Research On "Drilling,Hydraulic Punching,Hole Protection Integration" High-efficiency Gas Drainage Technology

Gas drainage is an important measure to reduce the risk of gas outburst,and it is also an effective means to achieve efficient gas drainage and utilization.With the increase of mining depth,most coal seams in my country have the characteristics of high gas pressure,soft coal quality and poor air permeability.The previous gas drainage technology was inefficient and could not meet the needs of production.Hydraulic cavitation is a common measure of pressure relief,permeability enhancement and enhanced drainage,but the borehole after the hole is formed is very easy to collapse and block the hole,resulting in a shallow depth of the hole protection screen,poor drainage effect,and failure to achieve production.The expected effect of acupuncture points.Therefore,based on the method of combining theoretical analysis and field test,based on the mechanism of hydraulic cavitation,pressure relief and permeability enhancement,and the mechanism of drilling hole protection,this paper proposes a"drilling,flushing and protecting integration"hydraulic pressure relief screen pipe protection technology with high efficiency.In addition,it has developed a supporting integrated device for drilling,punching and protection,which realizes the drilling and drilling of bedding gas drainage,hydraulic cavitation and the screen while drilling without drilling.（1）Through the research and analysis on the mechanism of hydraulic cave-making,pressure-relieving and permeability-enhancing and the mechanism of drilling and protecting holes,an effective way to ensure the rapid formation of the drainage channel after hydraulic cave-making and to ensure its smooth flow is determined,which is the"integrated drilling,washing and protection Provide theoretical basis for the research and development of the technology and equipment.（2）The"drilling,punching and protecting integrated"hydraulic pressure relief screen pipe protection hole high-efficiency extraction technology was proposed,the technical principle of"drilling,punching and protecting integrated"was explained,and the technical process and construction process parameters were formulated to provide on-site test construction.Scientific basis.（3）Developed a drilling-punch-protection integrated device that is currently the only hydraulic punch while drilling that can lower the screen through the inner hole.The device is composed of a high-low pressure conversion structure and an open-close core body.The opening and closing of the“water jet”is controlled by the pressure to complete drilling and hydraulic cavitation.After the hole is formed,the screen can be axially pushed out of the device core to realize the protection screen can be placed under the full-hole section without lifting the drilling.（4）Field tests show that the screen installation depth of the"drilling,hydraulic punching and hole protection integration"technology is 98%,which is 2.1 times that of the original hydraulic cavitation technology;The average gas drainage scalar volume of the borehole is 0.262m³/min,which is 1.52 times that of the original hydraulic cavitation technology and 2.26 times that of ordinary boreholes;The gas flow attenuation coefficient of the borehole is 0.0058d^-1,which is 24.5%of the original hydraulic cavitation technology and 14.25%of the ordinary borehole.The"drilling,punching and protecting integration"hydraulic pressure relief screen pipe protection hole high-efficiency drainage technology is superior to the original cave-making technology in terms of screen penetration rate,construction efficiency,and reduction of gas attenuation.It simplifies the construction process and improves the screen.The lowering rate slows down the attenuation of gas and effectively improves the efficiency of gas drainage.35 pictures,10 tables,84 references.