The life of the Tune field in the North Sea is extended and gas production increased following reconstruction to low-pressure production.
"A relatively limited investment gives us considerable benefits in the future," says Geir Hovland, project manager for StatoilHydro.
The gains from the reconstruction work are estimated at NOK 2.9 billion cubic metres of gas and 300,000 cubic metres of condensate from Tune.
The reconstruction will also have positive effects for the recoverable reserves from Oseberg Delta, which comes on stream in May, and Tune South, due to come on stream in one year.
The pressure drops
The Tune development consists of subsea installations. The field is located some 10 kilometres southwest of the Oseberg field centre.
The field has produced gas and condensate through reservoir depressurisation since the start-up in November 2002. During this period the pressure has dropped from 525 bar to about 125 bar.
Without this reconstruction the Tune production would have been shut down when Oseberg Delta and Tune South came on stream. Thanks to the reconstruction it is not necessary to increase the receiving pressure and Tune may remain on stream longer than previously expected.
Low-pressure production
In the future the field may produce gas at a pressure of down to 45 bar, and towards the end of the field life from around 2012 the receiving pressure may be reduced down to 30 bar for recovery of the remaining gas reserves.
The gas produced from Tune is injected into the Oseberg reservoir, and as of March 2008 14.7 billion cubic metres of gas and 3.1 million cubic metres of gas have been produced from the field.
The reconstruction was given the green light in the autumn of 2006, and the field has been shut down since 10 April during the replacement of compressor and gas cooler internals and the installation of two new gas meters.
Tune Field Key Facts
Tune lies 10 kilometres southwest of the Oseberg Field Center and is developed with subsea production installations tied into the Field Center.
The Tune field was discovered with an exploration well in 1995 and confirmed with an appraisal well in 1996.
Tune started producing just six years after its confirmation.
It has been developed with a sea-floor template with four wells tied into the Oseberg Field Center, and with hook-up possibilities for two additional satellite wells.
At plateau output, Tune will produce 3 billion cubic meters (Sm3) gas per year. Tune has an estimated productive lifetime of 15 years.
The gas volumes from Tune will be used for injection purposes to boost oil production pressure on Oseberg. The injected gas will later be recovered along with Oseberg gas and exported.
This contributes to more efficient recovery of resources from the Oseberg field.
Total development costs on the Tune project are NOK 3.2 billion (USD 453 million/EUR 413 million), including drilling of production wells.