Research And Application Of Borehole Deflection Control Technology For Gas Drainage In Coal Seam

Coal mine gas is the main factor that causes disasters such as coal and gas outbursts and gas explosions,which seriously affect the safe production of coal mining enterprises.At present,the construction of gas drainage boreholes in coal seams is the most important and most effective technical means to control coal mine gas.However,during the construction of gas drainage boreholes,the drilling trajectory seriously deviates from the design trajectory,forming a blank zone for gas control,which cannot be reached.The purpose of effective gas control is to bury potential safety hazards in the later coal seam mining.Therefore,research on the drilling deflection control technology for gas drainage along the coal seam is of great significance to the safe production of coal mine enterprises.Aiming at the serious deflection problem of coal seam gas drainage boreholes in Ping Coal Mine,this paper uses three methods:theoretical analysis,numerical simulation,and field experiment to analyze and study the deflection control technology of coal seam gas drainage boreholes.Through analysis and research on the deflection factors,deflection conditions,and force of the drill tool for gas drainage along the coal seam,it is found that the shape of the drill bit's working surface,the type of drill rod,the ratio of the drill tool assembly,the drilling pressure,and the drill tool speed Will affect the deflection of the borehole.Aiming at the influence of the shape of the bit working surface and the type of drill pipe on the deflection of the borehole,this paper uses numerical simulation methods to study,using ANSYS numerical simulation software to build the drill bit,drill pipe,isotropic coal,and anisotropic coal models.Simulate the deflection and bending of the drill pipe and the deflection of the drill bit,study the bending deformation of the drill pipe under the deflection force,and analyze the displacement deflection and stress distribution state of the drill bit in anisotropic and isotropic coal.Optimizing drill rods and drill bits.Then formulate a drill bit and drill pipe combination plan to conduct field experiments,and measure the drilling parameters for data processing,draw a drilling track deflection chart based on the processing results,and study and analyze the depth of the drilling interval(0m?40m,40m?70m,70m?100m)the inclination angle change,the azimuth angle change,and the average deviation of the borehole 100m,it is concluded that the borehole deflection in the Y-axis direction is the most serious in the depth of 40m?70m,followed by 70m?100m,and the ?113mm hole diameter is ?75mm-The deflection of the ?94mm-?113mm graded reaming bit is smaller than the ?113mm concave bit.The ?94mm concave bit with a larger diameter ratio and the ?73mm-22 threaded drill rod of the same type of drill has the smallest deflection.In order to further reduce the amount of borehole deflection,the angle compensation method was adopted to correct the deflection and the drilling parameters were optimized within the depth of 40m to 70m to control the borehole deflection,and the field effect was tested,and a good deflection control effect was achieved.Figure[50]table[11]reference[81]...