Sliding Sleeve Axial Force Packer Retraction
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Solution Overview
Problem
Inflatable packers in downhole tools often retain a large outer diameter after deflation due to high temperatures, causing difficulties in tool removal and potential damage or sticking within boreholes, especially when deployed via a drill string.
Innovation Solution
A mechanism involving a sliding sleeve and pump module that applies axial force to the packer by pumping pressurized fluid into a chamber, allowing for controlled retraction of the packer and preventing inadvertent expansion during tool rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inflatable packer is used to seal against a borehole, then hydraulic isolation is achieved, but the packer retains a large outside diameter after deflation due to high temperatures, preventing tool removal
Solution Approach 1:
The packer assembly incorporates a sliding member that can move axially relative to the tool body, transitioning the packer from a static sealed state to a dynamic retracted state. This dynamic mechanism allows the packer to be actively pulled back into the tool body after deflation, overcoming the elastic recovery that prevents natural contraction in high-temperature environments.
Solution Approach 2:
The invention replaces reliance on passive elastic recovery with an active mechanical retraction system. A sliding member with seals and a actuation mechanism (such as a wire rope, hydraulic cylinder, or mechanical advantage system) substitutes for the insufficient natural elasticity of the packer material in high-temperature conditions.
2Adaptability or versatility
If a packer element is left unsecured during rotation, then the downhole tool can rotate freely, but the packer may inadvertently expand and become wedged in the borehole, causing damage or sticking
Solution Approach 1:
The sliding member applies preliminary axial force to the packer element before rotation occurs, pre-compressing or pre-constraining the packer in its deflated state. This preliminary anti-action prevents the packer from expanding outward during rotation, counteracting the harmful effect before it can occur.
Solution Approach 2:
The mechanism performs preliminary retraction or constriction of the packer element prior to the rotation operation. By securing the packer in a compact state before rotation begins, the system eliminates the risk of inadvertent expansion during the rotational movement through the borehole.
3Reliability
If the packer is inflated to seal the borehole, then formation isolation is achieved, but the elastic material loses mechanical strength in high temperatures, reducing retraction effectiveness
Solution Approach 1:
The sliding member acts as an intermediary mechanical element between the actuation system and the packer element. It transfers and amplifies the retraction force, compensating for the reduced mechanical strength of the elastomeric packer material in high-temperature environments. The intermediary mechanism provides the additional force needed to overcome the weakened material's resistance to compression.
Solution Approach 2:
The system changes the physical state or properties of the packer assembly by applying axial compression through the sliding member. This parameter change (applying external compressive force) compensates for the temperature-induced degradation of the material's inherent elastic properties, enabling effective retraction despite the material's reduced strength.
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
Enables safe and efficient removal of downhole tools from boreholes by reducing the packer's outer diameter and preventing unwanted expansion, thereby minimizing damage and stuck-tool scenarios.
Implementation Method 1
pumping pressurized fluid into a chamber formed between a sliding sleeve coupled to an end of the packer and a body of the downhole tool
Implementation Method 2
An inner portion of the sleeve is sealed against the body of the downhole tool to form a chamber, and the chamber is fluidly coupled to a pump associated with the downhole tool to receive a pressurized fluid to cause the sleeve to apply an axial force to the packer
Data Source
AI summary
Methods and apparatus to apply axial force to a packer in a downhole tool are described. In one described example, an apparatus to apply an axial force to an inflatable packer associated with a downhole tool includes a sleeve slidingly coupled to a body of the downhole tool and an end of the packer. An inner portion of the sleeve is sealed against the body of the downhole tool to form a chamber, and the chamber is fluidly coupled to a pump associated with the downhole tool to receive a pressurized fluid to cause the sleeve to apply an axial force to the packer.