Ground bored well body structure for gas extraction

Abstract

The invention discloses a ground bored well body structure for gas extraction, comprising a surface layer section, a rock stratum section and a pressure relief extraction section, wherein the well body aperture of the surface layer section is gradually reduced, and the surface layer section is positioned from the ground to a bedding rock stratum; the rock stratum section is positioned between thesurface layer section and the pressure relief extraction section; the pressure relief extraction section is positioned between the upper side of an upper-group pressure relief coal bed top plate and alower-group extraction coal bed, and the lower end of the pressure relief extraction section is 10-30 m away from a lower-group extraction coal bed top plate; the surface layer section is provided with a surface layer sleeve pipe; the rock stratum section is provided with a rock stratum sleeve pipe; an extraction gas pipe extends to the ground from a well bottom, and a pipe section of the extraction gas pipe, which penetrates through an upper-group pressure relief coal bed is an extraction gas screen pipe, other pipe sections of the extraction gas pipe are extraction gas solid pipes, and theextraction gas screen pipe is wound with lead wires; and spacings are retained between the extraction gas pipe and the surface layer sleeve pipe and between the rock stratum sleeve pipe and the well wall of the pressure relief extraction section. The ground bored well body structure is stable and difficult to break and block, has good gas extraction effect and wide applied range and is suitable for a ground bored well of a coal mine, which is used for extracting gas.

Description

technical field [0001] The invention relates to a surface drilling shaft structure used for gas extraction in coal mines. Background technique [0002] In the Chinese invention patent specification whose patent number is "ZL200510040410.X", a shaft structure is disclosed. Gas drainage casings are installed in the quicksand layer and rock layer of the well drilling, and cement mortar is injected into the gap between the gas drainage casing and the well wall (sand prevention casing) to cement the well, and the pressure relief coal seam section is equipped with drainage The gas screen is used without cementing, and the gas flows into the drilling well through the gaps and screen holes around the screen. [0003] Due to the large amount of rock deformation, fast deformation speed and large bending stress during the mining of the lower group of coal seams, the gas drainage casings and gas drainage screens of some wells cannot adapt to these changes and are cut off, resulting in ...

AI Technical Summary

Problems solved by technology

[0005] In order to overcome the defect that the gas extraction casing and screen of the existing well structure are easily damaged by shearing and the drilling is blocked, the presen

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