Ground well casing capable of preventing mining damage

Abstract

The invention discloses a ground well casing capable of preventing mining damage, which comprises at least two casing bodies, a deflection joint and an expansion joint, adjacent casing bodies are connected by the deflection joint or the expansion joint, when in use, according to analysis results of strata displacement, the casing bodies are connected by the deflection joint in the depth corresponding to strata where the casing is easy to cut and twist, the casing bodies are connected by the expansion joint in the depth corresponding to strata where the casing is easy to pull and press, and the casing bodies are connected after the deflection joint and the expansion joint are connected in series in a small depth range corresponding to strata where the casing is easy to not only cut and twist but also pull and press, so that the casing can adapt to strata variation, thus reducing damage accidents of the well casing and guaranteeing smooth gas extraction through the ground well.

Description

technical field [0001] The invention relates to a casing used for well cementing in surface drilling construction, in particular to a flexible surface drilling and cementing casing capable of preventing rock formations from being damaged due to movement. Background technique [0002] During the mining process of the underground coal seam, a pressure relief space will be formed behind it, and a caving zone, a fissure zone and a curved subsidence zone will be formed successively in the vertical direction. The coal seam gas technology in the coal seam area affected by ground drilling and extraction is firstly drilled from the ground to the mining coal seam before the coal seam is mined, and the well is cemented and completed; then the overlying coal rock is affected by the mining of the lower coal seam through the mining of the coal seam "Three vertical belts" are formed in the vertical direction, forming a circulation channel for ground drilling and extraction of gas. The sou...

AI Technical Summary

Problems solved by technology

[0005] In the prior art, the surface drilling and cementing casing is usually a one-piece structure. According to the above analysis, under the condition of frequent displacement of the overlying strata above the coal seam, the casing of this structure will be subject to many factors such as shearing, tension, compression, torsion, etc. The repeated action of various forces is very vulnerable to damage, which affects the smooth extraction of gas

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