as the oil and rock site density, and oil and rock surface area, is not given much attention. In this study, we analyze the sensitivity of discussed factors. First, oil adhesion to the rock surface was simulated using PHREEQC software (a geochemical reaction model), then the simulation results were modeled using Design-Expert software (a statistical software package). According to the findings, oil site density had the most influence on the oil adhesion, followed by oil and rock surface area in the second place. Because oil site density indicates the amounts of carboxylate groups on the oil surface, the increase in these functional groups increases the electrostatic bonds resulting in increased oil adhesion. Furthermore, the effect of parameters increases by increasing pH, and impressment will decrease above pH 8.