The Langeled
Pipeline project, spearheaded by Exxon Mobil, Stat Oil and Royal Dutch Shell,
was undertaken to exploit one of the world’s largest reservoirs of natural gas
in Norway’s Ormen Lange (in Norse mythology: “Giant Serpent”) field, located on
the Norwegian Continental Shelf. The project included the construction of a new
gas terminal at Nyhamna to process the gas coming from Ormen Lange. A
consortium now exports natural gas from Nyhamna to Easington on the east coast
of England through this state of the art marine pipeline.
The pipeline has a
length of 1,166 km (745 miles) and delivers 26 billion cubic meters (900
billion cubic feet) of natural gas to the UK National Transmission System each
year; the price tag came in at 1.7 billion pounds ($2.8 billion). At the time
of completion it was longest sub-sea pipeline ever built.
Building the
pipeline was an immense technological challenge. The North Sea bed is not a
flat bottom but is a treacherous series of channels, trenches, and ridges and
it has cyclical plate tectonic events, not to mention a number of existing
pipelines. It plunges to depths of 5 km (3.2 miles) making water pressure a
significant factor in design and construction. An autonomous underwater
vehicle, Hugin, a product of Kongsberg Maritime, was employed to survey the sea
bed, using advanced radar to determine the most cost effective route.
With an
understanding of the features and hazards, design engineers went to work on
plans to allow a 44 inch pipe, with 25mm (1 inch) thick walls, to negotiate the
terrain while minimizing impact on fisheries and ecosystems.
Langeled pipeline simulated view |
In order to lay the
pipeline a remote-controlled underwater excavating vehicle called the Nexan
Spider, capable of moving underwater mountains, prepared the seabed floor.
Three million tonnes of rock was brought to areas of the sea floor to level the
terrain where needed.
The pipeline was
built using 100,000 pipe sections, each coated in asphalt to reduce corrosion
and a stability coating of concrete. Two pipe laying ships, including Solitaire,
the largest pipe laying ship in the world, laid 8 km (2.5 miles) of pipe a day.
Once the pipe was laid, deep water hyperbaric welding teams welded the pipes
together from inside a watertight enclosure called Pipeline Repair Habitat.
The project was
completed in 2006 after three years of work and both Norway and the UK have
benefited enormously from the project; the UK receives about 20% of its natural
gas directly from the pipeline.
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