Abstract: W90 fault block zone has been exploited for 12 years through water-injection. It has entered high water-containing period and its production has already declined. On the base of analyzing actuality of oil reservoir, the workers fully handle correlative technology, study oil reservoir and realize new structure. They make clear the regularity of container horizon and expand the border of the fault block. Meanwhile, they deploy high output and efficiency well. Exploitation effect of the fault-block is improved. It gets better economic and social effects.