Abstract: The instantaneous water cut-recovery percent ratio and water cut-recoverable percent ratio are proposed. The new parameters refer to the ratio of anytime composite water cut to corresponding recovery percent or recoverable percent, which can be used to evaluate efficiency of oilfield development by water flooding process, sutable for different types of reservoirs or different stages of the same reservoir. In particular, during mid-late period of oilfield development, such parameters tend to being constant, providing comprehensive and real evaluation of ultimate water flooding efficiency. Also, using these parameters can not only reflect inherent characteristic of reservoir rock and fluid in an oilfield, but also the levels of development technology and policy.

Key words: oil field, water flooding, development efficiency, evaluation