General information
A concrete Gravity Based Structure (GBS) for offshore oil production usually consists of a base caisson supporting several vertical columns which in turn support a deck containing productions facilities. Since the base of a GBS is large, it is easy to adapt it for oil storage. Some of the first were built for deep water fields in the Norwegian sector of the North Sea. The Troll platform in 303 m water depth remains the tallest object ever moved over the face of the earth. Gravity Based Structures (GBS) are now seriously considered as LNG import terminal. When the environment of wind and waves is strongly directional, with an optimum orientation of the GBS a significant shielding can be achieved, reducing the weather downtime.
A concrete Gravity Based Structure (GBS) for offshore oil production usually consists of a base caisson supporting several vertical columns which in turn support a deck containing productions facilities. Since the base of a GBS is large, it is easy to adapt it for oil storage. Some of the first were built for deep water fields in the Norwegian sector of the North Sea. The Troll platform in 303 m water depth remains the tallest object ever moved over the face of the earth. Gravity Based Structures (GBS) are now seriously considered as LNG import terminal. When the environment of wind and waves is strongly directional, with an optimum orientation of the GBS a significant shielding can be achieved, reducing the weather downtime.
Services & Activities
The Offshore Department is has been involved in many issues related to Gravity Based Structures:
Because of the optimized heading of a LNG GBS beam to the dominant sea direction, typically the survival conditions will be beam to the GBS as well. This means that the wave run-up and possible green water on the deck of the GBS is a problem that needs serious evaluation, see movies. This run up problem is studied numerically with the ComFLOW program.
Also the hydrodynamics of offloading from Gravity Based Structures is complex: this relates to the multi-body interaction in the wave forces, added mass and damping, but also to the drift forces. Further the viscous damping of the surge, sway, yaw and roll motion of the vessel in close proximity of another structure is a complex issue. This types of problems are studied in the basin or with the LIFSIM / aNySIM program
Other issues relate to the transportation of the GBS to the field, the lowering at its locations and the installation of decks on the GBS with a floatover installation method.
The Trials & Monitoring Department can be involved in full-scale measurements on Gravity Based Structures. Loads can be measured and analysed.
The Offshore Department is has been involved in many issues related to Gravity Based Structures:
Because of the optimized heading of a LNG GBS beam to the dominant sea direction, typically the survival conditions will be beam to the GBS as well. This means that the wave run-up and possible green water on the deck of the GBS is a problem that needs serious evaluation, see movies. This run up problem is studied numerically with the ComFLOW program.
Also the hydrodynamics of offloading from Gravity Based Structures is complex: this relates to the multi-body interaction in the wave forces, added mass and damping, but also to the drift forces. Further the viscous damping of the surge, sway, yaw and roll motion of the vessel in close proximity of another structure is a complex issue. This types of problems are studied in the basin or with the LIFSIM / aNySIM program
Other issues relate to the transportation of the GBS to the field, the lowering at its locations and the installation of decks on the GBS with a floatover installation method.
The Trials & Monitoring Department can be involved in full-scale measurements on Gravity Based Structures. Loads can be measured and analysed.
Facilities & Tools
FPSOs are tested in the following MARIN facilities :
FPSOs are tested in the following MARIN facilities :
- Offshore Basin: DP model tests in combined current, waves and wind
- Shallow Water Basin: DP model tests in combined current, waves and wind
- Seakeeping and Manoeuvring Basin: model tests in waves
The behaviour of FPSOs is simulated with the following tools :
DIFFRAC: 3-D potential theory including wave diffraction
DRIFTP/DBDRIFT: Second order wave excited (drift) forces
LIFSIM/LIFMOT: Analysis of multi body dyamics and lift operations
GREENLAB: Green Water Analysis
DRIFTP/DBDRIFT: Second order wave excited (drift) forces
LIFSIM/LIFMOT: Analysis of multi body dyamics and lift operations
GREENLAB: Green Water Analysis
Software Sales
Some software tools are available for commercial use outside MARIN. A complete overview of these software tools for sale can be found under Software Sales.
Some software tools are available for commercial use outside MARIN. A complete overview of these software tools for sale can be found under Software Sales.
Experience record
The list below gives a review of FPSO model tests carried out at MARIN :
The list below gives a review of FPSO model tests carried out at MARIN :
- LNG carrier – GBS interaction tests (MARIN, 2004)
- LNG GBS wave run up tests (Shell, 2004)
- Bayu Undan GBS wave run up and mooring tests (BHP, 1996)
- Wandoo GBS lowering and deck floatover tests (Wandoo Alliance, 1996)
- Troll GBS transportation tests (Norwegian Contractors/Shell, 1993)
Most recent papers on GBS presented by MARIN
(complete overview of papers can be found under Publications)
(complete overview of papers can be found under Publications)
Evaluating the Loading and Structural Response of an Offshore Platform Using Integrated Large and Small Scale Testing Combined With Diffraction and Finite Element Analysis and Offshore Measurements
Bas Buchner, Robert Heerink and Jaap de Wilde (MARIN), Joel Witz (Hess) and Karen la Cour Hjelholt (Ramboll), Offshore Technology Conference (OTC), 2009
Viscous Damping of Vessels Moored in Close Proximity of Another Object
Gerrit de Boer and Bas Buchner, ISOPE Conference, Seoul, 2005
Wave Run Up as Important Hydrodynamic Issue for Gravity Based Structures
Loots, Erwin and Buchner, Bas, OMAE Conference, Vancouver, 2004
Hydrodynamics aspects of Gravity Based Structures as LNG import terminal in shallow water
Buchner, B., Loots, G.E and Forristal, G.Z, OTC Conference, Houston, 2004
The Interaction Effects of Mooring in close Proximity of Other Structures
Buchner, Bas, de Wilde, Jaap and de Boer, Gerrit, ISOPE Conference, Toulon, 2004
Bas Buchner, Robert Heerink and Jaap de Wilde (MARIN), Joel Witz (Hess) and Karen la Cour Hjelholt (Ramboll), Offshore Technology Conference (OTC), 2009
Viscous Damping of Vessels Moored in Close Proximity of Another Object
Gerrit de Boer and Bas Buchner, ISOPE Conference, Seoul, 2005
Wave Run Up as Important Hydrodynamic Issue for Gravity Based Structures
Loots, Erwin and Buchner, Bas, OMAE Conference, Vancouver, 2004
Hydrodynamics aspects of Gravity Based Structures as LNG import terminal in shallow water
Buchner, B., Loots, G.E and Forristal, G.Z, OTC Conference, Houston, 2004
The Interaction Effects of Mooring in close Proximity of Other Structures
Buchner, Bas, de Wilde, Jaap and de Boer, Gerrit, ISOPE Conference, Toulon, 2004
GBS articles written for MARIN Report
(complete overview of articles can be found under Publications)
(complete overview of articles can be found under Publications)
Shuttle tool now ready for side-by-side Offloading Operations
Arjan Voogt, MARIN Report, 2009
GBS run up study combats hurricane aftermath
Erwin Loots, MARIN Report, 2003
MARIN focus on SHELL’s offshore LNG developments
Bas Buchnner, MARIN Report, 2003
Arjan Voogt, MARIN Report, 2009
GBS run up study combats hurricane aftermath
Erwin Loots, MARIN Report, 2003
MARIN focus on SHELL’s offshore LNG developments
Bas Buchnner, MARIN Report, 2003
Contact
For more information on how MARIN can help your organisation with GBS, please contact:
For model test and simulation activities: Offshore Department
For full-scale measurements: Trials & Monitoring Department
For more information on how MARIN can help your organisation with GBS, please contact:
For model test and simulation activities: Offshore Department
For full-scale measurements: Trials & Monitoring Department