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SUMMARYThis paper presents an analytical method to explain the role of gas energy in the occurrence of coal/gas outbursts. The main thrust of the proposed method is to compare the elastic work to be done for outbursts to occur with the released potential energy which includes the strain energy stored in coal seams and the internal gas energy due to desorption and expansion of methane gas in coal seams. It has been found that the release of gas energy due to desorption of methane from the coal matrix to the pores is the major cause for the occurrence of outbursts. Further, the results of the numerical analysis have been presented to illustrate the influence of various parameters on the energy release during outbursts.

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This paper presents the development of a mathematical model for methane gas migration in coal seams. The major focus of this model is the coupling between the gas flow and deformation of solid coal. The effect of diffusion of adsorbed methane gas from the solid matrix to the voids has been taken into account. The adsorption of gas in the coal seam causes a two-phase state of gas flow. The governing equation for the two-phase gas flow is a non-linear partial differential equation with non-linear boundary conditions. A finite element model has been developed for simulation of the distribution of pressure and concentration of methane gas due to gas migration in coal seams.

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