Offset Recess Semi-Submersible Hull Design
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Solution Overview
Problem
Conventional semi-submersible offshore platforms face challenges in maintaining balance and stability when accommodating large facilities, leading to potential shifts in the point of balance and reduced storage capacity, especially in deep water environments.
Innovation Solution
A semi-submersible platform body with a cross section design where the centre point of the open recess is offset from the centre point of the platform body, allowing for asymmetric side wall thickness and configuration, which enables compensation for shifts in balance and gravity, thereby accommodating various facilities without customizing them to fit the platform's balance point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional semi-submersible platforms use symmetric hull structures with columns to maintain stability, then the platform achieves appropriate stability and resistance to environmental forces, but the point of balance becomes fixed and cannot accommodate facilities that may shift the balance point
Solution Approach 1:
The patent applies asymmetry by intentionally designing the hull structure with asymmetric characteristics, where the centre of buoyancy is deliberately offset from the centre of gravity. This asymmetric configuration allows the platform to accommodate facilities that may shift the point of balance in unwanted directions, while the asymmetric hull form provides the necessary stability through its inherent geometric properties.
Solution Approach 2:
The patent utilizes parameter changes by making the centre of buoyancy movable relative to the centre of gravity through the asymmetric hull design. This allows the platform to dynamically adjust its balance point in response to facility placements, effectively changing the positional parameters of the buoyancy and gravity centres to maintain overall stability.
2Quantity of substance
If the platform uses a fixed symmetric hull structure, then manufacturing and construction are simplified, but the storage capacity is reduced when ballast is moved to compensate for balance shifts
Solution Approach 1:
The asymmetric hull structure eliminates the need for ballast movement to compensate for balance shifts, as the asymmetric design inherently accommodates facility-induced balance changes. This maintains full storage capacity without requiring operational ballast transfers, while the asymmetric form factor remains manufacturable using conventional hull construction methods.
3Stability of the object's composition
If columns are used to support the deck and minimize environmental force effects, then the platform achieves stability with multiple support points, but pipes and drilling equipment are subjected to the same environmental forces
Solution Approach 1:
The patent segments the platform structure into distinct functional zones: the asymmetric hull provides stability and buoyancy, while the deck area accommodates facilities and equipment. This segmentation allows the hull to bear the primary environmental loads while reducing the exposure of sensitive equipment on the deck to direct environmental forces.
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 design enhances the platform's versatility and stability, allowing for the positioning of facilities like LNG plants without compromising storage capacity, by effectively managing the centre of gravity and buoyancy, and reducing the strain on risers and drilling equipment.
Implementation Method 1
The centre point of the cross section of the open recess is displaced from the centre point of the cross section of the platform body. This provides for a shift in horizontal centre of buoyancy which permits a corresponding shift in centre of gravity
Data Source
AI summary
The present invention relates to a semi-submersible platform body for supporting drilling, storing, treatment or production of hydrocarbons. The platform body have a cross section with a center point in a first plane, and is defined by a side wall formed by at least one side wall section, the side wall is arranged around the periphery of an open recess. Each side wall section comprises a first and a second side, an upper and a lower edge, the first and second side of the side wall section defines at least a first side wall thickness. The first side of the side wall section faces away from the open recess and the second side of the side wall section faces towards the open recess. The mentioned open recess has a cross section with a center point in the first plane. Further is the center point of the cross section of the open recess displaced a distance in the first plane, from the center point of the cross section of the platform body. The present invention provides for a flexible and versatile platform body which is disposed of the need for custom applications of heavy equipment or facilities in order to prevent displacement of the center of buoyancy.