A method for stage-by-stage drainage of U-shaped wells for coalbed methane

A coalbed methane, U-shaped technology, applied in the fields of fluid extraction, earthwork drilling, wellbore/well components, etc., can solve the problems of unreasonable drainage system, poor gas production effect, unstable production, etc. The effect of bare area

Active Publication Date: 2021-11-12
SHANXI JINCHENG ANTHRACITE COAL MINING GRP CO LTD
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Problems solved by technology

[0005] The main purpose of the present invention is to provide a method for step-by-step step-by-step depressurization and extraction of U-shaped coalbed methane wells, so as to solve the problems of unstable output and poor gas production effect caused by unreasonable drainage systems in the horizontal well drainage process. question

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  • A method for stage-by-stage drainage of U-shaped wells for coalbed methane
  • A method for stage-by-stage drainage of U-shaped wells for coalbed methane

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Embodiment Construction

[0017] The present invention is aimed at the characteristics of the coal seam with a large dip angle, and uses the fracturing point of the U-shaped well as the key point of drainage control, and depressurizes step by step, and the specific process is as follows:

[0018] (1) The principle of gas production first in the remote butt joint horizontal well project. Since the horizontal section of the far-end docking well is generally drilled in the downhill manner, the coal seam section near the engineering well reaches the desorption condition first. If the coal seam dip angle is large, this phenomenon is more obvious.

[0019] (2) Three-stage drainage stage. The stage from the initial liquid level of the CBM well to the critical desorption pressure point is regarded as the first drainage stage; the liquid level from the critical desorption pressure point to the liquid level 20m above the roof of the target coal seam is regarded as the second drainage stage; subsequent drainage i...

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Abstract

The present invention relates to the technical field of coalbed methane drainage, in particular to a step-by-step step-by-step depressurization drainage method for U-shaped coalbed methane wells, which is divided into three drainage stages according to the trajectory characteristics of U-shaped wells in large-inclination coal seams; The stage from the initial liquid level of the CBM well to the critical desorption pressure point is regarded as the first drainage stage; the liquid level from the critical desorption pressure point to the liquid level 20m above the roof of the target coal seam is regarded as the second drainage stage; subsequent drainage is the third drainage stage . The different stages of U-shaped well drainage in high-dip coal seams are clearly divided to ensure that the coalbed methane well can be depressurized and desorbed stably; the fracturing point of the U-shaped well is used as the key point of drainage control, which can more accurately control the coalbed methane well. Drainage, so that each coal seam section can be fully desorbed, and prevent the coal seam from being exposed in a large area due to the rapid drop of the liquid level, which is not conducive to the desorption of coalbed methane.

Description

technical field [0001] The invention relates to the technical field of coalbed methane drainage, in particular to a step-by-step step-by-step depressurization drainage method for U-shaped coalbed methane wells. Background technique [0002] Conventional vertical well development has a small impact range, low single well production, and poor economic benefits, while horizontal wells have the advantage of penetrating more cleat fracture systems, communicating with a large number of fracture channels, expanding the area of ​​drainage, depressurization and gas release, and allowing more As more gas enters the main channel, horizontal wells, as an efficient development technology for low-permeability coal reservoirs, have been increasingly used in the exploitation of coalbed methane. [0003] However, coal seams, as gas-generating beds and reservoirs of coalbed methane, have the characteristics of low porosity, low permeability, low mechanical strength, strong heterogeneity, and ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/00E21B43/26E21B43/20
CPCE21B43/006E21B43/20E21B43/26
Inventor 陈召英郝春生李军军常会珍李进强赵晋斌姚晋宝王维杨昌永贾晋生
Owner SHANXI JINCHENG ANTHRACITE COAL MINING GRP CO LTD
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