THE RESERVOIR-FORMING CONDITION AND ENRICHMENT RULE OF THE NATURAL GAS IN THE DONGPU DEPRESSION, THE BOHAIWAN BASIN

There are two types of gas source rocks in Paleogene and Upper Paleozoic in the Dongpu Depression,the Bohai wan Basin.The distribution of the natural gas reservoirs are controlled by the center of hydrocarbon generation.The accumulations of the natural gas are controlled by the tectonic characteristics.The salt rock and thick mud rock are propitious to the preservation of the natural gas.Source bed,reservoir and cap rock determine the natural gas's subsection characters in portrait.The high abnormal pressure and secondary pore zone in depth are important conditions of the natural gas enrichment and high yield.There are two reservoir-forming modes of the natural gas in the Dongpu Depression,i.e.Upper Paleozoic coal-formed gas and Paleogene condensate gas.They are characterized by the later period and episodic reservoir-forming.The residual resources of the natural gas is bigger at present in the Dongpu Depression.It is an important exploration area of the natural gas in the eastern China.The Upper Paleozoic coal-formed gas and Paleogene condensate gas is the stress in the future.