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本文通过烃源岩生烃史、油气运移史和成藏史分析 ,对川西白马庙地区上侏罗统蓬莱镇组天然气成藏进行研究。首先 ,采用有机相分析、埋藏史分析、TTI计算和生烃率法 ,建立了烃源岩生烃史 :上三叠统泥质岩和煤为烃源岩 ,侏罗纪末进入生油门限 ,早白垩至晚白垩世进入成熟期 ,晚白垩至今处于高成熟期 ,总生烃量为 115 0 6× 10 8m3 。其次 ,采用平衡浓度法计算天然气运移量为 2 6 46 .6× 10 8m3 ,且散失量小 ,分子扩散相运移对蓬莱镇组天然气成藏起决定性作用。然后 ,结合生排烃史分析 ,采用流体包裹体分析技术确定关键时刻早第三纪。最后 ,通过分析蓬莱镇组天然气成藏的基本要素及其时空配置关系 ,建立了蓬莱镇组天然气的成藏模式 ,动态地再现了天然气成藏的地史过程。

Research on Natural Gas Reservoir Formation in Penglaizhen Formation of Upper Jurassic at Baimamiao Region in West Sichuan Basin

??Through analyzing the history of hydrocarbon generation,oil and gas migration and reservoir formation,the natural gas reservoir formation in Penglaizhen Formation of Upper Jurassic at Baimamiao region in West Sichuan Basin is discussed in the paper.First,in light of organic facies and buried history analyses,TTI calculation and hydrocarbon generation factor method,the hydrocarbon generation history of source rocks is established,i.e.the argillaceous rocks and coal are the source rocks,the oil generation threshold was entered into at the end of Jurassic,the mature stage ranged from Early Cretaceous to Late Cretaceous and the high mature stage began at Late Cretaceous,the hydrocarbon generating quantity being 11 506×10⁹m³ in total;second,the natural gas migration volume estimated with balance density method was 264.66×10⁹m³ with a little loss,in which the molecular diffusion migration volume played a decisive role in the gas reservoir formation in Penglaizhen Formation,and the critical moment of hydrocarbon migration was Paleogene according to the research on generating and expelling hydrocarbon histories and fluid inclusion analysis;and third,through analyzing the basic factors of forming gas reservoirs in Penglaizhen Formation and their space-time matching relations,a pattern of natural gas reservoir formation in Penglaizhen Formation is set up,by which the process of geological history of gas reservoir formation is reproduced dynamically.