Partners in Norwegian Sea gas discovery mulling over tie-back to existing infrastructure

Harbour Energy, former Wintershall Dea, has undertaken appraisal activities with one of Transocean’s rigs at a gas discovery in the Norwegian Sea, 270 kilometers north of Kristiansund, off the coast of Norway.

According to the Norwegian Offshore Directorate (NOD), Harbour Energy has proven gas in the appraisal well 6507/4-5 S in the Norwegian Sea, using the Transocean Norge rig. Harbour Energy is the operator of the production license 211 CS, while Petoro, Aker BP, and Orlen are the other licensees.

Before the appraisal well 6507/4-5 S was drilled, the operator’s resource estimate for the primary exploration target was 3-9 million standard cubic meters of recoverable oil equivalent, while the resource estimate for the secondary exploration target was 4-7 million standard cubic meters of recoverable oil equivalent.

Therefore, the primary objective of the well was to delineate the gas/condensate discovery from wildcat well 6507/4-2 S in the Lange Formation (Sabina), and to carry out formation testing. The secondary objective was to delineate the gas/condensate discovery (6507/4-2 S) in the Lysing Formation (Adriana).

The well encountered a 41-meter gas column in sandstone rocks in the primary exploration target, totaling 17 meters, with poor to moderate reservoir quality. The gas/water contact was not encountered. The well also encountered two sandstone layers in the Middle and Lower Lange Formation of around 4 and 21 meters, with poor reservoir quality but with traces of hydrocarbons.

In the secondary exploration target, the well encountered a 30-meter gas column in sandstone rocks, totaling 23 meters with good to very good reservoir quality. The gas/water contact was encountered at 2,897 meters below sea level. The Norwegian authorities have confirmed that extensive data acquisition and sampling have been carried out.

The preliminary estimate of the size of the discovery in the Lange Formation (Sabina) is said to be between 2.7 and 6.2 million standard cubic meters of recoverable oil equivalent. This corresponds to about 17-39 million barrels of oil equivalent.

Furthermore, the well has confirmed the size of the discovery at 4–7 million standard cubic meters of recoverable oil equivalent in the Lysing Formation (Adriana), which corresponds to around 28–43 million barrels of oil equivalent.

During the production test, conducted in the upper part of the Lange Formation, the maximum production rate was 530,000 standard cubic meters of gas and 80 standard cubic meters of condensate per flow day through a 28/64-inch nozzle opening.

The appraisal well, drilled to a vertical depth of 4,111 meters and a measured depth of 4,150 meters below sea level, was terminated in the Lange Formation in the Lower Cretaceous. The water depth at the site is 455 meters.

The appraisal well 6507/4-5 S has been permanently plugged and abandoned. The Norwegian Offshore Directorate claims that licensees are considering tying the discoveries back to existing infrastructure in the area.

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 reduction for offshore units.