Norwegian oil & gas firm bites the dust in North Sea well

June 14, 2024, by Melisa Čavčić

Norwegian oil and gas player Wellesley Petroleum has found no hydrocarbons in an exploration well, which was drilled using one of COSL Drilling Europe’s rigs in the North Sea off the coast of Norway.

The Norwegian Offshore Directorate (NOD) granted Wellesley Petroleum a drilling permit for the well 35/11-29 S (Toppand øst) in January 2024 to spud a wildcat well in production license 248 C, which was awarded on April 9, 2013 and is valid until June 4, 2035. This was carved out of production license 248 in 2013.

Wellesley Petroleum is the operator of the well with an ownership interest of 30%, while its partners, Equinor and Petoro, hold 30% and 40% stakes, respectively. The well, which ended up being dry, was drilled with the COSL Promoter rig. According to NOD, the objective of the well was to prove petroleum in Middle Jurassic reservoir rocks in the Brent Group and the Oseberg Formation.

Furthermore, the well encountered the Ness Formation with a total thickness of around 64 meters with an 18-meter sandstone reservoir with poor reservoir quality, the Etive Formation with a total thickness of around 51 meters with a 26-meter sandstone reservoir with good reservoir quality, as well as the Oseberg Formation with a total thickness of around 50 meters with a 50-meter sandstone reservoir with moderate reservoir quality.

The well 35/11-29 S, which was drilled to respective vertical and measured depths of 3,490 and 3,575 meters below sea level, was terminated in the Cook Formation in the Lower Jurassic. The water depth at the site is 355 meters. As the well is dry, it has been permanently plugged and abandoned.

The license area also covers the Swisher discovery in wells 35/11-24S A and B, with development being viewed in context with Equinor’s Ringvei vest project, which is exploring the possibility of linking several discoveries made in the area in recent years.

The 2012-built COSL Promoter is a semi-submersible drilling rig designed to operate in water depths of up to 750 meters. While the rig is currently on contract with Equinor, it also got a new deal with the same company in August 2023, which would start in Q1 2025.

Recently, COSL Drilling Europe hired Odfjell Technology, a spin-off of Odfjell Drilling, to provide tubular running services supporting its offshore drilling activities.