35/12-6 S

General

Well 35/12-6 S was drilled to test the Kallåsen prospect on the Uer Terrace south-east of the 35/9-7 Nova discovery in the North Sea. The primary objective was to prove commercial hydrocarbon volumes in Fensfjord Formation sands.

Operations and results

Wildcat well 35/12-6 S was spudded with the semi-submersible installation Transocean Arctic on 13 May 2018 and drilled to TD at 3370 m in the Middle Jurassic Oseberg Formation. Operations proceeded without significant problems. The well was drilled with seawater and hi-vis pills down to 445 m, with KCl/polymer/GEM mud with 4-6% glycols from 445 m to 1054 m, and with Innovert oil-based mud from 1054 m to TD.

The well penetrated a 39.8 m TVD thick, heterolithic Fensfjord Formation from 2997 m (2840.1 m TVD) to 3036.8 m (2879.9 m TVD). The reservoir is oil-bearing in the upper part down-to ca 3011 m (2854 m TVD), whereas an isolated sandstone in the basal part of the formation is water bearing. The proven oil column in-well is 14.4 m of which 3.1 m is effective reservoir of moderate quality. Oil shows, possibly OBM contamination, were described only in the oil-bearing Fensfjord Formation reservoir section.

One core was cut from 3013 m to 3066.93 m with 99.9% recovery. MDT fluid samples were taken at 2998.28 m (oil) and 3007.6 m (OBM filtrate and oil), while fluid scanning at station 3010.2 gave oil+irreducible water and scanning at station 3032.1 gave formation water.

The well was permanently abandoned on 13 June 2018 as an oil discovery.

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