Wellhead Lock Ring and Packoff Axial Installation
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Solution Overview
Problem
Existing wellhead systems face challenges in securely locking components and sealing annular spaces without causing damage through rotation, which can lead to increased installation complexity and risk of component damage.
Innovation Solution
The use of locking assemblies with an actuator that expands a lock ring radially to secure components axially within the bore, and sealing packoffs with inner and outer annular seals and an energizing ring to apply biasing forces, allowing for axial installation and setting without rotation, utilizing friction for retention and simplifying the installation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional locking mechanisms are used to secure components within the bore, then component retention is achieved, but rotation is required which increases installation complexity and risk of component damage
Solution Approach 1:
The locking mechanism inverts the traditional rotational engagement approach by using axial compression to expand a lock ring radially against the bore wall. The actuator applies axial force to compress the lock ring, which then expands radially to engage with the bore wall, eliminating the need for rotation during installation.
Solution Approach 2:
The locking assembly is divided into distinct functional segments: the actuator for applying axial force, the lock ring for radial engagement, and the retaining feature for maintaining position. This segmentation allows each component to perform its specific function independently, simplifying the overall installation process while ensuring reliable retention.
2Reliability
If traditional sealing mechanisms are used to seal annular spaces, then sealing is achieved, but rotation is required which increases installation complexity and risk of component damage
Solution Approach 1:
The sealing mechanism inverts the traditional rotational engagement approach by using axial compression to expand sealing elements radially against the bore wall. The actuator applies axial force to compress the packoff assembly, which then expands the inner and outer annular seals radially to seal the annular space, eliminating the need for rotation during installation.
Solution Approach 2:
The sealing mechanism utilizes parameter changes in the elastomeric material properties under compression. When the actuator applies axial compressive force, the elastomeric seals experience increased radial expansion due to material elasticity, enabling them to conform to the bore wall and create an effective seal without rotational movement.
3Reliability
If locking assemblies and packoffs are designed for secure retention and sealing, then reliability is improved, but the device complexity increases
Solution Approach 1:
The locking assembly merges the locking function and sealing function into a single integrated assembly that operates through the same axial compression mechanism. The lock ring and annular seals are compressed simultaneously by the actuator, allowing both retention and sealing to be achieved in one operation without requiring separate mechanisms.
Solution Approach 2:
The actuator serves multiple functions: it applies axial compression to the lock ring for retention, compresses the annular seals for sealing, and maintains both functions during operation. This multi-functionality reduces the overall device complexity by eliminating the need for separate locking and sealing mechanisms.
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
This solution enables secure component retention and sealing without the need for rotation, reducing the risk of damage and installation complexity, while also allowing for a more compact wellhead design and simplified tooling, with the locking assemblies and packoffs being effective in high-pressure and temperature environments.
Implementation Method 1
utilizing friction for retention
Implementation Method 2
apply a radially inward biasing on the inner annular seal and a radially outward biasing force on the outer annular seal
Data Source
AI summary
A packoff and a locking assembly installed in a bore of a wellhead component are provided. In one embodiment, a packoff includes inner and outer annular seals and an energizing ring shaped to be wedged between the inner and outer annular seals so as to apply a radially inward biasing force on the inner annular seal and a radially outward biasing force on the outer annular seal. In another embodiment, a locking assembly includes a lock ring that extends into a recess in a wall of the bore of the wellhead component and an actuator radially disposed between an inner component within the bore and the lock ring to retain the lock ring within the recess. The actuator can have an interference fit with the inner component to inhibit movement of the actuator between the lock ring and the inner component. Additional systems, devices, and methods are also disclosed.