The Relationship Between Sedimentary Facies And Oil-Gas Accumulation On Chang 6~2 In The Middle Of Shanbei Slope

Ordos Basin is rich in abundant oil and gas resources,and it's the second of Chinese largest oil and gas basins.The study area is located in the middle of Shanbei slope in the Ordos Basin.Chang 6~2 reservoir group is the researched layer in this paper.Under the guidance of theories of sedimentology,logging geology and petroleum geology,on the basis of abundant data from geology,drilling,logging,well testing,etc.Combined with regional geological setting,this paper researched the provenance analysis,sedimentary facies recognition and the classification and correlation of Chang6 oil layer of the Upper Triassic YanChang Reservoir,and analyzed the sedimentary faces and the exhibition of the sandstone in the study area.Finally,the connection between sedimentary characteristics and oil-gas accumulation regulation is summarized.Used the marker formation in the study area,combined with sedimentary cycle and the principle of the thickness of strata,according to the traditional division method,this study divided Chang6 into four sections: Chang 6~1,Chang 6~2,Chang 6~3 and Chang 6~4.The tectonic setting of Chang 6 is the west-dipping monoclinic,and developing small rows with nose uplift which is ranked distribution.Chang 6~2 is delta-front facies deposition.Overlapping sands of subaqueous distributary channel are the main reservoir.The lithology is mainly light gray – green fine grained feldspar sandstone.Chang 6 reservoir is low porosity,low permeability ones.The reservoir properties are poor,and belong to low-especially low porosity and especially low-ultra low permeability reservoir.Through the comprehensive analysis,the study believed the oil-generating center controls the distribution of reservoir,and near-source accumulation is the mainly accumulation type of oil and gas.Micro-facies controls the distribution of favorable reservoir,and the favorable reservoir controls the migration and accumulation of oil and gas.The nose type structure has no obvious control function on the oil and gas concentration.