Method for increasing extraction borehole gas extraction concentration through auxiliary boreholes

Abstract

The invention discloses a method for increasing extraction borehole gas extraction concentration through auxiliary boreholes, including the steps of (1), drilling a plurality of extraction boreholes side by side by a drilling rig with small-diameter drill pipe on a roadway coal seam, and broaching on the basis of the boreholes by a drilling rig with large-diameter drill pipe; (2), blocking the boreholes effectively, performing primary extraction of gas in the boreholes through gas extraction pipes, further blocking the extraction boreholes and filling the blocking sections with semi-fluid slurry when the extraction concentration of gas is lower than 50%; (3), drilling a plurality of auxiliary boreholes around the side-by-side extraction boreholes by the drilling rig with small-diameter drill pipe when the concentration of gas is lower than 30%, and pouring to block the auxiliary boreholes. The method has the advantages of increasing borehole extraction utilization rate and gas extraction concentration, shortening effective extraction cycle and relieving tension in succession of exploitation, and is easy to operate and low in cost.

Description

technical field [0001] The invention relates to a gas drainage method, in particular to a method for increasing the concentration of gas drainage in drainage boreholes through auxiliary drilling, and belongs to the technical field of underground gas prevention and control. 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 larg...

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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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