Floating Production Unit Hull Design with Moonpool for Riser Protection
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Solution Overview
Problem
Deep-sea hydrocarbon drilling and production face challenges with flexible risers in harsh weather conditions, as they require complex buoyancy elements to carry their own weight, and existing floating production units have limitations in load capacity, suspension, and protection against waves and ice.
Innovation Solution
A floating production unit with a hull design that allows for the use of loose hanging steel or titanium risers, featuring a moonpool for riser suspension and protection, with a buoyancy center positioned below the center of gravity, and a conical moonpool shape for angular deflections, enabling stable operation and reduced wave movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flexible risers are used in deep sea situations, then the ability to counteract relative movements between production unit and connection point is improved, but the complexity and cost increase due to required buoyancy elements
Solution Approach 1:
The patent extracts and removes the buoyancy elements from the riser system, allowing the use of simple steel catenary risers instead of complex flexible risers with buoyancy modules. The risers are made of steel and arranged in catenary formation, eliminating the need for buoyancy elements while maintaining the ability to counteract relative movements through the catenary configuration itself.
2Device complexity
If rigid risers are used to reduce complexity and cost, then device complexity is reduced, but the ability to handle deep sea conditions and relative movements becomes limited
Solution Approach 1:
The patent applies dynamics by allowing the risers to move and deflect dynamically in response to wave movements and relative motions between the production unit and seabed connection point. The catenary configuration enables the risers to adapt their shape and position dynamically, providing both simplicity and deep sea performance capability.
3Stability of the object's composition
If the production unit is designed for stability with center of buoyancy below center of gravity, then stability is improved, but the ability to accommodate various tools and equipment with different load capacities is limited
Solution Approach 1:
The patent extends the platform structure vertically with a tower rising from the cylindrical platform base. This dimensional extension provides additional space and structural capacity to accommodate various tools, equipment, and processing facilities with different load requirements, while the base platform maintains its stable configuration with center of buoyancy below center of gravity.
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 efficient and cost-effective hydrocarbon production and storage in deep waters by allowing risers to carry their own weight, reducing complexity and risk of incidents like explosions and fires, while maintaining stability and reducing wave-induced movements.
Implementation Method 1
a buoyancy center positioned below the center of gravity
Implementation Method 2
a conical moonpool shape for angular deflections
Data Source
AI summary
A floating production unit is operable for production and storage of hydrocarbons. The production unit exhibits in operation movement properties rendering connection of one or more loose hanging risers (5) of suitable material possible. Such a unit comprises a hull (1) and a deck (4) in an upper end of the hull, the deck being equipped adequately in accordance with the intended application. The floating production unit is distinguished in that the hull (1) is configured to allow suspension of the riser (5) on at least one frame (6) arranged in a shaft/moonpool (3) in a center of the hull (1) wherein vertical movements of the hull (1) are minimized, and that the moonpool (3) of the unit surrounds and protects an upper part of the one or more risers (5) and fixed tubes for transfer of fluid to a processing facility of the production unit against external forces such as waves, ice and vessel collisions, in addition to corresponding protection during connection of the one or more risers (5) unto the at least one frame (6).