Snøhvit development – gas from the Barents Sea

	Construction of the huge LNG storage tanks. The export quay in the foreground.

A few years ago it was not deemed possible to extract natural gas from the Barents Sea. But, where there are natural resource, there is a way. A group of international oil companies led by Norwegian Statoil had found gas in the area in the 1984 and in March 2002 the Norwegian authorities gave the go-ahead to develop what is commonly known as the Snøhvit field, including the finds at Albatross and Askeladd, located 140 kilometres north-west of Hammerfest in between 250 and 345 metres of water. Known reserves are 193 billion cubic metres of natural gas and around 113 million barrels of condensate. But to get the reserves from the deposits to the markets in the US, France and Spain involves a long and complicated process. But, although the technology employed is complex and the weather conditions can play engineers a trick or two, the operator should not face too many unknown factors. Nevertheless, the cost over-runs have started, because of unforeseen delays, leaving the total cost in todays money at staggering NOK 46.0 billion (EUR 5.5 billion). When the last invoice is finally paid the figure could be considerably higher. Added to this cost are four LNG carriers to transport the gas to the markets.
The plan (see Project Plan below) is to start regular deliveries sometimes in 2006. Some say this is rather optimistic because it requires perfect timing of all deliveries. They may have a point because the weather window is much shorter in the Barents Sea and only lasts from April to August for both the offshore installations and for some of the big deliveries to the gas liquefaction plant on Melkøya. Because of the difficult weather conditions Statoil has decided to build most of the plant in Germany and Spain (Linde and Izar), to be shipped up and installed.

The producing fields
Snøhvit, Albatross and Askeladd are developed without a fixed or floating platform, which is the norm in the North Sea and the Norwegian Sea. Rather a subsea production system is used to feed the land-based plant via a 68 cm pipeline stretching 160 kilometres to the north-western coast of Melkøya, at the entrance to the shipping channel into Hammerfest.
If that was not enough, the project also needs two chemical lines, an umbilical and a separate pipeline to transport carbon dioxide (CO2). These extra pipelines and the fibre-optic cables for remote operational control of the production will be laid in 2005. Although the technology used in the Snøhvit development is known it remains advanced. Great care is taken to avoid harming the surrounding marine environment. All the installations offshore can be overtrawled, the production is in a closed system and a biological treatment plan on land deals with environmentally harmful components. CO2 in the wellstream is separated on land and piped back offshore for storage.

Gas liquefaction
The volume arriving by pipeline from the offshore fields will be reduced 600-fold by way of decreasing the temperature of the gas to -168C° at a floating gas liquefaction plant developed jointly by German Linde and Statoil and currently building at Izar Construcciones Naval’s yard in Ferrol. 24,000 tonnes of process equipment is installed on a barge, shipped to Melkøya on a heavy-lift ship (Dockwise operation) and installed in a dock blasted out in advance.
Statoil and Linde developed the technology applied in the liquefaction plant. Passing through huge heat exchangers liquefies the gas. The heat exchangers are installed in a huge “cold box” measuring 15x17x40 metres.
We are looking at a large number of spiral-wound tubes through which the gas flows during cooling and liquefaction. It is an efficient technology, now also being use by Shell in its plants.

Transport and markets
Four LNG carriers of 140,000 cubic metres capacity each are necessary to supply contracts with the US, France and Spain. Statoil has taken a share in three of these vessels. One will be owned 32 per cent with Norwegian operator Leif Höegh & Co and Japanese Mitsui OSK Lines and another two- again with a 32 per cent stake – with the Japanese companies Kawasaki Kisen Kaisa, Mitsui & Co Ltd and Lino Kaiun Kaisa Ltd.
All vessels are to be built in Japan using the Moss design. Gaz de France and Total FinaElf are responsible for their own transport, and Gaz de France has ordered their own LNG carrier at Chantier d’Atlantique.
The gas from Snøhvit was not too difficult to sell and Statoil will supply 2.4 billion cubic metres to the US market annually.
In order to gain access Statoil has bought a stake in the Cove Point terminal close to Washington DC. However gas could also be shipped to the Lake Charles terminal in the US Gulf. Spanish energy company Iberdrola has bought 1.6 billion cubic metres per year and Gaz de France and TotalFinaElf takes 1.7 billion cubic metres to sell on the European network. LNG exports from Snøhvit should continue until 2035, unless more reserves are found and other fields can connect to the facilities at Melkøya.
However, the planned export requires one LNG carrier every six days on average to shift around 70 consignments per year.
//Petter Arentz

Back to SSG 20, 31 October