Abstract: The Jurassic reservoir in the eastern slope belt of western Sichuan depression is generally characterized by "dual-source" hydrocarbon supply of the high-quality source rocks from the Member 5 of Upper Triassic Xujiahe Formation and the Lower Jurassic, development of multi-stage, multi-set, superimposed channel sandstones in a large scale, hydrocarbon supply owing to the continuous activity of faults connecting source rock, and favorable conditions for configuration of the ancient and present faults and sand bodies. Thus, it has the geological conditions and temporal-spatial combinations of source and reservoir for forming a tight sandstone gas field. By summarizing and analyzing the geological conditions of the reservoir in Zhongjiang gas field, this paper proposes a new understanding that the reservoir in Middle Jurassic Shaximiao Formation is characterized by development of channel-controlled sand bodies, hydrocarbon transportation through faults and sand bodies, and accumulation under superposition and compound condition, and establishes the enrichment pattern with the characteristics of continuous fault activity, multi-period hydrocarbon charging, lithologic gas reservoir development and hydrocarbon enrichment far from faults. Based on the exploration and development of Zhongjiang gas field, key supporting technologies have been formed, such as the fine characterization technology of "sweet spots" of tight sandstone gas, high-efficient development technology for tight sandstone gas reservoir in complex narrow river channel, and dense cutting and strong-support volume fracturing technology of horizontal well. Through the integrated operation of geology and engineering, Zhongjiang gas field, as a tight sandstone gas field in the narrow river channel of Shaximiao Formation, has provided a cumulative proved reserve of natural gas of more than 100 billion cubic meters, with the gas output of over 20×10⁸m³/a.

Key words: Middle Jurassic Shaximiao Formation, geological conditions for accumulation, supporting technologies for exploration and development, eastern slope belt of western Sichuan depression, Zhongjiang gas field, Sichuan Basin

摘要： 川西坳陷东部斜坡的侏罗系油气藏总体表现出上三叠统须家河组五段和下侏罗统优质烃源岩"双源"供烃、多期多套叠置河道规模砂岩储集体发育、烃源断层持续活动供烃以及古今断裂-砂体配置条件有利的特征，具备形成致密砂岩大气田的成藏地质条件与源-储时空组合。通过总结分析中江气田的成藏地质条件，提出了中江气田中侏罗统沙溪庙组油气藏为"河道控砂、断裂-砂体输导、叠合-复合控藏"的成藏新认识，建立了"断层持续活动、烃类多期充注、岩性气藏发育、油气远离断层富集"的富集模式。基于中江气田的勘探开发实践，形成了致密砂岩气"甜点"精细刻画技术、复杂窄河道致密砂岩气藏高效开发技术以及水平井密切割强支撑体积压裂技术等关键配套技术。通过地质-工程一体化运行，中江气田作为沙溪庙组窄河道致密砂岩气田，累计提交天然气探明储量超过千亿立方米，建成产气量超过20×10⁸m³/a。

关键词: 中侏罗统沙溪庙组, 成藏地质条件, 勘探开发配套技术, 川西坳陷东部斜坡带, 中江气田, 四川盆地