Simulation Of Seepage Laws Of Gas Drainage From Drill Hole Along Coal Seam Based On Adsorption Effect

For deep coal mining to extension with each passing year in china, coal seam is assumed the characteristics of coal quality soft,low-permeability and high-gas,which has led to the increase difficulty of gas management accordingly. In the conditions of current technological level, gas drainage is a fundamental measure for solving the problem of coalmine gas. In order to ensure a reasonable distance of borehole in the pre-drainage coalbed, the low of seepage are analyzed thought under the influence of adsorption by using definite element calculation, field application and theory deduce. The following are the main contents and conclusions:(1) Solid-gas coupling model of coal containing gas was constructed which considers the gas absorption effect. It was based on the equations of seepage, deformation and Langmuir, coupling equation of dynamic equation of permeability in coal rock, which contains gas. This model was imported COMSOL Mutiphysics software.(2) Based on Numeric Simulation Results,changing law of gas pressure,seepage velocity,permeability are comprehensive analyzed, under condition of without adsorption and different of adsorption constant(VL PL), then gas drainage were divided three changing regions and obtained three periods of time under effect of volume adsorption constant and pressure adsorption constant. Coupled the space-time law of gas pressure, effective drainage borehole extraction radius was calculated under the different time and adsorption constant.(3) Based on adsorption effect and simulation results, a reasonable distance of borehole in the pre-drainage coalbed was ensured, and law of gas emission and state of recovery in the work face tested in field engineering,which effective assured safety mining of work face. With comparing of original design, the amount of drilling was decreased by about 25%.Thesis is important for ensuring mine safety,which can be based Predrainaging drilling arrangement that can be improve the coal seam gas pumping rate, reduce the chances of the gas concentration.