Hole sealing device used for deep coal gas extraction and capable of sealing boreholes twice, injecting once and exhausting once and application method

Abstract

The invention relates to a hole sealing device which is used for deep coal gas extraction and capable of sealing boreholes twice, injecting once and exhausting once and an application method thereof.The device comprises an outer sealing pouch, an inner sealing pouch, an extraction pipe and a slurry injecting pipe which are arranged in boreholes as well as a slurry discharging pipe, wherein the slurry discharging pipe passes through the outer sealing pouch, and an internal opening of the slurry discharging pipe is located in a slurry injection section. The application method comprises the following steps: (1) injecting slurry by utilizing the slurry injection pipe; (2) when slurry injecting pressure is higher than opening pressure of an explosion valve, enabling the explosion valve to be opened, injecting the slurry into the slurry injection section, and exhausting gas in the slurry injection section by virtue of the slurry discharging pipe; and (3) when the whole slurry injection section is full of the slurry, discharging excessive slurry by virtue of the slurry discharging pipe, sealing the slurry discharging pipe, continuously injecting the slurry, and enabling the slurry to enter cracks of coal mass at the periphery of the boreholes. The device provided by the invention has the advantages that the slurry discharging pipe can timely exhaust the gas in a sealing section in slurry injecting and sealing processes, so that the hole sealing quality is guaranteed, and the extraction concentration is improved.

Description

technical field [0001] The invention belongs to the technical field of mining, and in particular relates to a deep coal seam gas drainage borehole sealing device with two blocks, one injection and one row of holes and its use method. Background technique [0002] With the rapid development of mine mining technology, the mining intensity continues to increase and the mining level continues to extend. The depth of mining or development extension of many large-scale mining areas in China has exceeded 800m at present, entering the deep mining stage. The mine pressure in deep mines is significantly higher than that in shallow mines, and fractures in extraction boreholes are developed. Deep coal seam drilling applies the existing hole sealing technology. During the extraction process, the hole sealing is not strict and the extraction gas leaks, which will lead to a decrease in the concentration of drilling gas extraction, and the gas extraction rate of the working face is low, whi...

AI Technical Summary

Problems solved by technology

[0004] The traditional "two plugs and one injection" hole sealer uses the grouting pressure to judge the grouting state during use, and cannot intuitively indicate whether the drilled hole is filled with grout; A closed space is formed between the two plugged pockets of the hole. As the pressure of the grouting pump gradually increases, the increase of internal gas pressure hinders the grouting of the grouting pump. When the internal and external pressures reach a balance, the gas in the grouting section cannot be completely discharged , the slurry solidification is not dense, the effective plugging length of the upward drilling and downward drilling is reduced, and air pockets are easy to form in the grouting section of the horizontal drilling; there are problems of lax hole sealing and gas leakage during the gas extraction process This phenomenon will lead to a decrease in the gas extraction concentration in boreholes, and a low gas extraction rate in the working face, which cannot meet the needs of efficient extraction of gas in deep coal seams.

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