Evaluation of Favorable Targets for Deep-basin Gas in the Southern Qianliyuan Sub-sag in Dongpu Sag
According to the analysis of hydrocarbon source rock quality,salt rock distribution,and the thermal evolution degree of hydrocarbon source rocks,it is concluded that the lower sub-segment of the third member of Shahe Formation in Dongpu sag is the largest favorable exploration area for deep-basin gas,making it the preferred stratum for deep-basin gas risk exploration.The exploration target areas are optimized based on reservoir conditions,caprocks,and preservation conditions.The southern part of Qianliyuan sag in the lower sub-segment of the third member of Shahe Formation can be subdivided into two sets of reservoir-caprock combinations,characterized by fewer faults and good sealing properties,and is selected as the exploration target area for deep-basin gas.For the four sets of lacustrine fan reservoirs,including the 3rd,5th,6th,and 7th sand groups in the southern part of Qianliyuan sag in the lower sub-segment of the third member of Shahe Formation,well-controlled frequency expansion technology is used to improve the vertical resolution of sand bodies.In the selection of exploration targets,structural-lithologic traps with the largest reservoir thickness in the descending plate of Duzhai fault near the source area are preferred for risk exploration.This strategy provides a clear direction for the replacement of natural gas reserve increase and production establishment in the old Dongpu area.
deep-basin gasqianliyuan sub-sagfavorable zonedongpu sag
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