Well structure of pressure-releasing coal bed gas ground extraction well and arrangement method thereof

Abstract

The invention provides a well structure of a pressure-releasing coal bed gas ground extraction well and an arrangement method thereof, wherein the well structure includes a first aperture section, a second aperture section and a third aperture section, wherein the first aperture section is in a first vertical depth of a well deflecting drill, the second aperture section is in a second vertical depth of the well deflecting drill, the second aperture section is in a third vertical depth of a vertical drill, and the third aperture section penetrates deeply in a protected layer. The arrangement method comprises the following steps of: drilling outside an extraction region, directionally deflecting drilling the upper parts of the first aperture section and the second aperture section, adopting a straight well body for the lower part of the second aperture section and the third aperture section, and closing to a boundary final hole in the extraction region so that most of the well structure is arranged out of a mining influence range or the region with little mining influence, the stability of the ground extraction well is greatly increased, the construction danger is reduced, the extraction yielding of the coal bed gas well is improved, the damage to the ground well by movement of cover rocks is effectively reduced, and the service time of the ground extraction well is increased.

Description

technical field [0001] The invention relates to a well body structure, in particular to a well body structure suitable for pressure relief coal bed methane surface extraction wells in coal mine mining areas. Background technique [0002] The coalbed methane ground drainage wells for pressure relief in coal mine mining areas mostly adopt the technical mode of "ground vertical wells arranged on the centerline of the upper and lower airways in the mining area" or "ground vertical wells arranged in the mining area close to the upper return airway". For the pressure relief CBM surface wells designed in the early stage, the opening position and the final hole position are located on the central line of the mining area. The final hole is located at the bottom of the protective layer. On the top of the coal seam, a working screen is installed from below the gas transmission casing to the roof of the protective layer, and the cement slurry is sealed from the top of the protective sea...

AI Technical Summary

Problems solved by technology

The key problem is that the hole breakage rate of surface wells is high and the service time of surface wells is short

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