Coal bed methane multi-branch horizontal well system and auxiliary discharge well thereof

Abstract

The invention discloses an auxiliary discharge well matched with a coal bed methane multi-branch horizontal well. The multi-branch horizontal well comprises a straight well section, a deflection section and a horizontal section which comprises a plurality of wellbores; and the auxiliary discharge well is arranged on the coal bed relief declination side in the horizontal section of the multi-branch horizontal well. In the invention, the auxiliary discharge well adopts a mode of arranging the drilling engineering at the tail end of the horizontal section of the horizontal well to reduce liquid pressure in branches and produces channels in a target geologic body by utilizing a newly drilled well to make the target geologic body communicated with the multi-branch horizontal well and assist the multi-branch horizontal well in draining and decompressing so as to fulfill the aim of gas desorption in the geologic body, improve the development efficiency of an assisted well and increase the well producing rate of the multi-branch horizontal well. Meanwhile, the invention also provides a coal bed methane multi-branch horizontal well system.

Description

Technical field [0001] The invention relates to the field of underground fluid resource exploitation, in particular to a coalbed methane multi-branch horizontal well system and its drainage-assisted well. Background technique [0002] In the process of using multi-branch horizontal wells to mine CBM, the mining area and mining effect of CBM are directly related to the arrangement of horizontal sections of horizontal wells in the coal seam. When there is a multi-branch horizontal well with branches spreading downwards, due to the height difference, the water in the borehole cannot be discharged, resulting in a pressure difference, and the gas in the target geological body cannot be desorbed, causing many footages to be taken above the desorption pressure The resources in the system cannot be exploited, making this part of the footage actually invalid. The greater the height difference, the more serious the impact, and may even cause the productivity of the drilled well to be almo...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a drainage well, which solves the problem of the downward spread and extension of the branches in the multi-branch horizontal well in the prior art. Due to the limitation of the height difference, even if the liquid level of the production vertical well is discharged to the lowest level, the branch The gas in the drilled geological body still cannot be resolved, resulting in the problem that part of the footage in the multi-lateral horizontal well is actually invalid

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