Offshore Platform Columns with Curved Corners
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Solution Overview
Problem
Existing offshore platforms, particularly tension leg platforms (TLPs) and semi-submersibles, face challenges in deep water operations due to high cyclic fatigue stresses and limited operational flexibility, which affect their structural integrity and longevity.
Innovation Solution
The design incorporates a hull configuration with buoyant columns and pontoons that minimize the platform's response to ocean currents and wave action, featuring curved corner sections and adjustable tendon porches to enhance hydrodynamic properties and reduce fatigue, allowing for more efficient use in deeper waters and varying metocean conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional straight columns and pontoons are used in offshore platforms, then the structure is simpler to manufacture, but the platform experiences high cyclic fatigue stresses from wave action and ocean currents
Solution Approach 1:
The patent applies curved corner sections to both the columns and pontoons instead of straight edges. The columns have curved corners that radius around a center point, and the pontoons have curved ends that radius around a center point. This curvature design reduces the platform's response to wave action and ocean currents, thereby reducing cyclic fatigue stresses on the structure while maintaining manufacturability through standardized curved profiles.
2Device complexity
If the platform uses a compact footprint design, then the mooring system requirements are reduced, but the riser paths may be obstructed
Solution Approach 1:
The patent positions the columns asymmetrically with respect to the platform corners, and the tendon porches are located on the outboard faces of the columns rather than symmetrically distributed. This asymmetric arrangement creates unobstructed pathways for risers to extend from the seabed to the deck while maintaining a compact overall footprint that reduces mooring system requirements.
3Adaptability or versatility
If the platform is designed for deep water operations, then operational flexibility in deeper waters is achieved, but cyclic fatigue stresses from waves and currents increase
Solution Approach 1:
The curved corner sections on columns and pontoons reduce the platform's hydrodynamic response to wave action and ocean currents. By smoothing the transitions at corners and ends, the design minimizes vortex shedding and wave impact forces, thereby reducing cyclic fatigue stresses and maintaining structural integrity in deep water operations where wave loading is more severe.
Solution Approach 2:
The patent modifies the geometric parameters of the columns and pontoons by introducing curved corners with specific radius dimensions. The columns have curved corners that radius around a center point located at a specified distance from the column centerline, and pontoons have curved ends with similar radius specifications. These parameter changes optimize the hydrodynamic performance to reduce fatigue loading while enabling deep water operational flexibility.
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
This configuration reduces cyclic fatigue stresses, increases the operational lifespan of the platforms, and enables them to be used in water depths where conventional platforms cannot, while also providing an unobstructed path for risers and reducing the need for costly mooring systems.
Implementation Method 1
The columns have curved corners that radius around a center point. The pontoons have curved ends that radius around a center point. This configuration reduces the platform's response to wave action and ocean currents.
Implementation Method 2
The platform includes a hull configuration with buoyant columns and pontoons that minimize the platform's response to ocean currents and wave action.
Implementation Method 3
The tethers have relatively high axial stiffness (low elasticity) such that virtually all vertical motion of the platform is eliminated.
Implementation Method 4
A tension leg platform (TLP) is a vertically moored floating structure permanently moored by tethers or tendons grouped at each of the structure's corners.
Data Source
AI summary
A hull, suitable for use as a tension leg platform (TLP) or as a semi-submersible vessel, comprises columns having a generally polygonal transverse cross section at least one axis of which is generally radially aligned with the central vertical axis of the hull. Buoyant, subsurface pontoons interconnect adjacent columns. The pontoons are generally rectangular in cross section and the outboard, generally vertical surface of each pontoon is connected to a side surface of an adjoining column at a location which is substantially inboard of the outermost face of the column. In certain embodiments of the invention, tendon porches (configured to receive the upper tendon connectors of a TLP) are mounted to the outboard surface of one or more pontoons.