Method for sealing large-dip-angle downward gas pressure determination drill hole

Abstract

The invention discloses a method for sealing a large-dip-angle downward gas pressure determination drill hole. Through multiple plugging means, the phenomena of gas leakage and liquid leakage caused by that a downward hole is not tightly sealed can be avoided, the hole sealing quality can be improved, and the accuracy of determining gas pressure of a coal seam is guaranteed. The method comprises the following steps that firstly a large-dip-angle drill hole of which the diameter is 75mm is constructed towards a downward target coal seam from a tunnel; two discs are connected to the tail part of an antipriming pipe with bolts, and crude cotton yarns are clamped between the two discs so that a mop shape is formed; a pressure measuring pipe is conveyed into a specified drill hole position, and pebbles and coarse sand, with different particle diameters, are sequentially stuffed in the drill hole; finally the drill hole is filled with hole sealing slurry so that the drill hole is sealed. According to the method disclosed by the invention, the difficult problems that when polyurethane is used for blocking the slurry, the polyurethane is very fast to expand and is not easy to convey to a specified point and the hole sealing length is short are solved, and the difficult problems that the slurry blocking effect is not good, so that the slurry leaks into the hole bottom of the downward hole, and gas pressure measurement or extraction and exploitation of gas are influenced are also solved. The method disclosed by the invention has the advantages that the processes are simple, the reliability is high, the slurry blocking effect is good, the construction efficiency is high, the prices of the hole sealing materials are low, and the method is suitable for being widely used in mines.

Description

technical field [0001] The invention relates to a construction technique for sealing a large-inclination downward pressure-measuring borehole, which is suitable for the hole-sealing work of the borehole for measuring gas pressure in coal mines. Background technique [0002] Mine gas is one of the five major disasters in my country's coal mines. Gas explosions and coal and gas outbursts are fatal accidents that can easily cause mass casualties and pose a great threat to mine safety. The 2014 edition of the national "Coal Mine Safety Regulations" stipulates that the gas pressure of the coal seam must be measured before the coal seam is mined. Generally, upward holes are used for pressure measurement drilling, but in many cases, due to conditions, only downward holes can be used for pressure measurement. After the construction of downhole drilling, there are many difficulties in drilling and sealing the hole. It is easy to cause air leakage and liquid leakage due to the failure...

AI Technical Summary

Problems solved by technology

The 2014 version of the national "Coal Mine Safety Regulations" stipulates that the gas pressure of the coal seam must be measured before mining, and the construction pressure measurement drilling generally uses upward holes, but in many cases, due to conditions, only downward holes can be used for pressure measurement.

However, when polyurethane is used, the sealing length is generally short and the sealing depth is relatively shallow, which cannot seal the cracks well, is prone to air leakage, and requires high sealing operations and high sealing costs.

When using liquid materials such as cement mortar for hole sealing, it is necessary to place fillers such as capsules or kelp in the drilled hole to block the slurry, which is complicated to operate, especially when using dry kelp to fill the hole, water is easy to accumulate at the bottom of the hole, and additional drainage measures are required. The mud retaining effect is unstable, which affects the pressure measurement work

[0004] Therefore, the sealing effect of downholes in mines is generally not ideal

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