Cygnus appraises as southern gas basin giant

A group led by GDF E&P Suez plans to shoot a fieldwide 3D seismic survey over Cygnus field in the UK North Sea Southern Gas basin.

By OGJ editors
HOUSTON, Apr. 15
-- A group led by GDF E&P Suez plans to shoot a fieldwide 3D seismic survey over Cygnus field in the UK North Sea Southern Gas basin.

Preliminary estimates of Cygnus reserves and prospective resources could be as high as 2 tcf of gas based on new well information, said partner Endeavour International Corp., Houston. That would make Cygnus one of the largest fields in the southern gas basin.

Endeavour, which expects gas production to start from Cygnus in 2011, in mid-March launched a study of strategic alternatives for its North Sea assets. GDF discovered Cygnus in 2006.

The Cygnus discovery well and five appraisal wells support a common fieldwide gas-water contact within 10 ft with the exception of the 44/11-2 well in the extreme southwest, Endeavour said. The recent drilling has extended the field to the north and west.

The 44/11a-4 appraisal well encountered a high-quality, gas-saturated Leman sand reservoir 54 ft high to prognosis with 130 ft gross and 85 ft net sand thickness. The well was flow-tested at a rate of 28 MMcfd. TD is 12,207 ft true vertical depth subsea.

The rig will move to the southern part of the field to drill a sixth appraisal well, 44/12a-E.

Cygnus interests are GDF Suez 38.75%, Centrica 48.75%, and Endeavour 12.5%.

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