Fractal characteristics of pore structure of coal with different metamorphic degrees and its effect on gas adsorption characteristics

In order to study the fractal characteristics of coal pore structure with different metamorphic degrees and its effect on gas adsorption characteristics， the pore structure of nine different metamorphic coal samples were tested by mercury injection experiments.The Menger sponge model was used to analyze the fractal characteristics of coal pore structure with different metamorphism.Combined with the adsorption constant of coal samples， the influence of fractal characteristics of pore structure on gas adsorption characteristics was studied.The results show that coal pores have different fractal characteristics in different pore sizes， and the fractal dimensions D1 of seepage pores and the fractal dimension D2 of the adsorption pores increase linearly with the increase of metamorphism.Fractal characteristics of coal pores have certain influence on gas adsorption characteristics.The fractal characteristics of coal pores have a certain influence on the gas adsorption characteristics.The fractal dimension D1 of seepage pores has a good linear relationship with adsorption constant b，and has little correlation with limit adsorption gas quantity a， indicating that fractal dimension D1 of seepage pores has greater influence on gas adsorption rate and less influence on adsorption capacity.The fractal dimension D2 of the adsorption pore is positively correlated with the ultimate adsorption amount a and has no obvious correlation with the adsorption constant b， which indicates that the fractal dimension of the adsorp-tion pore D2 has an effect on the gas adsorption capacity and has no obvious influence on the gas adsorption rate.