Self-Adjusting Seal Assembly for Wellhead Lock Ring Fit
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Solution Overview
Problem
Conventional seal assemblies for wellheads require multiple trips and time-consuming installation processes to adjust for axial movement of casing hangers due to thermal expansion, leading to seal wear and inefficiency.
Innovation Solution
A self-adjusting actuator in the seal assembly expands the lock ring radially to fit the wellhead profile, ensuring a secure seal without gaps, allowing for a single trip installation and eliminating the need for additional measurement tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional seal assembly is used with lead impression tool measurements, then the seal assembly can be adjusted to fit the wellhead profile, but the installation process requires multiple trips and is time-consuming
Solution Approach 1:
The actuator is pre-configured with a stop mechanism that automatically limits the expansion of the lock ring to prevent over-expansion. This preliminary action eliminates the need for post-installation adjustments and multiple trips, as the seal assembly is self-regulating from the start of installation.
Solution Approach 2:
The actuator automatically adjusts the lock ring expansion based on the wellhead profile through its stop mechanism, eliminating the need for external measurement tools and manual adjustment. The system serves itself by automatically finding the correct expansion point without requiring multiple trips for measurements and adjustments.
2Reliability
If the lock ring is expanded radially outward to secure the casing hanger, then axial movement is prevented, but the expansion may cause over-expansion and seal wear without proper control
Solution Approach 1:
The stop mechanism is designed to preemptively counteract the harmful effect of over-expansion before it occurs. As the actuator expands the lock ring radially outward, the stop mechanism engages at the precise moment when optimal contact with the wellhead profile is achieved, preventing any further expansion that would cause seal wear or damage.
3Manufacturing precision
If the seal assembly is adjusted at the surface before installation, then the correct pre-load can be achieved, but additional measurement tools and multiple trips are required
Solution Approach 1:
The actuator with its integrated stop mechanism performs the adjustment function automatically during installation. The stop mechanism is designed to engage at the precise point where the correct pre-load is achieved, eliminating the need for external measurement tools and surface adjustments. The system self-regulates to achieve the correct pre-load accuracy.
4Measurement precision
If a lead impression tool is used to measure the distance, then the seal assembly length can be adjusted, but the process requires retrieving the tool to surface and multiple trips
Solution Approach 1:
The actuator with its stop mechanism eliminates the need for external measurement tools entirely. The stop mechanism is pre-configured to automatically identify the correct expansion point based on the wellhead profile, providing the same measurement precision functionally without requiring lead impression tools, retrieval trips, or manual measurements.
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 self-adjusting actuator provides a rigidized seal connection, preventing axial movement and reducing installation time and costs by allowing a single trip installation process.
Implementation Method 1
an actuator capable of transferring an axial force from the actuator into outward radial expansion of the lock ring
Data Source
AI summary
A system includes a seal assembly configured to retain a casing hanger within a wellhead. The seal assembly includes a main body; a lock ring coupled to the main body and configured to expand radially outward into a profile on an inner diameter of the wellhead; and an actuator, wherein the actuator is capable of transferring an axial force from the actuator into outward radial expansion of the lock ring until a tapered portion of the lock ring directly contacts a corresponding tapered portion of the profile, regardless of an initial distance from the lock ring to the profile prior to actuation of the lock ring.