Inline Subsea Accessory Structure With Foldable Mudmat Support
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Solution Overview
Problem
Current marine pipelaying techniques face challenges in efficiently integrating large in-line accessory structures, particularly in S-lay operations, due to space constraints on pipelaying vessels and the need for extensive mudmat support systems, which limits the size and stability of accessories that can be deployed on the seabed.
Innovation Solution
The design of a compact in-line subsea structure with inclined branches and foldable mudmats that expand upon deployment, allowing for reduced bulk during transit and enhanced stability, featuring a foundation that can be moved from a stowed to a deployed state to support the accessory and pipeline, minimizing the overall size and center of gravity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If large in-line accessory structures are deployed on the seabed, then operational flexibility and field layout capabilities are improved, but the structure requires extensive mudmat support systems which increases device complexity and limits deployment capability
Solution Approach 1:
The in-line accessory structure is divided into separate components: the accessory itself, a support frame, and a foundation system. This segmentation allows each component to be optimized independently and simplifies the overall deployment process, as the foundation can be prepared separately from the accessory installation.
Solution Approach 2:
The foundation is prepared and positioned on the seabed before the accessory is installed. This preliminary action allows the foundation to be independently deployed using standard pipelaying equipment, and the accessory is subsequently mounted onto the prepared foundation, simplifying the overall deployment process.
2Stability of the object's composition
If accessories are supported by a foundation on the seabed, then stability is improved, but the overall size and center of gravity of the structure increase
Solution Approach 1:
The support frame is designed with movable and adjustable components that can be configured in different positions and orientations. This dynamic design allows the frame to provide stable support while minimizing the overall volume of the structure, as components can be positioned to optimize both stability and compactness.
3Volume of moving object
If foldable mudmats are used, then the structure size during transit is reduced, but the mechanism for moving from stowed to deployed state increases device complexity
Solution Approach 1:
The mudmats are designed as foldable structures that can be collapsed into a compact configuration during transit and then deployed to a flat configuration on the seabed. The foldable design uses simple hinge connections that allow easy deployment without requiring complex mechanisms, achieving both compact storage and stable support.
4Productivity
If in-line accessory structures are integrated during S-lay operations, then pipelaying speed is improved, but space constraints on the vessel limit the size of accessories that can be deployed
Solution Approach 1:
The in-line accessory structure is segmented into separate components (accessory, support frame, foundation) that can be prepared and positioned independently. This segmentation allows the components to be installed in a compact sequence during S-lay operations, fitting within the space constraints of the vessel while maintaining pipelaying speed.
Solution Approach 2:
The foundation and support frame are prepared and positioned on the vessel before the accessory is installed. This preliminary preparation allows the components to be staged in a compact arrangement that fits within vessel space constraints, while enabling rapid assembly during the pipelaying operation.
Data Source
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AI summary
An in-line accessory structure for a subsea pipeline comprises an elongate pipe section arranged to be integrated into the pipeline, hence defining a flow axis through the structure. A branch has a lower end in fluid communication with the pipe section and an upper end in fluid communication with a connector hub. The structure further comprises a subsea foundation such as a mudmat, arranged to support the structure in an installed orientation. When the structure is in that orientation, the branch inclines inwardly from its lower end toward its upper end in a transverse direction, toward an upright longitudinal plane containing the flow axis.