Oil and gas discovery near the Troll field in the North Sea – 31/1-2 S and 31/1-2 A
05/02/2021 Equinor Energy AS, operator of production license 923, has concluded the drilling of wildcat well 31/1-2 S and appraisal well 31/1-2 A.
The wells were drilled about 10 kilometres northwest of the Troll field in the North Sea and 130 kilometres northwest of Bergen.
The objective of well 31/1-2 S was to prove petroleum in the Brent Group from the Middle Jurassic Age and in the Cook Formation from the Early Jurassic Age. The purpose of well 31/1-2 A was to delineate the discovery made in the Brent Group in 31/1-2 S.
Both wells proved hydrocarbons in two intervals in the Brent Group. Well 31/1-2 S encountered a 50-metre gas column in the Brent Group (Etive and Oseberg Formations) and an oil column of at least 50 metres in the Oseberg Formation and the Dunlin Group (Drake Formation from the Early Jurassic Age).
About 50 metres of the Brent Group consists of sandstone with good reservoir quality. A total of 6 metres of sandstone of moderate to poor reservoir quality was encountered in the Drake Formation. The oil/water contact was not encountered.
Appraisal well 31/1-2 A encountered a 12-metre oil column in the Etive Formation and a 17-metre oil column in the Oseberg Formation, in sandstone of good to moderate reservoir quality. The oil/water contact was not encountered in the first-mentioned unit.
Both wells encountered water in the Cook Formation, which has good to moderate reservoir quality.
The preliminary calculation of the size of the discovery is between 7 and 11 million Sm3 of recoverable oil equivalent. The licensees have classified the discovery as commercial and will consider development solutions in relation to existing infrastructure.
In order to gain a better overview of the resource base in the area, they will also consider drilling exploration wells in other adjacent prospects in production license 923.
The wells were not formation-tested, but extensive data acquisition and sampling was undertaken.
Well 31/1-2 S was drilled to a vertical depth of 3440 metres below sea level and a measured depth of 3555 metres. The well was terminated in the Amundsen Formation from the Early Jurassic Age.
Well 31/1-2 A was drilled to a vertical depth of 3452 metres below sea level and a measured depth of 3876 metres. The appraisal well was terminated in the Cook Formation.
The water depth is 349 metres. The wells have been permanently plugged and abandoned.
Wells 31/1-2 S and 31/1-2 A were drilled by the West Hercules drilling facility, which will now move on to drill wildcat well 31/2-22 S in production license 090 in the northern section of the North Sea, where Equinor Energy AS is the operator.