The Numeric Modeling Of Reservoir-forming History Of Upper Palaeozoic At Dacheng Convexity,Jizhong Depression

Dacheng convexity is located in northeastern Jizhong depression,Bohai Bay Basin. It is a monoclinal structure striking NW and covered by Neogene and Quaternary strata with stratigraphic dip about 2�-5�. Dacheng convexity was formed during Indosinian and yanshan period but shaped by the Himalayan movement.Overall,Dacheng convexity's structure pattern is relatively simple.Paralic-continental coal-bearing construction was developmented in Carboniferous-Permian syetem at Dacheng convexity including main source Rocks as dark mudstone, carbonaceous mudstone and coal. Results show that: dark mudstone and carbonaceous mudstone belongs to medium-good hydrocarbon source rocks,meanwhile the coal is poor-secondary hydrocarbon source Rocks. The kerogen type of organic matter is namely the III Kerogen.The Ro is about 0.65-1.6%, being in a stage of low to high mature stage. So overall, Dacheng Convexity has the basic condition of hydrocarbon generation and expulsion.Basin modelling(including burial history, geothermal history, thermal evolution history and hydrocarbon generating history)and fluid inclusion characteristics(wellblock Ge2 and Su50)are discussed in this article. Research shows that Dacheng convexity experienced two stage accumulation and adjustment. The first stage was taken in at the end of the Mesozoic era and later shut down due to uplift. The second accumulation stage(the main stage) happened in Neogene and Quaternary period.Due to the research area has experienced multistage hydrocarbon generation and pooling but hydrocarbon generated in the first stage was hard to save, the article points out that the favorable exploration target area maybe these Himalayan tectonic zones with high mature stage and low organic carbon loss coefficient while the main hydrocarbon accumulation match the trap formation period and not damaged after the oil and gas accumulation. Therefore, wellblock Dacan1 would be the most advantageous exploration area and wellblock Sheng1,D3,Ge8 are favorable exploration areas for progressive exploration and development.