Sealing Control Lines in Downhole Swelling Packers
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Solution Overview
Problem
Existing swelling packers in downhole applications face challenges in sealing conduits or control lines due to potential leakage and asymmetrical boreholes, which affect the reliability of the seal, especially when dealing with hydraulic or fiber optic lines.
Innovation Solution
A swelling element with a milled slot and a non-swelling underlayment wrapped around the control line, covered with a swelling material, is used, featuring a longitudinal or spiral split that fits into the slot of the packer, with clamps securing the line and allowing for thermal expansion, and an optional groove for enhanced sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a longitudinal channel for control lines is provided in the swelling element, then the control lines can pass through the packer, but the sealing reliability deteriorates due to asymmetrical boreholes preventing symmetrical swelling closure
Solution Approach 1:
The control line passage is segmented into multiple separate slots rather than a single longitudinal channel. Each slot is independently positioned and sized to accommodate control lines while maintaining sealing integrity. The swelling element contains multiple such slots arranged circumferentially, allowing control lines to pass through without compromising the overall sealing performance.
Solution Approach 2:
The swelling element exhibits local quality variations with different regions having different properties. The slots are strategically positioned in regions where swelling closure is most effective, and the geometry of each slot is optimized for its specific location. This allows the swelling element to maintain sealing reliability while accommodating control lines in asymmetrical borehole conditions.
2Ease of manufacture
If connections are made at the surface before running the packer, then the packer can be installed, but leakage risks increase for hydraulic control lines
Solution Approach 1:
The control lines are nested within the swelling element structure itself, with slots provided directly in the swelling element for line passage. This eliminates the need for separate connection assemblies and surface connections, as the swelling element integrates both the sealing function and the control line conduit function. The control lines pass through the swelling element in a protected manner, reducing leakage risks.
3Ease of manufacture
If fiber optic lines are spliced at the surface, then the packer can be installed, but connection cleanliness and reliability are compromised
Solution Approach 1:
The control line passages are prepared in advance as integral parts of the swelling element during manufacturing. The slots are precisely formed with appropriate geometry and positioning before the packer is deployed. This preliminary preparation eliminates the need for field splicing operations, ensuring that fiber optic lines can be installed without compromising connection cleanliness or reliability.
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 design enhances the sealing integrity by reducing leak paths and ensuring full contact with the surrounding tubular, improving the reliability of the seal even in asymmetrical boreholes and accommodating thermal expansion.
Implementation Method 1
Swelling packers respond to well fluids or introduced fluids to grow larger and seal in a wellbore
Implementation Method 2
The ends can overlap each other in a scroll fashion or can be otherwise joined together. An outer tube that can be longitudinally or spirally split is put over the control line underlayment
Data Source
AI summary
A swelling element on a packer has a trough formed on a longitudinal axis. The control line or cable or conduit that needs to run along the string where the packer is mounted is first wrapped in a preferably non-swelling underlayment that can be a loose scroll or have its seam sealed. A swelling cover is placed over the underlayment using a seam that can be longitudinal or spiral to allow rapid deployment. The covering assembly for the control line or conduit is placed in the slot of the swelling element of the packer. The line or cable continues out opposed ends and can be secured to the tubular string with clamps. The control line can be covered with a swelling material and forced into a groove that runs the length of the packer swelling element.