Micro-pore fractal characteristics of outburst coal in Western Guizhou and its influence on permeability

The migration and occurrence of coalbed methane are closely related to the internal pore structure of coal. In order to study the influence of the microscopic pores of the prominent coal bodies in Guizhou on their adsorption performance and permeability, the structural coal and primary coal samples of Qinglong and Xinglong Coal Mines in Western Guizhou were taken as the research objects and the coal samples were measured by an automatic nitrogen adsorption instrument. The low-temperature liquid nitrogen adsorption curve was calculated based on the fractal theory, capillary mean tortuosity fractal model and permeability model, the pore fractal dimension Df, capillary mean tortuosity fractal dimension DT, and permeability K are calculated according to the fractal theory. The relationship between the microscopic pore fractal characteristics of outburst coal in Western Guizhou and its adsorption performance and permeability was studied. The results show that outburst coal in Western Guizhou has low porosity and large tortuosity（τ）. As the fractal dimension（DT）and tortuosity of capillary mean tortuosity increase, the maximum gas adsorption capacity VL increases, the Langmuir pressure PL decreases, and the gas adsorption speed increases. There is a good negative correlation between permeability K and DT.Low coal permeability and strong gas adsorption capacity are the main reasons for frequent coal and gas outburst in mining areas in Guizhou Province.