An Investigation of Fractal Characteristics of Marine Shales in the Southern China from Nitrogen Adsorption Data

We mainly focus on the Permian, Lower Cambrian, Lower Silurian, and Upper Ordovician Formation; the fractal dimensions of marine shales in southern China were calculated using the FHH fractal model based on the low‐pressure nitrogen adsorption analysis. The results show that the marine shales in southern China have the dual fractal characteristics. The fractal dimension D 1 at low relative pressure represents the pore surface fractal characteristics, whereas the fractal dimension D 2 at higher relative pressure describes the pore structure fractal characteristics. The fractal dimensions D 1 range from 2.0918 to 2.718 with a mean value of 2.4762, and the fractal dimensions D 2 range from 2.5842 to 2.9399 with a mean value of 2.8015. There are positive relationships between fractal dimension D 1 and specific surface area and total pore volume, whereas the fractal dimensions D 2 have negative correlation with average pore size. The larger the value of the fractal dimension D 1 is, the rougher the pore surface is, which could provide more adsorption sites, leading to higher adsorption capacity for gas. The larger the value of the fractal dimension D 2 is, the more complicated the pore structure is, resulting in the lower flow capacity for gas.