A low-permeability coal seam supercritical carbon dioxide permeability enhancement system and method

Abstract

The invention discloses a low permeability coal bed supercritical carbon dioxide anti-reflection system and method. The anti-reflection system comprises an extraction pipe and an injection pipe, wherein the extraction pipe and the injection pipe are sleeved with a hole packer, an extraction device is connected to the outer end of the extraction pipe through an extraction pipeline, and an extraction stop valve and a main extraction stop valve are sequentially arranged between the extraction pipe and the extraction device; an injection stop valve, an injection supercritical carbon dioxide pump, a thermostat and a carbon dioxide gas tank are sequentially connected to the outer end of the injection pipe through an injection pipeline, a high-pressure buffer tank is arranged in the thermostat, and a temperature sensor and a gas injection pressure gauge are connected to a four-way valve. The anti-reflection system is reasonable and simple in structure, convenient to implement, safe and reliable, and capable of improving the permeability of a coal bed greatly. By the adoption of the anti-reflection method, the original pore structure of the coal bed can be changed, the permeability of the coal bed can be improved greatly, coal bed gas output efficiency can be improved, extraction effect can be improved greatly, the outburst danger of the coal bed can be effectively reduced, and safe production of a coal mine can be ensured.

Description

technical field [0001] The invention belongs to the technical field of coal seam anti-permeability systems and methods, in particular to a low-permeability coal seam supercritical carbon dioxide anti-permeation system and method. Background technique [0002] As the mine mining extends to the deep, the permeability of the coal seam is very low due to the influence of high geostress. The low permeability coal body can be regarded as a kind of gas-bearing porous and dense low permeability medium. Coal seams are larger. Therefore, a series of gas disasters caused by high geostress and high gas pressure gradient in deep low-permeability coal seams are also increasing. [0003] At present, coal mine production mainly increases the production of coalbed methane through the method of coal seam anti-permeability. The anti-permeability methods mainly include hydraulic anti-permeability, high-energy gas fracturing, directional long drilling method, mining protective layer method, and...

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Problems solved by technology

Although some of the above methods have good effect on improving the air permeability of coal seams, due to the limitations of natural conditions and development costs, it is still difficult to popularize and apply them in many mining areas.

[0004] Therefore, as the coal seam mining enters the deep part of the formation, the characteristics of high ground stress, high pressure gradient of gas and low permeability of coal seam become more and more obvious. The existing anti-permeability technology of coal seam has certain limitations in different mines.

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