34/4-4

General

The primary objective of the exploration well 34/4 4 was to drill the untested Triassic sequence in the fault blocks west of well 34/4-1. The well location was chosen to be stratigraphically higher relative to the Triassic sequence in well 34/4-1. The purpose of the well location was also to penetrate and core the maximum oil column above the tentative oil water contact interpreted in well 34/4-1 and to test possible lateral fluid communication with 34/4-1.

Operations and results

Wildcat well 34/4-4 was spudded with the semi-submersible installation Dyvi Alpha on 11 September 1982 and drilled to TD at 3800 in Middle Triassic sediments, Teist Formation. As much as 15 % of total rig time was WOW due to bad weather. While coring, after core number 12 was taken, the mud was replaced with seawater by accident and caused a kick, resulting in a 20 bbls influx. The well was drilled with spud mud down to 493 m, with gel mud from 493 m to 1212 m, with gypsum/polymer mud from 1212 m to 2116 m, with Lignosulphonate mud from 2116 m to 2475 m, and with lignosulphonate/Chem-X mud from 2475 m to TD.

First oil shows were recorded on cuttings from thin sandstone stringers below 2075 m, accompanied by increased gas readings. Sidewall cores from siltstone beds between 2100 and 2414 m also occasionally had oil shows.

The Early Cretaceous Åsgard Formation rested unconformably on the Late Triassic Lunde Formation at 2425 m. The Lunde Formation sandstones were oil bearing down to the oil water contact at 2586 m. The OWC was set mostly on the intersection of the oil and water pressure gradients from RFT data. The oil bearing sand was separated from the water zone by a 22 m thick