16/4-13 S

General

Well 16/4-13 S was drilled to test the D-segment prospect in a sub-basin northwest of the Solveig Field and south of the Edvard Grieg Field in the North Sea. The primary objective was to prove petroleum in reservoir rocks of Triassic to Paleozoic Age.

Operations and results

Wildcat well 16/4-13 S was spudded with the semi-submersible installation West Bollsta on 12 February 2021. The well was drilled to 1985 m where pack-off occurred and losses were experienced. The losses could not be cured. The decision was made to plug back and make a side-track. Technical side-track 16/4-13 ST2 was kicked off at 1365 m and drilled to TD at 2422 m (2324.3 m TVD) in Paleozoic basement conglomerates. The well was drilled with seawater and hi-vis pills down to 426 m, with Hydraglyde Optima water-based mud from 426 m to 1365 m, with Glydril Plus water-based mud form 1365 m to 2010 m and with Hydraglyde Optima water-based mud from 2010 m to TD.

Paleozoic basement sandstone and conglomerates were encountered with top at 2020 m (1973.4 m TVD), directly underlying Late Cretaceous Tor Formation chalk. No Jurassic or Triassic sediments were present. The Basement was oil bearing down to an oil-water contact at ca 2031 m (1983 m TVD). About seven metres of the reservoir had poor to moderate reservoir quality. Shows on cuttings (no stain, no odour, direct and cut fluorescence) continued down to 2098 m and weaker shows (weak direct fluorescence only) down to 2175 m). No shows were described above top reservoir.

Three cores were cut in succession from 2022.8 to 2048.3 m in the basement conglomerates. ORA fluid samples were taken at 2022.2 m (oil), 2027.04 m (oil), and 2034.5 m (water).

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