Method of Measuring Coal Seam Gas Pressure by Drilling in Soft Coal Seam

Abstract

A method for drilling holes on a soft coal seam to measure coal seam gas pressure comprises the steps of drilling a shallow hole on the coal seam, placing an orifice pipe in the hole, utilizing cement slurry to fix the orifice pipe in the coal seam; performing drilling through the orifice pipe to the deep part of the coal seam, quitting a drill rod, injecting mixed slurry A and B to solidify coal around the drilled hole, performing drilling again along the originally drilled hole to exceed grouting depth by 3-5m; quitting the drill rod, inserting a capsule hole sealing device with a gas pipe and a water pipe in the drilled hole, sequentially connecting a push rod to push the capsule hole sealing device to be near the drilled hole grouting depth; on an orifice, respectively connecting the gas pipe and the water pipe with a connector on a flange cover, fixing the flange cover on the orifice pipe, utilizing a manual pump to inject water into the capsule hole sealing device in the drilled hole through a water pipe connector, and expanding the capsule hole sealing device to seal the drilled hole; injecting high-pressure cement slurry through a grouting valve on the flange cover, and connecting a gas pipe connector with a pressure meter, so that the gas pressure of the soft coal seam can be measured. The method is simple and convenient to operate, and a measurement device is simple.

Description

technical field [0001] The invention relates to a method for measuring the gas pressure of a coal seam by drilling a hole in a soft coal seam, and is especially suitable for measuring the gas pressure of a coal seam under the condition that there are no rock roadways around the soft coal seam and only coal seam roadways, and is also suitable for the identification of outburst coal seams and the division of outburst coal seam areas. It belongs to the field of coal mine safety. Background technique [0002] As we all know, coal and gas outburst is a dynamic phenomenon that occurs in soft coal containing high-pressure gas. Once outburst occurs, it often endangers the lives of coal miners. Identify the coal seam within a certain range in advance, or divide the outburst area of ​​the coal seam within a certain range, and give the conclusion whether coal and gas outburst will occur during the mining process of the coal seam within this range. For determining the mine design type, ...

AI Technical Summary

Problems solved by technology

Among these hole sealing methods, the mucus hole sealer method has a better effect. Its principle is to seal the mucus in the middle with two capsules, and then use the mucus to seal the gas in the pressure measuring chamber to ensure that the gas in the pressure measuring chamber does not Leakage, the disadvantage is that the blocking distance is about 10-20 meters

The advantage of cement mortar sealing is that it can seal deeper boreholes. The disadvantage is that the cement mortar solidifies slowly. During the solidification, the gas in the pressure chamber is easily lost, and the pressure stability takes a long time.

However, in some mines where there is no suitable rock roadway, only coal seam roadway and the coal seam is soft, it is difficult to measure the accurate gas pressure value of the coal seam by using the above methods

The reason is that after the soft coal seam is drilled, due to the damage of the ground stress, it is difficult to form a regular circular hole, and the mucus hole sealer cannot be placed in place. In addition, the coal fractures around the drill hole communicate with each other, and the high-pressure gas in the pressure chamber can Bypass the sealing section and leak into the roadway space

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