7122/4-1

General

Wildcat well 7122/4-1 was drilled in the Northern part of the Hammerfest Basin. The objective of the well was to test the Åsgard prospect, a large, tilted horst with Middle-Lower Jurassic sandstones of the Stø formation as the primary objective. The underlying Nordmela and Tubåen formations were also considered to have potential for reservoired hydrocarbons. The trap was formed by a horst structure dipping towards the North-Northwest. Well 7122/4-1 was the first well on this prospect.

Operations and results

Well 7122/4-1 was spudded with the semi submersible installation Sonate Arcade Frontier on 13 November 1991 and drilled to a total depth of 3015 m in the Triassic Snadd Formation. The well was drilled with seawater and gel down to 815 m, with KCl/polymer from 815 m to 2015 m, and with KCl/NaCl/Polymer from 2015 m to TD.

Good reservoir quality sandstones were encountered in the Stø and Nordmela Formations. Core analysis indicated generally good porosity and permeability. FMT's run in the Stø confirmed good permeability. However, analysis of the wire line logs indicated clearly that the Stø and Nordmela sandstones are water wet. The Tubåen Formation consisted primarily of sandstone, but was very thin in this well. Log analysis indicated that these sandstones are also water wet. Thin, tight sandstones (interbedded with claystone and siltstone) were present through much of the Triassic, generally decreasing in thickness with depth. From 2970 to 2990 m a Carnian sandstone was penetrated. The drill gas was higher through this zone than in any other sandstone in the well, averaging about 0.8 %. The cutting samples showed the reservoir quality to be quite poor, with no visible porosity. Numerous unsuccessful attempts with the FMT tool to obtain a pressure measurement indicated that this zone has extremely low permeability. This was confirmed by the log analysis.

Hydrocarbon shows were first observed in the Early Cret