25/11-2

General

Well 25/11-2 was drilled to appraise the 25/11-1 Balder discovery on the Utsira High in the North Sea. The objective was to define the continuity and reservoir thickness of the Early Eocene oil bearing sands in a northward direction from well 25/11-1 and a southward direction from well 25/8-1.

Operations and results

Appraisal well 25/11-2 was spudded with the vessel Glomar Grand Isle on 13 September 1970 and drilled to TD at 1823 m in the Paleocene Sele Formation. No significant problems occurred during the operations. The well was drilled with seawater/gel down to 175 m, with seawater/Spersene/ XP-20/Salinex from 175 m to 945 m, and with fresh water/ Spersene/XP-20 from 945 to TD.

The well penetrated the Utsira Formation and several Skade Formation sand units and then entered a ca 600 m thick section of shales belonging to the lower Hordaland Group before top Balder formation was encountered at 1699 m. The Balder Formation contained several thin Intra Balder Formation sandstones, of which a seven meter thick sandstone at 1727 m was the thickest. The sands were oil bearing down to 1747 m. Hermod sandstones were penetrated from 1780 to 1817 m. They had better reservoir properties than the Intra Balder Formation sands, but were water bearing without shows.

No conventional cores were cut in the well. Out of four attempts with the Formation Interval Tester (FIT) three tests were seal failures while test no 4, at 1728.5 m, was successful and recovered 0.33 Sm3 gas, 6.9 l oil, and 3.25 l oil and gas cut mud.

The well was permanently abandoned on 24 September as an oil appraisal.

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