30/9-2 R

General

The wildcat 30/9-2 was planned as the first well on the Gamma structure in block 30/9. Well 30/6-9 had previously penetrated the structure but this well failed to encounter the oil/water contact. The primary objectives of 30/9-2 were to verify the reserve estimate for the main part of the gamma structure and penetrate the oil/water contact in the lower part of the Brent Group. Additional objectives were to obtain core material from the oil zone in the Etive Formation and perform a water injection test in this, obtain information on the quality of the reservoir in the water zone and stratigraphical information on the southern part of the Gamma structure.& The well was temporarily abandoned for about one year and then re-entered for an extended test.

Operations and results

Wildcat well 30/9-2 was spudded with the semi-submersible installation "Nortrym" on 1 April 1983 and drilled to a total depth of 2830 m in the Early Jurassic Dunlin Group. The well was drilled using water-based mud down to the 12 1/4" hole at 1715 m. The 12 1/4" hole was drilled to TD using oil based mud ("ENVIROMUL" and "IL 2832 oil" as oil base). While running the 13 3/8" casing, this got stuck at 1334 m. The casing was worked free using diesel in the mud and the casing was set at 1680 m. After drilling the 12 1/4" hole to 2203 m the drill pipe got stuck with the bit at 2170 m. Several unsuccessful attempts were made to free the pipe. The drill pipe was then backed off and the well was cemented back and sidetracked from 1482.5 m.

The Brent Group sandstones (2578-2767 m) RKB were hydrocarbon bearing down to 2737m where an oil/water contact was encountered within the Etive Formation sandstones (2698-2767m).& No additional hydrocarbon bearing reservoirs were encountered by this well. Poor hydrocarbon shows reported from Upper Cretaceous limestones were considered uninteresting. The Ness Formation (2578-2698 m) consisted of