Abstract: Mahu sag in Junggar Basin develops a typical Whole Petroleum System (WPS), which exhibits the ordered distribution of conventional and unconventional hydrocarbon reservoirs. This has important implications for advancing the development of petroleum geology theories. Through systematic analysis of the petroleum accumulation elements in WPS, the paper summarizes the hydrocarbon enrichment patterns in the study area. Specifically, the WPS of Mahu sag is characterized by distinctive alkaline lacustrine source rocks with sustained hydrocarbon generation throughout the thermal evolution, diverse reservoir types developed across all grain-size sequence (from sandy conglomerates to dolomitic siltstones and argillaceous mudstones), three-dimensional distribution of hydrocarbon transport system enabling efficient oil and gas migration, and a diverse range of orderly accumulated hydrocarbon reservoirs. The source-reservoir configuration, along with their spatiotemporal coupling with hydrocarbon accumulation, forms the core of WPS. Since the end of the Permian period, the Fengcheng Formation source rocks have undergone continuous burial and multi-phase hydrocarbon generation and expulsion, thereby providing a sustained resource basis for hydrocarbon accumulation; the development of sandy conglomerate, dolomitic siltstone and argillaceous shale reservoirs across all grain-size sequence controls the ordered distribution of both conventional and unconventional hydrocarbon reservoirs. The WPS of Mahu sag undergoes sustained and temporally sequenced hydrocarbon charging, demonstrated by early-stage accumulation in conventional far-source reservoirs while later-stage accumulation in unconventional intra-source shale oil and gas reservoirs. The study reveals the whole-process accumulation mechanism of WPS and highlights unconventional intra-source resources as a key frontier for deep exploration. These findings are valuable for refining WPS theory and guiding future exploration practice.

Key words: Whole Petroleum System, source-reservoir coupling, Fengcheng Formation, Mahu sag, Junggar Basin

摘要： 准噶尔盆地玛湖凹陷发育典型全油气系统,常规与非常规油气藏有序分布,对石油地质学理论发展具有重要研究意义。基于玛湖凹陷全油气系统成藏要素系统分析,总结了油气富集规律:碱湖烃源岩类型特殊全过程持续生烃、储层类型丰富全粒序发育、输导体系立体分布高效输导、油气藏类型丰富多样有序聚集等。源-储配置与时空耦合是形成全油气系统的核心要素。二叠纪末期以来,风城组烃源岩持续深埋并多期生/排烃,为油气成藏提供了充足的资源基础;砂砾岩至白云质粉砂岩、泥页岩的全粒序储层发育控制了常规—非常规油气藏的规律分布。玛湖凹陷全油气系统具有连续-有序充注特征,表现为远源常规油气藏早期成藏、源内非常规页岩油气藏晚期成藏的时序特征。研究揭示了全油气系统全过程成藏机制,明确了源内非常规油气是深层勘探的重要领域,对完善全油气系统理论及指导勘探实践具有重要价值。

关键词: 全油气系统, 源-储耦合, 风城组, 玛湖凹陷, 准噶尔盆地