四川盆地南部嘉陵江组烃源研究

四川盆地南部地区嘉陵江组中具有较大天然气储量的气井在天然气组分上与储量较小的微气井有明显差异,前者天然气以高成熟的甲烷为主.烃类碳同位素特征证明天然气来源于深层二叠系高熟-过熟的烃源岩.地球化学指标反映出嘉陵江组基本不具备生成大量烃类的条件.作者将向下断达二叠系或更深、向上断达嘉陵江组的断层称为嘉陵江组气藏的"烃源断层".烃源断层为二叠系或更深层烃源岩中的天然气向嘉陵江组储层中运移提供了通道,是嘉陵江组天然气富集的关键要素之一.

Study on hydrocarbon sources of Lower Triassic Jialingjiang Formation in south of Sichuan Basin, China

There is the difference in the gas composition between the commercial wells and the non-commercial wells in the Jialingjiang Formation, Lower Triassic in the south of Sichuan Basin. Hydrocarbon sources have been proven to be from Permian with the higher maturity by the higher CH_4 composition and the isotopic characteristics of the CH_4 and C_2H_6 of the commercial wells. It is confirmed in the geochemistry that lot of gas can not be generated from the Jialingjiang Formation. The fault breaks downward to Permian and upward to the Jialingjiang Fromation are defined as the fault of hydrocarbon sources of the Jialingjiang Formation gas pool. The fault of hydrocarbon sources provide the pathway of the gas from the Permian or the lower strata to the Jialingjiang Formation. The development of the fault of hydrocarbon sources is the key element of the gas migration and accumulation in the Jialingjiang Formation, Lower Triassic in the south of Sichuan Basin.