Wellhead Hanger Pack-off Sealing Inner Surface Inversion
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Solution Overview
Problem
Traditional wellhead hanger pack-off assemblies face challenges when the hanger is tilted, as the space on one side is insufficient to accommodate the annular pack-off assembly, increasing installation effort and allowing debris to be trapped, which reduces wear resistance.
Innovation Solution
The hanger and pack-off assembly design features a sealing configuration where the pack-off assembly seals against the inner surface of the wellhead body and hanger, with close tolerances between the surfaces to prevent tilting and reduce debris trapping, using complementary profiles and metal sealing features to enhance wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the hanger is tilted during installation, then the installation process becomes more difficult, but the space available for the pack-off assembly is reduced
Solution Approach 1:
Instead of sealing against the outer surface of the hanger as in traditional designs, this patent seals against the inner surface of the hanger. The pack-off assembly is positioned inside the hanger bore, with sealing elements that engage the inner cylindrical surface of the hanger, inverting the conventional sealing approach to resolve the space constraint problem caused by tilted hanger installation
2Device complexity
If traditional outer surface sealing is used, then the seal configuration is simple, but debris can be trapped between the hanger and wellhead body, reducing wear resistance
Solution Approach 1:
The sealing configuration is inverted by placing the pack-off assembly inside the hanger bore rather than outside. The sealing elements contact the inner surface of the hanger, creating a seal that prevents debris from being trapped between the hanger outer surface and the wellhead body, thereby improving wear resistance while maintaining reasonable design complexity
3Stability of the object's composition
If close tolerances are used between hanger and wellhead body, then tilting is reduced, but manufacturing precision requirements increase
Solution Approach 1:
By inverting the sealing approach to use the inner hanger surface, the patent allows for better alignment stability. The internal sealing configuration provides guidance and centering during installation, reducing tilting without requiring extremely tight manufacturing tolerances on the outer surfaces, as the seal itself helps maintain proper alignment
Data Source
AI summary
Various wellhead assemblies are provided. In one embodiment, the wellhead assemble includes a seal assembly that seals against an inner surface of a wellhead hanger and against an inner surface of a wellhead body. The wellhead hanger can be sized such that the upper portion of the hanger has an outer surface that abuts an inner surface of the wellhead.