Condeep is a make of gravity-based structure for

oil platform An oil platform (also called an oil rig, offshore platform, oil production platform, etc.) is a large structure with facilities to extract and process petroleum and natural gas that lie in rock formations beneath the seabed. Many oil platforms w ...

s invented and patented by engineer Olav Mo in 1972, which were fabricated by Norwegian Contractors in

Stavanger Stavanger, officially the Stavanger Municipality, is a city and municipalities of Norway, municipality in Norway. It is the third largest city and third largest metropolitan area in Norway (through conurbation with neighboring Sandnes) and the ...

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

.Fagerberg; Mowery; Verspagen, p.192 ''Condeep'' is an abbreviation for ''concrete deep water structure''. A Condeep usually consists of a base of concrete oil storage tanks from which one, three or four concrete shafts rise. The Condeep base always rests on the sea floor, and the shafts rise to about 30 meters above the sea level. The platform deck itself is not a part of the construction. The Condeep is used for a series of production platforms introduced for

crude oil Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring u ...

and

natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...

production in the

North Sea The North Sea lies between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium, and France. A sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Se ...

and Norwegian continental shelf. Following the success of the concrete oil storage tank on the

Ekofisk Ekofisk is an oil field in block 2/4 of the Norwegian sector of the North Sea about southwest of Stavanger. Discovered in 1969 by Phillips Petroleum Company, it remains one of the most important oil fields in the North Sea. This was the first ...

field, Norwegian Contractors introduced the Condeep production platform concept in 1973. This gravity-based structure for a platform was unique in that it was built from

reinforced concrete Reinforced concrete, also called ferroconcrete or ferro-concrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ...

instead of steel, which was the norm up to that point. This platform type was designed for the heavy weather conditions and the great water depths often found in the North Sea. Condeep has the advantage that it allows for storage of oil at sea in its own construction. It further allows equipment installation in the hollow legs well protected from the sea. In contrast, one of the challenges with steel platforms is that they only allow for limited weight on the deck compared with a Condeep where the weight allowance for production equipment and living quarters is seldom a problem.

Troll A

The Troll A platform is the tallest Condeep to date. It was built over a period of four years, using a workforce of 2,000, and deployed in 1995 to produce gas from the enormous Troll oil field. With a total height of , Troll A was the tallest object that has ever been moved to another position, relative to the surface of the Earth. Many sources incorrectly state that it was also the largest structure of any kind to be moved but the Gullfaks C was in fact heavier. The total weight of the Troll A Condeep when launching was 1.2 million tons. 245,000 m³ of concrete and 100,000 tons of steel for reinforcement were used. The amount of steel corresponds to 15

Eiffel tower The Eiffel Tower ( ; ) is a wrought-iron lattice tower on the Champ de Mars in Paris, France. It is named after the engineer Gustave Eiffel, whose company designed and built the tower from 1887 to 1889. Locally nicknamed "''La dame de fe ...

s. The platform is placed at a depth of 300 meters. For stability, it is dug 35 meters into the sea floor.

Gullfaks C

Gullfaks C rests below the sea surface and has a total height of . Gullfaks C was the heaviest object that has ever been moved to another position, relative to the surface of the Earth with a total displacement between 1.4 and 1.5 million tons.

Condeep platforms

Gerwick, Ben C. p.515 *The original concrete structure of Sleipner A sank during trials in the Gandsfjord on August 23, 1991. A new structure was built, and deployed in 1993.

Sources

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References

{{Reflist, 2 Oil platforms