35/12-5 S

General

Well 35/12-5 S was drilled to test the Crossbill prospect on the Uer Terrace, ca 15 km southwest of the Gjøa Field in the North Sea. The primary target were the Sognefjord and Fensfjord formation sandstones in the Late Jurassic and the secondary target was the Kimmeridgian aged turbidite sequence at slightly shallower level in the Late Jurassic.

Operations and results

Wildcat well 35/12-5 S was spudded with the semi-submersible installation Transocean Arctic on 10 May 2015 and drilled to TD at 3570 m (3370 m TVD) in the Middle Jurassic Oseberg Formation. The well was drilled S-shaped, vertical down to 957 m, deviated with a ca 32 ° sail angle from 1500 m to 2300 m and back to vertical again at 2750 m. No significant problem was encountered in the operations. The well was drilled with seawater and high-viscosity sweeps down to 957 m, with KCl/Polymer/glycol mud from 957 m to 961 m, with XP-07 oil-based mud from 961 m to 2767 m, and with Performadril water based mud from 2767 m to TD.

The well found reservoir quality sandstones at all target intervals, and also in the Krossfjord Formation. The Kimmeridgian sequences contain ca 10 m of net sand, the Sognefjord is mostly shaled out at this location with not more than 5 m net sand, whereas Fensfjord has a gross thickness of 95 m (35 m net) and Krossfjord 59 m gross (32 m net) thickness. All encountered reservoirs are water bearing. No shows were observed in the well.

No cores were cut. RCX water samples were taken at 2874.5 m, 3172 m and 3240 m.

The well was permanently abandoned on 19 June 2015 as a dry well.

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