Abstract: Sichuan Basin has abundant oil-gas resources. Several hydrocarbon accumulation systems develop vertically from marine to terrestrial facies. In recent years, significant oil-gas exploration achievements have made in multiple strata of the West Sichuan gas field. To deepen the understanding of hydrocarbon enrichment regularities, guide the exploration and development practice, and further expand achievements in oil-gas production, this paper reviews the exploration and development history of the West Sichuan gas field and systematically analyzes the hydrocarbon accumulation conditions. The results show as follows. There are many sets of high-quality source rocks in western Sichuan depression, which provide sufficient material conditions. The development of tidal flat dolomite pore reservoir in the Member 4 of Middle Triassic Leikoupo Formation in western Sichuan area can expand marine exploration field from high-energy reef-beach and karst to confined platform tidal-flat dolomites, and enrich the types of marine oil-gas exploration. The superposed high-energy sandbodies widely developed at mouth bar and underwater distributary channel in the Member 2 of Upper Triassic Xujiahe Formation form a complete source-reservoir assemblage with inner source rocks or underlying Xiaotangzi Formation source rocks. The high-energy sandbodies widely developed at fan delta and braided river delta underwater distributary channels in Shaximiao Formation form a complete source-reservoir assemblage with source rocks of the Member 5 of Xujiahe Formation.The direct and relay through-source faults developed from Permian to Triassic Leikoupo Formation, the network micro-faults and fractures developed in Leikoupo Formation, the fault-fracture-sandbody transport system developed in Xujiahe Formation, and the fault-sandbody transport system developed in Shaximiao Formation in western Sichuan area are all efficient oil-gas transport systems, which ensure the efficient migration and accumulation of natural gas. The fine techniques of ultra-deep tidal-flat thin interbedded reservoir prediction are established, and the techniques of thin reservoir prediction and middle-small fracture space characterization for the Member 2 of Xujiahe Formation are formed, thus achieving fine reservoir characterization and supporting the implementation of horizontal wells. The development goals of high yield with fewer wells and effective use of reserves have been realized through well-matched development plan and research on drilling and completion technology. In western Sichuan area, the development and production of tidal-flat dolomite gas reservoirs in the ultra-deep complex structural belt, the efficient development of Xujiahe Formation, and the exploration breakthrough of Shaximiao Formation tight sandstone promote the process of exploration and development as well as the innovations of method and technology in relevant fields.

Key words: Leikoupo Formation, Xujiahe Formation, Shaximiao Formation, accumulation condition, West Sichuan gas field

摘要： 四川盆地油气资源丰富,在纵向上从海相到陆相发育多个成藏系统。近年来,川西气田在多个层系均取得了重大油气勘探成果。为了深化油气成藏富集规律认识,指导勘探开发,进一步扩大油气成果,梳理了川西气田的勘探开发历程并系统剖析了油气成藏条件。研究结果表明:川西坳陷发育多套优质烃源岩,物质条件充足;川西地区中三叠统雷口坡组四段发育局限台地潮坪相白云岩孔隙型储层,可实现四川盆地海相勘探领域由高能礁滩、岩溶等气藏向局限台地潮坪相白云岩气藏的拓展,丰富海相油气的勘探类型;上三叠统须家河组二段发育河口坝和水下分流河道高能砂体,呈广覆叠置发育,与下伏小塘子组烃源岩或自身烃源岩构成了完整的源-储组合;中侏罗统沙溪庙组发育近物源扇三角洲和辫状河三角洲水下分流河道高能砂体,与下伏须家河组五段烃源岩构成了完整的源-储组合。川西地区从二叠系到三叠系雷口坡组发育的"直接式"和"接力式"通源断层、雷口坡组网状分布的微断层和裂缝、须家河组断裂-裂缝-砂体复合输导体系、沙溪庙组断层-砂体输导体系,这些均为高效的油气输导体系,确保了天然气能够高效运移成藏。建立了超深层潮坪相薄互层储层精细预测技术序列,形成了须家河组二段的薄储层预测及中-小尺度裂缝空间刻画技术,实现了储层的精细刻画,支撑了水平井的成功实施。通过量身打造开发方案并攻关钻完井工艺,实现了"少井高产"的开发目标和储量的有效动用。川西地区超深层复杂构造带潮坪相白云岩气藏的开发建产、须家河组的高效开发和沙溪庙组致密砂岩的勘探突破推动了相关领域的勘探开发及方法技术创新。

关键词: 雷口坡组, 须家河组, 沙溪庙组, 成藏条件, 川西气田