Abstract: Characteristics analysis and effectiveness evaluation of structural fractures are of great significance to predict favorable tight sandstone reservoir and to select development strategy in Keshen-8 gas pool,Kuqa Depression,Tarim Basin.We analyzed the basic characteristics and forming sequence of the structural fractures,and the factors influencing their growth through such data as core,image logging and single well productivity.In the end,the planar and vertical effectiveness of structural fractures was evaluated,and some suggestions for development were given.The results show that (1) the structural fractures,partly filled with anhydrites,dolomites and seepage sand particles,are mainly upright or have a high dip angle.The third-phase structural fractures developed during the deposition of the Pliocene Kuqa Formation are the most important ones for gas preservation in Keshen-8 gas pool.(2) Faults,lithology,stratum thickness and sedimentary microfacies function to control the development of structural fractures.Structural fractures on the upper part of anticline are highly effective,but their effectiveness would decrease dramatically when their dominant orientation intersects with the direction of present maximum principal stress at a large angle.(3) The controlling effect of unconformity on structural fracture effectiveness is limited within 70 m to the unconformity.The Bashijiqike Formation reservoirs in Keshen-8 gas pool should be produced primarily through hydraulic fracturing,and top priority should be given to the 3^rd sand unit in development,followed by the 4^th sand unit and its underlying reservoirs,and the 1^st and 2^nd sand units being the last ones.

Key words: formation sequence, structural fracture, ultra-deep, tight sandstone reservoir, Kuqa Depression, Tarim Basin