To tackle the problems of high water content and capacity loss in the development of low permeability reservoirs in Ansai oilfield, the feasibility study was carried out in the optimization of strengthen the micro-foam system and the improving mode of oil recovery.The oil displacement law and the influencing factors of the micro-foam system were evaluated by Blender Waring method and the foam flooding dynamic simulation device.The following results were obtained. For a self-developed non-anionic micro-bubble agent QHWP-121, the foam volume was 850 mL, the half-life was 380 min, the foam composite index was 323 000 mL·min, and the foam quality is 0.65. In this case, the foam is the best. Under the condition of oil reservoir, the oil displacement law is mainly manifested by improved heterogeneity, increased pressure,increased radius of pore throat,water shutoff but no oil shutoff and the oil can pass. The influencing factors in oil displacement of the micro-foam system were mainly related to the compatibility, concentration, permeability and gas/liquid ratio of the reservoir.The results revealed that the efficiency of oil displacement is mainly related to the compatibility between the strengthening micro-foam system and the reservoir. The suitable parameters used in the field practice are recommended as following. The concentration of micro-foam system is 0.5%, the gas-liquid ratio is 1∶1~2∶1, and the permeability is (10~10 000)×10-3μm2,which can provide a basis for enhanced micro foam flooding field in low permeability reservoir of Wangyao operation area in Ansai oilfield.

Ansai oilfield; low permeability reservoirs; high water cut; enhanced micro foaming; oil recovery