Abstract:

The adaptability and veracity of "7. 5B" in Tong Xian-zhang' s formula was discussed and this formula could not be applied to a single reservoir but to a whole oilfield. Theoretic expression of "7. 5B" was deduced and a useful precise method to calculate this parameter was put forward. At the same time, this paper makes some modification on Mr. Tongs wateroil ratio va.recovery formula and recovery vs. water cut curve. Also it ex-plains the importance of.these modifications.

Key words: oilfield development, 7.5B, water drive geo-logical reserve, appraisement of development effect