Characteristic analyses of proven OOIP in Jiyang depression.

The characteristics of OOIP in Jiyang depression, a non marine fault basin, are very representative. From the analysis of buried horizon, pool type, crude oil nature, production performance, reserves increase history and quality change, we know that pool distribution and enrichment have been controlled by the structure and sediment in Jiyang depression, and that the production performance of sandstone structural oil reservoirs is much better in all kinds of oil reservoirs. After the exploration of about 40 years, Jiyang depression has experienced peak reserves increase and stepped into such a present stage as mainly looking for medium and small sized subtle complex lithologic pools and structural pools, oil reserves increasing steadily and proven oil reserve quality having a tendency to decrease totally.