33/5-2

General

The prime objective of the well 33/5-2 was to test a Late Jurassic sandstone reservoir. The Middle Jurassic Brent Group and the Early Jurassic Statfjord Formation were considered secondary objectives. The Late Jurassic (Early Kimmeridgian) sandstone was assumed to be a continuation of the same deposits recorded at the Magnus Field and in the wells 211/8-1 and 211/13-3. These deposits constitute the oil reservoir at the Magnus Field and were also hydrocarbon bearing in 211/13-3. This objective was considered a high-risk prospect since the "Magnus Sandstone Member" had previously not been recorded on this side of the 211/13- 33/5- (Makrell-) horst. The Brent Group was expected to be as in the wells 211/13-2 and -6 where it is oil bearing. It was thought to be a typical shallow to marginal marine sandstone sequence, deposited during shoreline progradation. The location far down flank from the crest of the closure was considered to make hydrocarbon occurrence in the 33/5-2 Brent Group less likely. This was also the case for the Statfjord Formation. It was expected to consist of fine to coarse, occasionally pebbly sandstones with some shale interbeds of fluvial to marginal marine origin. The well was planned to drill approximately 50 m into the Statfjord Formation with an expected total depth at 4525 m.

Operations and results

A number of "pockmarks" typically 40 m across and 2 m deep were seen in the northern and eastern part of the area of the well location. To get some more information about the uppermost meters of soil, seafloor sampling and analysis were conducted by IKU. The seabed was found to consist of a fine sand, normally firm with shell fragments, plastic, silty clay and below greyish green sand.

Wildcat well 33/5-2 was spudded with the semi-submersible installation Nortrym on 31 July 1981 and drilled to a total depth of 4520 m in the Triassic Lunde Formation. The well was drilled with sea