35/3-1

The exploratory well, 35/3-1, was drilled on block 35/3 in the northern Norwegian North Sea, approximately 65 km west of Måløy in western Norway. The location is east of the Norwegian Trench. The general objective was to test the total stratigraphical sequence down to pre-Jurassic strata. Within the sequence, sand development was predicted for the Lower Cretaceous and the Early Jurassic, with a possibility for minor sands in Middle-Late Jurassic. The well should penetrate two seismic reflectors believed to represent top Early-pre Jurassic and basement, respectively. Planned TD was at 5250 m.

Operations and results

Wildcat well 35/3-1 was spudded with the semi-submersible installation Deepsea Saga on 19 July 1976. The well was terminated at 4475 m in the Dunlin Group (Middle Jurassic, Bajocian age). This was not the planned TD, but due to high pressure the well was abandoned at this depth for safety reasons. Because of this the two deep seismic reflectors were not tested in this well. The well was drilled with seawater and salt water gel/Milben mud down to 982 m, with gypsum mud from 982 m to 2474 m, and with lignosulphonate mud from 2474 m to TD.

A number of Tertiary sands not normally encountered in this part of the North Sea, were penetrated in this well. In the Early Jurassic, at 3805 m, a 215 m sequence of Agat Formation sandstone was penetrated. At 4145 m a 21 m sequence of Late Jurassic Intra Heather Formation sandstone was penetrated. Shows were encountered and described as follows:

"The first traces of hydrocarbons were encountered in Early Cretaceous sand at 3865 m. The sand gave a poor show of dead oil with no direct fluorescence, but with slow, streaming, cream cut fluorescence. Similar shows were occasionally encountered over the interval 3865 - 3975 m, partly with a fast, streaming, white cut fluorescence. At 3900 m a relatively clean, fine to medium grained silica cemented sand showed light brown stain, traces of pal