Deepsea Stavanger rig; Source: Odfjell Drilling

Hit-and-miss in North Sea: Aker BP finds more black gold in one well but bites the dust in another

Norwegian oil and gas players, Aker BP and Equinor, have made an oil discovery in one well drilled in the Norwegian sector of the North Sea near the Munin field, using Odfjell Drilling’s semi-submersible rig. However, the second well ended up dry.

Deepsea Stavanger rig; Source: Odfjell Drilling

The Norwegian Ocean Industry Safety Authority (Noisa), formerly known as the Petroleum Safety Authority Norway (PSA), gave Aker BP consent for exploration drilling in block 30/12 in the North Sea in 2023. The first prospect, Surtsey, entailed the spudding of the well 30/12-3 S. The activities at the second prospect, Jolnir, included the drilling of a side track well 30/12-3 A while operations at the third prospect, Brandur, were related to a potential side track well 30/12-3 B.

According to the Norwegian Offshore Directorate (NOD), former the Norwegian Petroleum Directorate (NPD), Equinor drilled the well 30/12-3 S on behalf of Aker BP, which is the operator of production license 272 B. This is the first well in this production license. Aker BP and Equinor each have ownership interests of 50% in the license, which was awarded in APA 2018.

The license is part of the Munin field, which was discovered in 2011 and the plan for development and operation (PDO) was greenlighted in June 2023. While oil was discovered in exploration well 30/12-3 S in the North Sea, the sidetrack, 30/12-3 A, was dry. These wells were drilled about 40 kilometers south of Oseberg and 150 kilometers west of Bergen. The drilling was conducted by Odfjell Drilling’s Deepsea Stavanger semi-submersible rig.

According to the NOD, the amount of recoverable oil equivalent, proven in well 30/12-3 S, is between 0.15 and 0.55 million standard cubic meters (Sm3). The preliminary calculations show that the discovery is not profitable with current price assumptions. The objective of wildcat wells 30/12-3 S and 30/12-3 A was to prove petroleum in Middle Jurassic reservoir rocks in the Tarbert Formation.

The well 30/12-3 S encountered a 3.5-meter oil column in the Tarbert Formation, in a sandstone reservoir with moderate reservoir quality. This formation was about 195 meters thick, 97 meters of which were sandstone rocks with moderate-good reservoir quality. The oil/water contact was encountered 3,110 meters below sea level. The Ness Formation was about 163 meters thick in total, 19 meters of which was a sandstone reservoir with moderate reservoir quality.

On the other hand, the well 30/12-3 A encountered the Tarbert Formation with a thickness of about 216 meters, 19 meters of which were sandstone rocks with poor reservoir quality. This formation was about 50 meters thick in total, 11 meters of which was a sandstone reservoir with moderate reservoir quality. The well was dry. Even though the wells were not formation-tested, data acquisition was undertaken.

The Norwegian Offshore Directorate explained that the well 30/12-3 S was drilled to measured and vertical depths of 3,663 meters and 3,465 meters below sea level, respectively, and was terminated in the Drake Formation.

The well 30/12-3 A, in contrast, was drilled to measured vertical depths of 4,520 and 3,718 meters below sea level, respectively, and was terminated in the Ness Formation. The water depth in the area is 106 meters and the well has now been permanently plugged and abandoned.

The 2010-built Deepsea Stavanger rig is a sixth-generation deepwater and harsh environment semi-submersible of an enhanced GVA 7500 design, which is capable of working at water depths of up to 3,000 meters. With a drilling depth capacity of 10,670 meters, the rig has eight mooring lines and can accommodate 157 people.