The Preparation Of Microemulsion And Evaluation On Oil Displacement Effect

In the late stage of water flooding development for oil fields in our country, chemical flooding is important to improve oil recovery technology. For low permeability reservoirs,pressure gradient, high injection pressure, and low natural oil prodution capacity are posed in injecting polymer, because of tight reservoir rock, small porosity, thin throat, reservoir heterogeneity and high clay content. To this end, we carried out the research of microemulsion flooding technology. Because of its unique performance, the microemulsion system was widely attention. Microemulsion flooding research has important guiding meaning for development of low permeability reservoirs.In this paper, quasi ternary phase diagram method is used for screening of various microemulsion components firstly. It analyzes the conditions of formation of microemulsion system which ultimately determined that sodium dodecyl sulfate was used for surfactant in microemulsion preparation, n-butyl alcohol used for additives, and surfactant and additives ratio is 0.67. At the same time, we also studied the influence of temperature on the formation of microemulsion system. The middle phase microemulsion system can greatly reduce the interfacial tension between microemulsion and crude oil that can be reduced 10-3 mN/m magnitude, even under 10-4 mN/m, and can reduce the resistance of oil droplets deformation,so oil displacement efficiency of the middle phase microemulsion system is the highest.Therefore, after finished the microemulsion components research, we conducted the study of middle phase microemulsion flooding system, which is to determine the best phase microemulsion formula. At the same time, We study the influence of components concentration on the phase behavior of middle phase microemulsion, which provides the theoretical foundation for the study of the microemulsion flooding. In order that microemulsion system has the very good dissolving ability and ultra-low interfacial tension,we studied the influence of distribution to the system of middle phase microemulsion and ultimately determined Sodium dodecyl sulfate and petroleum sulfonate distribution.Finally, the performance of middle phase microemulsion were studied, and we carried out the study of the oil displacement effects of it through core experiments. The experimental results show that the injection pressure of the middle phase microemulsion system and the mixed microemulsion system is higher than that of surfactant flooding, and the drag coefficient of it is higher. At the same time, the injection pressure of the middle phase microemulsion system and the mixed middle phase microemulsion system is close and not high, so they have good ability to inject.Compared with single surfactant flooding of sodiumdodecyl sulfate or petroleum sulfonate, Oil displacement efficiency of middle phase microemulsion is better, which can improve the recovery efficiency by 28.45%. Oil displacement efficiency of mixed middle phase microemulsion is best, which can improve the recovery efficiency by 30.12%.