The Snøhvit field in the Barents Sea supplies gas to the world's first LNG plant with carbon capture and storage.
The field has been developed with seabed installations and a 145-kilometre multiphase transport pipeline to shore.
An LNG factory has been built on the island of Melkøya near Hammerfest. There, the gas is liquefied by cooling it down to minus 163 degrees Celsius so that it can be exported by ship to Europe and the USA.
The Snøhvit gas contains carbon dioxide that freezes into solid form at a higher temperature than natural gas. The carbon dioxide therefore has to be removed before it is cooled to LNG.
Moreover, the carbon dioxide also has to be separated from the hydrocarbons at a sufficiently early stage in the process, so that the gas mixture does not freeze and block the heat exchangers in the processing plant.
A separate pipeline transports the carbon dioxide from the Melkøya plant back to the Snøhvit field. There, it is stored in a suitable geological layer of porous sandstone called the Tubåen formation. This structure lies 2,500 metres beneath the seabed and under the layers in Snøhvit containing gas.
More than 700,000 tonnes of carbon dioxide will be stored annually in this manner.
A separate monitoring programme has been established to examine how carbon dioxide behaves in the reservoir. This programme is partly financed by the EU.
StatoilHydro is operator for the development and operation of Snøhvit. Production started in October 2007.