Abstract The pore structure of coal-bearing shale is the space for storage and enrichment of shale gas. As the heterogeneity in characteristics of the pore structures and the controlling factors of shale, we investigated it in the Southern North China. We examined Permian shale in Yuzhou and Hudi coalmines, using low-temperature nitrogen adsorption with the two-dimension non-local density functional theory (2D-NLDFT), field emission scanning electron microscopy combined with argon-ion milling, and high-pressure mercury injection. We found lithofacies have a certain controlling effect on the pore structure characteristics of micropores and mesopores in coal-bearing shale. The organic-lean silicon bearing clay-rich shale lithofacies, and the organic-lean clay/silicon bearing mixed shale lithofacies have similar pore size distribution (PSD) trends and larger pore volume (PV) and specific surface area (SSA) in Yuzhou and Hudi coal mines. The main controlling factors are organic matter maturity, clay mineral and quartz content. The nanopores development in shale of Hudi was promoted by the clay minerals, and organic matter maturity. The PV and SSA in the shale of Yuzhou are smaller than those of other mine wells in the Southern North China, and the analysis shows that quartz inhibited the development of mesopores in the Yuzhou coal mine. The inhibitory effect of quartz on pore development is due to the influence of diagenesis and provenance composition. Due to different stages of organic matter maturation, pore development in shale is positively correlated with organic matter maturity in the Early Permian, and relationship is negatively correlated in the Middle Permian in the Southern North China. The mesopores provide the main PV and SSA in the coal-bearing shale.

中文翻译：

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华北南部晚古生代过渡相含煤页岩孔隙结构非均质性及其主控因素

摘要 含煤页岩孔隙结构是页岩气储集富集的空间。由于页岩孔隙结构特征的非均质性和页岩的控制因素，我们在华南北部进行了调查。我们利用低温氮吸附和二维非局域密度泛函理论 (2D-NLDFT)、场发射扫描电子显微镜结合氩离子研磨和高压汞检测了禹州和胡地煤矿的二叠纪页岩注射。我们发现岩相对含煤页岩微孔和中孔的孔隙结构特征具有一定的控制作用。贫有机硅富粘土页岩岩相，在禹州和胡地煤矿，贫有机质粘土/含硅混合页岩岩相具有相似的孔径分布（PSD）趋势和更大的孔隙体积（PV）和比表面积（SSA）。主要控制因素是有机质成熟度、粘土矿物和石英含量。粘土矿物和有机质成熟促进了胡地页岩纳米孔的发育。禹州页岩的 PV 和 SSA 小于华南南部其他矿井的 PV 和 SSA，分析表明石英抑制了禹州煤矿中孔的发育。石英对孔隙发育的抑制作用是由于成岩作用和物源组成的影响。由于有机质成熟的不同阶段，页岩孔隙发育与早二叠世有机质成熟度呈正相关，在华北南部中二叠世呈负相关。中孔为含煤页岩提供主要的 PV 和 SSA。