Downhole Isolation Tool for Coal Bed Methane Gas Recovery
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Solution Overview
Problem
Current methods for extracting gas from gas-producing formations, such as coal bed methane, often require the removal of formation water, leading to inefficient gas recovery and potential environmental issues, especially in abandoned or shallow wells where hydrostatic pressure is greater than the gas-bearing formation pressure.
Innovation Solution
A passive downhole isolation tool with a hydrophobic sleeve and wire mesh screen is introduced, which separates gas from water by creating a pressure sink below the static water level, allowing gas to flow upwards while keeping water and solids below, using a multi-part housing and perforated components to facilitate efficient gas collection without water removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If formation water is removed to extract gas from gas-producing formations, then gas can be recovered, but environmental issues arise and hydrostatic pressure is altered causing loss of porosity and permeability
Solution Approach 1:
The tool segments the wellbore into two distinct zones using a packer: an upper zone for gas production and a lower zone for water retention. This segmentation allows selective production of gas while maintaining formation water in place, thereby achieving gas recovery without environmental harm associated with water disposal
Solution Approach 2:
The invention extracts only the gas component from the formation while leaving the formation water in place. The packer isolates the water zone, and gas is selectively produced through the upper perforations,实现ing extraction of the desired substance (gas) without removing the harmful component (formation water)
2Productivity
If formation water is pumped off to produce gas, then gas desorption occurs, but the hydrostatic pressure change causes matrix shrinkage and reduces porosity and permeability
Solution Approach 1:
The packer divides the wellbore into separate zones, allowing the lower zone to maintain hydrostatic pressure and prevent matrix shrinkage, while the upper zone enables gas production. This segmentation resolves the contradiction by allowing productivity improvement in one zone without compromising the stability of formation properties in another zone
Solution Approach 2:
The packer acts as an intermediary element that isolates the formation water from the production zone. It mediates between the need for gas production and the need to maintain hydrostatic pressure, allowing gas to be produced while the packer prevents pressure changes that would cause matrix shrinkage
3Reliability
If conventional well isolation methods are used in abandoned wells, then gas pressure is contained, but continued gas recovery is prevented
Solution Approach 1:
The tool applies local quality differentiation by creating different conditions in different zones: the lower zone maintains high pressure for containment, while the upper zone provides a controlled pathway for gas production. The packer creates a localized high-pressure zone that contains gas while allowing selective production through perforations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables continued gas recovery from coal bed methane formations and other gas-bearing rock types without releasing formation water, improving efficiency and reducing environmental impact by allowing gas to be produced without altering the hydrostatic pressure, thus maintaining porosity and permeability.
Implementation Method 1
a hydrophobic sleeve member (18) positioned within the cylindrical internal tool insert (14) and in communication with the annulus (32), the sleeve member (18) having a pore size allowing passage of vaporized gas, but preventing passage of water through the sleeve member (18)
Implementation Method 2
separates gas from water by creating a pressure sink below the static water level, allowing gas to flow upwards while keeping water and solids below
Implementation Method 3
a wire mesh screen (16) positioned within the internal cavity (37) of the cylindrical internal tool insert (14)
Data Source
AI summary
A method and apparatus for removing dissolved gas from a coal bed or other type of gas bearing formation is provided.