Wellhead Casing Hanger Profile for Multiple Seal Landing Positions
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Solution Overview
Problem
Existing wellhead assemblies face challenges in effectively isolating high-pressure annular spaces within concentric members, which are critical for preventing pressure leakage and ensuring safe hydrocarbon production.
Innovation Solution
A wellhead assembly design featuring an annular inner member with a curved outer surface and series of sealing areas, paired with an annular outer member having a curved inner surface with complementary sealing areas, utilizes an energizing ring to urge sealing legs into contact with these areas, forming a robust pressure barrier across the annular space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sealing position is used in conventional wellhead assemblies, then the structure is simple, but the reliability of pressure isolation is insufficient under debris or damage conditions
Solution Approach 1:
The sealing structure is divided into multiple independent sealing positions (first sealing position with first seal, second sealing position with second seal) along the axial direction. Each sealing position can independently isolate pressure, and if one seal is compromised by debris or damage, the other sealing positions remain functional, thereby improving reliability without requiring a completely complex system redesign
Solution Approach 2:
The patent provides beforehand protection by incorporating multiple sealing positions and seals in advance. The energizing ring is designed to expand and apply radial outward force to both seals simultaneously, ensuring that even if debris or damage affects one sealing position, the other sealing positions are already in place to maintain pressure isolation, cushioning against potential failure modes
2Reliability
If multiple seals are positioned at different axial locations, then the sealing reliability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The energizing ring is designed to be expandable, allowing it to dynamically adjust its radial outward force to engage multiple seals at different axial positions. This dynamic expansion capability enables the system to accommodate reasonable variations in seal positioning during manufacturing and installation while still achieving reliable sealing contact at all positions, reducing the stringency of manufacturing precision requirements
Solution Approach 2:
The energizing ring changes its physical state from a compressed condition during installation to an expanded condition during operation. This parameter change allows the ring to adapt to the axial spacing between multiple sealing positions, providing consistent radial outward force to engage seals at different locations without requiring extremely tight manufacturing tolerances for seal positioning
3Reliability
If seals are made longer to cover more sealing area, then the sealing contact improves, but the risk of debris interference and damage increases
Solution Approach 1:
Instead of using one long seal that would be vulnerable to debris interference across its entire length, the patent segments the sealing function into multiple shorter seals positioned at different axial locations. Each seal has a limited exposure area, reducing the probability that debris will simultaneously affect the entire sealing interface. The segmented approach maintains overall sealing reliability while minimizing the harmful effects of debris on any individual seal
Solution Approach 2:
Each seal is designed with appropriate local sealing length to ensure adequate sealing contact at its specific axial position, without unnecessarily extending the seal length. The energizing ring provides localized radial outward force to each seal at its respective position, optimizing the sealing contact quality locally while avoiding excessive seal exposure that would increase vulnerability to debris interference and damage
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 design effectively isolates downhole pressure from the wellhead housing, providing a reliable and durable sealing mechanism that maintains pressure integrity even under conditions of debris or damage, with optional secondary seals for enhanced reliability.
Implementation Method 1
an expandable energizing ring... selectively inserted between the inner and outer legs for urging the inner and outer legs respectively into sealing contact
Data Source
AI summary
A wellhead assembly having a wellhead housing, a casing hanger set within the wellhead housing, and sealing areas provided on opposing surfaces of the wellhead housing and casing hanger. The sealing areas circumscribe an axis of the wellhead assembly along respective axial distances on the wellhead housing and casing hanger. A seal is included with the wellhead assembly that has inner and outer legs that respectively engage the sealing areas and form sealing surfaces against the sealing areas. The axial distances of the sealing areas exceeds the length of the inner and outer legs, so that an original seal can be removed and replaced by a secondary seal, wherein the secondary seal engages sealing areas different from the sealing areas engaged by the original seal.