Synopsis

This paper illustrates oil exploration in the West of Shetlands area from 1995 to 2001 by documenting the history of Block 205/9, awarded in the UK 16th Licensing Round in 1995. Good quality Paleocene sands had been encountered in the 1989 well 205/9-1 in the down-dip part of the block, and equivalent sands were absent on the adjacent Flett Ridge to the SE, setting up the possibility of a pinchout play. The first well testing the play, 205/8-1, was drilled on the overall pinchout on 2D seismic data, but 3D seismic data were acquired across the area to better delineate the depositional systems. The first well drilled on the 3D data to test the sand pinchout, 205/14-3, failed to encounter sands in communication with those in 205/9-1, so attention turned to alternative stratigraphic traps highlighted by seismic amplitude anomalies. Detailed evaluation of the seismic data revealed that the attractive seismic amplitude response of one potential prospect was actually an artefact associated with overlying basalt. Further analysis of the 3D seismic attributes identified a tongue of sand south of 205/9-1, and analysis of magnetic fabrics from core data in 205/9-1 revealed that sand was input to this area from the NE, contrary to previous models. Unfortunately the seismic attributes, supported by fluid inclusion data, suggested that the sand was water-wet. As a result of the evaluation work, the block was relinquished in 1999 without further drilling. While there is undoubtedly scope for stratigraphic traps in the area to prove hydrocarbon-bearing, experience on the 205/9 block and other studies led to a refocusing on dip-closed structures, and a resulting discovery, the first in the Faroes, consisted of 170 m of hydrocarbon-bearing sands in the T10 Paleocene interval.

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