Abstract: Based on theoretic study on the relationships among injection-production well ratio of different water injection well patterns, per water injection well unit and well spacing density, the formula was derived for calculating injection-production well ratio, well spacing density and water drive recovery efficiency, further improving the study method of water drive recovery efficiency, and providing a new way to in-depth research it. Furthermore, this method was used to Shuanghe, Xiaermen and Weigang oilfields to quanti tatively analyse the constitution of enhanced recoverable reserves.The results showed that this method is simple and easy to use.

Key words: Water injection well, Oil well, Oil displacement efficiency, Well spacing density, Recovery factor, Sweep efficiency