35/11-23

General

Well 35/11-23 was drilled to test the Echino Sør prospect on the Lomre Terrace north of the Troll Field in the North Sea. The primary objective was to prove petroleum in the Late Jurassic Sognefjord Formation. The secondary objective was to prove petroleum in the Middle Jurassic Brent Group and to investigate the presence of reservoirs and reservoir quality in the Middle Jurassic Etive and Oseberg Formations.

Operations and results

Wildcat well 35/11-23 was spudded with the semi-submersible installation Deepsea Atlantic on 6 October 2019 and drilled to TD at 2977 m in the Early Jurassic Cook Formation. While drilling 17 ½” section, a gas peak of 4% was observed at 455m MD. Flow check showed a stable well. However, a shallow water flow was observed after cementing the 13 3/8” casing. This was observed on the Wellhead with ROV, declining to no flow after 24 hrs. Otherwise operations proceeded without significant problems. The well was drilled with seawater and hi-vis pills down to 432 m, with Aqua-drill mud from 432 to 1297 m, and with Synteq oil-based mud from 1297 m to TD.

Two Sognefjord Formation sands were penetrated, a J56 sand from 2292 to 2321 m, and a J52 sand from 2385 to 2406 m. The J56 sand contained gas and oil with a GOC at 2312 m and an oil-leg down-to the base of the sand. The J52 sand contained oil with an OWC in-well at ca 2397 m. A 16 m thick Krossfjord Formation Equivalent with top at 2541 m had indications of hydrocarbons.

In the Brent Group, the Ness Formation consists of interbedded coal beds and claystone with thin sands. Ness had hydrocarbon indications from 2725 to 2743 m in four sandstone bodies based on elevated gas and resistivity readings, and a gas s