Method for improving drilling drainage concentration of gas in broken coal bodies

Abstract

The invention discloses a method for improving a drilling drainage concentration of gas in broken coal bodies. According to the method, firstly, a drill rod with small diameter is used for opening toreduce coal body breaking, then liquid gel is used for making the broken coal bodies around a drill hole condensed into one, then a drill rod with large diameter is used for reaming, in the way, cracks around the drill hole are greatly reduced, and a foundation is laid for subsequent effective hole sealing; after hole sealing is conducted, certain pressure is used for injecting semifluid into a sealed space formed in a sealed hole segment, moreover, injected hole sealing slurry is always in a relatively constant-pressure state, therefore, once newly-developed cracks appear around the drill hole, the semifluid slurry can permeate automatically, the cracks are automatically filled, air leakage channels are isolated, and inlet air is reduced, so that the gas drainage concentration is improved.

Description

technical field [0001] The invention relates to a coal gas drainage method, in particular to a method for increasing the gas drilling concentration in a broken coal body, and belongs to the technical field of underground gas drainage. Background technique [0002] With the increase of coal mining depth, the gas problem in coal mines is becoming more and more serious, especially the problem of gas control in high-gas and low-permeability coal seams, which has been seriously restricting the safe production of coal mines. Therefore, coal seam drilling gas drainage has been widely used as an important measure to prevent and control gas outburst. However, in the process of gas drainage, there have been various problems such as low extraction concentration, poor effect, and short duration. [0003] In order to improve the gas drainage effect of coal seam boreholes, most of the outburst mines in my country adopt high negative pressure and large flow drainage system, but this will i...

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Problems solved by technology

Therefore, coal seam drilling gas drainage has been widely used as an important measure to prevent and control gas outburst. However, in the process of gas drainage, there have been various problems such as low extraction concentration, poor effect, and short duration.

[0003] In order to improve the gas drainage effect of coal seam boreholes, most of the outburst mines in my country adopt high negative pressure and large flow drainage system, but this will inevitably increase the gas leakage and reduce the concentration of gas drainage, which not only does not shorten the effective gas drainage cycle , to alleviate the phenomenon of tension in excavation, but instead make the concentration of the gas drainage pumping station lower than 30%, so that the gas utilization conditions stipulated in the "Coal Mine Safety Regulations" cannot be met, and the gas will be emptied, which will have an impact on the environment

[0004] In addition, during coal seam gas drainage, the coal seam borehole is inevitably affected by various factors of in-situ stress, so that the cracks around the coal seam borehole continue to develop, and the outside air is easy to enter the drainage from these cracks under the action of the negative pressure of the extraction. The concentration of gas drainage in the borehole decreases, which shortens the effective drainage cycle of the drainage borehole and reduces the utilization rate of the drainage borehole

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