Buoyant Hull and Truss Assembly via Vertical Mating
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Solution Overview
Problem
The existing methods for constructing and assembling offshore oil drilling and production facilities, such as spar type structures and semi-submersibles, face limitations due to the need for horizontal assembly and upending, which restricts hull size and increases geographical, weather, and geotechnical risks, particularly when transporting and assembling in shallow waters or onshore facilities.
Innovation Solution
A method for assembling a buoyant hull and truss structure at the intended deployment site, involving mooring the hull, transporting and launching the truss structure into the water, upending it, and using haul-in and ballast control lines to position and attach it to the hull, allowing for rigid attachment and adjustment of the draft for operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If horizontal assembly and transport of spar structure is used, then assembly can be done at inshore facility, but draft exceeds dredged depths in inland navigable channels
Solution Approach 1:
The spar structure is divided into multiple horizontal sections that can be assembled separately at inshore facilities and then joined vertically at the offshore site. This segmentation allows each section to have a manageable draft for inshore assembly while the complete structure achieves the required vertical height and function offshore.
Solution Approach 2:
The assembly process transitions from horizontal assembly at inshore facilities to vertical assembly at the offshore site. By changing the dimensional orientation from horizontal to vertical, the structure can be assembled in shallow waters and then configured in its final vertical orientation where the full draft is accommodated by the deeper offshore environment.
2Ease of manufacture
If horizontal assembly of hard tank or truss sections is used, then assembly can be completed onshore, but draft exceeds water depths in inshore assembly areas
Solution Approach 1:
The hard tank or truss sections are segmented into smaller modular units that can be assembled in shallow inshore waters. These modules are then joined vertically at the offshore location where sufficient water depth accommodates the complete assembled height, resolving the conflict between shallow assembly depth and final structure height.
3Ease of manufacture
If complete hull is assembled horizontally, then full structure can be constructed, but size and weight exceed hydrodynamic stability capabilities of heavy lift transport vessels
Solution Approach 1:
The complete hull is divided into smaller weight modules that can be individually transported by available heavy lift vessels. These segments are assembled vertically at the offshore site, combining multiple lighter transport operations into one complete structure, thereby avoiding the need for a single oversized transport vessel.
4Ease of operation
If traditional upending sequence is used, then spar structure can be positioned vertically, but numerous restrictions complicate and limit the size of hull that can be constructed
Solution Approach 1:
The structure is preliminarily assembled in a horizontal configuration at inshore facilities where access and maneuverability are easier. This preliminary horizontal assembly avoids the complexities of assembling large structures vertically in constrained inshore environments, and the structure is then transitioned to its final vertical configuration offshore where space and maneuverability are less constrained.
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 approach enables the assembly of larger offshore structures at the deployment site, reducing geotechnical and weather risks, towing distances, and exposure times, while avoiding the limitations of traditional construction and transportation methods.
Implementation Method 1
a buoyant hull (10) is moored in place
Implementation Method 2
ballast control lines to allow the truss structure to be pulled into engagement with the buoyant hull
Data Source
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AI summary
A method of mating of a buoyant hull with a truss structure while at the installation site of the completed offshore structure is described. The buoyant hull can be moored in place. The truss structure can be placed in the water, self upended, and maneuvered near the buoyant hull. The buoyant hull and truss structure can be rigged with lines to allow the truss structure to be pulled into engagement with the buoyant hull. The truss structure can be lowered to a predetermined depth below the water surface but above the sea floor and the weight can be transferred to the lines from the buoyant hull. The truss structure can be aligned with the buoyant hull and lines from the buoyant hull can be used to pull the truss structure into engagement with the buoyant hull. The truss structure and buoyant hull can be rigidly attached together.