关键词: 渗吸,  , 周期注水, 毛管力, 附加压差

Abstract: Cyclic waterflooding is an important method to improve oil recovery of vertically heterogeneous reservoir. The experiment results showed that it was difficult to enhance oil recovery by means of imbibition after a certain degree of waterflooding. Coreflooding experiments confirmed the effectiveness of cyclic waterflooding to increase oil recovery for the vertically heterogeneous reservoir and the increase trend to lower as more cycles were applied. The mechanical mechanism of cyclic waterflooding was investigated by means of capillary bundle model. Imbibition will play a role until the force field on the fluid is balanced. The main mechanism for the cyclic waterflooding method is related to the change of capillary pressure instead of the absolute value of the capillary pressure. Additional pressure between the layers with different permeability which is induced by the change of water injection scheme can cause the corresponding change of capillary pressure in the reservoir. The research provides some insight to improve the understanding and practice of cyclic waterflooding.

Key words: Imbibition,    , Cyclic waterflooding,    , Capillary pressure,    ,  Additional pressure