Wellhead Hanger Shoulder Restraint Mechanism
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Solution Overview
Problem
In subsea or underwater well drilling, the casing hangers and annulus packoffs may not be sufficiently restrained after the running tool is retrieved, potentially compromising the seal integrity between the hanger and the wellhead.
Innovation Solution
A loading shoulder assembly with an energizing ring, lock ring, loading ring, and hold-down ring is used, featuring angled surfaces and threaded connections to provide a positive lock and restrain the casing hanger and packoff assembly, ensuring a secure seal and preventing movement within the wellhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the running tool is retrieved after setting the hanger and packoff, then the running tool can be reused for subsequent operations, but the hanger and packoff may not be sufficiently restrained and may travel within the wellhead compromising seal integrity
Solution Approach 1:
The loading shoulder is pre-installed in the wellhead housing before the hanger and packoff are set. This preliminary action creates a restraining structure that will automatically engage with the hanger after the running tool is retrieved, preventing the hanger and packoff from traveling within the wellhead and compromising seal integrity.
Solution Approach 2:
The loading shoulder acts as an intermediary component between the wellhead housing and the hanger. It provides a mechanical interface that restrains the hanger vertically, allowing the running tool to be retrieved and reused while maintaining seal integrity through the loading shoulder's restraining action.
2Reliability
If a loading shoulder assembly with multiple rings and threaded connections is installed, then the casing hanger and packoff are securely restrained, but the device complexity increases
Solution Approach 1:
The loading shoulder assembly is divided into multiple functional segments: an energizing ring for initial engagement, a lock ring for securing the assembly, a loading ring for applying restraining force, and a hold-down ring for final positioning. Each segment performs a specific function, allowing the complex restraint mechanism to be broken down into manageable, modular components that can be installed and adjusted independently.
Data Source
AI summary
A well production system including a wellhead and a first casing string supported from a first casing hanger landed on a shoulder in the wellhead bore. A loading shoulder assembly is installable in the wellhead and includes an energizing ring, a loading ring threaded into the interior of the energizing ring, a lock ring, and a hold-down ring threaded into the interior of the loading ring. The hold-down ring engages the first casing hanger to prevent rotation of the hold-down ring and restrain rotation of the loading ring. The lock ring is expandable from an unset position into supporting engagement with the wellhead in a set position upon rotation of the energizing ring. The hold-down ring is also moveable axially out of the loading ring to restrain the first casing hanger.