Rheology and interfacial activity distribution of surfactant-polymer systemin the seventh block of Gudong Oilfield

In order to reveal the property loss law of surfactant-polymer （SP） system in the reservoir, combining with the reservoir conditions of strong heterogeneity and unconsolidated reservoir structure in the seventh block of Gudong oilfield, flow experiments were carried out in the cores with different lengths. The interaction between surfactant and polymer was studied through the change of interfacial activity and viscosity after the polymer and surfactant were added into SP system. The produced fluid was taken out from outlet end of cores with different lengths, and interfacial activity and viscosity were measured to study distribution characteristics of rheology and interfacial activity of surfactant-polymer system in vicinity of wellbore and reservoir. The experimental results showed that, after adding polymer solution, SP system interfacial tension presented similar change law to that of single surfactant, but the time to reach ultra-low interfacial tension was longer. The surfactant had little effect on viscosity of polymer solution, and surfactant-polymer system could maintain a good property of viscosity-increasing. At the beginning of flowing, the viscosity retention rate of SP system A and B were larger than the value of single polymer solution. But most of interfacial activity of SP system lost in vicinity of wellbore 0~20%, the interfacial tension was stable in the relative distance of 60%~100%. After the flowing became stable, the viscosity retention rate of SP system reduced from 100% to 84.2% in the relative distance of 0~20%, the distribution was uniform at deep reservoir, and the relative distance influence was comparative less. Interfacial activity between SP system and oil drop was stable in the relative distance of 60%.