An Improved Numerical Simulator for Surfactant/Polymer Flooding

Abstract Due to the high demand to increase oil production combined with the huge potential in enhancing oil recovery, surfactant/polymer (S/P) flooding is under increasing interest and importance in recent years. Numerous studies have shown that interactions between surfactant and polymer can be extremely important to the final displacement performance of S/P flooding, since the desired effect of polymer and surfactant may be enhanced or degraded as various slugs become mixed underground. Nevertheless, as far as we know none of the available commercial numerical simulators can account for the impact of these interactions. The study focuses on constructing an improved S/P numerical simulator. A series of experiments were performed on S/P mixed system and flooding process. The results show significant influence of S/P interactions on viscosity, interfacial tension, and adsorption, and the interactions can be totally different when injected into different S/P systems. Quantitative relationships of the interactions were then provided based on the results. Then, an S/P flooding mathematical model was established on the basis of mass conservation, with the description of various important phenomena during flooding process being included, especially for the interactions between surfactant and polymer. Adaptive implicit method was applied to solve the equations and a simulator was developed. The simulator was finally used to perform the numerical study of different S/P mixed systems, in which synergistic promotion, non-interaction and competitive repulsion were respectively presented. The displacement performance was the best when synergistic promotion existed between surfactant and polymer, followed by non-interaction, and competitive repulsion. In summary, a new method for the treatment of interactions between surfactant and polymer in numerical simulation was derived in this work. The improved simulator could enhance the matching degree between mathematical model and field data.