A subsea giant
Celebrations welcome the world's longest subsea pipeline
By Karen Remo-Listana
Posted: 16 October 2006
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The opening of the southern section of the Langeled pipeline - the world's longest subsea pipeline - is being celebrated in some style in the UK right now.
There's a big tea party in Easington on Saturday, a formal inaugural ceremony presided over by prime ministers Tone Blair and Jens Stoltenberg in London on Monday and a celebratory dinner in Beverley on Tuesday - nobody can be in any doubt that new gas from Norway can now be supplied to the UK .
 The southern section of Langeled connects the gas intersection point Sleipner on the Norwegian Continental Shelf with Easington in England . Already gas transported through the new pipeline has been sold on the British gas exchange NBP.
Gas is the largest proportion of the UK's primary energy supply. In the past, the country could meet increased demand by boosting production from its North Sea gas fields. But as production has declined, gas has been imported from the rest of Europe and Russia . Last year the UK became a net importer of gas.
With political issues beleaguering Russia , UK finds more energy security in Europe . And Ormen Lange gas field which lies on the Norwegian Continental Shelf is a promising source of gas. With reserves close to 400 billion cubic metres and development costs of about $10 billion, the Ormen Lange field ranks as the largest development in the European offshore arena.
When the gas stream is opened next year through the world's longest subsea pipeline " from the processing plant in Aukra, in More and Romsdal municipality to Easington on the British coast " the Norwegian field will be able to supply 20% of UK gas consumer requirements.
But before it can supply such enormous amount of gas, Hydro and its partners have to travel great sea depths, overcome an unpredictable sea bed and powerful currents combined with sub-zero temperatures, extreme wind conditions and enormous waves.
 As one of the world's most incredible constructions, this project has won the attention of both National Geographic and Hollywood .
The Langeled pipeline and receiving facilities in Easington are part of the Ormen Lange project. According to Hydro, the project is now 80% complete and is moving ahead on schedule.
Hydro is the development operator for the Ormen Lange/Langeled project, while Statoil has the management of the Langeled project in cooperation with Hydro.
Despite the rocketing costs, the Langeled development is due to be completed on time and below budget of about $500 million, Hydro's project director Tom Rotjer said.
The project requires over a million tonnes of concrete and 25,000 tonnes of steel reinforcements. Two of the world's largest pipeline-laying vessels, Stolt Offshore's LB200 and Solitaire from Allseas, are called to lay the 1,200 kilometre long pipeline between Norway and UK , in addition to the pipelines from the field to the onshore processing plant.
Last year, Pipeline reported that about 400,000 tonnes of stone were installed. In other words nearly two million tonnes remained to be laid; while underwater installations were still in initial stage.
Hydro last month announced that a second gas pipeline was connected to the subsea plant. This means 600 kilometres of gas production and anti-freeze pipeline, as well as a support system control cable, have been laid.
All that remains, before pipeline laying is complete, is the laying of one control cable.
And anytime this month, Norwegian gas will arrive in Easington via the southern end of the Langeled pipeline as it begins to supply the UK with up to 20% of its future gas supplies. This marks the opening of southern part of Langeled, with official production to start in October next year.
Pipelay barge Acergy Piper has now laid about 400 kilometres of the Northern section of Langeled, and with the help of Solitaire, the whole pipeline will be completed this fall. Currently Solitaire is completing the installation of the pipelines from Nyhamna to the Storegga slide area, and S7000 is completing the deepwater installation part.
At Nyhamna, the main activity is installation of the huge prefabricated racks and pipes, with about 3000 workers in full swing most of the time. The construction and installation of pipelines, pipes, cables and equipment will continue throughout 2006, while in 2007 the main task will be to test out the equipment, before starting production in the autumn.
The two first remotely controlled subsea production stations are installed located 120 kilometres from shore at 850 metre water depths - making Ormen Lange one of the world's largest and most advanced subsea to shore development.
From these stations, two 30-inch pipelines will transport the well stream to the onshore plant at Nyhamna at the coast of mid-Norway for processing. The pipelines are laid across extreme irregular seabed with boulders and slide blocks up to 60 metre heights in the Storegga slide.
The pipelines are crossing the slide with an inclination up to 40 degrees. Nexan's Spider " a newly developed, remote-controlled excavator " has been preparing the seabed for the passage of the pipelines over steep slopes and very uneven terrain far below the surface of the sea.
The special water current condition gives water temperatures as low as minus one degree Celsius. Such extreme temperature conditions combined with high pressure can cause gas and water to form hydrates and ice, which again can form plugs in the pipelines. The subsea system has been designed to avoid hydrates.
When production from the Ormen Lange field starts in fall 2007, some 70 million cubic metres of gas, a volume comparable to Norway 's entire daily energy consumption, will flow through the Langeled pipeline.
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