Wellhead Annulus Seal With Dual-Side Pressure Energization
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Solution Overview
Problem
Conventional metal-to-metal annulus seals in wellheads lack pressure-energization from below, leading to reduced sealing reliability and increased mechanical force requirements at high pressures, which can result in seal failure and increased system deflections.
Innovation Solution
Incorporating notches on the seal that allow pressurized fluid to act on movable portions, such as wings or lips, to provide additional energization from below, complementing the initial energization by an e-ring, thereby enhancing sealing reliability and reducing mechanical preload needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal-to-metal annulus seals are used without pressure-energization from below, then the seal structure is simple, but the sealing reliability deteriorates at high pressures
Solution Approach 1:
The seal is divided into multiple functional segments: a rigid seal body, movable portions (wings/lips) that can deflect under pressure, and notches that enable fluid access. This segmentation allows each part to perform its specific function - the rigid body provides structural support while the movable portions provide pressure-energized sealing contact
Solution Approach 2:
The seal incorporates movable portions (wings or lips) that are capable of dynamic deflection in response to pressure differentials. These portions move from a neutral position to engage with the opposing surface when pressure acts on them through the notches, providing adaptive sealing that responds to operating conditions
2Force
If conventional metal-to-metal seals rely solely on mechanical preload, then the seal structure is simple, but the mechanical force requirements increase at high pressures
Solution Approach 1:
The seal utilizes hydraulic pressure from the fluid itself to energize the sealing action. Pressure differentials across the seal body force fluid through the notches onto the movable portions, which then deflect to engage with the opposing surface, converting fluid pressure into sealing force
Solution Approach 2:
The seal uses the process fluid's own pressure to energize itself. The pressure differential that exists during operation automatically drives fluid through the notches to act on the movable portions, eliminating the need for external energization systems or excessive mechanical preload
3Adaptability or versatility
If notches with movable portions are added to provide pressure-energization from below, then the sealing reliability improves across wider pressure ranges, but the device complexity increases
Solution Approach 1:
The seal has different local properties: rigid regions provide structural support and positioning, while localized movable portions (wings/lips) provide pressure-responsive sealing contact. The notches are strategically positioned to allow fluid access only to specific areas, creating localized pressure-energized zones where needed
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 ensures a more reliable seal across a wider range of pressures with reduced mechanical force requirements, maintaining contact pressure and preventing seal disengagement, even under high pressure conditions, by utilizing fluid pressure to enhance seal engagement with the wellhead and hanger surfaces.
Implementation Method 1
Fluid is received in the one or more notches. The one or more movable portions are enabled to press against the internal diameter of the wellhead and the hanger surface, thereby providing a second sealing based at least in part on the pressurization of the area behind (and optionally, under) the one or more notches
Data Source
AI summary
A system is disclosed as including a seal for sealing an area between a hanger and a housing of a wellhead. The seal is provided with at least a notch that defines at least a movable portion such as a wing or a lip. An e-ring is provided for a first energizing of the seal. The movable portion enables pressurized fluid from beneath the seal to cause the movable portion to protrude further against a mating side in the wellhead and the hanger for a second energizing of the seal. This type of seal maintains or improves the sealing of the wellhead in high pressure applications. Methods applied to the above seal are also disclosed.