Subsea Wellhead Load Relief Device for Riser System Loads
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Solution Overview
Problem
Existing subsea wellhead assemblies face challenges in reducing riser system-induced load effects, leading to potential structural failure and uncontrolled release of well fluids, with current solutions being time-consuming and cumbersome during installation and retrieval.
Innovation Solution
A wellhead load relief device with an adjustable support mechanism that provides a lateral support for well control equipment, allowing forces to be transferred directly to the seabed without going through the wellhead, thereby reducing horizontal shear loads and bending moments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If well control equipment is directly supported by the subsea wellhead, then the structure is simple, but the riser system induces excessive load effects on the wellhead causing potential structural failure
Solution Approach 1:
The support function is segmented between two independent structures: the subsea wellhead (providing fluid well access) and the load relief device (providing mechanical support). This separation allows each component to be optimized for its specific function, reducing the load burden on the wellhead while maintaining structural simplicity through modular design.
Solution Approach 2:
A load relief device acts as an intermediary structure between the well control equipment and the seabed. This mediator captures and redirects the riser system loads directly to the seabed foundation, preventing these loads from being transmitted through the wellhead structure, thereby protecting it from excessive stress.
2Reliability
If tensioned lines are used to tether well control equipment to reduce wellhead loads, then load reduction is achieved, but installation and retrieval become time consuming and cumbersome
Solution Approach 1:
The flexible tensioned line system is replaced with a rigid mechanical support structure featuring lateral supports and positioning mechanisms. This mechanical system provides more efficient load transfer and enables faster, more reliable installation and retrieval operations compared to the cumbersome tensioned line arrangement.
Solution Approach 2:
The support mechanism incorporates adjustable and movable components that can dynamically adapt during installation and retrieval operations. This dynamic capability allows for quick configuration changes and simplifies the operational procedures, reducing the time required for installation and retrieval while maintaining effective load management.
3Force
If the support mechanism provides rigid lateral support, then load transfer to seabed is improved, but the device complexity increases
Solution Approach 1:
The support mechanism is divided into distinct functional segments: lateral supports for horizontal stabilization, positioning mechanisms for precise location, and load transfer components for vertical force transmission. This segmentation allows each element to be optimized independently, achieving effective load transfer while keeping individual components relatively simple.
Solution Approach 2:
The support mechanism is designed with multi-functional components that perform multiple roles. For example, the lateral supports not only provide horizontal stabilization but also contribute to the overall structural rigidity and load distribution. This multi-functionality reduces the total number of separate components needed, thereby limiting the increase in device complexity.
Data Source
AI summary
A wellhead load relief device for reducing riser system induced load effects on a subsea wellhead and a method of installing a subsea wellhead assembly onto a subsea wellhead using the wellhead load relief device. The wellhead load relief device includes: a receptacle for receiving well control equipment, wherein the receptacle has an open top to permit the well control equipment to be received in the receptacle; and an adjustable support mechanism for rigidly supporting well control equipment received in the receptacle. The adjustable support mechanism is located within the receptacle and the adjustable support mechanism has a lateral extent that is adjustable relative to the receptacle. The wellhead load relief device is for providing a load path for forces exerted on the well control equipment to the seabed without going via the subsea wellhead. A subsea wellhead assembly including the wellhead load relief device is also provided.