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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。
Based on the simulation data, the chemical kinetics parameters of natural gas yield and carbon isotope of typical source rocks in the Kuqa Depression are established. Based on the geological data and the present and paleotemperature data of exploratory wells and artificial wells (230 artificial wells at 13 seismic sections), basinMod software was used to analyze the variation of each well’s maturity and natural gas yield over time. It was found that Triassic and Jurassic source rocks and their source rocks. It is pointed out that the Mesozoic source rocks in the Kuqa Depression have been rapidly buried and mature since the Neogene, especially since 5 × 106a Kuqa Formation rapidly deposited, resulting in a sharp increase in maturity, into the dry stage, showing the gas source 5x106a very high gas rate, which is an important reason for the formation of high efficiency natural gas reservoir Kuqa depression. The frontal uplift and Keyi tectonic belt in the Kuqa Depression capture the natural gas generated in different stages of the same TJ gas source. The Yaha condensate gas field in the uplift zone of the Kuqa mainly captured near the oil production window stage The natural gas generated by the source is characterized by relatively light carbon isotopes of natural gas. In the Kela-2 gas pool, the natural gas with a vitrinite reflectance of 1.0% -2.5% was mainly captured in the late stage (5 × 106a), showing natural gas methane Carbon isotopes are relatively heavy.