Key parameters for gas migration mechanism in coal seam
LIU Yongqian1，2，ZHANG Yugui3，ZHANG Lang1，2
(1. Mine Safety Technology Branch，China Coal Research Institute，Beijing 100013，China；2. National Key Laboratory of Coal High Efficient Mining and Clean Utilization China Coal Research Institute，Beijing 100013，China；3. Institute of Gas-geology，Henan Polytechnics University，Jiaozuo，Henan 454000，China)
Abstract：The coefficients of gas diffusion，concentration flow，initial migration strength and attenuation are the mechanical characterization of the pore structure and quality characteristics in coal matrix. In order to investigate the mechanism and to quantify the ability of gas migration in coal seam，a mathematical model about gas concentration and diffusion rate was established based on the Fick′s law and mass conservation equation. The method of variable separation was employed to solve the equation. The coefficients of gas diffusion and gas concentration flow were proposed with the data iterative method. The gas diffusion experiments were carried out for four kinds of coal samples. The results indicated that the mass increment of gas emission had a negative exponential relationship with the test time. The higher the coal rank is，the greater gas quality growth will be. The gas diffusion velocity and the attenuation coefficient were controlled by the pore structure and micro components of the coal matrix. There were obvious differences between the four coal species. The permeability varies linearly with the diffusion coefficient and parabolic with the flow coefficient. The flow coefficient and diffusion coefficient increase with the increasing of coal rank.
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2017, Vol. 36 
