Statoil opts for subsea gas compression for extending Asgard production
Statoil plans to install subsea compression for recovering additional gas from fields tied back to the Asgard development in the Norwegian Sea.
By OGJ editors
HOUSTON, Nov. 10 -- Statoil plans to install subsea compression for recovering additional gas from fields tied back to the Asgard development in the Norwegian Sea.
“With this technology in place, the recovery factor and producing life can be substantially increased for a number of gas fields,” Margareth Ovrum, Statoil's executive vice-president for technology and new energy said.
She noted that preparations for seabed compression have come furthest on Asgard, where the Midgard and Mikkel gas reservoirs tie back to the Asgard B semisubmersible production unit.
These two reservoirs have seabed installations 40-50 km from Asgard B.
Statoil said analyses shows that Midgard and Mikkel pressure will become too low to sustain their ability to produce to Asgard B towards yearend 2014.
“Installing compressors will sustain the gas flow and ensure a long producing life for the platform,” explained Stale Tungesvik, head of reserves and business development in Statoil.
“This makes it possible to recover large volumes—we’re adding 28 billion cu m of gas and 14 million bbl of condensate after a possible investment decision,” he added.
Statoil expects to make the investment decision in first-quarter 2011.
Its alternative to subsea compression would be to build a new platform with conventional surface compressor, which a detailed assessment indicated was less attractive than subsea compression, according to Statoil.
“Moving compression to the seabed gives both improved energy efficiency and lower costs compared with keeping it on a platform or on land,” explained Ovrum.
“The closer to the well we compress the gas, the higher the efficiency and the production rates,” she added.
Statoil said the subsea compression unit will include a gas cooler, liquid separator, and compressor, with the latter receiving power from the Asgard A oil production vessel.
Partners for Asgard are Petoro AS 35.69%, operator Statoil 34.57%, Eni Norge AS 14.82%, Total E&P Norge AS 7.68%, and Mobil Development Norway 7.24%.