Gas drainage method and equipment with alternative drainage

Abstract

The invention discloses a gas drainage method and equipment with alternative drainage, which are applicable to increasing the drainage diameter of a gas drainage drilling hole and improving the total gas drainage amount of the drilling hole. A main drainage pipeline at the front part and the rear part of a gas pump is connected with bypass pipelines in parallel by a front three-way ball valve anda rear three-way ball valve; the main drainage pipeline at the front part of the front three-way ball valve is connected with a high-pressure gas storage tank; the rear part of the high-pressure gas storage tank is connected with a gas filling pipeline controlled by a gas filling control ball valve; the gas filling pipeline is connected onto the main drainage pipeline between the rear three-way ball valve and the gas pump; a gas drainage pipe in the gas drainage drilling hole is connected with the main drainage pipeline to carry out gas drainage; in the operation process of the gas pump, by controlling the states of the front three-way ball valve, the rear three-way ball valve, the gas filling control ball valve and an outlet control ball valve, extracted gas flow and pressed-in gas flow occur alternatively on the gas drainage drilling hole, the cracks of coal bodies around the drilling hole are enlarged continuously under the action of alternative stress and develop gradually towardsthe deep part, so that the total gas drainage amount of the drilling hole is improved. The method and the equipment are simple, the operation is convenient and the cost is low.

Description

Technical field [0001] The invention relates to a gas drainage method and equipment with alternating pressure and drainage, and is particularly suitable for increasing the drainage radius of a gas drainage borehole and increasing the total gas drainage of the borehole. Background technique [0002] Gas drainage is the use of negative pressure generated by a gas pump to extract the gas that is stored in the coal seam through the gas drainage borehole. After a long time of extraction, the pressure and content of coal seam gas can be greatly reduced. Therefore, gas extraction is a fundamental measure to prevent coal mine gas disasters. In order to eliminate the threat of gas and ensure safe production in mines, my country's prominent mines, high-gas mines and some low-gas mines have carried out extensive gas drainage projects. [0003] After the gas drainage borehole construction, the stress of the coal in a certain area around it is released and deformed. During the deformation of t...

AI Technical Summary

Problems solved by technology

For example, when the hydraulic fracturing method is used, although the cracks in the coal seam are enlarged, the air permeability of the coal body is reduced after the water is saturated, and the flow of the desorbed gas cannot be accelerated. In addition, the coal body becomes muddy when it meets water, which can block the cracks Therefore, it cannot increase the gas extraction volume

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