A Norwegian company with a history of big works and a hunger for more is leading the coordinated development of a remotely-controlled deepwater gas field, an innovative landside processing plant and the world’s longest undersea pipeline. It is starting at the bottom, 1,000 meters down,where currents are strong and shifting, the cold water temperature hangs around -1° C and the sea floor is a maze of towering peaks, ravines and boulder-strewn confusion. click here to view map

The Ormen Lange Gas Field, with 400 billion Standard Cubic Meters of gas, (an industry term for gas volume at a standard temperature and pressure) and 28.5 million Sm3 of valuable condensate, is the second-largest gas deposit on Norway’s oil- and gas-rich continental shelf. The $9.5-billion project to bring its gas to market is led by Norsk Hydro ASA, Oslo, Norway (ENR 3/17/2003 p. 16). Landside civil work at a processing plant is being performed by Skanska Norway, Oslo, with engineering and construction for plant components awarded to Aker Kvaerner ASA and its unit Aker Stord, Oslo, which later merged those contracts, and Vetco Aibel AS, Billingstad, Norway. Hydro and Norway’s Statoil have joint responsibility for development of the export pipeline. Shell will be the operator.

Roaring Project. Contractors churn out the work at Nyhamna, digging water tunnels and caverns and pouring thousands of foundations. Solitair, a pipelaying ship, pulled in June 29. (Photos courtesy of Norsk Hydro)

"This job is the biggest in Europe," says Petter Eiken, executive vice president of Skanska AB, Solna, Sweden. "It’s the biggest industrial project in Norway since the Second World War."

Hydro started planning the project five years ago, shortly after the field was discovered in 1997. Execution began in February 2004.

The Ormen Lange deposit lies in a geologic disaster area called the Storegga Slide, the wreckage left by a 300 km-wide collapse of the Norwegian continental shelf 8,000 years ago. Developing the deposit now is the focal point of what some call an "extreme engineering" campaign. The three main components involve:

  • Installing four 1,150-ton templates with remotely controlled manifolds on the sea floor and routing pipelines, hydraulic cables and electrical and fiber-optic conduits through the undersea moonscape and up a 300-m escarpment, 120 km to the southwest coast of Norway.
  • Rapidly constructing a 70-million Sm3/day processing plant carved into the rock at Nyhamna, Norway, where the gas stream will be purged of impurities.
  • Laying the longest undersea pipeline in the world to export the product 1,200 km to England. Ormen Lange is expected to supply 20% of Great Britain’s natural gas needs for the next 40 years, beginning in October 2007.

All three productions are going at once. Norsk Hydro has marshalled the manufacturing, civil construction and marine pipelaying resources of firms from all over the world to produce the equipment, prepare the pipe and begin the deployment across a jobsite that stretches from the wells on the sea floor to a roaring construction site at Nyhamna and then under the sea again to a receiving plant for distribution to the stoves and boilers of Great Britian.

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Norsk Hydro has something to prove because a new opportunity to go after such a project is at hand, and there is another after that, and another and another. The world is hungry for natural gas and most of the easy harvesting has been done. It is the really tough jobs that remain, such as development of Russia’s Stockman gas field in the Arctic’s Barents Sea, with 2.2 trillion Sm3 of gas and 27 million Sm3 of condensate, and other development challenges in fields off Mexico, Angola and Australia.

Success with Ormen Lange will be a powerful card for Norsk Hydro to play. It already has joined the bidding on the next hand. It was one of the nine companies submitting proposals on Aug. 10 to develop the Stockman field.

Breaking Ground

The technique of drilling for gas on the sea floor and using remotely operated seabed equipment to pipe it to land for processing is referred to as a "tie-back," and while this is not the first, Ormen Lange is the most audacious yet. Melkøya, near Hammerfest, is Norway’s other example, (ENR 4/25 p. 30) "[Melkøya] has much lower production, lower reserves and a much less challenging environment," says Norsk Hydro spokesman Vegar Stokset. The technique, which eliminates the need for sea-surface facilities, is being considered for development of other difficult undersea reserves.

At 850 m to 1,100 m under the sea, Ormen Lange’s pipeline also will not be the deepest. The Blue Stream pipeline crosses the Black Sea in waters as deep as 2,150 m. But in terms of frigid water, high winds and waves and extremely difficult seabed terrain, getting the gas to shore from Ormen Lange takes the cake.

"We believe this is the most challenging pipeline project in the world," says Stokset.

Wells will be drilled and directed in groups of eight to the templates on the sea floor. Each template unit has a footprint of 33 m by 40 m and stands 15 m tall on the dock. Can-shaped piles at the corners are designed to sink into the sea floor as anchors under the 1,150-ton weight. Placement is critical. The prefabricated connecting pipelines will be installed by remotely operated equipment guided by sonic transponders serving as navigational aids. Winches planted on the seabed will pull cables to adjust horizontal placement to centimeter accuracy. Level tolerance is �1°.

The manifolds will be linked to the landside plant by two 30-in.-diameter delivery lines, two control cables carrying hydraulic power and electricity and data, and two 6-in. glycol lines to inject antifreeze into the moist gas to prevent ice from forming...