7120/6-1

General

Wildcat well 7120/6 1 was drilled in the middle eastern part of the block, on a structure comprising an east-west horst block extending into blocks 7121/4 and 7121/5 to the east, and with a central east west oriented fault at Middle Jurassic level. The primary objective of the well was to test Middle Jurassic sand sequences in the Stø Formation. A further objective was to evaluate geologic trends in stratigraphy, structure and reservoir development in a northerly direction in the Hammerfest Basin. The well was prognosed to be drilled into rocks of Triassic age

Operations and results

The well was spudded with the semi submersible installation Treasure Scout 2 February 1985 and drilled to TD at 2820 m in Late Triassic rocks (Tubåen Formation). No significant problems occurred during drilling. It was drilled and tested in 90 days with only 4.4 days down time. Of these 3.2 days were wait-on-weather (WOW). The well was drilled with spud mud down to 815 m and with KCl/polymer mud from 815 m to TD.

The well encountered hydrocarbon bearing Jurassic sands of the Stø Formation from 2385.5 m to 2469.5 m. The interval from 2385.5 to 2427 m was gas bearing and from 2427 to 2443 m oil bearing. In the interval 2559 - 2800 m (Tubåen Formation), thin gas bearing sandstone stringers were encountered. This interval spanned the Jurassic-Triassic boundary, and in the lower intervals below 2660 m net pay was associated with thin interbedded coals. Weak oil shows were observed in claystones in the Cretaceous below 2176 m. Good oil shows in sandstones were recorded throughout the hydrocarbon bearing zone and down to 2500 m. Below this level oil shows were in general associated either with mud stones or with coal seams and fragments.

Geochemical studies indicated that the Tertiary and Cretaceous sediments were immature. Above 2300 m there were alternating poor source rocks for oil and gas and very good oil-prone source rocks. The top J