Research On The Technology And Equipment Of Multi-stage Pressure And Permeability Sealing In Gas Drainage Drilling

The mining area is getting wider and wider.The following is the difficult gas control problem,the main problem is the gas extraction efficiency is low and the gas extraction cycle is too long,the current urgent problem is how to improve the quality of gas extraction sealing hole.To solve the problem,we should start with the basic sealing technology and sealing materials.Therefore,in this study,the design and improvement of the multi-stage pressure type hole sealing device is mainly based on the two-block one-injection hole sealing device.At the same time,the possibility of permeability of cement sealing material by adding surfactant is theoretically analyzed.Firstly,this paper summarizes and analyzes several factors of gas leakage in gas extraction borehole.Through analyzing the existence of air leakage channels such as hole sealing materials,hole extraction wall and tunnel wall,it shows that there is still air leakage after the completion of gas extraction and hole sealing,mainly because there are still invisible air leakage channels.The formation and the range of fractures in the wall of the drainage hole are analyzed by rock mechanics and mathematical formula.This further proves the existence of tiny cracks and the importance of permeability of pore sealing materials.Then,by collecting the data,we know that to make the cement sealing material permeable,we need to add surfactant to the cement sealing material.Because of the special molecular structure of the surfactant,the originally incompatible two substances can be made compatible,in the action of the wetting characteristics of the sealing material can have permeability.At the same time,according to the use of surfactant in the construction and road industry,the feasibility of adding surfactant to cement sealing materials to make cement sealing materials permeable is made clear.According to the design concept,the multi-stage pressure sealer is manufactured,and the improvement is made on the basis of two-block one-injection sealer.The hole sealer shortens the distance needed for grouting on the original basis,and adds another bag on the original bag,so that the hole sealer has the function of multi-stage pressure grouting,so as to improve the sealing effect.Finally,the completed multi-stage pressure-type hole sealer is used for field test.First,according to the coal storage conditions at the test site,the influencing factors,coal body strength,borehole diameter,and grouting pressure during the gas drainage operation are simulated.Between 2MPa-15 MPa,the greater the strength of the coal body,the better,the diameter of the experimental borehole is 50 mm,and the larger the grouting pressure is within a certain range(0MPa-2.5MPa),the better.Afterwards,an on-site experiment was carried out.The experiment was carried out on two working surfaces of through-hole drilling,and the inspection results on both working surfaces were good.The proportion of high-concentration extraction holes in the inspection hole is higher than that in the comparison hole,and the extraction concentration is getting higher and higher.