Study On The Diagenesis And Its Main Controlling Factors Of Ordovician Carbonate Rock In Tazhong Area Of Tarim Basin

In the middle lower Ordovician carbonate rocks of Tazhong area,Tarim Basin,formed successively generated hole,cavern and fracture in the geological evolution which is the main reservoir spaces in the reservoir,the reservoir layer is controlled by many factors,sedimentary environment,diagenesis and tectonic action,diagenesis has the greatest influence and so that study the reservoir diagenesis and its main controlling factors of the of reservoir prediction has an important practical significance.This paper,on the basis of summarizing the results of previous studies,based on the basic theory of sedimentology and reservoir geology,through observating and analysising the Tazhong area Ordovician core,thin section,and casting sheet.It is considered that the main reservoir space type of the carbonate reservoir in this area are the hole and fracture;there are many types of diagenesis,among which constructive diagenesis including diagenetic dissolution and recrystallization,dolomitization and fracturing and destructive diagenesis includes compaction and pressure dissolution,cementation,metasomatism,micritization and filling.The research in the area placed the identified types of diagenesis in the burial history,found that in Tazhong area,the carbonate rocks mainly through the undersea and atmospheric water,mixing water,shallow buried and deep burial diagenetic environment,osteoblast of the rock series can be divided into quasi contemporaneous-early,middle diagenetic stage,late diagenetic A and late diagenetic stage B.Research also make the diagenesis interaction under the sea level dynamic system,found that in lowstand period is mainly controlled by meteoric water eluviation,during the period of transgression domain subjected to seawater of burial environment and diagenetic environment of formation,HST period for seawater and burial environment,which to summarize the the area of four pore evolution stages: Caledonian primary pore formation and reduction,during the Caledonian Hercynian period,hole gap further development,the Hercynian Indosinian hole fracture reduction Indosinian Himalaya cracks in the mountain,buried dissolution and filling period.