15/12-21 A

General

The 15/12-21 A is a sidetrack to the 15/12-21 Grevling well, which discovered oil in Hugin, Sleipner, and Skagerrak Formations sandstones. No oil-water contacts were seen in 15/12-21. The sidetrack well was drilled to appraise the discovery down flanks and to the east on the structure.

Operations and results

Appraisal well 15/12-21A was kicked off from 2162 m in well 15/12-21 on 21 May 2009. It was drilled with the jack-up installation Mærsk Guardian to TD at 3702 m (3348 m TVD) in the Late Triassic Skagerrak Formation. The well was drilled with Carbosea oil based mud from kick-off to TD.

The Hugin Formation was encountered at 3378 m (3118 m TVD), the Sleipner Formation at 3412 m (3141 m TVD), and the Triassic Skagerrak Formation at 3493 m (3198 m TVD). All three formations proved to be oil bearing as in the main well, with total pay of 36 m MD. No oil shows were noted above reservoir level. Patchy oil shows were recorded down to 3570m and the higher gas components had died away by 3586m. Show description was compromised due to the fact that the sandstone cuttings were often altered to an amorphous rock flour. The shows were described as poor direct pale white fluorescence, slow white crush cut fluorescence, very pale tea colour residue.

No cores were cut in this well. RCI wire line fluid samples were taken at 3394.5 m in the Hugin Formation (oil), 3411.7 m in the Hugin Formation (oil), 3519.4 m in the Skagerrak Formation (oil), and at 3646 m in the Skagerrak Formation (water).

The well was permanently abandoned on 20 June 2009 as an oil appraisal.

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