Photo from wikipedia
Abstract: The mechanism and mathematical characterisation of a gas flow in a coal seam are used to prevent methane disasters, guide gas drainage problems and promote the development of coalbed… Click to show full abstract
Abstract: The mechanism and mathematical characterisation of a gas flow in a coal seam are used to prevent methane disasters, guide gas drainage problems and promote the development of coalbed methane. A borehole gas flow model applying a new dual-porosity model that integrates a free gas density gradient diffusion flow in a matrix, the gas source item, and a Darcy flow in a fracture is proposed. The finite difference method is used to generate a simulator, that can obtain a numerical solution and allow verification through onsite measurement data gathered from a coal mine. A range of simulations were carried out to describe the unsteady process of a gas flow around a borehole in a coal seam and quantify the influences of different parameters on the gas migration. A sensitivity analysis of the matrix microchannel diffusion coefficient, fracture permeability coefficient, matrix radius, original gas pressure of the coal seam, and gas pressure of the borehole were found to be helpful in optimising the gas drainage in a coal seam.