The Condeep series of oil production platforms was introduced for oil production in the North Sea.

Following the success of the concrete oil storage tank on the Ekofisk field, Norwegian Contractors introduced the Condeep production platform concept in 1973. The name is from «concrete deep water structure».

This platform was unique in that it was built from reinforced concrete instead of steel, which was the norm up to that point. The platform was purpose made for the heavy weather conditions and the great water depths found in the North Sea.

Troll A

The Troll A plattform is the largest 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 field.

With a total height of 472 meters, Troll A was the largest structure ever to be built and moved. The total weight when launching was 1.2 million tons. 245,000 m3 of concrete and 100,000 tons of steel for reinforcement was used,. The amount of steel corresponds to 15 Eiffel towers. The plattform is placed at a depth of 300 meters. For stability, it is dug 35 meters into the sea floor.

North Sea concrete platforms

• The original concrete structure of Sleipner A sunk during trials in the Gandsfjord on August 23 1991. A new structure was built, and deployed in 1993.