Coal seam drilling anti-collapse device and anti-collapse method

Abstract

The invention discloses a coal seam drilling anti-collapse device and method. The method is suitable for drilling hole collapse protection with a certain elevation angle (smaller than 8 degrees) in asoft coal seam. According to the method, porous concrete is injected into an easily-collapsed section of a drilled hole to actively support the drilled hole; and the porous concrete has the characteristics of high strength and large porosity, can effectively support the easily-collapsed section of the drilled hole, has good spatial pore characteristics, and can ensure that gas can freely pass through. In order to prevent porous concrete from flowing back to a hole opening of the drilled hole in the grouting process, the invention provides an umbrella-like device which is used in cooperation with a grouting pipe in a grouting process; the umbrella-like device is tightly arranged outside the grouting pipe in a sleeving mode and stretches into the front end of the easily-collapsed section ofthe drilled hole along with the grouting pipe; a switch sliding pipe on the umbrella-like device is pushed, and the porous concrete is injected into the easily-collapsed section of the drilled hole after an umbrella cover of the umbrella-like device is opened. The method can effectively support the drilled hole to prevent hole collapse, the device can be repeatedly used, and porous concrete can beeffectively prevented from flowing back.

Description

technical field [0001] The invention is a method for preventing coal seam borehole collapse from affecting the coal seam gas extraction, and is especially suitable for the protection of borehole collapse with a certain elevation angle (less than 8 degrees) in soft coal seams. Background technique [0002] Due to the advantages of simple construction and low cost, underground drilling for gas drainage has been widely used in the gas control of coal mines in my country. According to statistics, the amount of boreholes used for underground gas drainage in my country's coal mines has exceeded 150 million m each year. However, due to factors such as in-situ stress and gas pressure, the problem of borehole collapse is serious in the process of gas drainage in soft coal seams. Since the borehole collapse blocks the channel for gas to flow outward, this will significantly affect the efficiency of gas. Drainage and underground gas control affect the safe production of mines. [000...

AI Technical Summary

Problems solved by technology

However, due to factors such as in-situ stress and gas pressure, the problem of borehole collapse is serious in the process of gas drainage in soft coal seams. Since the borehole collapse blocks the channel for the gas to flow outward, this will significantly affect the efficiency of gas. Drainage and underground gas treatment affect the safe production of mines

[0003] Soft coal seams account for a large proportion of mineable coal seams in my country, and the collapse of boreholes in soft coal seams is the main problem restricting the efficient extraction of underground gas. There will be different degrees of residual coal debris after the hole is formed, and the hole in the soft coal seam may collapse partially in a short period of time, resulting in the fact that the screen cannot pass through the collapsed section of the hole in practical applications and affects the drilling Efficient extraction of gas

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