Low permeability coal seam gas pre-drainage method though intensive drilling holes and pipe pressure-up

Abstract

The invention discloses a low permeability coal seam gas pre-drainage method though intensive drilling holes and pipe pressure-up. The method includes the following steps: a plurality of through drilling holes are arranged on a pre-drainage coal seam; a first drainage pipe is laid on one side of an air inlet roadway close to the pre-drainage coal seam, and one ends of the plurality of through drilling holes are connected with the first drainage pipe; a second drainage pipe is laid on one side of an air return roadway close to the pre-drainage coal seam, the other ends of the plurality of through drilling holes are connected with the second drainage pipe so as to enable the plurality of through drilling holes to be communicated with the first drainage pipe and the second drainage pipe respectively to form a gas pre-drainage system, and a first negative pressure boosting pipe system is laid in the air inlet roadway and communicated with the first drainage pipe so as to boost negative pressure of the first drainage pipe; and a second negative pressure boosting pipe system is laid in the air return roadway and communicated with the second drainage pipe so as to boot negative pressure of the second drainage pipe.

Description

technical field [0001] The invention relates to a method for extracting coal mine gas, in particular to a method for pre-extracting low-permeability coal seam gas. Background technique [0002] For a long time, the pre-pumping of this coal seam is restricted by the construction equipment, construction engineering quantity and the tight quality of coal seam sealing. In the coal seam with poor air permeability, the extraction effect is not obvious. 10%. At present, the pre-drainage methods of bedding drilling in this coal seam mainly include parallel drilling, fan-shaped drilling and cross drilling, etc. The drillings are not penetrated. Once the hole collapses, the effective drainage section of the drilling will be reduced, which is not conducive to the overall drainage. Pick. The traditional parallel pre-drainage drilling spacing is generally 5-20m, and the pre-drainage effect is better for coal seams with good gas occurrence conditions, but for coal seams with poor air pe...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to overcome the problems of the above-mentioned prior art, and provide a method for pre-pumping low-permeability coal seam gas by means of intensive through-hole drilling and tube boosting. Pre-extraction, the pre-extraction time is short; and the negative pressure lifting system is used to increase the negative pressure of the extraction, which increases the amount of gas extraction, and the extraction efficiency is high. problem of instability

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