The Research And Evaluation On The Characteristics Of Carbonate Reservoir Of The Yijianfang Formation Of Ordovician In Tuoputai Area,Tarim Basin

Tuoputai area is located in the southwest of x Tahe Oilfield,and Yijianfang Formation of Ordovician is the main production layer,which deposited a sets of carbonates of open platform facies and mainly limestone,characterized by deep buried,tight reservoir,complex diagenesis,strong heterogeneity and complex reservoir genesis.Based on previous research,and combined with the theoretical knowledge of sedimentary petrology,reservoir geology,tectonic geology and reservoir geochemistry and so on,this paper is aimed to find out the controlling factors for reservoir,and a series of work has been carried out: the petrological characteristics,sedimentary facies,diagenetic evolution sequence,reservoir characteristics and distribution and so on.These are mainly based on data of drilling,core,seismic,production data and geochemical analysis of nine main single wells in the study area,results are follows.During Yijianfang Formation period,Tuoputai area was in an open platform environment,which could be further divided into interbank sea,intraplatform reef and intraplatform beach.And mainly are interbank sea and intraplatform beach facies,intraplatform reef can be seen locally.Compared with later period of Yijianfang Formation,the reef-shoal are more developed than that in the early stage of Yijianfang Frmation,which shows a more open water environment in the later.Three types of reservoirs are developed here: hole-type,fracture-hole and cave-type.Vertically,reservoirs are mainly concentrated in the range of 60 m from the top.And reservoirs distributes in strips in plane,which are well developed in the range of 750 m along both sides of the fault zone.Generally,compared with the south,reservoirs are more developed in the north.In addition,reservoris can be seen in local secondary fault development zones and structural highs.Diagenetic evolution and reservoirs distribution indicate that reservoirs developed in Tuoputai are controlled by high-energy reef-shoal,karstification,fracturing and structure highs.Late Caledonian-early Hercynian karst is the dominant,superimposing with facies and fracturing,are the key factors for reservoir development.Additionally,the models of karst reservoirs have been built.Compared with amplitude change,the reservoirs of Yijianfang Formation in Tuoputai area are divided into 8 areas marked A-H.Based on the development of reservoirs,the numble of the favorable development area of?,?and ? class are 4,1and 3.