Experimental Research on Influence of Porosity on Tectonic Coal Gas Permeability

Taking raw coal samples of tectonic coal that porosity is different as the research objects, using three axis stress seepage device to carry out the gas permeability experiments, the results show that the gas permeability of tectonic coal increases with the porosity of coal under the condition of constant temperature, and presents the quadratic function relationship between the permeability K₀ and the porosity σ, which is K₀=ασ²+βσ+δ. When the temperature is constant, the gas permeability of tectonic coal decreases gradually with the increase of mean effective stress, and the permeability of large-porosity tectonic coal has large amplitude of change. Under the condition of the constant mean effective stress, the permeability of tectonic coal with the same porosity decreases with temperature increasing, and the effect of porosity on the gas permeability of tectonic coal is more obvious than temperature.