Abstract: A major breakthrough has been achieved in the Cambrian subsalt natural gas exploration in Keping uplift of the northwestern Tarim Basin, providing important guidance for oil and gas exploration in multiple Cambrian subsalt strata across the entire basin. Although the Cambrian subsalt strata in Tarim Basin possess favorable source-reservoir-cap configurations, only a limited number of wells had previously achieved production, while most drilling operations had failed to obtain satisfactory results. Recently, Well KT1 and Well BY1 in Keping uplift have successively obtained high-yield gas flows of 104×10⁴m³/d and 42×10⁴m³/d respectively in the Cambrian Wusonggeer Formation, indicating that this formation possesses the conditions for large-scale hydrocarbon accumulation. Nevertheless, the enrichment patterns of natural gas still require further investigation. Drawing on core observations, geochemical analyses of source rocks, well-logging data, and three-dimensional seismic data, the hydrocarbon accumulation conditions in Keping uplift have been systematically analyzed, and an accumulation model has been established. This model confirms that in addition to the high-quality source rocks developed in Cambrian Yuertusi Formation, an additional effective set of source rocks is also developed in the Lower Member of Xiaoerbulake Formation. The average total organic carbon contents of the Yuertusi Formation and the Lower Member of Xiaoerbulake Formation are 6.80 % and 1.52 % respectively, indicating favorable hydrocarbon-generation potential. The Wusonggeer Formation exhibits superior hydrocarbon accumulation conditions. Multiphase tectonic activities from the Late Caledonian to Himalayan periods have played a key role in reservoir reformation and the enrichment and high yield of natural gas. The Keping uplift has undergone multiple stages of tectonic evolution, forming a large basement-involved thrust belt with well-developed fault systems and locally associated faulted anticline structures. Overall, the accumulation model of Keping uplift is characterized by "source rocks in lower strata and reservoirs in upper strata, fracture-controlled accumulation, and near-source charging". The continuous breakthroughs of the Cambrian subsalt exploration in the northwestern Tarim Basin have not only expanded new exploration plays and strata in the basin, but have also deepened the understanding of hydrocarbon accumulation in Keping uplift. These advances are reshaping the exploration landscape in western China and demonstrating broad exploration potential.

Key words: petroleum geology, Well KT1, Well BY1, accumulation condition and model, Cambrian subsalt, northwest Tarim Basin, Keping uplift

摘要： 塔里木盆地西北缘柯坪断隆寒武系盐下天然气勘探取得重大突破,对全盆地寒武系盐下多层系油气勘探具有重要指导意义。塔里木盆地寒武系盐下具备良好的生-储-盖配置,但此前仅部分钻井获产,多数钻井未取得理想效果。近期,柯坪断隆KT1井和BY1井先后在寒武系盐下吾松格尔组分别获得产气量为104×10⁴m³/d和42×10⁴m³/d的高产气流,表明该层系具备规模油气聚集条件,但其天然气的富集规律仍有待深化。基于岩心、烃源岩地球化学特征、测井和三维地震等资料,系统分析了柯坪断隆的油气成藏条件,建立了成藏模式,证实该地区除寒武系玉尔吐斯组发育优质烃源岩外,肖尔布拉克组下段(肖下段)亦发育1套有效烃源岩。玉尔吐斯组与肖下段的总有机碳含量平均分别为6.80 % 和1.52 % ,生烃条件良好;吾松格尔组储集条件优越,加里东晚期—喜马拉雅期的多期构造活动对储层改造及天然气高产富集起关键作用。柯坪断隆经历了多期构造演化,形成了大型基底卷入型冲断带,断裂发育,局部伴生断背斜构造,整体具有"下生上储、断裂主控、近源成藏"的特征。塔里木盆地西北缘寒武系盐下勘探的连续突破,不仅拓展了塔里木盆地油气勘探的新区带与新层系,也深化了柯坪断隆的油气成藏认识,引领塔里木盆地西部勘探的新格局,并展现广阔的勘探前景。

关键词: 油气地质, KT1井, BY1井, 成藏条件及模式, 寒武系盐下, 塔西北地区, 柯坪断隆