Experimental Study on the Startup Sequence and Oil Displacement Efficiency of Micro Remaining Oil by Chemical Flooding

Chemical flooding is one of the main technical means to further improve the recovery rate of water flooding. The present study on the mechanisms of chemical flooding, however, can only reveal the displacement process of different types of remaining oil by different flooding agents, not taking the different types of remaining oil as a whole and analyzing the startup sequence and complexity of different types of remaining oil, no more taking into account the effect of heterogeneity in the microscopic pore structure on the oil displacement efficiency. In this article, the author studies the startup sequence and complexity of remaining oil by different types of flooding agents by the means of photolithography micro physical model. The results indicate the startup sequence and complexity of remaining oil by different types of flooding agents are different. The polymer/surfactant binary system is the most active and can start up almost all types of remaining oil at the same time. As for the effect of heterogeneity in the microscopic pore structure on the oil displacement efficiency, in the case of the cores with the same permeability, the bigger the pore-throat, the poorer oil displacement efficiency, in the case of cores with the same pore-throat ratio, the bigger the coordination number, the better oil displacement efficiency.