3/7-3

General

Well 3/7-3 was drilled on a salt diapir in the southern part of the Søgne Basin in the North Sea. The primary target of the well was Danian/Late Cretaceous chalk, which had been found hydrocarbon bearing in the Ekofisk area and in the Danish well Lulu 1. Secondary target was Middle Jurassic sandstones, which had been found hydrocarbon bearing in well 2/6-2. The TD was planned below the top of the Zechstein salt in order to test possible Early Jurassic and/or Triassic sandstones.

Operations and results

Wildcat well 3/7-3 was spudded with the semi-submersible installation Dyvi Alpha on 21 June 1981and drilled to TD at 3540 m in the Late Permian Zechstein salt. At 1968 m, in the Late Eocene, a drilling break was experienced and the well started to flow. The flow was killed with a mud weight of 1.55 g/cc. After setting the 13 3/8" casing shoe at 1961 m, the well was controlled after gains and losses with a mud weight of 1.58 g/cc. No other problems were encountered while drilling. The well was drilled with seawater and bentonite down 666 m, with seawater/SST 202/FCL mud from 666 m to 1970 m, and with seawater/FCL/LC mud from 1970 m to TD.

Tertiary sands with a thickness of 37.5 m were encountered in the Paleocene. They were water bearing. The chalk, which was the main target, was relatively tight and water bearing. At 3325 m a 107 meter thick water bearing sandstone of Latest Jurassic - Earliest Cretaceous age (Kimmeridgian - Berriasian) was encountered. Below this sandstone Kimmeridgian shales rested directly on the Zechstein anhydrite. No shows were noted in the well.

Three cores were cut; one from 2830 to 2848 m in the Danian chalk (60% recovery) and two in the Beriasian Sandstones from 3337.5 to 3339 m (67% recovery) and from 3339 to 3348 m (100% recovery). No wire line fluid samples were taken.

The well was permanently abandoned on 31 August 1981as a dry well.

Testing

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