黔南坳陷下寒武统牛蹄塘组沉积环境与有机质富集机制——以贵都地1井为例【深层页岩沉积储层与有机质差异富集机制】
- 收稿日期:
2026-05-12
- 网络出版日期:
2026-09-01
摘要: 【目的】研究黔南坳陷下寒武统牛蹄塘组沉积古环境特征，分析有机质富集机制，支撑该区页岩气勘探开发。【方法】以贵都地1井岩心和测试分析资料为基础，开展牛蹄塘组矿物组成、岩相特征和地球化学特征分析，研究沉积作用方式和氧化还原条件、古生产力、陆源碎屑输入、水体滞留程度等古海洋环境特征，探讨牛蹄塘组沉积演化过程与有机质富集机制。【结果】结果表明，牛一段发育富有机质硅质页岩、富有机质含粉砂硅质页岩、含有机质混合质页岩，以泥质悬浮沉积、硅质生物沉积为主；牛二段发育贫有机质黏土质页岩，以泥质絮凝沉积为主；牛三段发育含有机质钙质混合质页岩，以钙质化学沉积和泥质絮凝沉积为主。【结论】研究区牛蹄塘组沉积时期古海洋环境和有机质富集呈现出明显的阶段性。牛一段沉积时期，受控于快速海侵作用形成的高生产力水平、强还原条件的古海洋环境，有机质大量富集；牛二段沉积时期，受氧化环境和高陆源碎屑供给的稀释作用共同影响，有机碳含量低；牛三段沉积时期，推测受水下古隆起的影响，强滞留环境促进碳酸盐矿物沉积和有机质较富集。研究成果可为黔南坳陷牛蹄塘组页岩气资源潜力评价提供参考。
- Received Date:
2026-05-12
- Available Online:
2026-09-01
Abstract: [Objective] The sedimentary paleoenvironmental characteristics of the Lower Cambrian Niutitang Formation in the Southern Guizhou Depression were studied, and the mechanism of organic matter enrichment was analyzed to support shale gas exploration and development in the area. [Methods] Based on the core and testing analysis data of Well Guidudi 1, the mineral composition, lithofacies characteristics, and geochemical characteristics of the Niutitang Formation were analyzed to study the sedimentary processes and characteristics of ancient marine environments, such as redox conditions, paleoproductivity, input of terrestrial debris, and degree of water retention. The sedimentary evolution process and organic matter enrichment mechanism of the Niutitang Formation were explored. [Results] The results indicate that the first section of the Niutitang Formation developed organic rich siliceous shale, organic rich silty siliceous shale, and organic mixed shale, mainly involves suspended sedimentation of mud and biological sedimentation of siliceous matter. The second section of the Niutitang Formation was mainly composed of poor organic clayey shale, with the main sedimentary model being mud coagulation and sedimentation. The third section of the Niutitang Formation developed organic and calcareous mixed shale, with the main sedimentary model being calcium chemical deposition and mud flocculation deposition. [Conclusions] The ancient marine environment and organic matter enrichment during the sedimentation period of the Niutitang Formation in the study area showed obvious stages. During the first sedimentary period of the Niutitang Formation, the ancient marine environment was controlled by the high productivity level and strong reducing conditions formed by rapid marine invasion, resulting in a significant enrichment of organic matter. During the second sedimentary period of the Niutitang Formation, the organic carbon content was low due to the combined effects of oxidative environment and dilution from high terrestrial debris supply. During the third sedimentary period of the Niutitang Formation, it is speculated that the strong retention environment promoted the deposition of carbonate minerals and the enrichment of organic matter due to the influence of underwater ancient uplift. The research results can provide a reference for the evaluation of shale gas resource potential in the Niutitang Formation of Southern Guizhou Depression.
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