Study On The Gradual Change Rule Of The Influence Range Of Hydraulic Flushing In Layer Drilling Of Changping Coal Mine

This thesis aims at the technical difficulty of optimizing and rationalizing the design parameters of borehole layout in the main coal seam No.3 of Changping Coal Mine of Jinmei Group when hydraulic measures are adopted to strengthen the extraction,leading to the lack of optimization and reasonable design parameters of drilling layout.Study on the gradual change law of the influence range of hydraulic punching along coalmines.This article mainly studies the following aspects:First,with the help of COMSOL Multiphysics simulation software,the mathematical model of fluid-solid coupling of coal bed gas transport is established.It is simulated that under different coal flushing conditions,hydraulic punching effectively affects the law of radius change,and based on this,a reasonable coal flushing amount is obtained.In addition,on the premise of determining the amount of coal to be flushed out,the gradual change rule of the influence range of hydraulic punching is obtained through simulation analysis.Secondly,the gas concentration and flow rate of the borehole and the borehole around the borehole after the implementation of the hydraulic punching measures were measured on the spot,and the fitting analysis obtained the gradual change rule of the hydraulic flushing impact range that changes with the change of gas drainage time,combined with the simulation analysis to determine a reasonable radius of influence,and accordingly the optimal design of hydraulic punching measures the distance between holes drilled layout design and other technical parameters.Thirdly,the theoretical values of coal breaking pressure,punching water pressure and other parameters are obtained through mathematical calculations,and the hydraulic punching field test is carried out,and the reasonable technical parameters of punching are finally determined through field test and numerical simulation.Finally,based on the flow method,a field test of the influence radius of the hydraulic punching hole is carried out.It is concluded that the effective influence radius of the drainage after the implementation of the hydraulic punching measures for 3months is 7m.It provides technical support for achieving efficient drainage in the punching area,and the effect of punching is investigated.The results show that before and after the hydraulic punching measures are implemented,the coal permeability coefficient is increased by 51.6 times,and the single-hole gas drainage concentration is increased by an average of 3.8 Times;the average daily extraction volume of a single hole has increased by about 8 times;the initial gas concentration,flow rate and maximum gas concentration and flow rate of the punching borehole are far better than the ordinary extraction borehole and the time of high concentration gas extraction is maintained longer;the concentration and flow of ordinary extraction boreholes within the effective radius of hydraulic punching have been significantly improved.Practice has proved that the optimized layered hydraulic drilling technology of Changping Coal Mine has a good pressure relief and permeability enhancement effect,which is beneficial to the extraction of gas for a long period of time.It also has certain reference.