A method for extracting residual coalbed methane in multi-layer old goaf areas by drilling ground wells through residual coal pillars

Abstract

The invention discloses a method for extracting residual coal bed gas in multiple layers of goafs by drilling a well from the ground and penetrating through residual coal pillars. The method comprises the following steps: drilling the well from the ground to the construction floor of the residual coal pillars, and penetrating through all the residual coal pillars; when the residual coal pillars are relatively narrow, drilling the well from the ground, penetrating through the residual coal pillars, and then directly connecting with the goafs; when the residual coal pillars are relatively wide, drilling the well from the ground, penetrating through one of the residual coal pillars to a bottom plate of the residual coal pillar, inserting a steel pipe, which is externally fixed with a high-pressure bag, to the bottom of the residual coal pillar into the well from the ground, connecting a high-pressure hose with the high-pressure bag to extend to the ground, pressing water into the high-pressure bag through the high-pressure hose to form a hole-sealing section, then injecting high-pressure water into the well through the steel pipe, fracturing the residual coal pillar, and then draining and depressurizing the high-pressure bag; continuously penetrating through the other residual coal pillars, inserting an extraction pipe into the well from the ground, and extracting the residual coal bed gas in the goafs. According to the method, the mode of drilling the well from the ground and penetrating through the residual coal pillars is adopted. The method has the advantages of low construction difficulty and low accident occurrence rate.

Description

technical field [0001] The invention relates to a method for extracting residual coal bed gas in an old goaf area, and is especially suitable for extracting residual coal bed gas in multi-layer old goaf areas through ground drilling through residual coal pillars. Background technique [0002] my country is a large coal country in the world, and a large number of old empty areas are left after coal mining. Due to the low coal recovery rate in my country, there are many coal residues in the old empty area, and the residual coal body contains abundant coalbed methane resources. Gas is a kind of clean energy. The energy utilization of residual coalbed methane in old empty areas can effectively alleviate the shortage of natural gas supply in my country, and has good environmental and economic benefits. At present, the gas in the old goaf is mainly drilled from the ground to the construction ground in the upper fracture zone of the goaf to extract the gas in the old goaf. This me...

AI Technical Summary

Problems solved by technology

At present, the gas in the old goaf is mainly drilled from the ground to the construction ground in the upper fracture zone of the goaf to extract the gas in the old goaf. This method can only extract the gas in a single old goaf

In order to extract the gas in the lower coal seam of the old goaf, ground drilling is often used to penetrate the old goaf and enter the lower coal seam to extract gas. Because this method needs to penetrate the old goaf, the construction is difficult and the accident rate is high. High, low porosity, and can not simultaneously drain multi-layer old goaf gas, it is urgent to develop a gas drainage method that is less difficult to construct, has a low accident rate, and can simultaneously extract residual coalbed methane in multi-layer old goats

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