ID: 514
OBJECTID: 514
wlbNpdidWellbore: 524
wlbName: 25/6-1
wlbHistory:

General

Well 25/6-1 was drilled on the northeastern part of the Utsira High. The main objective of the well was to test for hydrocarbons in a prospect west of the main fault in the southern part of the block. Primary targets were the Middle Jurassic reservoir sandstone belonging to the Vestland Group, which is partly eroded in this area, and the Early Jurassic Statfjord Formation sandstone. Secondary objective was the Early Tertiary sandstone. The total depth target was to drill through a strong seismic reflector between 2.5 and 2.6 second TWT. Shallow gas was expected at 282 to 344 m and 395 m.

Operations and results

Wildcat well 25/6-1 was spudded 18 December 1985 by Wilh. Wilhelmsen's Offshore Services semi-submersible installation Treasure Saga, and completed 3 February 1986 at a depth of 2881, 30 m into rocks of probably Early Palaeozoic/Pre-Cambrian age. The well was drilled with seawater and hi-vis pills down to 260 m, with bentonite gel mud from 260 m to 1028 m, with gypsum/polymer mud fro 1028 m to 2195 m, and with bentonite gel / polymer mud from 2195 m to TD. No shallow gas was encountered.

The Quaternary/Tertiary sequence was 2017 m thick, and consisted of the Nordland, Hordaland, and Rogaland Groups. The Nordland Group was marine claystone with sands frequently developed, especially in the lower part, with 163 m of the sandy Utsira Formation. The Hordaland Group was clay/claystone with some thin sand units. Slightly tuffaceous claystone and a lower sand/marl/ claystone sequence were the main lithologies of the Rogaland Group. A 65.5 m thick Cretaceous sequence represented by Shetland and Cromer Knoll Groups was penetrated. The main lithology was chalky limestone, calcareous claystone grading to marl and minor sand.

The Jurassic sediments represented by the Viking, Vestland, and Dunlin Groups and the Statfjord Formation were encountered at 2233.5 m.  Top Vestland Group was at 2277 m and top Statfjord Formation
wlbHistoryDateUpdated: 2016-07-06T00:00:00