Mechanism of interfacial characteristics of ASP-system on oil displacement efficiency

It is known that the effect of alkaline/surfactant/polymer (ASP) compound solution with the same interfacial tension at different alkali concentrations on residual oil is different. In addition to the difference of the ASP-solution viscoelasticity, factors affecting oil displacement efficiency could also be related to the interfacial viscoelasticity. In view of this phenomenon, the influences of ASP-system with the same interfacial viscoelastic modulus but different interfacial tension and the same interfacial tension but different interfacial viscoelastic modulus on residual oil displacement efficiency were studied using microscopic oil displacement experiment. It is indicated that the interfacial viscoelasticity and interfacial tension make contribution to the residual oil displacement efficiency. The ASP-system with low interfacial tension and low interfacial viscoelasticity has high oil displacement efficiency. Reducing interfacial viscoelasticity and interfacial tension plays an important role in enhancing oil displacement efficiency. The emulsification effect for the residual oil changes from emulsified oil droplets to emulsified oil silk along with the decrease of interfacial tension and interfacial viscoelastic modulus. The results of displacement experiment in Berea Rock Core are in agreement with the above understanding.