Clay minerals significantly alter the pore size distribution (PSD) of the gas hydrate-bearing sediments and sandstone reservoir rock by adding an intense amount of micropores to the existing intragranular pore space. Therefore, in the present study, the internal pore space of various clay groups is investigated by manually segmenting Scanning Electron Microscopy (SEM) images. We focused on kaolinite, smectite, chlorite, and dissolution holes and characterized their specific pore space using fractal geometry theory and parameters such as pore count, pore size distribution, area, perimeter, circularity, and density. Herein, the fractal properties of different clay groups and dissolution holes were extracted using the box counting technique and were introduced for each group. It was observed that the presence of clays complicates the original PSD of the reservoir by adding about 1.31-61.30 pores/100 μm² with sizes in the range of 0.003-87.69 μm². Meanwhile, dissolution holes complicate the pore space by adding 4.88-8.17 extra pores/100 μm² with sizes in the range of 0.06-119.75 μm². The fractal dimension () and lacunarity () values of the clays’ internal pore structure fell in the ranges of 1.51-1.85 and 0.18-0.99, respectively. Likewise, and of the dissolution holes were in the ranges of, respectively, 1.63-1.65 and 0.56-0.62. The obtained results of the present study lay the foundation for developing improved fractal models of the reservoir properties which would help to better understand the fluid flow, irreducible fluid saturation, and capillary pressure. These issues are of significant importance for reservoir quality and calculating the accurate amount of producible oil and gas.

中文翻译：

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从 SEM 图像获得的各种粘土矿物的分形特性

粘土矿物通过向现有的粒内孔隙空间添加大量微孔，显着改变了含天然气水合物沉积物和砂岩储层的孔径分布 (PSD)。因此，在本研究中，通过手动分割扫描电子显微镜 (SEM) 图像来研究各种粘土组的内部孔隙空间。我们专注于高岭石、蒙脱石、绿泥石和溶解孔，并使用分形几何理论和参数（如孔数、孔径分布、面积、周长、圆度和密度）表征了它们的特定孔隙空间。在此，使用盒计数技术提取了不同粘土组和溶蚀孔的分形特性，并针对每组进行了介绍。 μ m ²尺寸在0.003-87.69 μ m ²范围内 。同时，溶蚀孔通过增加 4.88-8.17 个额外孔/100 μ m ²使孔隙空间复杂化， 其尺寸范围为 0.06-119.75  μ m ²。粘土内部孔隙结构的分形维数( )和空隙度( )值分别落在1.51-1.85和0.18-0.99的范围内。同样，并且的溶解孔分别在 1.63-1.65 和 0.56-0.62 的范围内。本研究获得的结果为开发改进的储层特性分形模型奠定了基础，这将有助于更好地了解流体流动、束缚流体饱和度和毛细管压力。这些问题对于储层质量和计算可生产石油和天然气的准确数量具有重要意义。