Preloaded Casing Hanger Assembly for Single-Trip Annulus Sealing
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Solution Overview
Problem
Existing casing hanger installation methods require multiple trips and complex mechanical manipulation or hydraulic actuation, leading to potential detachment of parts and increased complexity, especially in subsea environments.
Innovation Solution
A method and tool assembly for installing a casing hanger and annulus seal assembly in a single trip, utilizing a running tool with anti-rotation devices and external locking mechanisms to lock and preload the casing hanger and seal assembly within a wellhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple trips are used to install casing hanger and annulus seal assembly, then installation reliability is improved, but installation time and operational complexity increase
Solution Approach 1:
The patent combines the installation of the casing hanger and annulus seal assembly into a single trip operation. The running tool is configured to lower both components simultaneously, and the locking mechanisms are designed to engage both the casing hanger and seal assembly in one continuous operation, eliminating the need for separate trips that were previously required.
Solution Approach 2:
The running tool is pre-configured with both the casing hanger and annulus seal assembly attached before entering the wellhead. The tool assembly includes pre-positioned locking mechanisms and sealing elements that are ready to engage immediately upon reaching the installation position, allowing both components to be secured in a single continuous operation without requiring intermediate trips.
2Reliability
If complex mechanical manipulation or hydraulic actuation systems are used, then locking reliability is improved, but device complexity increases
Solution Approach 1:
The locking mechanisms are designed to engage automatically through mechanical interaction between components. The casing hanger includes external locking elements that engage with corresponding features in the wellhead, and the annulus seal assembly includes self-actuating sealing elements that expand or engage without requiring external hydraulic pressure or complex actuation systems.
Solution Approach 2:
The patent removes complex hydraulic actuation systems and multi-step mechanical manipulation mechanisms from the installation tool assembly. Instead, it uses simplified mechanical locking elements and self-actuating sealing components that achieve reliable locking through basic mechanical principles, reducing the overall complexity of the device while maintaining installation reliability.
3Ease of operation
If annulus seal assembly is allowed to move cyclically, then ease of installation is improved, but sealing reliability deteriorates
Solution Approach 1:
The annulus seal assembly is pre-positioned on the running tool at the correct height and orientation before installation. The seal elements are pre-compressed or pre-positioned in their sealing configuration, ensuring that when the assembly is lowered into the wellhead, the seal is immediately effective without requiring cyclic movement or adjustment during operation.
4Reliability
If rigidizing nut is used to prevent cyclic movement, then sealing reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The patent removes the rigidizing nut component entirely from the installation system. Instead of using a separate rigidizing nut that requires additional installation steps, the design integrates rigidizing features directly into the running tool and annulus seal assembly, such as pre-positioned sealing elements and integrated locking mechanisms that prevent cyclic movement without requiring additional components or complex installation procedures.
Data Source
Figure 1
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AI summary
A running tool (87) having an annulus seal assembly (86) and casing hanger (89) attached thereto may be sent into to the wellhead (1) to lock and preload the casing hanger (89) in a single trip. The running tool (87) may be rotated a first time to drop the annulus seal assembly on the casing hanger (89), a first pressure may be applied axially above the annulus seal assembly to set the annulus seal assembly, the running tool may be rotated a second time to close a gap between the annulus seal assembly and the wellhead, and a second pressure may be applied axially above the annulus seal assembly to preload the casing hanger.