广西富有机质页岩含气潜力研究与勘探对策

    Gas bearing potential and exploration strategy of organic shale in Guangxi

    • 摘要: 为了加深对广西页岩含气潜力方面的认识,通过页岩等温吸附实验方法结合页岩内部总有机碳(total organic carbon, TOC)含量、有机质类型、镜质体反射率(RO)、全岩和黏土X衍射等分析测试,分析了广西地区重点富有机质页岩层位的含气潜力及页岩吸附甲烷气量的控制因素,探讨了含气潜力层的有利分布区及勘探对策。研究认为: 鹿寨组页岩含气潜力最好,饱和吸附量平均为2.87 m3/t,其他依次为罗富组、清溪组、升坪组、石炮组; 罗富组在上林、南丹一带,鹿寨组在南丹—柳州一带、马山周鹿一带,石炮组在上思一带的页岩吸附性能最优; 控制广西页岩吸附甲烷气量的主要因素有TOC含量、有机质类型、RO、介孔和微孔孔容、伊蒙混层含量、盖层条件等,但不同页岩层位的主控因素略有差异。在后期勘探评价中应重点查明沉积微相、页岩的TOC含量、黏土矿物类型与相对含量、构造与盖层保存条件,对构造活动较强、RO较高的地区应遵循“动中找静,高中选低”的勘探原则,以期指导广西页岩气勘探开发取得新突破。

       

      Abstract: In order to deepen the understanding of shale gas-bearing potential in Guangxi, the authors in this research analyzed the gas-bearing potential of key organic-rich shale layers in Guangxi and the controlling factors of shale adsorbed methane gas volume, and discussed the favorable distribution area and exploration countermeasures of gas-bearing potential layers, through shale isothermal adsorption experiment method combined with TOC content, organic matter type, vitrinite reflectance (RO), whole rock and clay X-ray diffraction analysis and testing. The study shows that the shale of Luzhai Formation has the best gas potential, and the average saturated adsorption capacity is 2.87 m3/t, followed by Luofu Formation, Qingxi Formation, Shengping Formation, and Shipao Formation. The areas with the best shale adsorption performance are Shanglin and Nandan in Luofu Formation, Nandan-Liuzhou and Mashan Zhoulu in Luzhai Formation, and Shangsi in Shipao Formation. The main factors controlling the methane gas adsorbed by shale in Guangxi include TOC content, organic matter type, RO, pore volume of mesopore and micropore, content of illite /smectite mixed layers, and caprock conditions, but the main controlling factors of different shale layers are slightly different. In general, the exploration evaluation should focus on finding out the sedimentary microfacies, TOC content of shale, clay mineral types and relative content, structure and caprock preservation conditions. For areas with strong structural activity and high RO, the exploration principle of “looking for static in motion and selecting low from high” should be followed. The study aims to guide the exploration and development of shale gas in Guangxi for a new breakthrough.

       

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