Method for improving crossing-hole gas extraction concentration

Abstract

The invention discloses a method for improving crossing-hole gas extraction concentration, which is particularly applied to crossing-hole later-stage pre-extraction coal bed gas in a hole cluster mode. When the gas extraction concentration is lower than 30 percent, a plurality of small peripheral holes are formed around the crossing-hole cluster, and at least one inner small hole is formed insidethe hole cluster; powder conveying pipes are arranged inside the small peripheral holes and the inner small hole and hole openings are sealed by a polyurethane sealant; and fine powder is respectively blown into the small peripheral holes and the inner small hole through the powder conveying pipes due to an underground air pressure system, and the fine powder enters fracture air leakage channels around crossing holes and blocks channels through which airflows enters the crossing holes in a tunnel under the coaction of positive pressure of the underground air pressure system and negative pressure of extracting the gas. The method for improving the crossing-hole gas extraction concentration has the advantages of capacity of greatly improving the crossing-hole gas extraction concentration, prolonging the drilling hole effective extraction period, along with simple, convenient and rapid operation.

Description

technical field [0001] The invention relates to a method for increasing the concentration of gas extraction, in particular to a method for increasing the concentration of gas extraction after long-term pre-extraction of coal seam gas through bed-through drilling arranged in the form of hole groups. Background technique [0002] The pre-extraction of coal seam gas by drilling through the bed is one of the main measures taken to prevent and control coal and gas outburst. However, due to the long period of gas extraction, the succession of mine excavation is tense. In order to improve the effect of pre-extraction of coal seam gas, most of the outburst mines in my country adopt high negative pressure and large flow drainage system, which will inevitably increase the amount of gas leakage and reduce the concentration of gas extraction. The tight problem of excavation replacement makes the concentration of the gas drainage pumping station lower than 30%, so that the gas utilization...

AI Technical Summary

Problems solved by technology

[0003] The drainage cycle of the pre-extraction of coal seam gas by drilling through the bed is generally more than one year. During this period, the drilling through the bed is inevitably affected by the ground stress, so that the cracks around the drilling through the bed begin to develop, expand and communicate. Finally, the outside air easily enters the drainage boreholes from these cracks under the negative pressure of drainage, which leads to a decrease in the gas drainage concentration, shortens the effective extraction life of the drainage boreholes, and reduces the drilling efficiency. utilization rate

At present, relevant units at home and abroad have not carried out research on effectively increasing the concentration of gas drainage in the process of drilling gas drainage through interlayer drilling.

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