Wellhead Annular Seal Assembly With Rigid-Flexible Load Paths
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Solution Overview
Problem
Existing wellhead annular seal systems face challenges in maintaining integrity under pressure due to relative movement between the lockdown ring and wellhead housing, leading to seal degradation, as the system struggles to accurately align components amidst debris and varying positions.
Innovation Solution
An annular seal system with an actuator ring featuring both rigid and flexible portions, where a rigid load path ensures the seal's axial position is locked, and a flexible load path allows variability in the lockdown ring's position relative to the wellhead housing, reducing play and maintaining seal integrity by decoupling axial loads through a compliant support member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lockdown ring is directly engaged with the wellhead housing to maintain seal position, then the seal's axial position is stable, but relative movement occurs between the lockdown ring and wellhead housing due to debris and positional variations, leading to seal degradation
Solution Approach 1:
The actuator ring transitions from a rigid structure to a compliant structure by changing its material or structural parameters, allowing it to deform and absorb misalignment between the lockdown ring and wellhead housing, thereby preventing seal degradation while maintaining seal position stability
Solution Approach 2:
The actuator ring is constructed as a composite structure combining rigid and flexible portions, where the rigid portion maintains structural integrity and the flexible portion accommodates positional variations, resolving the contradiction between stability and alignment tolerance
2Manufacturing precision
If the actuator ring is made completely rigid to maintain precise seal positioning, then positioning accuracy is improved, but axial loads are transmitted to the seal assembly causing degradation
Solution Approach 1:
The actuator ring is divided into distinct rigid and flexible segments, where the rigid portion provides precise positioning and the flexible portion isolates the seal from axial loads, simultaneously achieving positioning accuracy and seal durability
Solution Approach 2:
The flexible portion of the actuator ring acts as an intermediary element between the rigid structure and the seal assembly, absorbing axial loads and preventing their transmission to the seal, while the rigid portion maintains positioning accuracy
3Adaptability or versatility
If the lockdown ring is allowed to move freely relative to the wellhead housing to accommodate debris, then adaptability is improved, but play between components increases leading to seal degradation
Solution Approach 1:
The actuator ring's flexibility parameter is optimized to allow controlled movement that accommodates debris and positional variations while limiting excessive play, thereby maintaining both adaptability and seal integrity
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 maintains the seal's integrity by reducing play between components and absorbing or limiting axial loads, thereby enhancing the system's ability to withstand pressure and maintain accurate positioning despite debris and positional variations.
Implementation Method 1
the flexible portion of the actuator ring adapted to axially compress to allow positional variation between the lockdown ring and the wellhead housing
Data Source
AI summary
An annular seal system for sealing between a casing hanger and a wellhead housing, the system including an actuator ring having a rigid portion and a flexible portion, and a lockdown ring positioned adjacent the actuator ring. The annular seal system further includes a seal assembly capable of moving between a de-energized position and an energized position, wherein the seal assembly in the de-energized position has a defined a space between the seal assembly and the rigid portion of the actuator ring, wherein the seal assembly in the energized position has the space closed, wherein the rigid portion of the actuator ring is to contact a surface of the casing hanger, wherein the flexible portion of the actuator ring is to push the lockdown ring into engagement with the wellhead, and wherein the flexible portion of the actuator ring adapted is to axially compress to allow positional variation between the lockdown ring and the wellhead housing.