16/5-7

General

Well 16/5-7 was drilled on the Klaff prospect on the basement high just west of the southern edge of the Johan Sverdrup field in the North Sea. The objective was to prove petroleum in graben fill of pre-Cretaceous age, with potential reservoir of Late Jurassic, Triassic or Permian age, or fractured and weathered basement.

Operations and results

Wildcat well 16/5-7 was spudded with the semi-submersible installation Transocean Spitsbergen on 12 June 2019 and drilled to TD at 2028 m, 112 m into basement rock. Operations proceeded without significant problems. The well was drilled with seawater and hi-vis pills down to 1128 m and with KCl/polymer/GEM mud from 1128 to TD.

The Jurassic section was absent. Base of the Early Cretaceous Åsgard Formation rests unconformably on fractured and weathered basement rock at 1916 m. No shows were observed on drilled cuttings from well 16/5-7. Good oil shows (with fluorescence, cut, oil odour and stains) were observed from 1918 to 1940 m in the core chips from the first three cores. The log readings in Basement are hard to interpret as the granite is rather tight. Pressure points indicate an oil gradient, but fluid samples showed that the formation was water bearing. The measured gas was very low throughout the well, with less than 1% recorded.

Four cores were cut in the interval 1911 to 1949 m with 86.2% overall recovery. RCX fluid samples were taken at 1926 m (water), and 1934 m (water).

The well was permanently abandoned on 12 July 2019 as a well with shows.

Testing

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