Low-cost construction process for passing through goaf

A construction technology and goaf technology, applied in earthwork drilling, drilling equipment, wellbore/well components, etc., can solve the problems of drainage and inability to take effectively, and achieve the effect of low cost

Inactive Publication Date: 2015-09-23
山西蓝焰煤层气集团有限责任公司 +2
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  • Claims
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AI Technical Summary

Problems solved by technology

Affected by the fractured subsidence zone formed by the mining of coal in the upper formation of the Permian strata, it is impossible to effectively use conventional coalbed methane surface drilling to extract the coalbed methane (coal mine gas) of the lower coal formation in the carboniferous formation

Method used

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  • Low-cost construction process for passing through goaf

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Embodiment Construction

[0019] Such as figure 1 As shown, in order to avoid buried drill bits and buried well holes when crossing the goaf (7) broken subsidence zone formed after the mining of the upper group of coal, the surface drilling construction adopts a three-split shaft structure. Its specific construction steps are as follows:

[0020] First opening: Use the drill pipe to drive a φ444.5mm drill bit to open hole A to the bedrock, and lower the φ377.7mm surface casing 3 to the bottom of the first hole A, cement the well, and return the cement to the ground.

[0021] Second opening: Use φ311.1mm air down-the-hole hammer to drill the second opening B, and use a compressor on the upper part (according to the drilling situation, connect two compressors in parallel in time). When drilling with air down-the-hole hammer, the wellhead uses The special device seals and connects the conduit away from the wellhead, and at the same time injects a small amount of water into the wellhead to prevent undergr...

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Abstract

The invention belongs to the technical field of coal gas mining, particularly relates to a low-cost construction process for passing through a goaf and aims to realize passing through a broken and collapsed belt of a permian formation to extract coal gas of carboniferous formation lower group coal. The low-cost construction process includes: adopting a three-holing well body structure for on-ground well drilling, and holing to bed rock for the first time; holing to a position of 22m below a baseplate of the goaf for the second time, lowering a bilayer sleeve, sealing and fixing a bottom port of the bilayer sleeve, and pouring cement between the bilayer sleeve and a well wall for well cementation; holing to a position of 50m below a baseplate of a lower group coal layer for the third time to finish drilling, lowering an inner-layer sleeve, performing well cementation and depth returning to the baseplate of the goaf, and performing well completion after solidification. No sleeve for replacing a drill rod is used, but conventional sleeves are adopted; red soil is filled between the bilayer sleeve and the well wall, cement paste is utilized to intrude the broken belt above the goaf, and the cement is utilized between the bilayer sleeve below the goaf and the well wall for well cementation to stabilize the goaf, so that the circumstance that a drill bit and a wellhole are buried caused by breaking and collapsing of the goaf can be prevented effectively.

Description

technical field [0001] The invention belongs to the technical field of coal bed gas exploitation, and in particular relates to a low-cost construction process for crossing goafs. Background technique [0002] The coal-bearing strata in some mining areas are Carboniferous Permian strata, the Carboniferous strata contain the lower group of recoverable coal seams, and the Permian strata contain the upper group of recoverable coal seams. This type of mining area has a high degree of coal metamorphism. During the geological history period, there was no large amount of gas escape during the coal-forming gas (mainly methane gas) period due to severe geological structures. The content of coalbed methane (coal mine gas) per ton of coal is high, and coal mining is carried out. At present, coalbed methane (coal mine gas) needs to be extracted from surface coalbed methane wells and underground drainage boreholes, and coal mining can only be carried out after the content of coalbed metha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B33/13E21B4/06E21B17/00E21B33/06
Inventor 李俊峰王军赵小山翟德锁赵晓龙何丽娜
Owner 山西蓝焰煤层气集团有限责任公司
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