Sedimentary and Reservoir Characteristics and Hydrocarbon Exploration Significance of Triassic Taliqike Formation in Kuqa Depression

The concomitant source-reservoir is developed in the Upper Triassic Taliqike Formation of Kuqa depression, Tarim Basin. However, it has not yet attracted much attention for exploration and relevant studies on the reservoir have not been initiated. Based on the comprehensive analysis of sedimentary characteristics, physical property testing, and thin section identification, results of this study show that Taliqike Formation presents a "sandwich" of source-reservoir interbeds due to the alternation of sand/glutenite stone and dark mudstone or coal seams. The compositional maturity of sandstone is low, mainly composed of lithic sandstone, but as the particles become coarser, the quartz content tends to increase. Sandstone is in the middle diagenetic stage, and the most important pore reducing effect and the most obvious pore increasing effect are compaction and dissolution, respectively. The type of storage space is mainly intragranular dissolved pores and intergranular dissolved pores, and dissolution is the main contribution of the sandstone reservoir space of the Taliqike Formation. As the content of quartz particles increases the porosity tends to increase, and as the grain size of the sandstone becomes coarser, the porosity and permeability tend to become better; sedimentary facies is the key factor to control the reservoir and the sandstone/glutenite of distributary channel is the best reservoir. The physical properties of the sandstone of Taliqike Formation are similar to other important hydrocarbon reservoirs of Bashijiqike and Ahe Formations. The thicker Type Ⅱ-Ⅲ large-scale reservoirs are developed in the northern structural belt, and they are sandwiched in high-quality hydrocarbon source rocks formed by coal seams and dark mudstones. It is of great significance to search for middle-deep conventional and unconventional structure-lithologic reservoirs.