A large share of the world’s remaining petroleum reserves is located in cold Arctic regions where people, the environment, vessels and installations are all more vulnerable. Statoil is one of the oil industry’s pioneers when it comes to production in these areas.
Snøhvit is located at 70 degrees north, at the same latitude as the frozen seas north of Alaska. Winds, freezing temperatures and turbulent seas make extreme demands of those intending to function and survive here, whether it is the region’s flora and fauna, traditional industry or oil and gas operations. In fact, the Snøhvit development represents an important breakthrough for energy recovery in the northern regions.
Sheltered on the seabed
The surface of the sea reveals nothing. The Snøhvit field, the world’s most northerly offshore gas-field, is in fact sheltered from the elements at a depth of 300 metres beneath the surface. Every day 20.8 million scm natural gas liquids and condensate are transported 143 kilometres through the seabed pipeline to Melkøya in Hammerfest.
The Gulf Stream keeps the sea free of ice all year round. Winter storms, however, can whip up huge waves that make surface installations difficult to operate.
On the seabed, however, all is peaceful. Here we can maintain a steady and stable production, unaffected by the temperature and conditions on the surface, in energy-efficient installations controlled remotely from land. The Snøhvit seabed installations have also been constructed in such a way that the fishing fleet can still operate here. Trawlers may be drawn over the seabed templates with no risk of entanglement.
The transport of unprocessed wellstream, through such a long seabed pipeline, poses several challenges. Due to the high pressure and the low temperature on the seabed, ice plugs will tend to form in the pipeline. We can avoid this by adding antifreeze at the wellheads, or by heating up the pipeline electrically as required. Such technology has been specially developed for the Norwegian continental shelf – a technology that is vital to the operation of offshore oil and gas fields in the far northern regions.