HYDROCARBON ACCUMULATION ZONES OF ORDOVICIAN CARBONATE RESERVOIR IN TAZHONG AREA OF THE TARIM BASIN

Tazhong area of the Tarim Basin is restricted-open platform facies carbonate rock sediments from early to middle Ordovician.During the early stage of late Ordovician,the region develops to peninsula-like isolated platform and reef-band facies sediments along platform margin are deposited.Due to uplifts from middle Caledonian to early Hercynian,Tazhong area has experienced stages of supergene karst effects.Based on analysis of stages of tectonic evolution,it is pointed out that,Ordovician carbonate rock reservoirs in this region are controlled by palaeo-geography,sedimentary facies and diagenetic deformation stages.There are 4 types of reservoirs correspondingly: supergene karst,reef-band along platform margin,dolomite and hydrothermal deformation.Hence 4 types of accumulation zone are divided.