In order to improve the development effect of the weak alkaline compound system in the three oil layers of Daqing Oilfield, it is necessary to optimize the formulation of compound system. Based on the combination of CMG numerical simulation and physical experiments, the effects of different concentration of formulation on the interfacial tension, emulsification performance and viscoelasticity of the system were compared and analyzed. The optimum concentration of the formulation was determined. The mechanism of the experimental results and the applicability of the system were also analyzed. The research indicates that the system can achieve ultra⁃low interfacial tension when the concentration of CHSB is between 0.2% and 0.3%, and the water absorption of the system remains below 40% when the concentration of CHSB is 0.3%, which indicates that the system has good emulsifying performance. The measured interfacial shear viscoelasticity is best when the Na2CO3 concentration is 1.2%. The results of the flooding experiment are mutually verified with the numerical simulation results. Based on development effectiveness and economic evaluation, the weak⁃alkaline ASP flooding system with the concentration of polymer HPAM is 1 000 mg/L, surfactant concentration of CHSB is 0.3%, and alkali concentration is 1.0%,which can increase the recovery rate by 23.31%. The results of this study have a guiding role in the application of weak⁃alkaline ASP flooding in the three oil layers.

    The new hydroxylsulfobetaines N, N-dimethyl-N-(p-dodecylbenzene methylen) propane ammonium (2-hydroxyl) propyl-sulfobetaine is synthesized with dodecyl benzyl chloride, dimethyl amine and sodium 2-hydroxy-3-chloropropanesulfate as the main materials and the target product is characterized by IR. The interfacial tension, adsorbability and emulsification property are evaluated, and then compared with the other two surfactants. Meanwhile, its mechanism and applicability are also analyzed. The result shows that the property can be improved effectively, due to the addition benzene ring and hydrophobic structure in hydroxyl-sulfobetaines (NHSB). When the concentration is 0.43%, the interfacial tension can reach to 10 ^-3 mN/m. In certain range of concentrations, the adsorption capacity of NHSB is always less than 2.1 mg/g. According to the water absorption of the surfactant is below 40% after 60 minutes and then remains stable, which has a relatively good performance of surfactant. At last, an indoor flooding experiment is carried out showing that the NHSB can improve the recovery by 5.64%.