Multi-Level Slip Hanger for Load Transfer and Seal Integrity
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Solution Overview
Problem
Traditional casing hangers face issues with load distribution and sealing integrity, leading to potential failure and high maintenance costs due to varying loads and thermal expansion, with single-point sealing causing leaks and difficulty in repair.
Innovation Solution
A multi-level slip hanger system with upper and lower slips, a compressible seal, and load transfer bolts that distribute weight across multiple points, ensuring consistent sealing by engaging lower slips when needed, using a shear ring to transfer load and a compressible seal to adapt to changing loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional single-level casing hanger is used, then the structure is simple, but the sealing reliability deteriorates due to single-point sealing vulnerability
Solution Approach 1:
The hanger is divided into multiple levels with upper slips, lower slips, and intermediate slips, each capable of independent engagement with the casing. This segmentation allows the sealing function to be distributed across multiple locations, so that failure at one sealing point does not compromise the entire sealing system. The multi-level structure creates redundant sealing paths that enhance overall sealing reliability.
Solution Approach 2:
The invention transitions from a single-level sealing approach to a multi-level vertical arrangement. By adding the vertical dimension with multiple sealing interfaces at different heights, the system gains redundancy and robustness. The load transfer mechanism operates vertically to activate lower sealing levels, creating a three-dimensional sealing architecture that prevents leaks even when one level fails.
2Reliability
If the casing hanger supports full casing weight continuously, then the hanger design is simple, but the seal performance deteriorates due to excessive or insufficient loading
Solution Approach 1:
The hanger employs a dynamic load transfer mechanism where the upper slips initially support the casing weight, and as the casing settles, the load is progressively transferred to the lower slips through load transfer bolts. This dynamic redistribution ensures that the seal remains properly loaded throughout the operational life of the hanger, accommodating thermal expansion and contraction of the casing without losing sealing effectiveness.
Solution Approach 2:
The holding screws are designed to be removed prior to casing installation, allowing the upper slips to initially engage and support the casing. This preliminary configuration enables the system to adapt to the actual casing weight and thermal conditions before the full load transfer mechanism activates, ensuring optimal seal performance from the beginning of operation.
3Reliability
If a single sealing location is used, then the device complexity is low, but the reliability deteriorates due to single-point failure risk
Solution Approach 1:
The sealing system is segmented into multiple independent sealing locations corresponding to upper slips, intermediate slips, and lower slips. Each sealing location can function independently, and the failure of one sealing interface does not necessarily lead to overall sealing failure. This segmentation creates a redundant sealing architecture that significantly improves reliability.
Solution Approach 2:
Each sealing location is equipped with its own compressible seal and loading mechanism, allowing local adaptation to casing conditions. The compressible seals at different levels can independently compensate for local variations in casing roundness, surface condition, and thermal expansion, ensuring that each sealing interface maintains its integrity under local conditions.
4Reliability
If the casing weight varies due to thermal expansion, then the operating conditions change, but the seal pre-loading is reduced causing seal loss
Solution Approach 1:
The multi-level slip mechanism provides dynamic adaptability to thermal expansion and contraction. As the casing expands or contracts with temperature changes, the slips can move relative to each other along the casing surface, maintaining continuous contact and seal pre-loading. The load transfer bolts allow progressive engagement of lower slips, ensuring that seal loading is maintained throughout thermal cycles.
Solution Approach 2:
The system allows changes in the positional parameters of the slips relative to the casing as thermal expansion occurs. The slips can slide along the casing surface while maintaining engagement, and the compressible seals can deform to accommodate parameter changes in casing dimensions, thereby maintaining effective seal pre-loading under varying thermal conditions.
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 system provides reliable load distribution and sealing across varying loads, maintaining integrity and reducing maintenance by adapting to thermal expansion, preventing leaks, and minimizing repair costs.
Implementation Method 1
The compressible seal can be positioned between the upper and lower slips. The load transfer bolt can be positioned to transfer force through the compressible seal.
Implementation Method 2
The compressible seal can be made of an elastomer, metal, flexible graphite, thermoplastic or composite materials.
Implementation Method 3
The lower slips can be supported out of contact from the adjacent casing by a shear ring.
Implementation Method 4
Slip type casing hangers used to support a casing string by engaging the casing with wedge-type members (slip segments).
Data Source
AI summary
A casing hanger and seal system for supporting a casing string in a hydrocarbon well. The hanger can have a deformable seal with an ability to transfer force through the seal to a lower portion of the hanger. The hanger can have multiple slips which engage a casing wall and support an upper casing string independent from the deformable seal such that changes in the forces being supported cannot disengage the seal when positioned.