Offshore Lifting Device Using Spring Stiffness to Reduce Horizontal Loads
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Solution Overview
Problem
Current methods for lifting offshore platforms are either time-consuming, require heavy and expensive lifting vessels, or risk damaging the support structure due to horizontal loads during the lifting process.
Innovation Solution
A support device with a main cylindrical casing, a reservoir for granular or fluid material, and a spring support system that reduces horizontal stiffness during load transfer, allowing for a cost-efficient and reliable lifting operation with reduced risk of structural damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a heavy lift vessel with large capacity cranes is used to lift the topside, then the lifting capacity is sufficient, but the cost and availability of the vessel become problematic
Solution Approach 1:
Instead of using a heavy lift vessel with cranes to lift the topside from above, the invention inverts the approach by using a barge positioned underneath the topside to lift it from below. The barge uses ballast tanks to generate upward buoyant force, reversing the traditional lifting direction and avoiding the need for expensive heavy lift vessels with large capacity cranes.
Solution Approach 2:
The invention employs hydraulic principles through ballast tanks that can be filled or emptied with water to control the lifting force. By adjusting the ballast water volume, the barge can precisely control the upward force applied to the topside, providing a cost-effective alternative to mechanical crane systems.
2Device complexity
If the reversed float-over method is used to lift the topside, then heavy lift vessels are not required, but large horizontal loads are introduced into the support structure
Solution Approach 1:
The invention introduces a dynamic element by allowing the barge to move horizontally independently of the topside during the lifting process. The barge can adjust its position to follow wave motion and wind forces without transferring these horizontal movements to the support structure, thereby eliminating the harmful horizontal loads that plague the traditional float-over method.
Solution Approach 2:
The invention introduces an intermediary system - a horizontal clearance or gap between the barge and the topside support structure - that decouples the barge's horizontal movements from the support structure. This intermediary space allows the barge to absorb environmental forces independently while maintaining vertical lifting capability, preventing force transmission to the support structure.
3Strength
If the topside is removed in small pieces, then the support structure is not overloaded, but the process becomes very time consuming
Solution Approach 1:
The invention applies partial action by using multiple barges simultaneously to lift different portions of the topside structure. Rather than removing the topside in small sequential pieces, several barges work in parallel, each supporting a section of the topside, thereby maintaining structural integrity while dramatically increasing decommissioning speed.
4Force
If a specialized lift vessel such as a purposively built barge is used, then heavy lift vessels are avoided, but the vessel becomes quite expensive to build and operate
Solution Approach 1:
The invention makes the barge design universal and adaptable to different topside sizes and configurations. Rather than building specialized expensive vessels for each project, the standardized barge design with adjustable ballast tanks can be used repeatedly for various decommissioning tasks, reducing construction costs through economies of scale and versatility.
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
The solution enables efficient and safe lifting of offshore platforms by minimizing horizontal loads on the support structure, reducing the risk of damage, and providing a cost-effective method with a large lifting capacity.
Implementation Method 1
a spring device positioned on the spring support, the spring device being compressible in a vertical direction between an extended state and a compressed state
Implementation Method 2
a reservoir located inside the main casing for holding a granular material or a fluid
Data Source
AI summary
A support device configured to be positioned on a lifting vessel in order to support a topside of an offshore platform, the support device comprising: a main cylindrical casing having an upper opening, the main casing defining a main vertical axis, the main casing further defining an upper support rim, a reservoir located inside the main casing for holding a granular material or a fluid, the reservoir having a discharge opening for emptying the reservoir, a spring support slideably arranged within the main casing, the spring support resting on the granular material or the fluid and being movable from an upper position to a lower position in dependence on a filing degree of the reservoir, a spring device positioned on the spring support, a receptor support positioned on the spring device, the receptor support defining an upper surface, and a receptor device.