Unitary Seal Assembly Radial Preloading for Wellhead Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing seal assemblies for wellhead and hanger applications often fail to effectively seal under high temperature and high pressure conditions, and they tend to lose sealing effectiveness over time due to axial travel and radial gap creation when fluid pressure is applied, which compromises their sealing performance.
Innovation Solution
A unitary seal assembly with C-shaped locking members and an actuation mechanism that preloads the wellhead and hanger surfaces radially outward and inward, respectively, to maintain a reliable seal under high fluid pressure, using a seal body with radially internal and external seals and a force tool for installation and engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional threaded components are used to connect seal body components, then assembly is easier to manufacture, but axial travel between components causes seal wear and reduces sealing reliability
Solution Approach 1:
The patent merges multiple seal body components into a single unitary seal body structure. This eliminates the threaded connections between separate components that cause axial travel and seal wear. The unitary structure provides inherent axial rigidity while maintaining manufacturing feasibility through monolithic construction methods.
2Stress or pressure
If high fluid pressure is applied from below the seal assembly, then the wellhead interior surface expands radially outward and the hanger exterior surface contracts radially inward, but this creates a significant radial gap that reduces sealing effectiveness
Solution Approach 1:
The patent applies preliminary radial preloading forces through the unitary seal body structure before fluid pressure is applied. The seal body is designed to exert continuous radial outward force on the wellhead interior surface and radial inward force on the hanger exterior surface, creating a pre-compression that counteracts the gap-opening effect of subsequent fluid pressure application.
Solution Approach 2:
The patent changes the radial position parameters of the sealing surfaces by designing the unitary seal body with specific radial dimensions and stiffness characteristics. This allows the seal assembly to maintain optimal radial contact pressure under varying fluid pressure conditions, preventing gap formation while accommodating thermal and pressure-induced expansions.
3Reliability
If high seal setting forces are applied, then sealing effectiveness is improved, but it becomes difficult to transmit these forces through a seal body with threaded components
Solution Approach 1:
The patent combines multiple force transmission elements into the unitary seal body structure, eliminating the weak threaded connections that limit force transmission. The monolithic structure provides direct load paths from the actuation mechanism to the sealing surfaces, enabling high seal setting forces to be transmitted efficiently without component failure or excessive axial travel.
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 seal assembly effectively maintains a reliable seal under both high fluid pressure from below and above, preloading the wellhead and hanger surfaces to prevent radial gap formation, ensuring consistent sealing performance and withstanding significant radial forces, thus enhancing sealing effectiveness and durability.
Implementation Method 1
An actuation member axially movable downward through a portion of the unitary body forces the second locking ring radially outward for engagement with the wellhead
Implementation Method 2
forces the first locking ring radially inward for engagement with the hanger
Implementation Method 3
a lower portion with one or more radially internal seals for sealing with the exterior hanger surface and one or more radially exterior seals for sealing with the wellhead surface
Data Source
AI summary
A seal assembly (10) is provided for sealing between an interior surface (14) on a wellhead (12) and a tapered exterior surface (18) on a hanger (16). A unitary seal body (20) includes an upper portion for engagement with a force tool and a lower portion for sealing with the wellhead and the hanger. A first locking ring (24) is movable radially inward for securing the sealing assembly to the hanger, and a second locking ring (22) is movable radially outward for securing the seal assembly to the wellhead. An actuation member (60) including a plurality of downward extending fingers passing through slots in the seal body move downward through a portion of the body to force the first and second locking rings into engagement with the wellhead and the hanger.