Wedge Spiral Back-Up Ring for Packer Extrusion
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Solution Overview
Problem
Current packer assembly designs for oil wells are limited by pressure capabilities and durability under high pressure conditions, and they struggle to effectively retain sealing pressure and prevent extrusion of packer elements.
Innovation Solution
A back-up ring assembly with a wedge-shaped spiral ring that expands up a conical surface to retain a packer element, forming a labyrinth seal and providing spring force to maintain sealing pressure and prevent extrusion, while being retrievable due to its ability to return to an unexpanded configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current packer assembly designs are used, then basic sealing function is provided, but pressure retention capability and durability under high pressure conditions are limited
Solution Approach 1:
The back-up ring is pre-positioned between the packer element and retainer before expansion occurs. When the packer element expands, the back-up ring is already in place to immediately engage with the conical surface and provide structural support, preventing premature failure under high pressure conditions
Solution Approach 2:
The back-up ring is constructed from high-strength, pressure-resistant materials that combine durability with the ability to expand elastically. This composite approach integrates a rigid structural component with flexible expansion capability, enabling the assembly to maintain both strength and reliability under high pressure
2Stress or pressure
If packer element is expanded to provide sealing, then sealing pressure is achieved, but extrusion of packer element may occur
Solution Approach 1:
The back-up ring serves as an intermediary component between the packer element and retainer. It mediates the interaction by providing a controlled engagement surface that allows the packer element to expand and achieve sealing pressure while preventing uncontrolled extrusion through the labyrinth seal geometry
Solution Approach 2:
The conical surface engagement and labyrinth seal geometry utilize curved surfaces to distribute forces evenly across the packer element. The curved engagement surface between the back-up ring and conical surface prevents stress concentration, maintaining position stability while allowing necessary expansion for sealing
3Stress or pressure
If back-up ring expands to retain packer element, then sealing pressure is maintained, but retrieval difficulty increases
Solution Approach 1:
The back-up ring is designed with dynamic expansion and contraction capability. It expands during operation to provide strong retention and sealing pressure, then contracts during retrieval to reduce engagement force. This dynamic behavior allows the same component to excel at both pressure retention and ease of retrieval
Solution Approach 2:
The retrieval function is merged into the same back-up ring structure that provides pressure retention. The spiral geometry and elastic properties of the back-up ring allow it to perform both sealing/retention and retrieval functions without requiring separate mechanisms, simplifying the overall assembly while maintaining both capabilities
4Adaptability or versatility
If mechanical set or hydraulic pressure set element packers are used, then well segment isolation is achieved, but pressure capability limitations exist
Solution Approach 1:
The back-up ring is segmented into spiral sections that can independently engage and expand. This segmentation allows each section to adapt to local pressure conditions while collectively providing enhanced overall pressure capability, enabling the packer to maintain well segment isolation at higher pressures than conventional designs
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 enhances the pressure retention and durability of packer assemblies by forming a labyrinth seal and maintaining sealing pressure, while the spring force aids in retrieval and reduces the likelihood of pressure loss, making it suitable for high-pressure conditions.
Implementation Method 1
The at least one wedge shaped spiral ring may act as a spring force as it expands up the conical face of the at least one retainer
Implementation Method 2
The at least one wedge shaped spiral ring may act as a spring force as it expands up the conical face of the at least one retainer and contacts the casing or liner
Implementation Method 3
the spring force aids in retrieval and reduces the likelihood of pressure loss
Data Source
Figure 1~2A
Figure 2B~3A
Figure 3B~3C
AI summary
A method of retaining a packing element including utilizing a back-up ring assembly in contact with at least one packing element, the assembly comprising: at least one wedge shaped spiral ring comprising: at least one outer circumferential face configured to contact a wellbore casing or liner; at least one conical, inner circumferential face configured to contact a portion of a retainer with a conical face; and an axial end face configured to contact the at least one packing element. A back-up ring assembly including at least one wedge shaped spiral ring comprising: at least one outer circumferential face configured to contact a wellbore casing or liner; at least one conical, inner circumferential face configured to contact a portion of a retainer with a conical face; and an axial end face configured to contact a packing element.