Feasibility Study On Enhanced Oil Recovery By Surfactant/Polymer Flooding After Polymer Flooding

Laboratory experimental results show that after polymer flooding,there is still a large number of the remaining residual oil in the formation, how to make the best potential residue of crude oil is an urgent need to resolve. Although ASP flooding used after polymer flooding can be significantly enhanced oil recovery, the use of alkali, not only reduces the viscosity of the polymer solution, also causes series of problems such as clay dispersion and migration of formation, permeability decreasing,oil and bottom scale, decreasing of liquid-producing capacity and pump inspection period, difficult of produced liquid demulsification and dehydration.For the above-mentioned issues caused by ASP flooding,feasibility of SP flooding after polymer flooding to enhancing oil recovery is studied at the base of some laboratory modelling experiments on oil displacement in artificial cores in this paper.In this paper, the initial formula of binary composite system which is identified at the base of laboratory and field tests.,is optimized through performance evaluation experiments. Some laboratory modelling experiments on oil displacement based on optimized SP binary composite system and evaluations on viscosity,the stability of interfacial tension and oil recovery of SP binary composite system are conducted. are conducted,and at the same time the oil recovery comparison of SP flooding and ASP flooding through oil displacement experiments on homogeneous cores and heterogeneous core. Besides,streamline distribution of SP flooding and.SP distributing law are studied through oil displacement experiments carried out on physical plane model.The following are studied:the interfacial tension between oil and SP solution can reach 10-3 mN/m in a high surfactant concentration range;viscosity and interfacial tension of SP the stability of binary composite system is stable;After polymer flooding with the SP slug drive going on again thereafter,the average enhanced recovery is about 10%,seen from the oil recovery regardless of homogeneous core or heterogeneous core,and oil recovery is higher than that of ASP flooding...