Abstract: Well Hashan-5 in the Hala’alate Mountain (Hashan) of Junggar Basin has achieved a major breakthrough in the Permian Fengcheng Formation, marking the discovery of a new oil-bearing stratum and opening a new frontier for petroleum exploration in the Hashan piedmont zone. Based on an integration of drilling, three-dimensional seismic, and geochemical data, this study performs a detailed analysis of geological structures along with the restoration of tectonic deformation. Furthermore, the source-to-sink system, source rock potential, and hydrocarbon accumulation characteristics of the Permian Fengcheng Formation are systematically investigated. The research results show as follows. (1) During the deposition of Fengcheng Formation in the Hashan area, three major depocenters were developed, i.e., the Mahu subsag in the south of Well Hashenxie-1, the Hashan subsag near Well Hashan-5, and the Hongqiba subsag near Well Xin-1. (2) From the basin margin to the lacustrine center, Fengcheng Formation exhibits a progressive fining of sedimentary grain size, where sedimentary lithofacies display concentric zonation transitioning from sandy conglomerate to dolomitic sandstone, limestone/dolomite, and alkali-containing mud shale. (3) The Fengcheng Formation source rocks exhibits the mixed characteristics of broad oil windows and high hydrocarbon-generation intensity, which provides a robust material foundation for large-scale petroleum accumulation. (4) Fengcheng Formation demonstrates accumulation characteristics of the Whole Petroleum System, with the progressive development of conventional oil, tight oil, and shale oil from the provenance to the lacustrine center and the spatially ordered coexistence across the full accumulation continuum. The exploration breakthrough in Fengcheng Formation of the Hashan area not only serves as a guide for oil and gas exploration in the northwestern margin of Junggar Basin, but also provides a significant reference for hydrocarbon exploration under similar geological conditions.

Key words: source rock, mixed hydrocarbon generation, deep layers, Permian Fengcheng Formation, Hashan area, Junggar Basin

摘要： 准噶尔盆地哈拉阿拉特山(哈山)地区哈山5井在二叠系风城组获重大油气勘探突破,标志着准噶尔盆地哈山山前地区发现一套新的含油层系,进一步开创了哈山山前地区油气勘探新局面。基于钻井、三维地震和地球化学测试等资料,进行了地质结构精细解析与构造变形量恢复,开展了二叠系风城组源—汇体系分析、烃源岩潜力评价和成藏特征研究。研究结果表明:①哈山地区风城组沉积期发育3大沉积中心,分别为哈深斜1井南部的玛湖洼陷、哈山5井附近的哈山洼陷和新1井附近的红旗坝洼陷;②风城组从盆缘至湖盆中心依次发育砂砾岩相、白云质砂岩相、灰岩/白云岩相和含碱性矿物泥页岩相,沉积粒度逐渐变细,岩相呈环带状分布;③风城组烃源岩的实际生烃具有"混合"特征,呈现"宽生油窗、强生烃"的特点,具备形成规模油气聚集的物质基础;④风城组展示出全油气系统成藏特征,由物源区到湖盆中心依次发育常规油、致密油、页岩油,全类型油藏有序共生。哈山地区风城组油气突破不仅对准噶尔盆地西北缘油气勘探具有指导意义,也对类似地质条件下的油气勘探提供了重要借鉴。

关键词: 烃源岩, 混合生烃, 深层, 二叠系风城组, 哈山地区, 准噶尔盆地