Numerical simulation research on coal gas drainage by nitrogen injection

doi:10.16265/j.cnki.issn 1003-3033.2021.11.018

Abstract

Abstract: In order to study influence of binary gas pressure and adsorption-desorption effect on practices of nitrogen injection to promote gas drainage, a multi-field coupling model of such practice was established, which included coal deformation equation, dynamic coupling equation of porosity/permeability and binary gas migration control equation. Then, Comsol software was used to simulate coal deformation, permeability and gas drainage effect with or without consideration to binary gas pressure and adsorption-desorption effect. The results show that when these two factors are not considered, axial deformation of coal will be the largest while permeability is the lowest. When one of the factors is taken into account, axial deformation decreases, permeability increases, and ability of binary gas pressure to restrain coal deformation is stronger than that of adsorption-desorption effect. For the case where two factors are both considered, deformation inhibition capacity and permeability are both further improved. For the same nitrogen injection time, gas pressure drop amplitude at the injection port is significantly greater than that at exhaust port, and effect of gas drainage gradually weakens along with increase of distance to injection port.

Key words: nitrogen injection to promote gas drainage, coal deformation capacity, permeability, binary gas pressure, adsorption-desorption effect

CLC Number:

X936

JI Pengfei, LIN Haifei, KONG Xiangguo, LONG Hang, LI Botao. Numerical simulation research on coal gas drainage by nitrogen injection[J]. China Safety Science Journal, 2021, 31(11): 127-134.

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