Research On Reservoir Characterization And Key Controlling Factors Of The Bioclastic Limestone Member Of Bachu Formation In Bachu-Maigaiti Region

The thesis aims at the practical demand of hydorearbon exploration of marinecarbonate rock in Tarim Basin.In this thesis,combining various kinds of methodsbased on theories of carbonate rock sedimentology,reservoir geology and depend ondrilling, logging, core information,thin section,cathodoluminescence,scanningelectron microscopy and analysis of reservoir geochemistry,Systematically studied thereservoir characterization and key controlling factors of the bioclastic limestonemember of Bachu formation in Bachu-Maigaiti region, and predicted favorable areasof the reservoirs.By utilization of well drilling, logging and core information, the thesis studiesthe sedimentary facies distribution about the bioclastic limestone member of Bachuformation. Development of a large area of the target layer restricted platform.Thefeatures of drill core and slice indicate different lithology. Combined with a series ofgeochemical testing methods,analysis of the types of diagenesis,diagenesis sequenceas well as the impact of the reservoir.Dolomitization and dissolotion are the mostadvantageous diagenesis types. Based on the study and analyses of different geneticmodels of dolomitization in the bioclastic limestone member, the seepage-refluxdolomitization develop widely in Bachu-Maigaiti region.On the basis of well logging,bore core and thin section observation, detaileddescription of the characteristics of the type and composition of the reservoir space.Secondary formation of intergranular holes, intergranular dissolved pores, holes aswell as cracks are the main reservoir space. Primary porosity is not development. Poretype, pore-fracture type and fracture type are the main composition of the reservoir space.Summarized four-property relations of the existing five wells.Indicated fivedifferent lithology in the bioclastic limestone member:crystal powderdolomite,lime-dolomite,bioclastic limestone, bioclastic limestone intercalatedthin-layer argillaceous limestone,dolomitic limestone. Crystal powder dolomite hasthe best physical and reservoir space. pore-fracture type, fracture type and Pore typeare the main reservoir space.Structural fault activity, dolomitization and dissolotionplay the constructive roles.Reservoir mainly develops in thin-layer crystal powderdolomite on the top of target layer.Dolomitization and dissolotion are the the key controlling factors about reservoir.Reservoir mainly develops in lagoon and interplatform beach facies. Dissolotion ismainly develops in the dolomite on the top of target layer of Bashituo region,andfractural systems are very development as well as hydrothermal fluid paly adissolution role. Dolomitization also develops in Bashituo region.Dolomite does notdevelop in other areas.Finally, according to the formation mechanism and the key controlling factor,predicted favorable areas of the reservoirs in this thesis.