9/2-1

General

Well 9/2-1 was drilled in a new separate structure and designed to test the hydrocarbon potential of the Egersund Basin. The main target of the well was to test sandstones of middle Jurassic age. Furthermore, the well was expected to improve the paleontological, the geological and the geochemical understanding of the area.

Operations and results

Wildcat well 9/2-1 was spudded with the semi-submersible installation Dyvi Delta on 21 February 1987 and drilled to TD at 3756 m in the Triassic Skagerrak Formation. The well was drilled with a 36" bit down to 189 m, but the drill bit got stuck due to boulders and the string had to be blown off just above the bit. The well was respudded 23 February 1987 and this time a 17 1/2" pilot hole was drilled before opening to 36". It was drilled to 587 m without a riser. NPD gave suspension from conventional logging through this sequence because the MWD log was of good quality, with continuity and correlatable to other wells in the area. Further drilling proceeded without significant problems. The well was drilled with spud mud down to 788 m and with gypsum/polymer mud from 788 m to TD.

The top of the Jurassic sand (Sandnes Formation) was reached at 3174 m, 178 m deeper than prognosed. The oil water contact was difficult to determine exactly from logs, but was believed to be somewhere in the transition zone between 3230 and 3239 m. There were good shows down to 3240 m. Core and log analysis indicated a fairly low porosity sandstone with small amounts of silt, shale and limestone. Compaction, quartz cementation, calcite cement, and clay minerals occurring as fine-grained pore filling aggregates, are the main porosity-reducing factor in the reservoir. The core and log analysis indicate a general trend of decreasing reservoir quality with increasing depth. The Bryne Formation at 3309 m to 3601 m was water wet. Organic geochemical analyses show many intervals with good to excel