Downhole Retaining Ring Dampener for Slip Wedging
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Solution Overview
Problem
Downhole tools, such as bridge plugs, face challenges in maintaining proper sealing and engagement with the well casing due to the spring effect of retaining rings, which can cause premature movement and failure to set or operate correctly under high differential pressures.
Innovation Solution
Incorporating a retaining ring with a dampener, or spring suppressor, made from materials like fiberglass composite with affixed rubber, to reduce the spring effect and enhance holding force, allowing the retaining ring to break and move radially outward without wedging or preventing proper engagement with the casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a retaining ring is used to hold slip segments in an unset position, then the slip segments are retained securely, but the retaining ring exhibits a spring effect upon breaking that causes it to move away and potentially wedge between the slip segments and casing, preventing proper tool setting
Solution Approach 1:
The retaining ring is divided into multiple discrete retaining segments rather than a continuous ring. Each segment is retained in a groove and can break independently. This segmentation reduces the spring effect because the energy release is distributed across multiple smaller segments rather than one large continuous ring, while still providing sufficient holding force through the collective action of all segments.
Solution Approach 2:
Different portions of the retaining ring system have different properties - the retaining segments have high strength for holding, while the grooves and damping features are designed to control the breakage behavior. The local geometry of the grooves and the material properties are optimized to minimize spring effect in specific areas while maintaining overall holding strength.
2Ease of operation
If the retaining ring is designed to break upon slip segment expansion, then the slip segments can move outward to engage the casing, but the breaking process releases stored energy that causes the retaining ring to spring away and wedge, preventing proper engagement
Solution Approach 1:
By segmenting the retaining ring into multiple independent segments, the energy release during breakage is divided into smaller increments. This prevents the large spring effect that would occur with a continuous ring breaking, thereby eliminating the wedging problem while still allowing slip segments to expand freely.
Solution Approach 2:
The groove geometry and damping features are designed beforehand to absorb and dissipate the energy released when retaining segments break. This pre-designed cushioning prevents the segments from springing away violently and wedging between the slip segments and casing, ensuring smooth expansion operation.
3Stability of the object's composition
If a continuous retaining ring is used, then it provides uniform holding force around the slip segments, but it releases large amounts of energy upon breaking causing significant spring effect and potential wedging
Solution Approach 1:
The continuous retaining ring is replaced with multiple discrete retaining segments distributed around the slip segments. This maintains uniform holding force through the collective action of all segments while reducing the energy released upon breakage, as each segment breaks independently with minimal energy release.
Solution Approach 2:
The design changes the physical parameters of the retaining structure - from a continuous high-strength ring to multiple smaller segments with optimized geometry. This parameter change reduces the stored elastic energy in each segment while maintaining the overall holding capability through the combined effect of all segments.
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
The solution effectively suppresses the spring effect of the retaining ring, ensuring it stays in place and maintains the tool's sealing and operational integrity, even under high loads, by reducing the energy released upon breakage, thus preventing premature movement and ensuring secure anchoring of the downhole tool.
Implementation Method 1
The dampener will dampen, or suppress the spring effect that would occur if the retaining band were used without the dampener
Implementation Method 2
The retaining rings often have a 'spring effect' upon breaking which causes the broken retaining band to spring with enough energy to move away from the slip segments
Data Source
AI summary
A downhole tool has a mandrel and an expandable packer element for sealingly engaging the well. A slip assembly is positioned on the mandrel and will anchor the downhole tool in the well. The slip assembly may include a slip ring that moves from an unset to a set position. A retaining ring is disposed about the slip ring and will hold the slip ring in the unset position until sufficient force is applied to break the retaining ring. The retaining ring may comprise a retaining band with a dampener to suppress the spring effect experienced by the retaining band when it breaks upon the application of force.