Study On Oil Displacement Mechanism Of Air-Foam And Factors Influencing On Its Efficiency

Air-Foam flooding has two advantages both including air injection and foam injection. It is a new creative technique for enhanced oil recovery. In the basis of analyzing the theories and experimental results, the paper sets forth in detail oil displacement mechanism of Air-Foam. By experiments in laboratory, it is mainly study on oxygen contents in produced gas at the time of gas breakthrough, the blocking ability of air- foam and the factors which influence the efficiency of air-foam flooding. The results of experiment showed some facts as follows: Factors such as temperature and the time of gas breakthrough affect consumption of oxygen in air injection, and oxygen contents in produced gas at the time of gas breakthrough decrease with the increase of temperature and extension of the time. Some factors including of core permeability, core oil saturation, foam injection means, the ratio of gas to liquid, the injected alternating slug size and so on influence on the blocking ability of air- foam system. The factors such as injection pressure, injection slug and the ratio of gas to liquid which influence the efficiency of air-foam flooding. The results show that oil recovery increase with the increase of injection pressure, the optimum ratio of gas to liquid is 3:1 with it varying in range 1:1 to 3:1, and the alternating slug of foam and air is the best among the three of alternating slugs (slug of foaming agents and air, slug of foaming agents, air and water, slug of foam and air). In the basis of studying the theories and experimental results that the oil recovery of air-foam flooding is much higher than that of water flooding, specially to the reservoir of high water cut and heterogeneous, and it is a promising technique for enhanced oil recovery.