The Numerical Simulation Research Of Hydraulic Cutting Seam In The Tunneling Faces Extraction Of Coalbed Methane

One-time energy consumption in our count`ry, the proportion of coal decreased from 74.6% in 2009 to 63.3% in 2015, decreased to 62% the proportion of around 2020. Over the next several years, the coal is still the main energy consumption. Coal and gas outburst and gas explosion a serious threat to coal mine safety production, accident casualties and direct economic losses caused by the huge, bring negative effects to the country’s image. In order to ensure the safety of coal mine production, minimize casualties, the mine gas extraction and the use are necessary task of our country’s various coal mines.Drilling and hydraulic cutting seam extraction gas is by far the most common way of gas.On mine gas extraction, the gas occurrence and migration laws is necessary, at the same time of coal and rock physical properties and main content of the research. Based on porous medium mechanics of elasticity, the mine rock fluid mechanics and seepage mechanics, the finite element analysis theory, using COMSOL Multiphysics simulation software, solid-liquid couplingmodel is set up, the regulation of gas migration in coal and extraction has carried on the simulation analysis, get some conclusions:(1) describes the physical properties of coal and rock, the gas occurrence and migration laws. Based on porous elastic mechanics, seepage flow mechanics, the mine rock fluid mechanics, the finite element analysis theory, the fluid-structure interaction model is established and the deformation control equation of coal and rock containing gas. Established the permeability,stress and pore pressure mathematical expression of the three influence each other.(2) the 3 holes and 5 holes tunneling faces extraction of coalbed methane, simulations, 5 holes pumping CaiLiang, extraction rate, extraction efficiency is higher than 3 holes. Drilling conditions of extraction ways only on working face of coalbed methane pressure, permeability of coal seam, coalbed gas pressure around working face, coal seam permeability does not change. The flow of extraction of coalbed methane from coal seam edge to the influx of tunneling faces.(3) to 3 seams working face tunneling faces and 5 seams extraction of coalbed methane, simulations, 5 of quantity of drainage, extraction rate,extraction efficiency is significantly higher than 3 seams. Slot extraction way not only to face in the cases of coalbed gas pressure, has remarkable effect on permeability of coal seam around working face of coalbed gas pressure at the same time, great changes have taken place of coal seam permeability.(4) on both sides of tunneling working face to drill the slot,simulations, drilling field and the face of the triangle area, coalbed gas pressure,the largest coal seam permeability change, at the same time, the whole of excavating coal seam permeability change. Drilling and cutting conditions of CBM extraction CaiLiang, extraction rate, extraction efficiency to obtain enhances maximum.(5) simulation, and only make drilling working face increased by 0.7times, the permeability of coal seam permeability around working face didn’t change. Face slot to improve permeability of coal seam by 2 times, high permeability of coal seam around 1 times the left and right sides. Drill a slot to improve permeability in the working face by eight times, increase the permeability of coal seam, surrounding edge the permeability of coal seam was increased by 2 times.Using COMSOL Multiphysics simulation software simulation of coalbed methane extraction, analysis comparison, the current drilling technology of extraction of coalbed methane in tunneling faces the need for change, the hydraulic cutting seam technology of extraction of coalbed methane is worthy of application. In drilling field for hydraulic cutting seam on either side of the working face has yet to practice in the industry, through the theoretical calculation and simulation, slotted drilling field not only make the whole coal unloading, stress of the coal and coalbed methane pressure redistribution, at the same time, make the coal seam permeability changing regional.