Scarabeo 8 rig; Source: Saipem

Confirmation of ‘significant’ oil discovery in North Sea comes with details galore

Norwegian oil and gas player Aker BP recently revealed a new oil discovery in the North Sea off Norway, which was made using a Saipem-owned rig. This discovery has now been confirmed by the Norwegian Petroleum Directorate (NPD), which provided more information about it.

Scarabeo 8 rig; Source: Saipem

Aker BP received a drilling permit for the well 25/2-24 S in February 2023, just a week after the firm obtained consent for exploration drilling in block 25/2 – covering the drilling of pilot hole 25/2-U-12 and three optional side tracks: 25/2-24 AY1, 25/2-24 AY2 and 25/2-24 B – in the North Sea from the Petroleum Safety Authority Norway (PSA).

The Norwegian player disclosed at the end of May 2023 that it was nearing the completion of the drilling activities for the Øst Frigg Beta/Epsilon prospect and announced a “significant” oil discovery near its Yggdrasil development, which was recently approved by Stortinget – the Norwegian parliament – and is planned to start production in 2027. 

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In an update on Friday, 9 June 2023, the NPD confirmed that Aker BP had concluded the drilling of appraisal wells 25/2-24 S, 25/2-24 A, 25/2-24 B and 25/2-24 C. These are the third, fourth, fifth and sixth exploration wells in production licence 873, which was awarded in APA 2016.

The primary exploration target for wells 25/2-24 S and A 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. According to the NPD, 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.

Furthermore, 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, while 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 secondary exploration target for well 25/2-24 B was to delineate the Frigg Gamma discovery (25/2-10 S) in the Frigg Formation, which is part of the Yggdrasil development.

The NPD further explains that the well 25/2-24 S (Øst Frigg Beta) encountered a 12.5-metre oil column in the Frigg Formation, in a sandstone reservoir totalling 117 metres with very good to extremely good reservoir quality. The oil/water contact was encountered 1,949 metres below sea level. While the well was not formation-tested, data acquisition and sampling have been carried out. The well was drilled to a vertical depth of 2,029 metres below sea level and was terminated in Eocene sandstone layers in the Frigg Formation.

Regarding the appraisal well 25/2-24 A (Øst Frigg Beta), it was drilled horizontally along the Beta structure. The well proved a continuous oil column up to 20 metres thick, with an indication of an oil/water contact at 1,945 metres below sea level, and was drilled to a measured depth of 5,156 metres. When it comes to the appraisal well 25/2-24 C (Øst Frigg Alfa), it proved oil in the Alfa structure. The well was drilled to a measured depth of 4,078 metres but did not reach the planned depth. The oil/water contact is estimated at 1,949 metres below sea level.

Moreover, the appraisal well 25/2-24 B (Epsilon) encountered a continuous oil column about 14 metres thick with up to 30 metres of the overlying gas cap in the Epsilon structure. The Frigg Formation exhibited very good to extremely good reservoir properties. The gas/oil contact was encountered at 1,935 metres below sea level and the oil/water contact was encountered at 1,949 metres below sea level.

In addition, the well 25/2-24 B encountered oil and gas in the western part of the Frigg Gamma structure, which is already included in the Yggdrasil PDO. The well encountered the previously proven gas/oil and oil/water contacts. The well was terminated in the Frigg Formation at a vertical depth of 1,925 metres below sea level and measured a depth of 8,168 metres, more than 6,000 metres horizontally in the Frigg Formation.

Based on the NPD’s statement, the preliminary estimates place the total volume of the Epsilon and Øst Frigg structures between 8.5 and 14.3 million standard cubic metres of recoverable oil equivalent. As a result, the licensees intend to assess the deposits as part of the development of the Yggdrasil area.
Even though the horizontal sidetracks 25/2-24 A, B and C were not formation-tested, data acquisition has been carried out.

The water depth at the site is 110 metres and the wells are now permanently plugged and abandoned. These wells were drilled by Saipem’s Scarabeo 8 semi-submersible rig, which will now proceed to drill wildcat well 6405/7-2 S in production licence 1005, where Aker BP is also the operator.

In a separate statement, Aker BP explained that the updated estimate of the discovery size was 53-90 million barrels of oil equivalent (mmboe), which is twice as large as the original pre-drill estimate and slightly larger than the preliminary estimates announced on 25 May. For the company, this marks the longest exploration well ever drilled on the Norwegian Continental Shelf.