6406/3-3

General

Well 6406/3-3 was drilled to appraise the southern part of the Beta structure, named Smørbukk South. This well was the fourth well on Smørbukk South, and it was a joint well between licenses PL 091 and PL 094. The primary target for the well was sandstones in the Middle-Early Jurassic age Halten Group (present nomenclature: Fangst and Båt Groups). The well location was chosen so that the Tomma I Formation (Garn Formation) was expected to be hydrocarbon bearing with hydrocarbon/water contacts in the Tomma III - Aldra Formations (Ile - Tilje Formations).

Operations and results

Appraisal well 6406/3-3 was spudded with the semi-submersible installation Dyvi Delta on 4 August 1986 and drilled to TD at 4416 m in the Early Jurassic Åre Formation. Operations went without significant incidents and were finished twenty days ahead of schedule. Only 5.2% rig time was registered as down time. The well was drilled with seawater/hi-vis pills/bentonite down to 1070 m, with gypsum/polymer mud from 1070 m to 2320 m, with gypsum/lignosulphonate/lignite mud from 2320 m to 3936 m, and with lignosulphonate/lignite/Anco resin mud from 3936 m to TD.

The top of the reservoir came in at 3933 m, 49 m deeper than prognosed. Cores showed poor - medium visible porosity and good to poor oil shows from the top and down to ca 3955 m (ca 3925 m TVD MSL). The oil/water contact was thus almost 65 m higher than the other holes in the Beta structure. RFT-data indicated that the rest of the Fangst and Båt Groups contained water. Weak shows were however recorded on sidewall cores in the interval 4210 m to 4262 m in the Ti1je Formation, while weak shows were recorded on well site cuttings all through Middle - Early Jurassic down to TD.

A fixed offset VSP with the source 2.6 km north of the location was shot in order to explain the surprising and negative results of the well. The VSP sections indicated a probably sealing, east-west striking fault at reser