Wellhead Wicker Recesses to Prevent Hydraulic Lock in Seal Rings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Trapped liquids between wickers in subsea wellhead assemblies can lead to hydraulic lock and reduced effectiveness of the seal ring due to high pressure buildup, limiting the depth of engagement and seal efficiency.
Innovation Solution
Incorporating recesses through the wickers to allow trapped fluids to flow out, ensuring the wickers do not seal with the seal surfaces, and using metal-to-metal sealing bands with specific dimensions and configurations to enhance the sealing engagement and prevent axial movement restrictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wickers are used to form seals and resist axial movement, then sealing effectiveness and axial resistance are improved, but trapped liquid causes hydraulic lock and reduces seal ring engagement depth
Solution Approach 1:
The wicker structure is segmented by introducing recesses that divide the continuous wicker into sections. These recesses allow trapped liquid to escape while the remaining wicker segments maintain sealing and axial resistance functions, resolving the contradiction between seal effectiveness and engagement depth.
Solution Approach 2:
The harmful trapped liquid is extracted from the wicker structure through recesses. By providing escape pathways for the liquid, the hydraulic lock is eliminated, allowing the seal ring to engage deeper into the wickers without restriction, thus improving engagement depth while maintaining seal effectiveness.
2Reliability
If wickers embed into seal ring surface to form seals, then sealing and axial resistance are achieved, but trapped liquid builds up pressure and restricts embedding depth
Solution Approach 1:
The wicker is segmented by recesses that create channels for liquid escape. This segmentation allows the wicker to embed deeper into the seal ring surface while trapped liquid can escape through the recesses, preventing pressure buildup and enabling greater embedding depth while maintaining seal formation.
Solution Approach 2:
The recesses act as intermediary channels that facilitate liquid escape between the wicker and seal ring interface. These channels mediate between the sealing function (requiring contact) and the hydraulic lock problem (requiring liquid escape), allowing deep embedding while preventing pressure buildup.
3Reliability
If metal-to-metal sealing bands are used with wickers, then sealing engagement is enhanced, but trapped liquid still causes hydraulic lock
Solution Approach 1:
The sealing bands are designed with integrated recesses in the wicker structure that segment the liquid-trapping zones. This allows metal-to-metal sealing engagement to occur while providing escape pathways for liquid, eliminating hydraulic lock while maintaining enhanced sealing engagement.
Solution Approach 2:
The harmful trapped liquid is extracted from the sealing interface through recesses in the wicker structure. This extraction eliminates hydraulic lock while allowing the metal-to-metal sealing bands to maintain their enhanced sealing engagement function.
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 recesses in the wickers prevent fluid entrapment, reducing the likelihood of hydraulic lock and allowing for deeper engagement of the seal ring, thereby improving the seal efficiency and effectiveness.
Implementation Method 1
A recess extends through each of the ridges from the upper flank to the lower flank to allow any fluid trapped between the ridges to flow out
Implementation Method 2
The crests of the ridges embed into said at least one of the seal surfaces
Implementation Method 3
The running tool pushes an energizing ring into the slot, which radially deforms the inner and outer legs into sealing engagement with the wellhead housing and the casing hanger
Implementation Method 4
The embedded wickers form seals as well as resisting axial movement of the seal assembly relative to the wellhead and casing hanger
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
A wellhead assembly includes a wellhead housing having a bore with a wellhead housing sidewall and a longitudinal axis. A hanger lands in the bore, the hanger having a hanger sidewall. Parallel circumferentially extending hanger sidewall ridges are located on the hanger sidewall. Each of the hanger sidewall ridges have upper and lower flanks that converge to a crest. Hanger sidewall bands are located between adjacent ones of the hanger sidewall ridges. A metal seal ring has an outer seal surface in metal -to-metal sealing engagement with the wellhead housing sidewall and an inner seal surface in metal -to-metal sealing engagement with the hanger sidewall bands. Crests of the hanger sidewall ridges embed into the inner seal surface to restrict relative movement between the hanger and the seal ring. A recess extends through each of the hanger sidewall ridges from the upper flank to the lower flank to allow any fluid trapped between the hanger sidewall ridges to flow out.