柴达木盆地马北地区氦气运移富集主控因素研究

    Controlling factors of helium migration and enrichment in the Mabei Area, Qaidam Basin

    • 摘要: 氦气属于战略稀缺资源,柴达木盆地马北地区氦气含量远超工业标准,展现出巨大的氦气资源潜力,但其差异富集规律与主控因素尚不明确,制约了资源开发利用。本研究在综合前人研究成果的基础上,开展了天然气组分测定和基底岩石地球化学分析,探究马北地区差异富氦的主控因素和氦气富集模式。研究结果表明:9个天然气样品的氦气含量(0.070~0.290%)均超工业标准,且不同构造间差异显著(马北八号>马西一号>马北一号);不同类型基底岩石中U、Th含量分别介于1.92~3.50 μg/g和14.90~18.80 μg/g之间,其中,元古宇花岗片麻岩基底形成时代老、体积大、生氦时间长、强度大,是主力氦源岩;区内断裂和构造活动主要受燕山期和喜山期构造运动影响,马仙断裂及其派生断裂与基岩顶不整合面共同构成富氦流体运移通道。其中,喜山晚期差异构造抬升为富氦流体运移提供动力,是富氦气藏形成的主控因素;马北不同构造氦气含量受差异抬升幅度及天然气充注强度控制,其中,马北八号构造喜山晚期抬升幅度最大,是其富氦的主因,而马西一号构造则因经历高强度的烃类气体充注,对氦气产生稀释效应,导致其相对贫氦;研究区氦气富集模式可概括为“基底生氦-水体暂存-晚期构造驱动运移-气相携氦-高点成藏”。本研究明确了马北地区差异富氦的主控因素,建立了马北地区氦气富集模式,可为马北地区氦气富集有利区和钻探目标优选提供指导。

       

      Abstract: Helium is recognized as a strategic scarce resource. The Mabei Area in the Qaidam Basin exhibits helium contents significantly exceeding industrial standards, indicating substantial resource potential. However, the mechanisms controlling its differential enrichment remain poorly understood, hindering resource exploration and development. This study investigates the primary controlling factors and enrichment patterns of helium in the Mabei Area by integrating previous research findings with gas composition measurements and geochemical analyses of basement rocks. The results indicate that helium concentrations in nine natural gas samples range from 0.07% to 0.29%, all surpassing industrial grades, with notable variation among blocks (Mabei-8 > Maxi-1 > Mabei-1). Uranium and thorium contents in different basement rock types are 1.92-3.50 μg/g and 14.90-18.80 μg/g, respectively. Among these, the Paleoproterozoic granitic gneiss basement is identified as the primary helium source rock, characterized by its old formation age, large volume, and prolonged helium generation history. Faults and tectonic activities in the study area form a migration pathway for helium-rich fluids through the Maxian fault system and its derived faults, combined with the bedrock unconformity surface. Differential tectonic uplift during the late Himalayan period provides the driving force for helium-rich fluid migration and serves as a key controlling factor for helium accumulation. Helium content in different blocks is governed by varying uplift intensities and natural gas charging strengths. The Mabei-8 block experiences the most significant late Himalayan uplift, representing the primary reason for its helium enrichment, while the Maxi-1 block undergoes intense hydrocarbon charging that dilutes helium concentration. The enrichment pattern is summarized as “basement generation-aqueous phase storage-late tectonic-driven migration-gas phase transport-accumulation in structural highs”. This study systematically identifies the main controlling factors of differential helium enrichment in the Mabei Area and establishes a comprehensive enrichment model, providing guidance for identifying favorable exploration targets and optimizing drilling locations.

       

    /

    返回文章
    返回