Gas-solid Coupling Model With Gas And Its Application In Drilling Gas Drainage In Pansan Coal Mine

The coal seam is formed under special geological conditions,and the gas produced as a by-product during the formation process.There is a complex pore structure in the coal seam,which is not only a place for gas gas storage,but also provides flowing channels for gas.Gas drainage in bedding borehole is one of the important methods for controlling methane gas.In order to explore the characteristics and influencing factors of gas flow during gas drainage in bedding borehole,and to reveal the change law of coal seam gas pressure and coal seam deformation during the drainage process,In this paper,through the experimental study of the coal-rock seepage law under the of gas-solid coupling influence,the gas-solid coupled seepage model of coal containing gas is established,which is used to conduct a numerical study the gas extraction process of 11-2 bedding boreholes in Pansan Coal Mine.Using the laboratory steam to displace gas seepage experiment system,based on the Darcy's law the stable flow calculation method was derived,The permeability of the raw coal with increasing gas pressure at different temperatures are obtained by experiment,the variation between permeability and temperature and gas pressure was analyzed by professional software,The results show that at the same temperature condition,the gas permeability shows a change law that first decreases and then increases;at the same gas pressure,the gas permeability of coal samples shows a gradually changing law that decreases with temperature changes.The relationship betweem permeability and temperature as well as that between permeability and pressure was obtained perspectively.A mathematical model for gas-solid coupling of coal and rock mass is established on the basis of fracture-pore dual media theory.The model includes the coal rock deformation control equation and coal rock gas motion control equation.The one equation contains coal rock elastic modulus,gas pressure,coal Rock density and other parameters and the other contains parameters such like permeability,porosity,and adsorbed quantity of gas.Based on the gas drainage engineering test of the bedding layer 11-2 coal seam in Pansan Mine,a numerical simulation on gas drainage in bedding borehole was performed.The simulation results are in good agreement with the field tests.it shows that the drainage can effectively reduce the gas pressure of the coal seam around the borehole and increase the deformation displacement of the coal seam around the borehole,and the effect becomes more obvious with the increase of the extraction time.The gas pressure around the borehole and the displacement of the coal seam are distributed in the form of "water droplets." With the increase of extraction time,the effective radius of extraction will increase,but the increase will decrease gradually.The research results can provide a theoretical basis for the design and prediction of gas drainage in the bedding of coal mines.The pipe with many small holes to protect the bedding borehole in the drilling of coal seams.When using the perforated pipe protection for gas extraction in the drilling of coal seams,the residual gas pressure and content around the bedding borehole are obviously lowest,indicating that the pumping The use of pipe with many small holes for hole mining has a beneficial effect on gas extraction,and with the increase of the extraction time,the more obvious the effect of pipe with many small holes on gas drainage is,the more beneficial it is to promote gas extraction.Figure[27]table[6]reference[88]...