Brine Reservoirs (2600 m)
A liquefied natural gas (LNG) facility has been built at Melkøya, near Hammerfest in northern Norway. At this Hammerfest LNG plant the gas is liquefied by cooling it down to -163 degrees Celsius. This makes it possible to export the gas by ship to Europe and the USA. The Snøhvit gas contains 5-6% CO2 which freezes to solid matter (so-called Dry ice) at a higher temperature than natural gas. It must therefore be removed before the gas is cooled into LNG. Moreover, the CO2 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 CO2 from the Hammerfest LNG 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.
Statoil is operator for the development and operation of Snøhvit. Gas production started in October 2007 and the first CO2 was injected into the reservoir in April 2008.
Other sources and press releases:
The CO2 is injected in the so called Stø-formation, a bit longer up the well, still at the same location as Tubåen. This was done in 2011 to reduce the resevoir pressure in Tubåen, and is proved successfull.