Study On Pressure Relief And Reflection Improvement Effect Of Hydraulic Cavitation Technology Along Coal Seam In Baiyangling Coal Mine

Aries ridge coal seam adsorption,the author of this paper,the characteristics of low permeability and high drilling large quantities,extraction rate,low extraction problem of poor effect,using suitable coal seam hydraulic made hole pressure relief anti-reflection technology change around the borehole coal pore and fracture development degree,increase the permeability of coal seam,coal seam extraction to amount to mark as soon as possible and disappear,and the purpose of promoting along coal seam hydraulic hole technology.The theoretical analysis,numerical simulation and field test to verify the method of combining hydraulic made holes on 15108 face gas drilling parameter change law were tested before and after the analysis of research to determine the bedding made hole hydraulic drilling effective radius of influence and the best technology parameters of hydraulic made holes,and measures made hole hydraulic pressure relief anti-reflection effect.The specific research results are as follows:(1)By analyzing and studying the characteristics of water jet structure,the change law of coal permeability around hydraulic cavitation borehole and the mechanical characteristics of pressure relief and anti-reflection of surrounding coal,the mechanism of hydraulic cavitation breaking coal and pressure relief,anti-reflection and outburst elimination is revealed.The permeability of coal around the borehole is studied.The permeability of coal at the wall of the borehole is the largest,and the permeability of coal in the broken zone and plastic zone is obviously higher than that of the original coal seam.In the stress concentration area,the coal is squeezed and the pores are denser,which greatly increases the permeability of coal seam.By analyzing the mechanical properties of coal around hydraulic cavitation drilling,the calculation equation of pressure relief zone radius can be listed,and the radius of pressure relief zone increases gradually with the progress of hydraulic cavitation,indicating that hydraulic cavitation can greatly improve the effect of pressure relief and reflection improvement of coal around drilling.(2)The influence of different cavitation radii on the effect of coal seam cavitation is simulated and analyzed with COMSOL software.The analysis shows that with the increase of the radius of hydraulic cavitation,the migration range of the maximum principal stress of coal body is larger,and the faster the gas pressure of coal body around the cavitation chamber decreases,the larger the corresponding effective influence radius is.The stress distribution of the coal around the hydraulic cavitation chamber shows a good pressure relief state.The closer it is to the borehole wall of cavitation drilling,the smaller the stress of coal body will be realized,and the farther it is from the borehole wall,the stress of coal body will gradually return to the original stress.Moreover,the pressure relief zone of coal around the cavitation hole will gradually increase with the increase of the radius of the hydraulic cavitation chamber.(3)In view of the comprehensive investigation of the pressure relief and reflection improvement effect of the hydraulic cavitation test,the gas flow method was used to investigate the effective impact range of pressure relief of the hydraulic cavitation test in Baiyangling Coal Mine,and the effective radius of pressure relief was finally determined to be 3.0m<R<4.0m.According to the gas flow of the drainage hole,the permeability of coal seam is investigated.The residual gas content and gas pressure are used to verify the effect of hydraulic cavitation on pressure relief and outburst elimination.When the spacing of hydraulic cavitation holes is 4m,the residual gas content in the coal seam between boreholes is all below 6m3/t,and the residual gas force is below 0.6MPa.It can be seen that bedding hydraulic cavitation technology can effectively eliminate the risk of coal seam outburst.It can be found that the enhanced drainage,pressure relief and reflection improvement technology of hydraulic cavitation along the coal seam has higher efficiency and more significant effect than conventional drilling drainage.