Abstract: In view of the unclear producing conditions of the film remaining oil, Polyflow software analog computation and micro-visual displacement experiment were used to study the effect of the interfacial tension of the ASP flooding system on the film remaining oil production, and compare and analyze the critical rupture conditions of the film remaining oil under different conditions. The results showed that when the capillary force of the oil film was less than the normal force of the displacement fluid on the oil film, the oil film would rupture. For the same oil film, the larger the number of capillaries in the flow field, the higher the deformation rate of the oil film. When the number of capillaries is less than 0.10, the deformation range of oil film was small; when the number of capillaries was 1.00, the deformation of oil film was increased significantly. At the same oil film length, the smaller the oil film height, the smaller the oil film volume, the more the capillaries on the critical surface, and the lower the critical interfacial tension. At the same oil film height, the smaller the oil film length, the larger the oil film volume, the less capillaries on the critical surface, and the higher the interfacial tension of oil film rupture. The microscopic oil displacement images and numerical simulation results showed that when the interfacial tension reached the order of 10^-2 mN/m, the film remaining oil attached to the pore wall could be used. This study is of guiding significance for the study of microcosmic remaining oil production.

Key words: ASP flooding system, interfacial tension, film remaining oil, capillary force, microscopic visualization of oil displacement