Characteristics Of Reservoir Caprock Of Upper Paleozoic In Ordos Basin GanQuan-ZhiDan Region And Controlling On Gas Accumulation

It's well-known that low porosity,low permeability and low abundance are the main characteristics of tight sandstone reservoir of Upper Paleozoic in the Ordos basin.On the basis of the previous researches,by making full use of the geological data such as logging data,gas testing data and so on in the study area,under the guidance of the theories of Sedimentology,reservoir geology and the natural gas geology,we make a deeper study of the reservoir and caprock characteristics of of Upper Paleozoic in the Ordos basin GanQuan-ZhiDan region by combining the geological theories with the experimental analysis,and making comparison of the static data and dynamic data,and finally summarize the tight sandstone reservoir and caprock controlling effects to the whole gas pool.Research area mainly develops two kinds of sedimentary system:P2h8,P1s1 and P1s1 are Delta sedimentary system;C2b is Barrier coast sedimentary system.The Upper Paleozoic sandstone reservoirs in the study area are mainly composed of fine-grained sandstone and median-grained sandstone,and the rock types are dominated by quartz sandstone,lithic-quartz sandstone and lithic sandstone.The reservoir porosity is between 2.0% ~10.0%,permeability between 0.01 mD ~ 0.6 mD,There is a positive correlation between porosity and permeability.The four reservoirs mentioned above all possessed a obvious heterogeneity,and Belongs to low porosity,low permeability reservoir.The mainly including reservoir sandstone in upper palaeozoic has entered the stage of diagenesis in the middle of A general.P1s1 caprock as the main caprock in research area.Caprock determines the accumulation and scale of the gas reservoir.Under the condition of the gas and caprock,reservoir controlenrichment of natural gas,scilicet reservoir condition and natural gas are positively correlated.At the same time,Eachsand layerof the effective thickness of sand and sand distribution and also have a more significant role in controlling gasreservoir.Due to the reservoirsall havea strong heterogeneity,the reservoirs withgood porosity and permeability are always gas enrichment reservoir.