Analysis And Research On Dual-Power-slag-discharge Drill Pipe For Outburst Coal Seam

Gas coal mine production safety hazard is a threat of natural disasters, the use of drilling for gas extraction is one of the main gas control,Is also the basis for comprehensive utilization of gas.Drilling depth of the gas treatment efficiency and effectiveness, the efficiency of the drilling and drilling outburst hole depth limited by existing technology, making difficult to implement large-scale outburst, high-efficiency gas extraction.This paper aimed to parameter optimization,intensity matching and slagging effect of high-strength groove drill pipe,which was designed for improving the drilling efficiency and drilling depth of outburst coal seam. First, the influential factors of difficult to achieve deep hole drilling for outburst coal seam were analyzed, Working principle of dual power slagging was explaned combining the concept of "drill hole", and lists the types of the dual-power-slag-discharge drill pipe.And then, as the representative of groove drill pipe(Ф50), optimization design for its groove parameters and strength analysis and materials selection for rod body and drill pipe sub were done, groove parameters were determined as follows: pitch S = 76mm,depth H=1.1mm, width L=12mm ,helix angleα=25.8o,the materials of rod body and drill pipe sub were STM-R780-2steeland 40CrMo.Optimization design and strength analysis for groove drill pipe(Ф63) and low spiral drill pipe(Ф50和Ф63) were done by the same method.After that the groove drill pipes were processed,and the experiments of simulation slag discharge for various drill pipes were done.Finally, industrial experiments were done in the Sijiazhuang coal mine , the drilling efficiencyof the seam layer holes improved 41.5%,drilling depth improved 36.2%,drilling efficiency of pre-drainage holes which were drilled from stone drift to coal drift was also greatly improved,The strength and wear resistance of drill pipes were also been tested.