30/7-8

General

Well 30/7-8 was drilled in the Norwegian part of the Shetland Basin. The primary objective was to test the hydrocarbon potential in the Middle Jurassic Brent group, which had previously proved gas and condensate bearing in wells 30/4-2 and 30/7-6. The Early Jurassic Cook Formation and Statfjord Group were secondary targets. The planned TD was 4600 m in the Triassic Red Beds.

Operations and results

Appraisal well 30/7-8 was spudded with the semi-submersible installation Treasure Seeker on 19 November 1980 and drilled to 4287 m in the Middle Jurassic Brent Group . The drill pipe became differentially stuck at 4069 m. After unsuccessful fishing, the well was suspended with top of the fish at 4058 m, and 4287 m became official TD for the well. The well was drilled with seawater and hi-vis pills down to 215 m, with water based "lost circulation mud" from 215 m to 962 m, with gypsum/lignosulphonate mud from 962 m to 2648 m, with a bentonite/lignosulfonate/lignite mud type from 2648 m to TD.

Frequent traces of oil shows were described in many intervals from 1820 m and down to well TD. Most of the shows occurred in limestone stringers and were rated poor. The primary target Middle Jurassic (Bathonian-Bajocian) Brent Group reservoir was encountered at 4066 m. The shows in the Brent Group sandstones were rated good.

Five cores were cut in the well. One was cut in the Draupne Formation from 3888.5 m, while the other four were cut in the Brent Group reservoir section from 4082.3 m to 4129.3 m. No fluid sample was taken.

The well was suspended on 4 April 1980 as a gas/condensate appraisal well.

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