30/11-2

General

Well 30/11-2 was drilled on the Bjørgvin Arch between the Stord Basin and the Frigg Field in the North Sea. The primary objective was a potential stratigraphic trap, formed by a shale-out of the Early Eocene "Frigg Sand" equivalent. Secondary objectives were sand bodies in the under-lying Paleocene (Cod and Danian Sands).

Operations and results

Wildcat well 30/11-2 was spudded with the semi-submersible installation Ocean Vanguard on 18 March 1975 and drilled to TD at 2590 m in the Late Cretaceous Shetland Gp. A shallow gas incident occurred at 343 m where the total mud gas increased to more than 30% for 5 minutes. The mud weight was increased to 490 psi. No further significant problem was encountered in the operations. The well was drilled with seawater and viscous slugs down to 215 m, with H921 Polymer/lignosulphonate/Gel and Ferrobar weighting material from 215 m to 1158 m, and with Dextrid/gel/lignosulphonate and Ferrobar weighting material from 1158 m to TD.

All targets including the Frigg sand were water bearing. The Frigg Formation was encountered at 2052 m and was 86 m thick. Based on petrophysical analysis it contain 58 m net sand (N/G = 0.69) with 33% average porosity. The Cod and Danian Sands were absent, or represented only by thin sandstone streaks and tight siltstones. Apart from the shallow gas, all gas readings were low throughout the well. The only oil show described was "a very faint solvent cut fluorescence" on a sidewall core from 2120.2 m in the Frigg sand.

No cores were cut and no fluid sample was taken.

The well was permanently abandoned on 16 April 1975 as a dry well.

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