Effect Analysis And Evaluation Of Up-hole And Down-hole Butt Joint Gas Pre-drainage Technology In Shaqu Coal Mine

Gas drainage is one of the most fundamental way to prevention gas outburst andsolve the gas disasters of coal，but traditional gas drainage technology has manydisadvantages when in the drainage of low permeability and high gas of coal seams.This thesis take the new technology of effective pre-drainage gas which butt joint theup-hole and down-hole in Shaqu coal as the research object，it study the relationshipbetween microstructure of coal and gas migration from the micro basic experiment，and it analyze the drainage effect of the new technology for the24307working faceand research of the numerical simulation using Comsol software from macroscopic，main work includes:1.According to measure and calculation the basic gas parameters of Shaqu coal，it make sure that the no.4is outburst coal seam，which it can be and must beextracted，the effect of govern gas is not obvious by using the traditional gas drainagemethod;2.This thesis experiment with the coal industrial analysis，scanning electronmicroscope and mercury injection experiment and adsorption desorption experimentsfor no.4coal sample from the microcosmic view.It development a large number ofmicropores of the coal sample，the pore volume and pore size is mainly controlled bypore and micropore，the gas adsorption ability is determined by micropore below50nm，the coal pore channel is complex and bend， the resistance of gas flow is biggerand the fissure of big hole is less.The desorption gas quantity gradually increase whenthe pressure of adsorption equilibrium crease each time，but the proportion ofcumulative total desorption percentage of total gas content are less，it make theadsorption state gas desorption out difficult by improving the pressure of adsorptionequilibrium，which restricts the gas drainage effect;3.On the basis of research the production of multi-branch horizontal well，itanalyze the production principle and advantages of drainage new technology，and thetechnology is divided into three steps，construct the the multi-branch horizontal welldrilling on surface，docking the multi-branch horizontal well drilling and undergroundgas drainage borehole，drainage using coal mine gas drainage system，and analyze theconstruction parameters and technology;4.Establish the solid-gas coupling model of gas drainage of drilling through jointcontrol equations of stress field，the equation of permeability and porosity，controlequation of seepage field，and gives the definite condition of stress field and seepage field;5.Analyze the drainage effect of the24307working face from the macroscopic，verify the validity of the established model through compared the simulation drainagedata by numerical simulation and actual drainage data，it get effective influence radiusof the gas drainage by simulation on this basis，and forecaste the capacity of gasdrainage，and verify the high efficiency of the drainage new technology.