Research on Reservoir Dynamic Retention Rule and Oil Displacement Effect of Polymer-Surfactant Agent Flooding

After polymer flooding in the main reservoir of Daqing Oilfield, about 50% of the reserves remain underground, which is an important potential for oil field production replacement. Through the study of reservoir dynamic retention and oil displacement effect of polymer-surfactant agent, the adsorption and retention characteristics and oil displacement and washing characteristics of polymer-surfactant agent were defined. The research results show that: The hydrophobic groups in the molecular structure of polymer-surfactant agent will associate with each other in aqueous solution to form a 3D elastic network structure, which will give play to the characteristics of structural viscosity. Due to the characteristic of self-adaptive viscosity composed of the structure viscosity and bulk viscosity of the polymer-surfactant agent, it is possible to cut into the low-permeability layer of the throat with a smaller hole while plugging the high-permeability layer, so as to realize the self-adaptive displacement characteristic. The dynamic retention of polymer-surfactant agent is 1.5 times more than polymer, which can play a better role than polymer in the process of plugging adjustment and flooding, and save the amount of chemical while expanding the sweep volume. By comparing the results of microscopic oil displacement experiments, it is shown that the polymer-surfactant agent is better than the polymer in the application of medium and low permeability layer, and can effectively block the high permeability layer, so it is more suitable for the development after polymer flooding. The field test of EOR after polymer flooding further verified that the reservoir activation degree under the permeability condition of less than 300 × 10−3  μm2 in the whole process of polymer-surfactant agent flooding was better than that of the polymer flooding. The final total pay-gross thickness ratio of field test was 2% higher than that of polymer flooding, and the ultimate recovery was 2.0% higher than that of polymer flooding.