Folding Backup Ring for Packer Seals
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Solution Overview
Problem
Existing backup rings for packer sealing elements face challenges in maintaining sealing integrity during axial compression and release, as they can either be too stiff to allow extrusion gaps or too soft to withstand pressure, and may become twisted and stuck in the tubular wall upon release.
Innovation Solution
A folding or collapsing backup ring design with a V-shape configuration, featuring thinner walls at the bend and thicker walls at the extremities, which allows for radial extension without excessive resistance and easy release, providing enhanced strength at the tubular interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the backup ring is made stiff to prevent extrusion, then sealing integrity is improved, but the ring cannot be released easily and becomes twisted and stuck in the tubular wall
Solution Approach 1:
The backup ring is divided into multiple discrete elements rather than being a continuous rigid structure. This segmentation allows each element to move and fold independently, enabling the ring to maintain structural integrity during compression while allowing easy release when compression is removed.
Solution Approach 2:
The backup ring transitions from a static rigid structure to a dynamic collapsible structure. The ring elements are designed to fold and collapse when axial compression is applied, and to unfold and return to original configuration when compression is released, providing both sealing integrity and easy release capability.
2Ease of operation
If the backup ring material is made soft to allow folding, then release ability is improved, but the ring cannot withstand pressure and extrusion occurs
Solution Approach 1:
Different parts of the backup ring structure have different thicknesses and material properties. The walls are thinner at the bend location to facilitate folding and release, while the walls are thicker at the opposed extremities to provide strength and pressure resistance where needed.
Solution Approach 2:
The backup ring utilizes a composite structural design combining varying wall thicknesses within the same component. This creates a composite structure that integrates both flexible regions (thinner walls at bends) for easy release and rigid regions (thicker walls at extremities) for pressure resistance.
3Ease of operation
If the backup ring is made thin-walled to reduce resistance during folding, then release ability is improved, but the ring lacks strength to prevent extrusion
Solution Approach 1:
The backup ring employs non-uniform wall thickness distribution, with thinner walls specifically at the bend locations to reduce resistance during folding operations, while maintaining thicker walls at the opposed extremities to provide sufficient strength for extrusion resistance and pressure containment.
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 design effectively prevents extrusion during compression and facilitates easy release by minimizing resistance and stress concentration, maintaining sealing integrity while avoiding twisting and sticking issues.
Implementation Method 1
When packer sealing elements are axially compressed to grow in radial dimension to the surrounding tubular they have a tendency to axially extrude. As a result backup rings are used to close the extrusion gap
Implementation Method 2
The present invention uses a folding or collapsing design for the backup rings that features a thinner wall at the bend location and a thicker wall at the opposed extremities
Implementation Method 3
The legs in that instance can be thicker than the vertex thickness to aid in folding while providing enhanced strength at the surrounding tubular where shear forces apply as a result of seal compression against the surrounding tubular
Data Source
AI summary
A backup ring design for a packer sealing element features a folding shape where opposed legs are pushed together for extension in a radial direction toward the surrounding tubular to span the extrusion gap. The design can use a V-shape where the vertex is toward the mandrel and the legs are oriented toward the surrounding tubular. The legs in that instance can be thicker than the vertex thickness to aid in folding while providing enhanced strength at the surrounding tubular where shear forces apply as a result of seal compression against the surrounding tubular. The design features a single or multiple vertices that are similarly aligned or alternatingly oppositely aligned to create a zigzag shape in cross-section. Material selection can vary with the expected service conditions.