【摘要】 根据模拟实验数据,建立了库车坳陷典型源岩天然气产率和碳同位素的化学动力学参数。基于探井和人工井(13条地震剖面共230个人工井点)地质数据和今、古地温数据,采用BasinMod软件,分析了各井点成熟度和天然气产率随时间的变化规律,查明了三叠、侏罗系源岩的生烃历史和烃源灶的演化特征,指出,库车坳陷中生界源岩自新近纪以来快速埋藏和成熟,特别是5×106a以来,上新统库车组快速沉积,引起成熟度急剧增高,进入干气阶段,表现为5×106a以来气源灶极高的生气速率,这是库车坳陷形成高效天然气藏的重要原因。库车坳陷的前缘隆起带和克依构造带捕获了同一腐殖型气源灶(T-J)不同阶段生成的天然气;前缘隆起带的牙哈凝析气田主要捕获了生油窗阶段近源生成的天然气,表现为天然气甲烷碳同位素相对较轻;克拉2气藏主要是晚期(5×106a以来)捕获了镜质体反射率在1.0%～2.5%阶段生成的天然气,表现为天然气甲烷碳同位素相对较重。更多还原

【Abstract】 Based on the simulated test data, the chemical kinetics parameters of natural gas generation rate and carbon isotope from the typical source rocks in Kuqa depression of Tarim basin are established. In view of the geologic data and the presentand paleogeothermal data from exploration wells and artificial wells, the changes of maturity and gas generation rate with time for each well are analyzed with BasinMod software. And the hydrocarbon generating history and source kitchen evolution of Jurassic-Triassic source rocks are recognized. It is suggested that the late and fast burial and mature of source rocks in Kuqa depression since the Neogene, in particular, the rapid deposition of Kuqa formation since the Pliocene (5×106 a BP) lead to sudden increase of the maturity of source rocks, entering into dry gas stage with extremely high gas generation rate. This is a significant reason for formation of highly active natural gas pool in this depression. As shown by the chemical and stable carbon isotope compositions of the discovered gases, the formation of the giant gas pool in Kela-2, Yaha underwent very different geological processes due to the differences in their gas source kitchens. Gases in Yaha condensate gas field in the frontal uplift zone appear to represent gases generated within early to middle oil window with relatively isotopic light gas, whereas the isotopic heavy gases in Kela-2 gas field in Kelasu-Yigikelike Yi structural belt are most likely high maturity gases (Ro:1.0%～2.5%) generated since 5×106 a BP.更多还原