Method for increasing permeability of inert gas and extracting gas

Abstract

A method for increasing the permeability of an inert gas and extracting gas under the coupling action between temperature and pressure, belongs to a method for extracting the gas. A permeability increasing hole is formed in the middle of a workface coal bed; gas extraction holes are formed on vertexes of an equilateral triangle with the permeability increasing hole as a center; after the gas extraction holes are sealed, the gas is extracted; the inert gas under the coupling action between temperature and pressure is injected into the permeability increasing hole one by one; under the coupling action of temperature and pressure of the nitrogen, a small-size clearance of a coal body is pressed by the inert gas to be opened, so that an original crack in the coal body is stretched, the stretched crack further extends and no protrusion by induction occurs; 90 percent of adsorption gas in the coal body absorbs energy and the separating speed of the gas from the coal body is increased, so that gas which is difficult to desorb in the coal body is converted into free gas which is convenient to quickly extract in a large flow; and a permeability increasing medium is gas, and the gas subjected to permeability increase can be exhausted from a crack channel without blocking the gas flowing channel, so that the conditions for the extraction of the gas is provided. The method has the advantages of simplicity in operation, favorable effect, high extraction efficiency of the gas and applicability.

Description

technical field [0001] The invention relates to a method for extracting gas, in particular to a method for extracting gas by injecting nitrogen gas under the coupled action of temperature and pressure. Background technique [0002] The structure of coal seams in my country is complex, and the permeability is generally low. Many high-gas coal seams are low-permeability coal seams. At the same time, with the gradual increase of coal mining depth, the stress increases, which further reduces the gas permeability of the coal seam. In coal mines with poor air permeability, the effect of gas pre-extraction in coal seams without decompression is often unsatisfactory, so it is particularly important to increase the air permeability of coal bodies. At present, hydraulic measures, such as hydraulic fracturing and hydraulic cutting, are mainly used in the process of increasing coal gas permeability in my country. If the hydraulic anti-permeability measures are adopted, the coal body w...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for gas desorption under the coupling effect of injecting temperature and pressure with nitrogen gas, which solves the problems of poor coal body anti-reflection effect and difficult gas desorption, effectively accelerates gas desorption efficiency, and realizes large flow rate, Rapid Gas Drainage

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