6507/6-4 S

General

Well 6507/6-4 S was drilled on the Sinbad prospect in the Norwegian Sea. Structurally the prospect is located on the Sør High of the Nordland Ridge in the Norwegian Sea. The target prospect was an amplitude anomaly in the lower part of the Triassic Grey Beds. The distance to the Skarv Field immediately to the west is 10 km and to the Heidrun Field (to the SSW) approximately 30 km. Well 6507/6-4 S was drilled outside the amplitude anomaly to the south drilled by well 6507/6-1 in 1988 by Saga Petroleum.

Operations and results

Wildcat well 6507/6-4 S was spudded with the semi-submersible installation Borgland Dolphin on 26 October 2011 and drilled to TD at 1339 m (1333 m TVD) in the Late Triassic Red Beds. Due to coldwater corals the 36" hole, pilot hole and 26" hole were drilled with a subsea cuttings transport system (CTS) to transport the drilled cuttings 500 m away from the spud location. A 9 7/8" pilot hole was drilled from 471 to 907 m. Small gas bubbles were observed at the CTS funnel when flow checking at 790 m. The source of the gas was believed to be +/- 767 m. No significant problem was encountered in the operations. The well was drilled with sea water and Bentonite based high-viscosity sweeps down to 749 m and with Carbo-Sea oil based mud from 749 m to TD.

The formations came in close to prognosis with the Late Tertiary Kai Formation resting on top of the Early Jurassic Åre Formation at 1042 m. Top Grey Beds came in at 1208 m, with the Sinbad reservoir section at 1256 m. The latter was 12 m deep to prognosis. The Grey Beds Group consisted of rapidly changing sand-, silt- and claystone. Individual units were up to 5m thick, but generally 1-3 m. Trace of coal was reported. There were no indications of h