34/4-8

General

Well 34/4-8 is located on the "Beta Terrace", a down faulted terrace northwest of the Snorre Block in the central part of the block. The main objective of well 34/4-8 was to test the presence of hydrocarbons and the reservoir quality of the Statfjord Formation on the Beta Terrace. The well should also test the presence of hydrocarbons in the Lunde Formation, improve depth conversion and seismic tie for the pre-Cretaceous levels in this previously undrilled structural element, and give indications on further prospectivity north-westwards in block 34/4.

Operations and results

Wildcat well 34/4-8 was spudded with the semi-submersible installation "Vildkat Explorer" on 22 May 1994 and drilled to TD at 3110 m in the Triassic Lunde Formation. Since possible shallow gas levels had been predicted, a 9 7/8" pilot hole was first drilled. No shallow gas was found. The well was drilled with spud mud and gel down to 1460 me and with KCl mud with a glycol additive from 1460 m to TD.

The Nordland and Hordaland Groups were mainly silty claystones except for the sandy Utsira Formation, which came in at 1123 m. The Nordland and Hordaland Groups had a very high content of drilling gas (average 2-3%), but no signs of gas were seen on the logs. The Rogaland Group was penetrated at 1690 m, and consists of the Balder and Sele Formations. The Balder Formation was dominated by tuff interbedded with claystone. The Sele Formation consisted of silty claystones with traces of limestones. At 1838 m the Shetland Group was penetrated. The Shetland Group consisted predominantly of silty clay stone with some limestones and thin sandstone beds. The Cromer Knoll Group had marl as the main lithology. The marl was interbedded with silty claystones and sandstones. The Dunlin Group consisted of claystone interbedded with marl and minor sandstone beds. The Statfjord Formation was penetrated at 2799 m and consisted of sandstones alternating with shale/claystones. The Hegre Group proved to be