下扬子地区望江坳陷二叠系富有机质页岩孔隙结构特征与影响因素

下扬子地区虽发育有厚层富有机质页岩，但目前尚未取得明显突破。以页岩气地质调查井WWD4井二叠系大隆组与吴家坪组2套富有机质页岩为研究对象，对下扬子地区望江坳陷二叠系富有机质页岩的微观孔隙进行了定性观察与定量化表征，讨论TOC含量与矿物组成对不同尺度孔隙结构的主控因素。结果表明：大隆组和吴家坪组页岩孔隙分布以微孔与中孔为主。下扬子地区望江坳陷上二叠统大隆组与吴家坪组的孔隙发育与有机质关系密切。其中微孔比表面积与孔体积和TOC含量良好的相关关系证明了有机质是微孔发育的主要控制因素。而介孔—大孔的比表面积与孔体积与TOC含量之间相关关系减弱表明除了有机质的贡献外，还有黏土矿物、长石等矿物产生的粒间孔与溶蚀孔的贡献。同时，吴家坪组页岩黏土含量、TOC含量及比表面积（孔体积）存在内在联系。对于脆性矿物而言，大隆组石英与碳酸盐矿物含量和页岩总比表面积（孔体积）之间不存在相关性。而吴家坪组石英含量与页岩总比表面积（孔体积）之间存在一定的负相关性，页岩总比表面积（孔体积）随着石英含量的升高而降低。通过该项研究，为下扬子地区页岩气的勘探与开发提供基础参数与理论依据。

Pore structure characteristics and main controlling factors of Permian organic-rich shale in Lower Yangtze Region

It is well accepted that organic-rich shale has been widely developed and distributed in the Lower Yangtze Region. However, no obvious breakthrough has been made in this area. In this study, two sets of organic-rich shale in the Permian Dalong Formation and Wujiaping Formation in Well WWD4 were collected, and the microscopic pores of the Permian organic-rich shale in the Wangjiang Depression of the Lower Yangtze Region were qualitatively observed and quantitatively studied. Based on this, the main controlling factors of TOC and mineral composition on the specific surface area of ?pores at different scales were discussed. The results show that the distribution of shale pores in the Dalong and Wujiaping shale is dominated by micropores and mesopores. The development of pores in the Upper Permian Dalong shale and Wujiaping shale in the Wangjiang Depression of the Lower Yangtze Region is closely related to organic matters. The positive correlation between micropore specific surface area and pore volume and TOC content proves that organic matter is the main controlling factor for the development of micropores. The weak correlation between the specific surface area and pore volume of meso-macropores and TOC content indicates that clay minerals, feldspar and other mineral could contribute to the intergranular pores and dissolution pores. Meanwhile, clay content, TOC content and specific surface area (pore volume) in Wujiaping Formation shale exist internal relations. However, no correlation between the content of quartz and carbonate minerals and the total specific surface area (pore volume) exist in the Dalong shale. However, a certain negative correlation between the quartz content and the total specific surface area (pore volume) of Dalong shale can be found, and the total specific surface area (pore volume) of shale decreases with the increase of quartz content. Overall, this study provides basic parameters and theoretical basis for the exploration and development of shale gas in the Lower Yangtze Region.