Appraisal activities with Odfjell Drilling’s rig shed more light on gas discovery

Norwegian oil and gas player Aker BP has used one of Odfjell Drilling’s semi-submersible rigs to delineate a two-year-old gas discovery in the Norwegian Sea and will contemplate a subsea tie-back to existing infrastructure as a development option.

The Norwegian Ocean Industry Authority (Havtil) granted Aker BP consent in May 2024 to undertake further drilling activities in the Norwegian Sea in production license 261, which was awarded on May 12, 2000, and is valid until May 12, 2036.

Aker BP has an ownership interest of 70% and acts as the operator of the license, while its partner, Wintershall Dea Norge, now part of Harbour Energy, holds the remaining 30% stake. The water depth at the location is around 340 meters.

The Storjo West 6507/2-7 S well was spudded with the 2009-built Deepsea Nordkapp, former Stena Midmax, semi-submersible drilling rig, which Odfjell Drilling bought from Samsung Heavy in April 2018. During drilling operations, Aker BP has proven gas in this appraisal well, located 230 kilometers west of Sandnessjøen and around 12 kilometers west of the Skarv field.

The well was drilled to confirm the size of the previous discoveries made in 2022 in 6507/2-6, Storjo East and Kaneljo in Jurassic and Cretaceous reservoir rocks, respectively. The appraisal well 6507/2-7 S, drilled to vertical and measured depths of 5,098 meters and 5,140 meters below sea level, respectively, was terminated in the Åre Formation from the Lower Jurassic age.

According to the Norwegian Offshore Directorate (NOD), the primary exploration target for well 6507/2-7 S was to prove gas in reservoir rocks in the Tilje Formation in the Lower Jurassic and the secondary exploration target was to prove gas in reservoir rocks in the Middle Jurassic (the Garn Formation) and the Upper Cretaceous (Lysing Formation). 

While the well 6507/2-7 S encountered gas in the Tilje Formation, which is 133 meters thick, with 43 meters in sandstone rocks with moderate to poor reservoir quality in the primary exploration target, the gas/water contact was not encountered. In the secondary exploration target in the Garn Formation, the well 6507/2-7 S encountered a 30-meter gas column in sandstone rocks totaling around 14 meters with poor reservoir quality.

Moreover, the well 6507/2-7 S encountered a gas column of around 8 meters in the Lysing Formation in sandstone rocks totaling 65 meters with very good reservoir quality in the other secondary exploration target. However, the gas/water contacts were not encountered in any formations but extensive data acquisition and sampling had been done.

Aker BP’s resource estimate for the primary exploration target was between 2.6-10.3 million Sm³ of recoverable oil equivalent before drilling well 6507/2-7 S, while the secondary exploration target had estimated resources of 0.9-1.5 million Sm³ of recoverable oil equivalent.

Based on the data provided by NOD, the preliminary estimates place the size of the discoveries between 2 and 8.7 million standard cubic meters (Sm³) of recoverable oil equivalent in the primary exploration target, corresponding to around 13-55 million barrels of oil equivalent.

On the other hand, the preliminary estimate is between 1.3-1.8 million Sm³ of recoverable oil equivalent in the secondary exploration target, equivalent to around 8-12 million barrels of oil. Aker BP and Harbour Energy will consider tying the discoveries back to existing infrastructure in the area, as outlined by the NOD.

Furthermore, a production test was conducted in technical sidetrack 6507/2-7 S T2 in the upper part of the Tilje Formation, resulting in the maximum production rate of 300,000 Sm³ of gas per flow day through a 20/64-inch nozzle opening.

As the appraisal well 6507/2-7 S has been temporarily plugged, the Deepsea Nordkapp rig will proceed to production license 932 where Aker BP is also the operator. This is a sixth-generation dynamically positioned harsh environment and winterized semi-submersible of a Moss-enhanced CS 60E design.

Odfjell Drilling was one of the three offshore drilling contractors that entered into drilling and wells alliance agreements with Aker BP in January 2023 to undertake drilling activities on the Norwegian Continental Shelf (NCS).

Thanks to this, the Deepsea Nordkapp rig was contracted to the end of 2024 with an option to extend the contract further. The two players agreed to prolong the rig’s work in December 2023 for two years.