Relationship between pore structure and gas permeability of raw coal and briquette coal

Abstract

In order to study the correlation between the gas permeability coefficient and the pores characteristics of coal, the permeability coefficients of raw coal and briquette coal were measured, and the relationship between permeability and the pore structures parameters such as Klinkenberg correction coefficient, mean pore radius, effective surface porosity, average surface number, Knudsen diffusion coefficient, was analyzed. The differences of the pore parameters between briquette coal and the raw coal under the same permeability were also compared. The results show that the surface porosity of raw coal is lower and the number of pores is less, while the pore diameter is larger compared with nearly isotropic briquette coal. The correction coefficient of gas permeability in bedding direction of raw coal is obtained through comparing the pore structure coefficients of raw coal and briquette coal. The empirical relationship between permeability and pore structures of natural raw coal is established. It aims to provide more accurate rules for gas migration in coal seam field.

Keywords

• pore structure
• gas permeability
• gas diffusion
• raw coal and briquette coal
• correction coefficient