Method for extracting coal bed gas in stable mining region by ground well drilling

Abstract

The invention discloses a method for extracting coal bed gas in a stable mining region by ground well drilling, comprising the following steps of: hole distribution, well drilling, well cementation and well completion, wherein the hole distribution step can effectively reduce the destroy rate of a drilling well and improve the utilization rate of the drilling well by adopting a reasonable distribution principle so as to achieve the optimal extraction effect by using the least number of drilling wells; and simultaneously, the well drilling step adopts a third-opening well drilling way and selects reasonable well parameters, and two well completion processes of uncased hole well completion or liner tube well completion are adopted so that the well drilling structure and the construction process are reasonable, the extraction efficiency is also effectively improved, the possibility of destroying the drilling wells is reduced, and the well drilling accidents are reduced.

Description

technical field [0001] The invention relates to a method for drilling and extracting coal bed gas in a dynamic and stable area. Background technique [0002] When the coal seam is mined, since the recovery rate cannot reach 100% during the mining process, a large amount of floating coal must remain in the goaf. At the same time, coal pillars with a certain thickness also exist at the boundary of the goaf, and the desorption of methane from floating coal and coal pillars leads to the accumulation of higher concentration of coalbed methane in the goaf. In addition, the pressure-relieving coalbed methane produced after the coal seam within the mining influence area is affected by mining will also enter the goaf through mining fractures. After all the mining of the working face or mining area is completed, in order to reduce the impact on production and safety caused by the coalbed methane in the goaf rushing to the mining space or to the mine, and in order to effectively utili...

AI Technical Summary

Problems solved by technology

[0004] Most of the existing technologies for coalbed methane extraction in coal mining areas use underground drilling through layers, drilling along layers, and buried pipes in goafs to extract coalbed methane. , the drilling utilization rate is not high, and the buried pipes in the goaf are easily bent and broken by the caving roof strata to block the extraction. To solve this problem, the use of ground drilling to extract coalbed methane in the mining area However, there are still several deficiencies: ① During the coal seam mining process, it is easy to cause the displacement change of the overlying strata in the stope, which makes the drilling casing easy to be damaged; The development effect of coalbed methane is not good; ③The design of the well body structure and the selection of the completion method are unreasonable, and it is easy to cause drilling accidents during the drilling process, and it is also easy to cause drilling and drainage efficiency low, poor economy

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