Research On Dolomite Reservoir Characteristics Of Cambrian Formation In Central Uplift Belt,Tarim Basin

The study area of this paper is the Centre Uplift Belt of Tarim basin and the target horizon is Cambrain formation of Lower Paleozoic.Using kinds of data that including core description,thin section identification,logging curves,physical property analysis andmercury intrusion test to analyze the characteristics ofsedimentary strata,sedimentary facies,rock types,reservoir space types,pore structure,diagenesis,diagenesis evolution,physical property and its influence factors of dolomite reservoirs of Cambrain formation in study area.Investigation results show that the main sedimentary faciesof Cambrain formationare evaporation platform,restricted platform,open platform,platform margin,slope,shelf and basin.Dolomite can be divided into four types,which are residul-grained dolomite,grain dolomite,mud microcrystalline dolomite and transitional dolomite.There are several reservoir space,such asintercrystalline pores,intercrystalline solution pores,intergranular pores,intergranular solution pores,mold pore,dissolved pores and cracks.Reservoir space combination types contained intercrystalline solution pores-intercrystalline pores,solution pores-cracks and cracks-solution pores.The Cambrain dolomite of study area experienced several diagenesis,contained campaction and pressure-solution,cementation,dolomitization,recrystallization,silicification and dissolution.Diagenesis stages can be divided into penecontemporaneous diagenetic stage,early diagenesis stage and late diagenesis stage.Pore structure of dolomite is complex and physical property of reservoir shows big heterogeneity extent because the Cambrian dolomite reservoir experienced complex diagenesis and structural fracture.Based on capillary pressure test data and physical data,pointed out study area has four types of reservoirs.Type?and type ?reservoirs(good reservoirs and better reservoirs)are distributed in the middle and west parts of study area.Type ? reservoirs(medium-quality reservoirs)are developed in the north and south,while Type ? reservoirs(poor reservoirs)are distributed in the East.