Transocean Norge; Source: Transocean

Appraisal of gas/condensate discovery boosts resource estimate

Wintershall Dea Norge, a subsidiary of Germany’s oil and gas company Wintershall Dea, has undertaken appraisal activities with one of Transocean’s rigs. This led to a minor increase in the resource estimate for a gas/condensate discovery near the Dvalin field in the Norwegian Sea.

Transocean Norge; Source: Transocean

Wintershall Dea’s appraisal well 6507/4-4 S was drilled to confirm the size of the previous discovery 6507/4-2 S (Adriana), which was made in 2021, proving gas/condensate in reservoir rocks from the Cretaceous Lysing Formation, as well as gas and oil in reservoir rocks from the Cretaceous Lange Formation.

While the primary exploration target for well 6507/4-4 S was to confirm the size of the discovery in the Lysing Formation (Adriana), including investigating the reservoir’s lateral development, the primary exploration target for the sidetrack 6507/4-4 A was to confirm the size of the gas/oil discovery in the Lange Formation (Sabina).

The preliminary calculations following appraisal drilling activities place the size of the discovery at 4-7 million standard cubic meters (Sm3) of recoverable oil equivalent while the operator’s previous resource estimate for the gas/condensate discovery was 3-5 million Sm3 of recoverable oil equivalent.

Wintershall Dea is the operator of the production license 211 CS, where the appraisal well was drilled, and Petoro, Aker BP, and PGNiG are the other licensees. The well was drilled by the Transocean Norge semi-submersible rig 14 kilometers north of the Dvalin field and 270 kilometers north of Kristiansund.

The appraisal well 6507/4-4 S encountered a 21-meter gas column in the Lysing Formation with sandstone layers totaling about 16 meters with good to very good reservoir quality. The gas/water contact was proven at 2,885 meters below sea level.

After the appraisal well 6507/4-4 S was drilled to a vertical depth of 3,039 meters and a measured depth of 3,067 meters below sea level, it was terminated in the Lange Formation from the Cretaceous. The water depth at the site is 446 meters and the well has been permanently plugged and abandoned.

According to the Norwegian Offshore Directorate (NOD), the drilling of sidetrack 6507/4-4 A, which aimed to delineate gas and oil discovery 6507/4-2 S (Sabina) in the Lange Formation, had to be aborted due to technical drilling issues. The licensees will consider tying the discovery to existing infrastructure in the area.

While the appraisal well was not formation-tested, extensive data acquisition and sampling were carried out. The Transocean Norge drilling rig is now headed to production license 475 BS in the Norwegian Sea, where the Wintershall Dea-operated Maria field is located. While the semi-sub won a 17-well contract in September 2022, a one-well extension with Wintershall Dea was also recently secured for the rig.

The original contract, with day rates between $350,000 and $430,000, was awarded after two oil and gas companies, Wintershall Dea and OMV, entered into an exclusive partnership with Transocean for the use of the rig in the period 2023 to 2027.

The Transocean Norge rig is the first semi-submersible rig that secured the Abate (Power+) notation, designed to reflect the best industry practices in greenhouse gas abatement for offshore units.