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of these platforms, they are often susceptible to scour of their foundation and

sinkage. Another example of a successful GBS is the gas extraction platform Troll

A (fig. 3.5).

Figure 3.5 – GBS Troll A

Troll A is a gas production platform and the pinnacle of the Norwegian

condeep concept: moveable deepwater concrete structures. It is located in the

Norwegian Troll gas field in the North Sea.

With a total height of 472 meters, and a subsea structure of concrete measuring

369 meters, it is the highest concrete platform ever constructed for the oil and gas

sector. In fact, it is the largest construction ever moved on the planet.

The construction contract was awarded by Shell Norway to Norwegian

Contractors (NC) in March 1991. It took a little more than four years to construct

the gigantic supporting structure, and 2,000 people were involved in the

construction at Vats in Rogaland, Norway.

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