Coal-bed gas multi-branch horizontal well and construction method thereof

Abstract

The invention discloses a coal-bed gas multi-branch horizontal well, which is matched with a straight well on which a communicated cave is formed. The multi-branch horizontal well comprises a straight well section, a kick-off section and a horizontal section, wherein the horizontal section comprises a horizontal wellbore and two sets of branch wellbores; the horizontal wellbore is connected with the communicated cave and is extended in a preset distance along the extension direction of the kick-off section from the communicated cave; a plurality of branch wellbores are formed in each set of branch wellbores; each branch wellbore comprises a sidewise section and a forward section; the sidewise section is transversely extended to one side opposite to the extension direction of the horizontal wellbore in an included angle theta 1; every sidewise section in every branch wellbore is connected end to end in turn; the forward section is connected with a corresponding sidewise section and is extended forwards opposite to the extension direction of the horizontal wellbore in an included angle theta 2; and the theta 2 is less than the theta 1. In the multi-branch horizontal well, two adjacent wellbores are fully separated in an extremely short distance, so that the resource control area of unit drilling footage is improved as much as possible. Simultaneously, the invention also provides a construction method of the multi-branch horizontal well.

Description

technical field [0001] The invention relates to the field of coal bed gas exploitation, in particular to a coal bed gas multi-branch horizontal well and a construction method thereof. Background technique [0002] In the existing coalbed methane multi-branch horizontal well project, a multi-branch horizontal well and correspondingly connected vertical wells constitute one project. A multi-branch horizontal well usually includes a vertical well section extending downward parallel to the vertical well, a build-up section extending obliquely downward from the lower end of the vertical well section to a cave connected to the vertical well, and a horizontal section extending a predetermined distance from the connected cave in a direction away from the build-up section. part. The mining area and mining effect of coalbed methane are directly related to the arrangement structure of horizontal wells and horizontal sections in the coal seam. In traditional designs, the horizontal se...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a coalbed methane multi-branch horizontal well, which overcomes the large footage in the horizontal section of the horizontal well in the prior art, where the distance between the branch borehole and the main borehole is very close, which makes the wellbore trajectory densely distributed and the main borehole. The footage on the wellbore contributes little to the drainage and pressure reduction and the drainage effect, resulting in a lot of waste of footage, the control area per unit footage is significantly reduced, and the development efficiency is low.

Images