Abstract: Water storage is one of important parameters to describe the utilization factor of water injection energy and evaluate the effective-ness of water flooding reservoir. However, the traditional water storage could not be widely used for its limitation of concept. This paper pro-posed the definition of generalized water storage,which could reflect the effectiveness of water flooding reservoir with edge or bottom water and take the elastic energy into consideration. The case study showed that the effectiveness of water flooding reservoir can be embodied by the speed of generalized phase water storage decline; there exists different linear correlation between the generalized cumulative water storage and the water cut.

Key words: water storage, water flooding, water influx, water cut