Abstract: The Bashijiqike Formation of the Keshen 8 gas reservoir in the Kuqa depression contains ultra-deep fractured-porous tight sandstone reservoir. Systematic researches on reservoir properties and modeling provide a geological basis for locating development wells with high and stable production and establishing a development plan in the Keshen 8 gas reservoir. Comprehensive analysis based on thin section observation, scanning electron microscopy, laser confocal microscope and electron probe shows that the Bashijiqike reservoir is dominated by lithic feldspar sandstone, pores are mainly intergranular pores and less intragranular dissolved pores. Based on structural and lithofacies modeling, the matrix porosity model was established by sequential Gaussian simulation method, and the matrix permeability model was established by using the pore-permeability curve equation, and three matrix porosity-permeability zones were divided. The tectonic fractures in the Keshen 8 gas reservoir were mainly formed with the near SN tectonic compression caused by the Himalayan movement. They are dominated by upright shear fractures and high-dip tensile fractures, and appear as parallel combination and skewed combination on image logs. Some high-dip tensile fractures are filled with minerals such as anhydrite and dolomite. Based on the finite element numerical simulation of the tectonic stress field, the numerical simulation of tectonic fracture parameters was carried out, and based on this, the tectonic fracture property model was established through sequential Gaussian simulation, and four high-porosity areas and five high-permeability areas were identified. Finally, the reservoir matrix property model and the tectonic fracture property model were added to establish a dual-medium property model, three high and stable production areas, Wells KS807, KS8-5 and KS8-8-KS806, were divided on plane, and in the vertical direction, the third sandstone group was proposed as a high and stable production interval. They should be given priority in future development.

Key words: ultra-deep reservoir, fractured-porous reservoir, tight sandstone reservoir, property model, Kuqa depression, Bashijiqike Formation