The Relationship Between Sedimentary Facies And Rservoir Of Changxing Formation In The Wubaitidong-Mcaoba Tectonic Region In The Eastern Sichuan Basin

Carbonate reservoirs have a very important position in oil and gas exploration,and Marine carbonate reservoirs account for half of the world's oil and gas production.For China's extensive marine strata,its oil and gas resources are rich,and its exploration potential is undoubted.With the rapid development of oil and gas exploration,there is a corresponding breakthrough in the understanding of marine carbonate rocks in the Upper Permian Changxing Formation in the Eastern Sichuan basin.From the existing data,it can be found that the potential of oil and gas reserves in the construction area of the Eastern Wubaiti-Macaoba is amazing.Therefore,it is urgent to study the reservoir development characteristics of the region and explore its distribution.This paper takes the Changxing Formation of the East Wubaiti-Macaoba structure area in the Eastern Sichuan basin as the research object,in carbonate reservoir geology,carbonate sedimentology,petroleum geology and other related disciplines as theoretical guidance,the integrated use of wild ground observation,logging data,thin section identification,scanning electron microscopy,analysis of geochemical data,combining with the combination of macro to micro research methods,to build up the relationship between sedimentary facies and reservoir in Changxing Formation of the research area and get the following understanding:1.In the Northeast Sichuan area,the Changxing Formation has clear boundaries of both top and bottom.The Changxing Formation conformable contact with the limestone in the underlying Longtan Formation,and also conformable contact with the muddy limestone or mud at the bottom of the overlying Feixianguan Formation.There is partial unconformity or exposure.The rocks in Changxing Formation have many types,mainly including micritic limestone?dolomite?,grainstone,reef limestone?dolomite?,flint-containing limestone,muddy limestone?dolomite?and mud.There are many types of palaebioses.The distribution of the Changxing formation layer in the study area is stable on the plane,and has the tendency of the overall thickness thinning of the south to north strata,but the deposition thickness of the reef beach body is relatively large.2.In order to study the sedimentary facies of Changxing Formation in the East Wubaiti-Macaoba structure area,the fieldwork of field profile was carried out.The samples of field collection and the identification and analysis of the drilling cores were carried out,and the characteristics of petrology and paleontology were compared,and the logging phase markers were comprehensively studied.There are two kinds of sedimentation patterns in the Changxing formation:the"ramp mode"in the early Changxing Period and the"platform mode"in the middle-late Changxing Period.There are two isolated platforms in the study area,and they are separated by depressional platform.3.The reservoir rocks are mainly composed of grain dolomite in Changxing Formation in the East Wubaiti-Macaoba structure area,the second is the crystalline dolomite,the reservoir thickness is thin.There are several reservoir space,such asintercrystalline pores,intercrystalline solution pores,intergranular pores,intergranular solution pores,mold pores and cracks.According to the statistics of physical data,the average porosity of Changxing Formation was 1.2%,and the average permeability was0.0056×10^-3?m²,and it was low porosity and low permeability reservoir.4.Combined with the plane distribution of sedimentary facies in the study area believe that the most favourable reservoir of Changxing Formation is reef flat on the edge of platform,the second is the barrier reef deposition microfacies in reef core subfacies,the inter-shoal subfacies were the worst.