Gas extraction method for extra thick coal seam

Abstract

The invention relates to a gas extraction method for an extra thick coal seam. The method comprises the following steps that a ground perpendicular drilling well and a vertical and horizontal drillingwell are arranged on the ground, the perpendicular drilling well and the vertical and horizontal drilling well go deep into the coal seam, fracturing fluid and sand carrying fluid are injected into the perpendicular drilling well in sequence, and coal seam pulse water hydraulic fracturing is conducted; and critical carbon dioxide is injected into the vertical and horizontal drilling well to carryout critical carbon dioxide fracturing, underground pre-excavation tunnel excavation is conducted, construction of multiple rows of sequence-layer drill holes is conducted on the coal seam in the mining tunnel, and sequence-layer drill holes are connected within an underground gas extraction system for gas extraction of the underground coal seam. By means of the gas extraction method, the integrated penetration enhancement and gas extraction of the whole extra thick coal seam are achieved, the efficiency of gas extraction is improved, the occurrence of coal mine gas accidents is reduced, andthe effective managing scope of the gas is increased.

Description

technical field [0001] The invention belongs to the technical field of coal mine gas control, and in particular relates to a method for extracting gas from an extra-thick coal seam. Background technique [0002] With the increase of mining intensity of coal resources, the depth of coal mining is also gradually increasing, and the deep coal seam has the characteristics of high ground stress, high gas pressure and high gas content, and various factors lead to frequent occurrence of mine disasters. One of the important factors for the occurrence of coal seam disasters is that most of the coal seams in my country are low-permeability coal seams, especially for some deep thick coal seams, the coal seams have poorer gas permeability and low gas extraction efficiency. Due to the characteristics of high pressure and other characteristics, it is more difficult to control gas. At present, the control methods used for extra-thick coal seam gas mainly include surface drilling gas drainag...

AI Technical Summary

Problems solved by technology

At present, the control methods used for extra-thick coal seam gas mainly include surface drilling gas drainage, bedding borehole gas drainage, protective layer mining, and bed-crossing drilling gas drainage, etc., but these methods have single methods and poor gas control effects and other shortcomings, aiming at this, the present invention provides a method for gas drainage in extra-thick coal seams. The method of the present invention has the advantages of high extraction rate, good gas control effect, and large effective gas control range.

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