Abstract: WAG integrates the respective characteristic of gas drive and water drive, it can effectively control mobility ratio and stabilize displacement front to raise macroscopic sweep efficiency, and has been put in extensive use in oil field production practice. This paper summarizes the history of WAG both home and abroad, studies the technical classification of WAG and distinguishes the different methods of partition by WAG which include mixed phase state, injected gas and some other way. Moreover, the research of IOR mechanisms by WAG is summerized, the direction in research for the future is put forward, good sense in tertiary recovery and early stage WAG in oil field is made.

Key words: IOR, WAG, tertiary recovery, development of research