Statoil ASA installed what it is calling the world’s first subsea wet gas compressor at its Gullfaks C platform offshore Norway. By compressing at the sea floor, the company expects to add 22 million boe and 2 years additional production at Gullfaks.
Statoil says subsea compression is more efficient and effective than conventional topside methods and represents a substantial technological leap forward for improving gas recovery on the Norwegian Continental Shelf.
When reservoir pressure falls below a critical level, subsea wet gas compression maintains production. The company believes that later-stage recovery at Gullfaks could be as much as 62-74%. Statoil said current recovery rate from the main Gullfaks field is 59%. Since start of oil production in 1986, the field has produced more than 2.56 billion bbl of oil and exported more than 70 billion cu m of gas (OGJ Online, Apr. 19, 2013).
The technology consists of two 5-Mw wet gas compressors installed in a subsea template at a depth of 135 m. They will be tied in to existing templates and pipelines 16 km from Gullfaks C. Statoil says it will be able to tie production from other fields into the Gullfaks compressor, which will start up in this year’s fourth quarter. Statoil operates the development with 51% interest. Partners are Petoro 30% and OMV AG 19%.
Statoil is currently implementing two other subsea compression projects at Aasgard and Gullfaks on the NCS. (OGJ, May 4, 2015, p. 70).