Study Of Sequence Stratigraphy And Favorable Reservoir Prediction For Es3 Formation In The North Of Dongpu Depression

Dongpu depression is a typical oil rich salt-lake basin of Bohaiwan basin in the east of China. Structural trap was the main oil/gas exploration target since 1980s, with the development of exploration, there are less and less structural traps being found. So the lithologic trap becomes the main exploration target. In views of the existing problems of the current sequence stratigraphy and geological characteristics, based on the core observation data and combined with drilling, well logging and seismic data, the thesis built up the isochronous stratigraphic framework by using lithofacies, well logging facies, high resolution sequence stratigraphy technology and reservoir sedimentology, moreover, the thesis discussed the sand body type and control factor and the favorable reservoir distribution rule of Es3 formation, which can provide theoretical reference for future oil/gas exploration.According to high resolution sequence theory and the sedimentary character of continental basin, Es3 formation can be divided into 3 long-term cycles (third order sequence) and 7 middle-term cycles (fourth order sequence) by recognizing various types of sequence boundary in Es3 formation. Based on the standard geologic profile of 15 blocks, the paper built up sequence framework in mid-term unit and analyzed the develop character of stratum in the sequence framework.The paper points out that there are many provenances in Dongpu depression and they are oblique enter the lake. The structural transfer zone importantly control on the entrance and pathway of the provenance. Generally, fan delta deposited in the east of Dongpu depression while braided river delta in west and normal delta in eastern limb of the center uplift zone and Liuzhuang-Qiaokou area. Many provenances are convergent in the center uplift zone. The lacustrine deposition mainly formed in each sag and deep water turbidite fan mainly formed in the downthrown block of the trunk fault. Salt and sand exist alternately in horizontal direction while having an interfingering relationship vertically.After the sequence stratigraphic correlation and depositional system analysis, the thesis build up the depositional infilling mode in ling-term cycle unit. And the mode indicates that the main deposition system is delta. Fan delta, small and abundant, is in the east, braided river delta, large and wide, is in the west and bird-foot delta is in the macroaxis direction. The main sedimentary facies of Dongpu depression is delta front; there also have storm deposition in deep lacustrine and turbidite in delta front. Based on the comprehensive analysis, we considered that the east sag belt, the west sag belt and around the Pucheng-Weicheng sag belt is the favorable zone where the lithologic trap developed well. Underwater distributary channel of the delta front and turbidite fan are the profitable facies of Dongpu depression.