Aker BP confirms Yggdrasil area hydrocarbon discovery
Aker BP ASA has confirmed its Yggdrasil area hydrocarbon discovery in Norwegian North Sea production license (PL) 873 (OGJ Online, May 25, 2023).
Preliminary estimates place the total volume of the Epsilon and Øst Frigg structures at 8.5-14.3 million std cu m of recoverable oil equivalent. The licensees will assess the deposits as part of Yggdrasil area development.
The Øst-Frigg Beta/Epsilon well has a vertical main track (25/2-24 S) and three horizontal sidetracks (25/2-24 A, 25/2-24 B, and 25/2-24 C), all drilled by the Scarabeo 8 drilling rig in 110 m of water.
The first sidetracks were drilled in the Beta structure to prove oil and appraise the discovery. The sidetrack to Epsilon (25/2-24 B) was the last one. Most of the Beta well was used to reach the Epsilon structure. The last casing landed in the reservoir and the final sidetrack was drilled towards Epsilon.
The primary exploration target for wells 25/2-24 S and A (Øst Frigg Beta) was to prove and delineate remaining petroleum deposits in the Frigg formation in the Øst Frigg Beta structure, which produced gas from 1988 to 1997. Oil was proven in exploration wells 25/2-9 and 25/2-2 which were drilled in the 1970s, but oil was never produced from the field.
Well 25/2-24 S was drilled to a vertical depth of 2,029 m subsea. It was terminated in Eocene sandstone layers in the Frigg formation. The well encountered a 12.5-m oil column in the Frigg formation in a sandstone reservoir totaling 117 m with very good-extremely good reservoir quality. The oil-water contact was encountered 1,949 m subsea. The well was not formation-tested, but data acquisition and sampling have been carried out.
Appraisal well 25/2-24 A was drilled horizontally along the Beta structure to a measured depth of 5,156 m. The well proved a continuous oil column up to 20 m thick, with indication of an oil/water contact at 1,945 m subsea.
The primary exploration target for well 25/2-24 C was to prove and delineate petroleum deposits in the Frigg formation in the Øst Frigg Alfa structure, north of the Beta structure. The well was drilled to a measured depth of 4,078 m but did not reach the planned depth. It proved oil in the Alfa structure, and the oil-water contact is estimated at 1,949 m subsea.
The primary exploration target for well 25/2-24 B was to prove petroleum deposits in the Frigg formation in the Epsilon prospect, east of the Beta structure. The well was terminated in the Frigg formation at a vertical depth of 1,925 m subsea and measured depth of 8,168 m, more than 6,000 m horizontally in the Frigg formation.
The well encountered a continuous oil column about 14 m thick with up to 30 m of overlying gas cap in the Epsilon structure. The Frigg formation exhibited good-extremely good reservoir properties. The gas-oil contact was encountered 1,935 m subsea and the oil-water contact was encountered at 1,949 m subsea. The well also encountered oil and gas in the western part of the Frigg Gamma structure, which is already included in the Yggdrasil PDO.
Horizontal sidetracks 25/2-24 A, B, and C were not formation-tested, but data acquisition has been carried out. The wells are now permanently plugged.
The rig will now proceed to drill wildcat well 6405/7-2 S in PL 1005, where Aker BP is operator.
Aker BP is operator at PL 873 (47.7%) with partners Equinor Energy AS (40%) and PGNiG Upstream Norway AS (12.3%).
Alex Procyk | Upstream Editor
Alex Procyk is Upstream Editor at Oil & Gas Journal. He has also served as a principal technical professional at Halliburton and as a completion engineer at ConocoPhillips. He holds a BS in chemistry (1987) from Kent State University and a PhD in chemistry (1992) from Carnegie Mellon University. He is a member of the Society of Petroleum Engineers (SPE).
