Study On The Dynamic System Of Oil And Gas Migration And Accumulation In Chengdao Area

Using the theory of the dynamic system of oil and gas migration and accumulation,the paper studies on dynamic mechanism of oil and gas distribution, subdivides different dynamic system of oil and gas migration and accumulation, researches on dynamic mechanism of different patterns of reservoir formation, and evaluates different zones and series of strata in Chengdao area.Chengdao area is encircled by Chengbei sag,Bozhong sag and Zhuangdong sag, geothermal gradient is high,has Es3,Es1 and Ed three hydrocarbon kitchens, the intensity of bear and discharge hydrocarbon is big, and this provides ample material base for reservoir formation in Chengdao area. Surpressure offers dynamic condition for oil migration; Turn knob stress field accelerates oil and gas discharge and migration and makes Chengdao low relief turn into a hydrocarbon convergence belt.The hydrocarbon migration pathways consist of faults,communicating sands,unconformity and their combination.By the analysis of activity faults , we conclude that the activity of Chengbei fault which provides the effective pathway for vertical migration is intense in main bleeding time of hydrocarbon. Considering the different effection of faults to oil-gas reservoir formation. All kinds of Neogene fans in Chengdao area are contacting with source rock and formed effective migration pathway.The lower member of Guantao Group featured by large depositional thickness,wide distribution,good transverse connectivity is important carrier bed. The existence of 3 unconformity provides good lateral oil—gas migration channels. In Chengdao area, the main migration systerm of fault zone is ladder type, buried hill drape structure and ramp region is meshwork—carpet type and the depression zone is fissure type.There are three types of pool forming environment in Chengdao area: hydrostatic pressure environment, transitional pressure environment and overpressure environment. Overpressure intensity, properties and distributions of seal coat, pressure structure, characteristics and activity of fault and other factors control the hydrocarbon abundance and enrichment degree of different pressure environment. Main expulsion stages have a good matching with fault late-stage activity,and this make the buried hill structure belt, abundant in hydrocarbon in large scale. On the basis of background of hydrocarbon forming force and the characters of hydrocarbon forming elements, hydrocarbon reservoirs-forming dynamic systems can be divided into three kinds: bottom semi-closed buried hill hydrocarbon reservoirs-forming dynamic system originated from other strata, middle closed hydrocarbon reservoirs-forming dynamic system originated from self strata which is located in the lower bench of Shahejie group-Dongying group, top open style hydrocarbon reservoirs-forming dynamic system originated from other strata which is located in the upper bench of Dongying group-Minghuazheng group.Petroleum pool in eastern slope are concentrated in Ed32-Ed4, maximum flooding surfaces(MFS) acts as pressure compartment,under the MFS, lithologic and stratigraphic–lithologic pool is main. Buried hill oil pool in Zhuanghai area is controlled by reservoir development and injection conditions, the intensity of fault activity decides hydrocarbon can reach series of strata. Neogene channel sand and Paleogene glutenite has a good exploration potential in Chengbei sag.