Research On Cambrian Carbonatite Reservoir In Tarim Basin

Cambrian carbonate rocks distribute widely in Tarim Basin.There are several sets of effective hydrocarbon source rocks in Palaeozoic and several sets of gypsum-salt rock as effective caprock in Tarim Basin.Industrial oil and gas flows has been found from inter-salt and under-salt dolomite reservoir in the middle and lower Cambrian in Well ZS1 in Tazhong area.It is confirmed that favorable hydrocarbon accumulation conditions exsist around 7000 m deep in Tarim Basin.Xiaoerblak Formation dolomite reservoir has a wide oil and gas prospect,which is stably distributed in the basin.However,Cambrian is buried deep generally at the centre of Tarim Basin and its comprehensive knowledge is still limited.Based on the previous study of the structure,sediment,this paper conducts a study through multiple field geological investigation,drilling datas,seismic datas and indoor analysis.Then the paper studies the reservoir rock types and characteristics of reservoir spaces of Xiaoerblak Formation,the longitudinal sections of Xiaoerblak Formation and reservoir lateral comparison,analyzes the genesis and the main controlling factors of dolomite reservoir.Research suggests that Xiaoerblak Formation developes in platform facies.Seepage reflex effect is the main formation cause of Xiaoerblak Formation dolomite in the study area,the main dolomitization fluid was seawater.It can be divided into two sections in Kalpin,Tazhong,Northern Bachu.The upper section in Kalpin can be subdivided into three segments.The main reservoir space combination is pores and holes,the main reservoir types are type ? and type ?.Xiaoerblak Formation reservoir in the study area is mainly affected by sedimentary facies,diagenesis,tectonic action.The distribution of Xiaoerblak Formation reservoir is related to the sections.In Kalpin the high quality reservoir mainly distributes in the upper section,there may be caverns in the lower section.In Northern Bachu and the Tazhong the best reservoir exists in the upper section.In Southern Bachu the best reservoir exists in the lower section.Generally,Xiaoerblak Formation dolomite reservoir distributes stably in Kalpin,Bachu and Tazhong.