Characteristics and Control Factors of Carboniferous Bioclast Limestone Member Reservoir in the Qunkuqiake Area,Tarim Basin

Microcosmic characteristic of reservoir and experimental analysis in this study shows that the favorable reservoir of Carboniferous bioclast limestone member in the Qunkuqiake area consists of silt crystal dolomite and clay-silt crystal dolomite.Pore space is dominated by pores(intercrystalline and intercrystalline)and tectonic dissolution fractures,with an average porosity of 10.4% and an average permeability of 2.6×10-3 μm2,suggesting that reservoir pores belongs to medium to high porosity and permeability.Dolomite of evaporation tableland in the epilittoral zone and limy dolomite in the eulittoral zone are the primary conditions to develop the high quality reservoir,while dolomitisation,meteoric water dissolution,tectonic fracture-hydrocarbon infusion play constructive roles in development,connection and preservation of reservoir space.The favorable reservoir layer vertically controlled by depositional setting is approximately 1～5 meters thick and developed mainly on the evaporation tableland in the upper and top segments of the bioclast limestone member.Horizontally controlled by both paleohigh(the Qunkuqiake area)and late Hercynian and Himalayan tectonic movement,the paleohigh and late Hercynian and Himalayan fracture zones will be potential area for gas developing,which should be the target for oil and gas exploration.