Study On Sealing Technology Of Gas Drainage Borehole Crossing Coal Seam Floor In Shoushan No.1 Coal Mine

The sealing technology of "two plugging and one injection" cement slurry with pressure grouting is used for sealing.Due to the influence of drilling rock deformation,roof lithology,layer spacing,roadway section,support anchor cable drilling and other factors,the through layer drilling is not easy to seal the hole,the sealing section is easy to be damaged and other problems,thus forming a gas leakage channel and reducing the effect of gas drainage.In this paper,through the observation and analysis of the deformation of the surrounding rock of the layer-through drilling and its influence on the sealing effect of the extraction drilling,the causes of the formation of the air leakage channel are expounded,and the dynamic adaptive sealing technology of the gas drainage borehole crossing coal seam floor is put forward.Through the combination of the "three block and two injection" solid-liquid two-phase sealing technology and the retractable extraction pipe,the integrity of the surrounding rock,the extraction pipe and the sealing section in the extraction process is ensured,to enhance the sealing effect,cut off the leakage channel,and improve the efficiency of extraction.The main research results are as follows:(1)Observe the deformation of the surrounding rock and analyze its influence on the sealing effect.By using the horizontal tube roof separation instrument and the developed extraction hole diameter deformation detection device,due to the influence of tunnel excavation,drilling construction,geological conditions and other factors,the surrounding rock of the borehole has tensile deformation,extrusion or dislocation deformation,and then affects the effect of hole sealing.(1)Before and after sealing,the cracks in the surrounding rock of the borehole are developed,which is difficult to be effectively sealed.(2)After sealing,the integrity and sealing of sealing material and extraction pipe will be destroyed.(2)Through the influence of the deformation of the surrounding rock of the layer-through drilling on the sealing effect,the air leakage channel is produced in the drill hole.(3)In view of the influence of the dynamic deformation of the surrounding rock of the borehole on the sealing effect of the through layer borehole,the dynamic adaptive sealing technology of the gas drainage borehole crossing coal seam floor is proposed.Through the combination of "three plugging and two injection" solid-liquid two-phase sealing and expandable extraction pipe,it can adapt to the deformation and damage of drawing,staggering and squeezing of extraction hole caused by the deformation of surrounding rock separation and hole diameter shrinkage.It can timely seal and repair the dynamic cracks formed by surrounding rock of the tunnel around the drilling of solid-phase sealing section,block the air leakage channel of the drilling hole,and ensure the integrity of sealing section and extraction pipe in order to ensure the high efficiency of layer-through drilling.(4)The field industrial comparison test of the dynamic adaptive sealing technology of the gas drainage borehole crossing coal seam floor and "two plugging and one injection" hole sealing technology shows that:(1)With the extension of extraction time,the influence of wall rock separation deformation and pore shrinkage deformation on the development of gas leakage channel is becoming more and more serious.The main gas leakage channel of the contrast drilling is the gas leakage of the extraction pipe and the sealing section.The dynamic adaptive continuous sealing repair of the gas leakage channel of the extraction pipe and the sealing section is carried out by the test drilling,which effectively reduces the gas leakage of the extraction pipe and the sealing section and improves the gas extraction concentration of the drilling hole The effective extraction time is prolonged;(2)The average net flow of gas drainage in the test borehole is about 2 times of that in the contrast borehole.After 200 days of sealing,compared with the comparison borehole,the average gas concentration of the test borehole is increased by 74.28%.