A gas extraction method for extra-thick coal seams

Abstract

The invention relates to a gas extraction method in an extra-thick coal seam. The method includes setting a vertical drilling well and a vertical horizontal drilling well on the ground. fluid and sand-carrying fluid to perform pulsating hydraulic fracturing of coal seams; inject critical carbon dioxide into vertical horizontal drilling to perform critical carbon dioxide fracturing; carry out underground pre-excavation roadway excavation and construct multiple rows of bedding-aligned drilling holes in the coal seam in the mining roadway, along the The drill holes in the coal seam are connected to the underground gas drainage system for underground coal seam gas drainage; realize the integrated anti-reflection and gas drainage of the entire extra-thick coal seam, improve the efficiency of gas drainage, reduce the occurrence of coal mine gas accidents, and increase the scope of effective gas control.

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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