Application Of Medium And Low Pressure Water Injection Technology For Enhancing Permeability Of The Difficult Gas Drainage Coal Seam In Shanmushu Coal Mine

The declining coal mine resources and the increase in the depth of coal mining have put forward higher requirements for the safe,efficient and energy-saving production of coal mine enterprises.Coal and gas outbursts have always been major hidden dangers that cannot be ignored in coal mining.For coal and gas bodies with the danger of coal and gas outburst,water injection and permeability enhancement is an effective technique to reduce the risk of coal and gas outburst.It also provides the possibility for efficient use of gas drainage.Based on the background of in-situ stress test,theoretical analysis,numerical simulation and practical engineering application in the South Sichuan Mining Area,this article studied the N30+133m?+167m centralized air intake lane+151m section of the N30 mining area of Shanshushu Coal Mine.The gas drainage effect and permeability range after the medium and low pressure water injection enhances permeability;compares the effect and difference of enhancing permeability in the coal seam and the interface between the coal seam and the roof.The study has obtained: 1)When the medium and low pressure water injection is used to increase the permeability,the range of the permeability enhancement in the coal seam is greater than that in the roof near the bedding,but in the process of antireflection,the antireflection holes located at the junction can affect the layer faster The weakened surface causes a plastic zone along the bedding,where the gas concentration is higher.2)Due to the soft coal body in the mining area,it is difficult to form holes in the coal and rock bodies,and it is easy to collapse.The sealing time of medium and low pressure anti-reflection coating is shorter and it is easier to form holes;it is safer and more reliable to extract gas after anti-reflection.3)After the medium and low pressure water injection is used to increase the permeability,the gas concentration in the single hole in the observation hole and the total gas drainage concentration both increase significantly.The average gas concentration is 3.2 times before water injection and permeation,the maximum single-hole gas concentration and the maximum total gas drainage concentration are 21 times and 7.5 times before water injection and permeation,respectively,indicating that medium and low pressure water injection can achieve coal seam permeability enhancement and improve coal seam.Gas extraction concentration.Combining with the on-site situation of fir tree N30,through the medium and low pressure water injection enhancement of coal seam,the gas extraction effect before and after the coal seam enhancement analysis is analyzed and compared,and the gas extraction concentration is effectively improved.Reduced the coal and gas outburst danger coefficient,and improved the safety production capacity of coal mines.