Swivel Stack Buoy Connection System for Rapid Disconnection
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Solution Overview
Problem
Existing subsea connection systems between floating units and buoys face challenges in maintaining orientation, rapid and controlled connection/disconnection, and fluid drainage to prevent pollution, especially in adverse weather conditions, requiring flexible and minimally invasive solutions.
Innovation Solution
A system utilizing a swivel stack arrangement with a turret bearing for controlled orientation and a drainage system, allowing for lateral movement and rapid disconnection, with integrated actuator-controlled isolation valves and a temporary locking mechanism for secure coupling and decoupling, facilitating fluid transfer and minimizing vessel modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the buoy is equipped with anchoring devices to the seabed, then the buoy can maintain position independently, but the connection system becomes more complex and requires additional components
Solution Approach 1:
The system separates the anchoring function (buoy to seabed) from the connection function (buoy to vessel). The buoy can be anchored independently using simple anchoring devices, while the connection to the vessel uses a dedicated swivel stack arrangement with locking mechanisms. This segmentation allows each subsystem to be optimized independently, maintaining reliability without excessive overall complexity.
2Adaptability or versatility
If the vessel uses dynamic positioning with engines to stay in position, then the vessel can operate without anchoring, but the connection system requires more complex positioning control and may fail in bad weather
Solution Approach 1:
The system prepares for adverse weather conditions by implementing a rapid disconnection capability and a drainage system that can be activated before disconnection occurs. The drainage system empties hydrocarbon compounds from pipes and valves before the vessel must disconnect in bad weather, preventing pollution. The temporary locking arrangement and swivel stack arrangement are designed to withstand storm forces, cushioning against the effects of severe weather on the connection.
3Reliability
If the connection system is designed for rapid disconnection in sudden weather changes, then safety is improved, but the complexity of control systems and drainage mechanisms increases
Solution Approach 1:
The drainage system is designed to be activated before disconnection occurs, preliminarily emptying hydrocarbon compounds from pipes and valves. The temporary locking arrangement is engaged before the actual disconnection of locking devices, ensuring controlled separation. This preliminary action sequence ensures safety and prevents pollution without requiring complex real-time control during the disconnection event itself.
4Reliability
If the buoy must maintain original orientation relative to wells while the vessel rotates, then pipe and cable connections are protected, but the connection system requires a swivel mechanism adding complexity
Solution Approach 1:
The swivel stack arrangement combines multiple functions into a single integrated structure: it provides the swivel mechanism for orientation control, incorporates the temporary locking arrangement for secure connection, and integrates the drainage system for hydrocarbon removal. The actuator-controlled isolation valves are integrated into the stack arrangement. This merging reduces overall system complexity compared to having separate systems for each function.
5Adaptability or versatility
If the connection system is designed to work with as many types of vessels as possible, then versatility is improved, but the system requires more standardized and potentially less optimized components
Solution Approach 1:
The swivel stack arrangement is designed as a universal interface that can connect to different types of buoys and be mounted on various vessel types (production vessels, storage vessels, offloading vessels, floating platforms). The standardized connection interface and mounting system allow the same basic design to be adapted to different applications without requiring complete redesign, balancing versatility with manufacturing efficiency.
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The present invention relates to a connection system and a method for connecting and disconnecting a floating unit to and from a buoy which is connected to a subsea installation, where the buoy comprises a first connection device for connecting pipes and/or lines for transfer of fluid, control signals and/or electric power between the buoy and the floating unit. The connection system further comprises a support structure which is laterally movable relative to the floating unit and a swivel stack arrangement movably mounted on the support structure. The swivel stack arrangement comprises a second connection device for connecting to the first connection device in the buoy; shut-off devices for opening and closing at least one of the pipes and/or lines in the first and second connection devices by connecting and disconnecting the buoy; and a turret bearing for rotating the buoy relative to the floating unit.