Exploration of the basins to the West of Shetland has, historically, been slower and more difficult than exploration in the North Sea.

The main West of Shetland Faeroe-Shetland Basin began to develop in the Permian Period and continued to subside throughout the Mesozoic and Tertiary Eras. In certain areas, oil and gas has migrated from the Kimmeridge Clay source rock into a ridge of much older Devonian and Carboniferous rocks that separates the two basins.

Exploration began in the West of Shetland area in the 1970’s, and the Clair field was the first significant discovery to be made in 1977. This is located on a ridge where oil is trapped in fractured Devonian and Carboniferous reservoir rocks.

Exploration drilling continued in the Faeroe-Shetland Basin during the 1980’s and early 1990’s but without significant success until the Foinaven and Schiehallion fields were discovered in 1992 and 1993 respectively. These fields are in younger Tertiary sandstones, and exhibit good quality reservoir properties.

DONG Energy entered the West of Shetland region in 2001, by which time a number of non-commercial discoveries had been made during the 1990’s, predominantly in Tertiary sediments covering a range of depositional systems, from fluvial through deltaic/shoreface and into shallow marine and turbidite deposits.

West of Shetland interest picked up significantly in 2004, which proved to be a very successful year for exploration and appraisal. During this year DONG Energy participated in the successful Laggan appraisal well and in a, Chevron-operated, significant oil and gas discovery with the Rosebank/Lochnagar well (213/27-1Z) located in the Faroe-Shetland Channel near the UK/Faroes border.

The rapidly improving success rate in finding new discoveries in the West of Shetland area, and the key to unlocking their development, stems from the application of cutting-edge technology and the greater regional knowledge now available. Advanced seismic techniques are allowing us to identify hydrocarbons directly in the seismic signal, and new seismic acquisition techniques are allowing us to image the reservoirs better, even below the volcanic material common in the region. Deep-water drilling and subsea production technology allow us to efficiently develop significant discoveries.

Today, both Tertiary and deeper Devonian and Carboniferous targets offer a wealth of exploration opportunities in the West of Shetland region, and DONG Energy expects to be at the forefront of this activity for many years to come.