Abstract: On the base of the evidences on structure geology, the paper presents that the natural gas in Kuqa basin of Northwestern China comes mainly from the north thrust belt. Firstly, based on the basin prototype, the Triassic and Jurassic mudstone and coal, the main source rocks of the basin, did not develop better in Baicheng sag than in the northern thrust belt including Keyi structural belt; Secondly, because of the thrusting happened in late Cenozoic, the Triassic and Jurassic source rocks reach to a high to over high maturity and thus generate gas or condensate oil mainly. Thirdly, the thrust faults compelled the natural gas to migrate from the north to the south or from the deep to the shallow. As a result, the Keyi structural belt and the eastern Qiulitage structural belt enriched in natural gas because they were not only located on the migration routines of the natural gas, but also developed simultaneously when the gas migration happened.

Key words: Kuqa basin, north thrust belt, gas source, Baicheng sag

摘要： 从盆地构造史研究的角度认为库车盆地的天然气主要来源于北部山前冲断带：（1） 受原型盆地构造格局的制约，三叠系、侏罗系烃源岩发育的最有利位置不是在拜城凹陷，而是在克依构造带及其以北的北部山前冲断带；（2）晚第三纪以来的逆冲推覆作用使得烃源岩提早进入高—过成熟阶段，并以产气和凝析油为主；（3）逆冲推覆作用所产生的北倾逆断层控制天然气自下而上、自北而南运移，位于运移路线上的克依构造带和秋里塔格构造带的东段与烃源岩的排气期匹配较好，从而使这些地区最富集天然气。

关键词: 库车盆地, 北部冲断带, 气源, 拜城凹陷