1. College of Petroleum Engineering,Petroleum University of China
Aiming at the problems of low water flooding recovery and high thermal recovery cost in Shengli normal heavy oil reservoir, emulsion viscosity reduction flooding is an effective way to improve recovery and reduce production cost. In this paper, considering the emulsifying ability and reducing interfacial tension of two surfactants TB and AC in different ratios, two kinds of emulsion flooding systems with different properties were constructed by using micro dynamic emulsification experimental device: TB (0.3%) and TB + AC (0.3%, 3:2). The micro stability of the emulsion formed by the two systems and Shengli heavy oil was analyzed by multiple light scattering method. The results showed that the stability parameter TSI of the emulsion formed by the strong emulsification and ultra-low interfacial tension system TB + AC and crude oil was the lowest and the stability was the best. On this basis, the oil displacement performance of the two emulsification systems was evaluated by the sand filled tube displacement experiment. The results showed that the TB + AC system has the best EOR effect, reaching 11.20%. The microscopic oil displacement mechanism was studied by using the glass etching model. It was concluded that the system can "pull" the residual oil through ultra-low interfacial tension and strong emulsification, make it deformed, reduce the flow resistance and residual oil content It can also enter into the depth of the oil film to produce further emulsification and make the oil film expand and rupture to enhance oil recovery.