Downward gas drainage drill hole and pressure testing drill hole sealing method

Abstract

A downward gas drainage drill hole and pressure testing drill hole sealing method includes the following steps that: a downward hole is constructed in the direction from a roadway downwards to a coal seam, drilling is stopped when the downward hole is drilled to the roof of the coal seam, and a drill pipe is withdrawn; a steel sleeve is arranged in the downward hole, and a distance from the frontend of the steel sleeve to the bottom of the downward hole is about 1m; wedge-shaped wooden plugs are plugged into a gap between the steel sleeve and the downward hole at intervals; grouts are injected into the gap between the steel sleeve and the downward hole and injected into the steel sleeve; an inner bore is constructed in the steel sleeve along the direction of the downward hole, the drill pipe is withdrawn after entering the coal seam or penetrating through the coal seam; grouts are continuously injected into the gap between the steel sleeve and the downward hole, and hole sealing is completed when the gap is fully injected. Through drilling for two time, contraction distortion of drill holes can be effectively resisted, pressure relief and displacement can not occur on coal and rock mass around the drill holes, and the phenomenon of air leakage due to the generation of fractures is avoided; and grout blocking is not needed to be carried out, the drainage concentration of a gasdrainage hole is more than 70 percent, the method provided by the invention is simple and easy to operate, and the sealing effect is good.

Description

technical field [0001] The invention relates to a drilling hole sealing method for downgoing gas drainage and pressure measurement, and is especially suitable for drilling downholes for draining coal seam gas and testing the pressure of coal seam gas. Background technique [0002] Coal seam gas is one of the main factors leading to mine gas explosion and coal and gas outburst. In order to ensure that the gas in the working face exceeds the limit and eliminate the risk of outburst in the working face during the mining process, coal seam gas drainage is one of the main measures. The drainage effect is closely related to the sealing effect of the borehole. When the borehole seal is poor, gas leakage will occur. The negative pressure of the borehole is generally low, and the gas drainage capacity is reduced. For this reason, in order to improve the effect of drilling gas drainage, it is necessary to improve the sealing quality of the drilling. [0003] Draining coal seam gas by...

AI Technical Summary

Problems solved by technology

It is best to use the upward hole to test the coal seam gas pressure. However, under many conditions, the construction conditions for the upward hole are not available, and the downward drilling test must be used. It will also be affected by the drilling hole damaged by mud blocking and ground stress evolution, resulting in the inability to accurately test the coal seam gas pressure.

Therefore, the sealing effect of the downgoing gas drainage holes and pressure measuring holes is generally unsatisfactory

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