Research on Gas Seepage Characteristics of Coal Seam Drilling
In view of the gas extraction problem in the 72 coal seam of the Ⅱ 7224S working face of Yangquan Xinyu Geotechnical Engineering Co.,Ltd.,a 3D geometric model of gas extraction through layered drilling is established.The gas seepage characteristics around the holes,the distribution characteristics of coal seam stress,permeability changes situation,and the effective extraction radius of the drilling holes in the drilling and extraction scheme are studied and analyzed.Combined with the joint extraction method of the hole group and the impact of the extraction superposition effect,the hole spacing of the extraction drilling is reasonably planned.The width of the gas emission zone near the goaf and coal mine roadway is studied.The simulation results show that the width of the gas emission zone near the goaf and coal mine roadway is 22.3 m and 28.1 m,respectively.The results show that the effective radius for drilling and extraction is 0.87 m for 30 days,and 1.5 m for 90 days;The actual measured width of the gas emission zone around the roadway is 25 m,and the width of the gas emission zone around the goaf is 30 m,which is close to the simulation results.