苗凤彬, 张国涛, 张保民, 罗胜元, 岳勇, 田巍, 王强. 0: 湘中涟源凹陷石炭系测水组页岩气富集主控因素与成藏模式. 地质通报. DOI: 10.12097/gbc.2023.06.016
    引用本文: 苗凤彬, 张国涛, 张保民, 罗胜元, 岳勇, 田巍, 王强. 0: 湘中涟源凹陷石炭系测水组页岩气富集主控因素与成藏模式. 地质通报. DOI: 10.12097/gbc.2023.06.016
    fengbin miao, guotao zhang, baomin zhang, shengyuan luo, Yong YUE, wei tian, qiang wang. 0: Main controlling factors of enrichment and accumulation pattern of Carboniferous Ceshui Formation shale gas in Lianyuan sag, Central Hunan. Geological Bulletin of China. DOI: 10.12097/gbc.2023.06.016
    Citation: fengbin miao, guotao zhang, baomin zhang, shengyuan luo, Yong YUE, wei tian, qiang wang. 0: Main controlling factors of enrichment and accumulation pattern of Carboniferous Ceshui Formation shale gas in Lianyuan sag, Central Hunan. Geological Bulletin of China. DOI: 10.12097/gbc.2023.06.016

    湘中涟源凹陷石炭系测水组页岩气富集主控因素与成藏模式

    Main controlling factors of enrichment and accumulation pattern of Carboniferous Ceshui Formation shale gas in Lianyuan sag, Central Hunan

    • 摘要: 湘中坳陷是是四川盆地外围页岩气勘探的重要区域,石炭系测水组是该区重点页岩气层位。以区内次级构造涟源凹陷为对象,基于野外剖面和钻井资料、实验分析测试及现场含气性监测数据,开展测水组页岩气成藏地质条件与差异分布特征研究,并在此基础上探讨了页岩气富集主控因素与成藏模式。结果表明:1)泻湖沉积相区测水组主要发育暗色泥页岩,厚度为30-80m,有机质含量高(TOC>1.5%),以Ⅱ型为主,热演化程度适中(2.0<Ro<3.0%),具备良好的生烃条件;2)测水组属高脆性矿物含量的硅质页岩和混合质页岩类型,储集空间包含有机质孔、无机质孔与裂缝,具有特低孔特低渗的物性特征;3)测水组页岩气藏为残留型常压气藏,主要经历早期原地聚集、中期调整改造和晚期逸散-残留3个成藏演化阶段,中侏罗-早白垩世是最主要的成藏改造期;4)泻湖相还原环境形成的富有机质页岩是测水组页岩气富集成藏的物质基础,适宜热演化程度是富集成藏的重要影响因素,良好的保存条件是富集成藏的关键,层内滑脱控制气体的富集程度。综合分析,建立了测水组“沉积相供烃控区、构造-滑脱双重控保定富”的页岩气成藏模式,泻湖相区宽缓向斜构造为富集有利区,向斜两翼封闭性逆断层下盘为有利富集部位。

       

      Abstract: The central Hunan depression is an important area for shale gas exploration in the periphery of the Sichuan Basin, and the Carboniferous Ceshui Formation is the key shale gas layer in this area.Taking the secondary structure Lianyuan sag in the area as the object, based on the field stratigraphic section and drilling data, experimental analysis and field gas-bearing monitoring data, the geological conditions and differential distribution characteristics of shale gas accumulation of the Ceshui Formation were studied. The main controlling factors of enrichment and accumulation pattern of shale gas were discussed above. And the following research results were obtained. (1) Dark shale are mainly developed in the lagoon sedimentary facies area. The shale with a thickness of 30-80m, high content of organic matter(TOC>1.5%), mainly type II organic matter and moderate thermal evolution degree(2.0o<3.0%)has good hydrocarbon generation conditions. (2) The Ceshui Formation shale is a type of siliceous shale and mixed shale with high content of brittle minerals. The shale reservoir space includes organic pores, inorganic pores and fractures, and has the physical characteristics of ultra-low porosity and ultra-low permeability. (3) The shale gas reservoir of Ceshui Formation is a residual normal pressure gas reservoir. It mainly experienced three stages of forming and evolution: early in-situ accumulation, medium-term adjustment and transformation, and late dissipation-residue. The Middle Jurassic-early Cretaceous is the most important period of accumulation and transformation. (4) Organic-rich shale formed in the reduction environment of the lagoon facies is the material basis for gas enrichment and accumulation in Ceshui Formation. The suitable thermal evolution degree is an important factor affecting the enrichment and accumulation. Good preservation conditions are the key to enrichment and accumulation. The Intraformational detachment structure controls the enrichment degree of gas. Based on the comprehensive analysis, the shale gas accumulation pattern of ' sedimentary facies hydrocarbon supply control area, tectonic-decollement double control Baoding rich ' in Ceshui Formation is established. The wide and gentle syncline structure in the lagoon facies area is a favorable region for gas enrichment, and the footwall of the closed reverse fault on both wings of the syncline is a favorable location for gas enrichment.

       

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