Disconnectable Mooring Element for Cylindrical FPSO Relocation
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Solution Overview
Problem
Current turret-moored FPSO systems become complex with increasing production lines, making it difficult for cylindrical FPSOs to easily leave their offshore location for maintenance or harsh weather conditions without a disconnectable mooring and riser system.
Innovation Solution
A disconnectable mooring and riser system for cylindrical FPSOs, featuring a cylindrical mooring element with tension members and propulsion means housing, allowing stable engagement and disengagement with the FPSO, enabling easy relocation and reconnection while maintaining stability and facilitating riser positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a turret-moored FPSO system is used to allow the FPSO to weathervane into the most favourable heading, then the FPSO can operate in harsh environments, but the system becomes increasingly complex with increasing number of production lines (risers)
Solution Approach 1:
The system is divided into separate functional modules: a disconnectable mooring element, independent tension members, and separate propulsion means. This segmentation allows each component to be optimized independently and simplifies the overall system architecture, resolving the complexity issue while maintaining adaptability.
Solution Approach 2:
The mooring system incorporates dynamic elements including tension members that can be actively adjusted, propulsion means for repositioning, and a disconnectable mooring element that can move between engaged and disengaged states. This dynamic capability enables the system to adapt to varying operational requirements without increasing permanent complexity.
2Ease of operation
If a disconnectable mooring system is implemented to allow the FPSO to easily leave the offshore location, then the FPSO can be relocated for maintenance or repairs, but the mooring system requires additional operating means for engagement and disengagement
Solution Approach 1:
The FPSO's own propulsion means are utilized to facilitate the engagement and disengagement operations. The propulsion system, already necessary for repositioning the FPSO, serves dual purposes: moving the FPSO to the mooring location and assisting in the connection/disconnection process. This eliminates the need for separate, complex operating means.
Solution Approach 2:
The propulsion means of the FPSO is designed to perform multiple functions: normal navigation, repositioning over the mooring element, and assisting in the engagement/disengagement operations. This multi-functionality reduces the total number of specialized components required while maintaining ease of operation.
3Ease of operation
If the mooring element has specific weight to float at a pre-determined depth below sea level when disconnected, then the FPSO is free to move away easily, but the mooring element requires precise buoyancy control
Solution Approach 1:
The mooring element incorporates variable buoyancy characteristics through adjustable ballast systems or movable counterweights. By changing the weight parameter dynamically, the system can achieve precise buoyancy control to float at the predetermined depth when disconnected, enabling easy FPSO separation while maintaining manufacturing feasibility.
Solution Approach 2:
The system includes sensors and control mechanisms that monitor the mooring element's depth and position. This feedback enables real-time adjustments to buoyancy, ensuring the element maintains the predetermined depth when disconnected. The feedback loop compensates for manufacturing tolerances and environmental variations, achieving precise buoyancy control.
4Reliability
If the mooring element comprises a recess for housing the propulsion means of the FPSO, then the propulsion means can be protected when not in use, but the mooring element design becomes more complex
Solution Approach 1:
The propulsion means is housed within a recess in the mooring element, creating a nested configuration where one component (propulsion means) is integrated into another (mooring element). This nesting provides protection for the propulsion means while utilizing the existing mooring element structure, minimizing additional design complexity.
Solution Approach 2:
The mooring element design combines multiple functions: mooring attachment, propulsion means housing, and structural support. By merging these functions into a single integrated component rather than separate elements, the system achieves propulsion protection without proportionally increasing overall complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables easy movement and reconnection of cylindrical FPSOs, providing stability and efficient riser management, suitable for harsh environments and reducing installation complexity.
Implementation Method 1
the mooring element has such a specific weight that, when disconnected from the FPSO, it floats at a pre-determined depth below the sea level
Data Source
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AI summary
System for mooring a substantially cylindrical floating production, storage and offloading unit (FPSO) (2), comprising a substantially cylindrical mooring element (1) having un upper side for engaging the lower side of the FPSO, further comprising mooring lines (4) for connection to the seabed, and operating means for realising an engagement between the mooring element (1) and the FPSO (2), wherein the mooring element (1) has such a specific weight that, when disconnected from the FPSO, it floats at a certain depth below the sea level.