塔里木盆地满西地区奥陶系台缘礁滩断溶体新认识及勘探方向OA

Based on data including seismic interpretation,well logs and core slice,analyses were conducted on seismic reflection patterns,stages and distribution of faults,planar distribution of sedimentary facies,types of reservoir spaces,and genesis of reservoirs.This study identified the types of Ordovician carbonate platforms in the Manxi area of the Tarim Basin,analysed the controlling factors for high-quality reservoirs and hydrocarbon accumulation,established an accumulation model,and proposed potential exploration targets of oil and gas.The research indicates that the Ordovician in the Manxi area is characterized by a rimmed platform depositional system,where the platform-margin reef-shoal complexes cover an area of approximately 5 091 km2.These complexes,superimposed with multi-stage karstification and reticulated fractures,form high-quality fracture-cavity reservoirs,which exhibit a north-south orientation,large-scale distribution,and excellent storage capacity.The Ordovician platform-margin reef-shoal zone is situated within the hydrocarbon-generation center comprising the source rocks in the Precambrian Yuman rift trough,the Yuertusi Formation,and the Cambrian to Ordovician platform-margin foreslope facies.Large-scale hydrocarbon-enriched zones are densely distributed in a north-south trend within the interval from the Ordovician Penglaiba Formation to the third member of the Yingshan Formation,while exhibiting a linear distribution pattern from the second member of the Yingshan Formation to the Yijianfang Formation.Guided by these insights,Well Qingyu 2 was drilled,and it achieved a high flow rate of 105.6×104 m3/d gas from the second member of the Yingshan Formation during test,with a stable tubing pressure of 107 MPa.This records a significant exploration breakthrough in the Ordovician platform-margin zones in the Manxi area,and reveals a new domain for reserve growth.The research results provide valuable guidance for exploring ultra-deep carbonate reservoirs in the Tarim Basin.