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A gravity-based structure (GBS) is a support structure held in place by
Early deployments of offshore
gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
, most notably offshore oil platforms
An oil platform (or oil rig, offshore platform, oil production platform, and similar terms) is a large structure with facilities to extract and process petroleum and natural gas that lie in rock formations beneath the seabed. Many oil platf ...
. These structures are often constructed in fjords
In physical geography, a fjord or fiord () is a long, narrow inlet with steep sides or cliffs, created by a glacier. Fjords exist on the coasts of Alaska, Antarctica, British Columbia, Chile, Denmark, Germany, Greenland, the Faroe Islands, Icela ...
due to their protected area and sufficient depth.
Offshore oil platforms
Prior to deployment, a study of the seabed must be done to ensure it can withstand the vertical load from the structure.Dean, E.T.R. (2010). Offshore Geotechnical Engineering - Principles and Practice. Thomas Telford, Reston, VA, U.S.A., 520 p. It is then constructed with steelreinforced concrete
Reinforced concrete (RC), also called reinforced cement concrete (RCC) and ferroconcrete, is a composite material in which concrete's relatively low ultimate tensile strength, tensile strength and ductility are compensated for by the inclusion ...
into tanks or cells, some of which are used to control the buoyancy. When construction is complete, the structure is towed to its intended location.
Wind turbines
Early deployments of offshore wind power
Wind power or wind energy is mostly the use of wind turbines to generate electricity. Wind power is a popular, sustainable, renewable energy source that has a much smaller impact on the environment than burning fossil fuels. Historically ...
turbines used these structures. As of 2010, 14 of the world's offshore wind farms had some of their turbines supported by gravity-based structures. The deepest registered offshore wind farm with gravity-based structures is Thornton Bank 1, Belgium, with a depth up to 27.5 m. Newer generations of wind turbines are much larger, and deployed in deeper waters, gravity based structures are no longer considered competitive in comparison to support structures such as the floating moored.
See also
*Offshore concrete structure Offshore concrete structures have been in use successfully for about 50 years. They serve the same purpose as their steel counterparts in the oil and gas production and storage. The first concrete oil platform has been installed in the North Sea in ...
* List of tallest oil platforms
This is a list of the tallest oil platforms over in height. The current highest oil platform is the Petronius platform operated by Chevron Corporation and Marathon Oil in the Gulf of Mexico, 210 km southeast of New Orleans, United States.
...
* Troll A platform
The Troll A platform is a Condeep gravity-based structure offshore natural gas platform in the Troll gas field off the west coast of Norway. Built from reinforced concrete, , it was the tallest structure that has ever been moved to another posit ...
* Gullfaks C
Gullfaks is an oil and gas field in the Norwegian sector of the North Sea operated by Equinor. It was discovered in 1978, in block 34/10, at a water depth of 130-230 meters.Petterson, O., Storli, A., Ljosland, E., Nygaard, O., Massie, I., and Ca ...
* Hibernia (oil field)
Hibernia is an oil field in the North Atlantic Ocean, approximately east-southeast of St. John's, Newfoundland, Canada, in 80 m of water.Hurley, T.J., Kreisa, R.D., Taylor, G.G., and Yates, W.R.L., 1992, The Reservoir Geology and Geophysics of ...
References
Offshore engineering Structural engineering Oil platforms {{Engineering-stub