【摘要】 塔里木盆地中—下寒武统膏盐岩是制约盐下深层—超深层油气勘探成败的关键封盖层，但其成岩演化过程及对储层孔隙发育的影响机制尚不明确，制约了勘探部署。基于岩心薄片观察、钻测井资料，结合前人研究成果综合分析，系统研究并厘定了膏盐岩岩石类型、空间展布规律及成岩演化特征，进而探讨了其与盐下储层孔隙保存的耦合关系。结果表明：(1)膏盐岩岩性以膏岩、盐岩及含膏/膏质云岩为主，膏岩呈纹层状、块状，盐岩呈块状，含膏/膏质云岩呈条带状、透镜状，平面上以巴楚—塔中地区为聚盐中心，厚度向外逐渐减小，纵向分布上表现出下寒武统厚度小、中寒武统厚度大的演变特征。(2)膏盐岩具有复杂的成岩历史，可划分为三个阶段：同生期萨布哈环境的石膏结核与白云石化；埋藏期的石膏—硬石膏转变，该过程极大提升了岩石致密性；晚期构造作用下发生塑性流动形成致密封盖体。(3)机制分析表明，中寒武统巨厚膏盐岩形成的封闭体系，能有效阻隔中—深埋藏阶段外部成岩流体活动，显著抑制储层的压溶—胶结作用，是盐下早期原生和次生孔隙得以保存的主控因素。研究结果深化了对蒸发岩盖层控储机制的认识，为深层—超深层油气勘探提供了地质指导。更多还原

【Abstract】 The gypsum-salt rocks of the Lower and Middle Cambrian in the Tarim Basin are the critical cap rocks controlling the success of deep to ultra-deep subsalt hydrocarbon exploration. However, their diagenetic evolution and the influencing mechanisms on reservoir pore development remain unclear, thereby constraining exploration deployment. Based on core thin-section observations, drilling and logging data, and integration of previous research findings, the lithological types, spatial distribution patterns, and diagenetic evolution characteristics of the gypsum-salt rocks were systematically identified. The coupling relationship between these characteristics and reservoir pore preservation in subsalt reservoirs was further investigated. The results showed that:(1) The lithology of the gypsum-salt rocks was predominantly composed of gypsum rock, salt rock, and gypsum-bearing/gypsiferous dolostone. The gypsum rock exhibited laminated and massive structures, the salt rock was massive, and the gypsum-bearing/gypsiferous dolostone formed banded and lenticular structures. In planar view, the Bachu-Tazhong area served as the salt accumulation center, with thickness gradually decreasing outwards. The vertically distribu-tion exhibited evolutionary characteristics of thinner strata in the Lower Cambrian and thicker strata in the MiddleCambrian.(2) The gypsum-salt rocks experienced a complex diagenetic history, which could be divided intothree stages: syngenetic gypsum nodule growth and dolomitization in a sabkha environment; gypsum-to-anhydritetransformation during burial, which significantly enhanced rock densification; and plastic flow under late-stagetectonic stress, forming a dense sealing caprock.(3) Analysis of mechanisms revealed that the closed systemformed by the thick gypsum-salt rocks of the Middle Cambrian could effectively block external diagenetic fluidactivity during the mid-to-deep burial stages, significantly suppressing pressure dissolution and cementation inthe reservoirs. This was the primary controlling factor for the preservation of early primary and secondary pores inthe subsalt reservoirs. The research findings deepen the understanding of the reservoir-controlling mechanisms ofevaporite cap rocks and provide geological guidance for deep to ultra-deep hydrocarbon exploration.更多还原