Freezing fracturing type permeability improving and drainage promoting method for coal body

Abstract

The invention provides a freezing fracturing type permeability improving and drainage promoting method for a coal body. The method comprises the following steps that bedding drilling is conducted on the coal body from a working face crossheading, and any two adjacent drill holes are named as a liquid injection hole and a drainage hole correspondingly; drainage pipes are mounted in the drainage holes and the liquid injection holes for hole sealing, and after sealing, an underground drainage system is connected for gas drainage; high-pressure water is injected into the liquid injection holes; special hole sealers are fed into the drainage pipes in the liquid injection holes and perform hole sealing; liquid nitrogen is injected into the liquid injection holes through the special hole sealersto freeze the coal body around the liquid injection holes; under the effect of the ground temperature, the liquid nitrogen is slowly sublimated into nitrogen, and the nitrogen effectively replaces anddisplaces gas in the coal body; and the drainage pipes in the liquid injection holes are connected with the drainage system for gas drainage work. The principle is scientific, design is ingenious, hole sealing is tight, the method can be widely applied to work such as cross-cut coal uncovering, fault crossing and anti-reflection and drainage-promoting of a mining working face, the anti-reflectionand drainage-promoting effects are good, and the application prospects are wide.

Description

technical field [0001] The invention belongs to the technical field of coal mine safety production, and in particular relates to a method for improving permeability and promoting pumping of frozen fracturing coal bodies. Background technique [0002] Most coal seams in my country have the characteristics of "three lows and one high" (low permeability, low saturation, low reservoir pressure, and high degree of metamorphism). The low permeability of the coal seam makes it difficult to extract gas, resulting in the imbalance of "pumping-excavation-mining" in the mine, forming a major safety hazard, and laying hidden dangers for the occurrence of coal mine gas accidents. Therefore, scholars at home and abroad have proposed hydraulic punching, protection layer mining, CO 2 Phase change fracturing and other technical measures to increase permeability of coal seam and promote drainage. However, due to various reasons, from a technical and economic point of view, the anti-reflecti...

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Problems solved by technology

[0007] In order to solve the deficiencies in the prior art, the present invention provides a method for improving the permeability of frozen fracturing coal and promoting drainage, so as to solve the problem of conventional hole sealing devices and sealing methods in the process of freezing fracturing coal and gas drainage. Poor hole effect, low coal gas permeability and other problems lead to poor drainage effect, so as to improve the degree of freezing and fracturing of coal body and improve the effect of coal seam gas drainage

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