Study of interfacial tension between a weakly alkaline three-component flooding system and crude oil, and evaluation of oil displacement efficiency

We have measured the interfacial tension between Daqing crude oil and a ternary system containing a weak base, S6 surfactant, and a polymer. We have studied the effect of the concentrations of the weak base Na2CO3, S6, and the polymer on the interfacial tension. The results show that a weakly alkaline three-component system reduces interfacial tension better than a nonalkaline two-component system. As the polymer concentration increases, the time required to achieve ultra-low interfacial tension increases. Sodium carbonate not only reduces interfacial tension but also acts as a sacrificial agent to reduce surfactant consumption.