Deep coal seam permeation enhancing method

Abstract

The deep coal seam permeation enhancing method comprises the steps that a mother hole is drilled in a target coal seam in the ground or a roadway, the mother hole penetrates through the target coal seam, branch holes are formed in the inner wall of the mother hole in the target coal seam in the radial direction of the mother hole, a fracturing pipe is installed in the mother hole, one end of the fracturing pipe is fed into the target coal seam, a constant pressure relief valve is arranged at the end, located at the target coal seam, of the fracturing pipe, the part between an orifice of the mother hole and a top plate of the target coal seam is blocked and maintained, supercritical carbon dioxide is injected into the target coal seam through the fracturing pipe, the target coal seam is fractured, and after the injection pressure of the supercritical carbon dioxide is reduced, supercritical carbon dioxide is continuously injected into the target coal seam to conduct pressure maintaining on the target coal seam, the pressure maintaining time is 2-3 days, and the supercritical carbon dioxide is fully permeated and diffused. According to the deep coal seam permeability increasing method, the coal seam is fractured through the multi-branch-hole composite supercritical carbon dioxide, a fracture network is constructed in the coal seam in a large-range balanced mode, and comprehensive and efficient permeability increasing can be performed on the coal seam.

Description

technical field [0001] The invention relates to the technical field of coal bed gas exploitation, in particular to a method for increasing permeability of deep coal seams. Background technique [0002] Improving the air permeability of coal seams in a large range is the key to efficient extraction of coal bed methane (gas). However, the occurrence environment of coal seams in my country is complex, with high gas, strong adsorption, and low permeability coal seams being the majority, and as coal mining moves deeper, coal seam joints and cleats in deep coal seams have a high degree of compression and closure, fewer communicating channels, and lower air permeability. As a result, it is increasingly difficult to extract gas from deep coal seams. How to balance the structural fracture network in a large scale in the coal seam has become the key to realize the comprehensive and efficient extraction of coal seam gas. Contents of the invention [0003] The present invention is ba...

AI Technical Summary

Problems solved by technology

However, the occurrence environment of coal seams in my country is complex, with high gas, strong adsorption, and low permeability coal seams being the majority, and as coal mining moves deeper, coal seam joints and cleats in deep coal seams have a high degree of compression and closure, fewer communicating channels, and lower air permeability. It makes it more difficult to extract gas from deep coal seams

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