Research On Reservoir Characteristics Of Cambrian In Longdong Area,Ordos Basin

Under the guidance of new principles and methods of modern sedimentlogy,reservoir geology,integrated with core observation,the data of thin section identification(conventional and casting thin section),logging,laboratory analysis,etc this thesis has carried out detailed study on Mao Zhuang formation,Xu Zhuang formation,Zhang Xia formation and Sanshanzi formation of Upper Cambrian,and distribution stratigraphy,petrological characteristics,sedimentary facies,diageneses and reservoir characteristics in the Lower Paleozoic carbonatc rocks Cambrian reservoir in Longdong Area,Ordos Basin,as objects of study.Research region each formation of Cambrian gradually overlap sedimentary from west and south directions to basin interiorly,stratigraphic thickness gradually thickened overall in the direction of the central uplift to the surrounding.Research region Cambrian carbonate rocks are based on oolitic limestone and micritic dolomite,and contain a certain amount of chlorite,ankerite,fluorapatite,siderite,pyrite,Oolitic chlorite,etc mineral composition,reflecting the deposition environment.of the formation formed.Research region Cambrian experienced a littoral-carbonate ramp-carbonate platform depositional environment,mainly developed littoral,carbonate rocks within the ramp,restricted platform,open platform,etc sedimentary facies.Research region Cambrian carbonate deposits(rock)undergo diagenesis have transformed the role of calcium carbonate minerals,dolomitization,dedolomitization,metasomatism,dissolution,cementation,compaction pressure solution and recrystallization.The main destructive diagenesis consist of compaction and pressure solution,cementation and metasomatism.Recrystallization,dedolomitization and some pressure solution,has double effects.The preserving spaces are mainly secondary pore feature;high quality of reservoir space include intergranular corrosion pores,intragranular dissolved pores,holes,fissures,etc.The carbonate reservoirs of research region belongs to low porosity and low permeability reservoir type,porosity between 0.12%?14.15%,average 0.86%;penetration between 0.01 m D?26.54 m D,average 0.38 m D.Carbonate reservoir development in the study area is mainly controlled by sedimentary facies and diagenesis,mainly developed limestone reservoir and dolomite reservoir.Mostly limestone reservoir belongs to potential reservoirs,limited distribution range;Mostly dolomite reservoir is relatively good,wide distribution and well potential.