33/6-5 S

General

Well 33/6-5 S was drilled to test the Tail prospect on the Tampen Spur in the North Sea. The primary objective was to prove presence and commercial volumes of movable hydrocarbons in the Jurassic sandstones of the Rannoch Formation.

Operations and results

Wildcat well 33/6-5 S was spudded with the semi-submersible installation Deepsea Yantai on 26 August 2021 and drilled to TD at 3515 m in the Early Jurassic Drake Formation. The top hole was first drilled as a 9 7/8" hole down to 500 m to check for shallow gas. No shallow hazards were encountered, and the hole was opened to 26". After running the 20" surface casing, the well was suspended on 1 September when the rig moved to the nearby Dugong discovery for an appraisal well test. The rig returned on 25 September and the operations resumed. The well was drilled S-shaped, vertical through the target reservoir. Operations proceeded without significant problems. The well was drilled with seawater and hi-vis pills down to 500 m, with Glydril mud from 500 m to 1302 m, and with Rheguard oil-based mud from 1302 m to TD.

The target Rannoch Formation was penetrated at 3357 m. It consisted of 91.4 m gross sandstone with limestone stringers. XPT pressure points were taken with good results and identified two, possibly three different pressure zones: the Rannoch Formation sandstone, the Tarbert Formation sandstone and the Intra Draupne Formation sandstone. The reservoir properties in Rannoch/Tarbert are fair to good (porosity average = 19% from log analysis). The Intra-Draupne sandstone have medium reservoir properties (porosity average = 16% from log analysis). All three sandstones are water wet and there were no oil shows above the OBM.

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