In recent years, with the growth of oil consumption and the reduce of new proved reserves, the development of high viscosity oil reservoir was paid more and more attention. As Kongnan block of Dagang oilfield has characteristics of hypercoagulability, high viscosity and high salinity, core flow experimental apparatus and core displacement experiment apparatus were used to study the effect of oil displacement efficiency of polymer/surfactant combination system, and analyze the mechanism of the relationship between recovery growth and core permeability. The results showed that, for the weak heterogeneous reservoir, with the increase of core permeability, the resistance coefficient and residual resistance coefficient of the polymer/surfactant combination system were decreased. With the increase of viscosity ratio (μsp/μo) and core permeability, the oil recovery increased, but the increase rate decreased. With the increasing of the core permeability, the size of the rock increased, while the inaccessible pore volume decreased. So the adaptability of the reservoir and the polymer/surfactant combination system was affected by the average permeability, and then the effect of the polymer flooding of the polymer/surfactant combination system flooding was influenced. Comprehensively considering technical and economic effects，the reasonable viscosity ratio (μsp/μo) in polymer flooding should be about 0.5~1.0．

In recent years, more attention was paid to unconventional reservoir development due to the increase in oil consumption and the reduction of new proved reserves. The reservoirs of Kongnan Block in Dagang Oilfield belong to the high temperature, high salinity and hypercoagulable reservoirs. In order to improve the effect of polymer/surfactant binary combination flooding, the effect of solvent water treatment on polymer/surfactant binary combination based on Kongnan Block of Dagang Oilfield reservoir geologic al characteristics and fluid properties was studied. The results show that, elimination of the Ca2+ and Mg2+ in the injected water can enhance the association of hydrophobic associated polymer and improve the viscosity and flow turning ability of polymer/surfactant binary combination. After adding into the polymer/surfactant binary combination, not only can eliminate the adverse effect of Ca2+ and Mg2+ on the salt resistance of hydrophobic associated polymer, but also can form a large number of particles which can further enhance flow turning ability by entering reservoir porosity. Compared with injected water and softened water, the flow turning ability and recovery of the polymer/surfactant binary combination which is configured by softened water with particles are better.