Equinor makes North Sea discovery, considers Troll infrastructure tie-back

Equinor Energy AS and partners will consider tying a new oil and gas discovery into existing infrastructure in the Troll area of the North Sea. Preliminary estimates place the size of the Røver Sør discovery at 17-47 MMboe, the majority of which is oil. 

Two exploration wells, appraisal 31/1-3A and wildcat 31/1-3S, were drilled by the Transocean Spitsbergen rig about 10 km northwest of Troll field and 130 km northwest of Bergen in production license (PL) 923 in 348 m of water.

Well 31/1-3 S was drilled to a vertical depth of 3,558 m subsea and a measured depth of 3,568 m. The well was terminated in the Johansen formation from the Early Jurassic. The primary exploration target was to prove petroleum in the Etive and Oseberg formations in the Brent Group from the Middle Jurassic. The secondary exploration target was to prove petroleum in the Cook formation from the Early Jurassic.

The well encountered a gas column of about 80 m in Tarbert and Ness formations and an oil column of around 50 m in the Ness, Etive, and Oseberg formations. About 20 m in the Tarbert and upper part of the Ness formation was in sandstone layers with poor to moderate reservoir quality, and about 65 m in the Ness, Etive, and Oseberg formations are in sandstone layers with moderate to good reservoir quality. Oil-water contact was encountered at a depth of 3,227 m subsea in the Oseberg formation.

The Cook formation was water-filled and contained sandstone with moderate to good reservoir quality.

Well 31/1-3 A was drilled to a vertical depth of 3,368 m below sea level and a measured depth of 3,791 m. The well was terminated in the Drake formation. The objective was to delineate the discovery made in the Brent Group in well 31/1-3 S in January 2023.

The well encountered an oil column of about 20 m in the Ness formation, with sandstone layers of around 30 m with moderate to poor reservoir quality in the lower part of the Ness formation. Oil-water contact was encountered at 3,211 m subsea in the Ness formation.

The wells were not formation-tested, but extensive data acquisition and sampling have been carried out. The wells have been permanently plugged.

The rig will now drill wildcat well 34/6-6 S (Heisenberg) in PL 554 in the northern North Sea. Results are expected in March, with additional exploration wells planned in the area later this year.

Equinor is operator of PL923 (40%) with partners DNO Norge AS (20%), Wellesley Petroleum AS (20%), and Petoro AS (20%).