Ultra-high pressure hydraulic slotting pressure relief and permeability enhancement technology in high gassy medium-hard coal seam and its application
In order to improve the effect of pressure relief permeability enhancement and gas extraction in high gas medium hard coal seams,the ultra-high pressure hydraulic slotting technology for long boreholes along the seam was studied,its pressure relief and permeability enhancement mechanism and equipment were analyzed,and field tests of ultra-high pressure hydraulic slotting were conducted to determine the equivalent slotting radius and effective gas extraction radius,and the application effect of the technology was investigated.The research results show that:The technology has the characteristics of high cutting speed and large cutting radius,which is equivalent to mining extremely thin protective layers in the coal body around the borehole.The average single cutter slotting time is 9 minutes,the single cutter coal output is 0.32 to 0.42 tons,and the equivalent slotting radius is 1.55 to 1.78 meters;The average single hole extraction concentration of the ultra-high pressure hydraulic slotting group is 76.5%,and the average single hole extraction net amount is 0.089 m3/min,which is 4.58 times and 4.05 times of that of the ordinary drilling hole,1.2 times and 1.43 times of that of the hydraulic punching hole,respectively.Using this technology can greatly improve the pressure relief permeability enhancement and gas extraction effects.
ultra-high pressure hydraulic slottingmedium hard coal seampressure relief and permeability enhancementhydraulic punchinghigh gas content
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