25/11-27

General

Well 25/11-27 was drilled on the Grane F-structure, ca nine kilometres northeast of the Grane field in the North Sea. The primary objective was to prove petroleum in Paleocene reservoir rocks (the Heimdal Formation), but also to find out if there could be communication with the Grane field in the event of a discovery.

Operations and results

Wildcat well 25/11-27 was spudded with the semi-submersible installation Songa Trym on 4 May 2013 and drilled to TD at 1890 m in the Late Cretaceous Tor Formation. The first attempt to spud failed due a very competent seabed. The re-spud was successful and operations proceeded without further significant problems. No shallow gas was seen. The well was drilled with seawater and hi-vis sweeps down to 1159 m and with XP-07 oil based mud from 1159 m to TD.

Top of the primary target Heimdal Formation was encountered at 1743 m, 10 m shallow to prognosis. The Heimdal Formation contains four sandstones in the upper part, varying in thickness between 2 to 5 meters, and a 39 m thick massive sandstone with top at 1766 m in the lower part. The sandstones were oil bearing with all five sandstones on the same oil gradient. The OWC was clearly defined at 1785 m in the middle of the lower sandstone. The reservoir had excellent properties. Pressure measurements show a highly undersaturated oil with similar properties and the same pressure regime as the main Grane Field reservoir. No oil shows were described in the well other than in the oil-bearing sandstones in the Heimdal Formation.

One core was cut from 1769.4 to 1796.5 m in the lower Heimdal massive sandstone. MDT fluid samples were taken at 1766.5 m (oil of density 0.929 g/cm3) and 1803 m (water).</s