中文摘要：

川西地区中三叠统雷口坡组顶部在近期钻探中呈现出良好油气显示。为了探究其油气成藏条件,通过岩石薄片观察、有机地化分析、同位素分析等技术手段,在前人研究的基础上对川西地区雷口坡组顶部古风化壳喀斯特气藏的成藏地质条件进行分析并恢复其油气成藏过程。结果表明,该类型气藏具备马鞍塘组与小塘子组2套烃源层系,油气源充足;雷顶古风化壳喀斯特储层次生孔洞发育,储集性能良好;气藏生储盖组合为：马鞍塘组与小塘子组烃源岩＋雷顶古风化壳喀斯特储层＋上三叠统泥质盖层,匹配关系好,保存条件佳;油气在运聚过程中受印支古隆起构造带及雷顶不整合面双重控制,气藏圈闭类型为构造-地层复合型圈闭;气藏在形成演化过程中经历了中三叠世末表生成岩孔隙建造期、晚三叠世中晚期有利于油气聚集的古隆起构造带形成期、燕山期古隆起构造带继承发育-油气大规模聚集期、喜马拉雅期气藏最终定型期4个重要阶段。川西地区雷口坡组古风化壳喀斯特气藏成藏条件较为优越,具有广阔的天然气勘探前景。

英文摘要：

Good evidences of oil and gas appear in the top of Middle Triassic Leikoupo Formation in West Sichuan in recent drillings.In order to look into the accumulation conditions of the oil and gas in West Sichuan,this paper analyzes the accumulation geologic conditions of the weathering crust paleokarst gas reservoir by the methods including the rock thin section observation,organic geochemical analysis,and isotope analysis on the basis of the previous study,and reconstructs the process of hydrocarbon accumulation of the paleokarst reservoir of the top of Leikoupo Formation in West Sichuan.The result shows that the type of gas reservoir has two sets of hydrocarbon source ofMaantang Formation and Xiaotangzi Formation with sufficient oil and gas source.The weathering crust paleokarst reservoirs of Leikoupo Formation have good behaviors and develop secondary pores.The source-reservoir-caprock association of the gas reservoir is as follows.The source rocks of Maantang Formation and Xiaotangzi Formation,the weathering crust paleokarst reservoirs of Leikoupo Formation,and the cap rock of the Upper Triassic muddy rocks match well and have good preservation conditions.In the process of migration and accumulation,the hydrocarbon is affected by the Indosinian paleouplift tectonic belt and the unconformity surface of Leikoupo Formation.The trap type of this gas reservoir is a tectonics-strata combination trap.In the process of formation and evolution,the gas reservoir has experienced four important stages,that is the building stage of epidiagenesis and pores in the end of Middle Triassic,the formation stage of the paleouplift tectonic belt beneficial to hydrocarbon migration and accumulation in the middle and late period of Late Triassic,the stage of the paleouplift tectonic belt inheritance and development and large-scale oil-gas accumulation in Yanshanian,and the final shaping stage of the gas reservoir in Himalayan.The gas reservoir accumulation conditions of the top of Middle Triassic Leikoupo Formation in West Sichuan are fa