A construction method of coalbed methane multi-branch horizontal well and multi-branch horizontal well

Abstract

The invention discloses a multi-branched horizontal well and a construction method for a coalbed methane multi-branched horizontal well, wherein the construction method for a coalbed methane multi-branched horizontal well is a method for sequentially using circulating media in different phases to mine coalbed methane The construction method of coalbed methane multi-branch horizontal well. The end of the main wellbore is located above the target coal seam, and reservoir pollution is not considered during drilling. The main wellbore can be drilled with liquid circulating medium, and no reservoir protection measures are required to ensure the smooth drilling of the main wellbore. Yes, liquid circulating medium drilling not only ensures the drilling speed of the main wellbore, but also ensures the safety of the main wellbore drilling; the branch wellbore is located in the coal seam, and the gas circulating medium is used to drill the branch wellbore to ensure the safety of the main wellbore. Avoid the damage caused by the liquid circulating medium to the reservoir, and the main wellbore and the branch wellbore are drilled separately without affecting each other, meeting the requirement that liquids cannot be used in the drilling and completion process of some special coal seams, and realizing horizontal wells in dry coal seams drill set.

Description

technical field [0001] The invention relates to the technical field of coalbed methane exploitation, in particular to a construction method for a coalbed methane multi-branch horizontal well and a multi-branch horizontal well for dry coal seams without water. Background technique [0002] In the prior art, liquid drilling fluid or drilling fluid mixed with liquid and gas is used in the construction of horizontal wells, but for dry coal seams without water, as long as the drilling fluid contains water, the coal seam will be damaged. [0003] At present, researchers have proposed to use gas as the circulating medium to drill horizontal wells in dry coal seams, but there are the following defects: the product life is short, and the maximum construction length of the horizontal section does not exceed 300 meters; the stability of the wellbore cannot be guaranteed. Stop drilling, there is no pressure support in the wellbore, and the horizontal well will collapse. Therefore, once ...

AI Technical Summary

Problems solved by technology

[0002] In the prior art, the construction of horizontal wells uses liquid drilling fluid or drilling fluid mixed with liquid and gas, but for dry coal seams without water, as long as the drilling fluid contains water, it will cause damage to the coal seam

[0003] At present, researchers have proposed to use gas as the circulating medium to drill horizontal wells in dry coal seams, but there are the following defects: the product life is short, and the maximum construction length of the horizontal section does not exceed 300 meters; the stability of the wellbore cannot be guaranteed. Stop drilling, there is no pressure support in the wellbore, and the horizontal well will collapse. Therefore, once the life of the drilling tool is exhausted when drilling with gas, the drilling tool must be withdrawn as soon as possible. At this time, the well can no longer be drilled; the above reasons cause , when using gas to implement horizontal wells in coal seams, only one horizontal wellbore can be implemented, and sidetracking cannot be implemented, that is, multi-branch horizontal wells cannot be implemented. The area is very small, and the ideal gas production cannot be obtained

Images