30/9-6

General

Well 30/9-6 was drilled on the C-prospect on the southeast flank of the Oseberg Fault block. The structure is a rotated fault block with overall easterly dips towards the Horda Platform fault. The prospect is further bounded by faults to the west and to the northwest. The primary objective was to prove hydrocarbons in the Brent Group and verify possible pressure communication between the C-structure and the Oseberg Field Alpha structure to the North.

Operations and results

Wildcat well 30/9-6 was spudded with the semi-submersible installation Polar Pioneer on 8 March 1987 and drilled to TD at 3034 m in the Early Jurassic Statfjord Group. Drilling proceeded without significant problems. The well was drilled with spud mud down to 970 m and with KCl/polymer mud from 970 m to TD.

The Brent Group was encountered at 2591 m and had oil in three differently pressured sand bodies, one in the Tarbert Formation and two in the Ness Formation. The lowest seen oil was at 2645 m in the Ness Formation. Four different pressure regimes were found in the Brent group. The Tarbert Formation has 6 m gross with 4.5 m net pay. The average porosity is 19% and the average water saturation is 44%. The Ness Formation has 49 m gross (hydrocarbon-bearing interval) with 13.3 m net pay (combining the two oil bearing sand bodies). The average porosity is 23% and the average water saturation is 39%.

Weak shows were described in limestones in the interval 2318 m to 2358 m in the top of the Shetland Group. Otherwise, no oil shows were described outside of the oil-bearing Brent reservoirs.

Five conventional cores were cut in the Brent Group from 2593.5 - 2