The Research On Effective Technology Of Chemical Flooding After Polymer Flooding

China has rich oil resources, after the long-term development, oil field has entered the stage of high water cut and low oil recovery. Therefore, the polymer flooding has been large scale in Daqing oil field. But the results showed that there are still a lot of residual oil after polymer flooding in the formation. With the development of major oil reservoir and A class of reservoir, Blocks and oil layers that is polymer is flooded by polymer are growing. How to make the development of crude oil left in the ground that is a serious problem.The main reasons for the limited enhanced oil recovery by polymer flooding are polymer flowing in the major channels (or high permeability) and invalid serious water cycle of sequent water-drive. Thus, the use of the polymer is low; crude oil in the low-permeability has no effective displacement. If ASP flooding is used after polymer flooding, Although enhance oil recovery is significant, there are many issues such as reducing the viscosity of polymer, clay dispersion, migration, permeability decline, scale formation in reservoir and the well bottom, reducing the ability of production wells and monitor pump cycles, DEMULSIFICATION and dehydration is difficult by using alkali.In this paper, the performance of new surfactants and binary systems with no alkali are evaluated, high efficiency displacing agent was screened, verify the stability performance of surfactant under different conditions, determine and optimize the formula of compound system. By measuring the resistance coefficient and residual resistance coefficient, matching and flow characteristics of binary flooding system and high-concentration polymer flooding system in different permeability reservoir are studied. So, the displacement system was screened in different permeability reservoir. Through physical simulation experiments, chemical flooding enhanced oil recovery after polymer flooding was studied. Flooding systems formulation, slug size, and injection methods were optimized, the economic benefits was also evaluated. Experiments include high-concentration polymer flooding and SP system flooding after conventional polymer flooding. Experiments show that the improving recovery of AS flooding system is better than high-concentration polymer flooding system, and high-concentration polymer flooding can also achieve a very good displacement effect.This paper show that how to further improve the oil recovery after the polymer flooding, aim at advanced technology research. And provide technical reserves. It's important for sustainable development in Daqing oil field.