Condeep is a make of

gravity-based structure A gravity-based structure (GBS) is a support structure held in place by gravity, most notably offshore oil platforms. These structures are often constructed in fjords due to their protected area and sufficient depth. Offshore oil platforms Pri ...

for oil platforms invented and patented by engineer Olav Mo in 1972, which were fabricated by

Norwegian Contractors Norwegian Contractors AS was a concrete gravity base (GBS) structure supplier from 1974 to 1994. Aker Marine Contractors AS (AMC) was established in 1995 and is a continuance of the marine activities in Norwegian Contractors AS. Norwegian Contracto ...

in Stavanger,

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and the ...

.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 and

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

production in the

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

and

Norwegian continental shelf The Norwegian continental shelf ( no, Den norske kontinentalsokkelen) (abbreviated as NCS) is the continental shelf over which Norway exercises sovereign rights as defined by the United Nations Convention on the Law of the Sea. The area of the s ...

. 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 fir ...

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 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 ( ; french: links=yes, tour Eiffel ) 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. Locally nicknamed "' ...

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