|BRITAIN'S OFFSHORE OIL & GAS
A number of deep basins are located off western Britain from the Shetlands to the Western Approaches. Most began life in the Permian Period.
(F26) formed by the 'trap-door' mechanism are common; large basins like the East Irish Sea Basin and the Faeroe-Shetland Basin (F25) are comprised of several such half-grabens. In these basins discoveries have been slow in coming. A gap of 16 years occurred between the discovery of the giant Morecambe field, and the oil and gas discoveries of the Liverpool Bay complex. The Irish Sea gas and oil come from underlying Carboniferous coals and shales. They have been trapped in Triassic sandstones beneath impermeable mudstone.
In the Faeroe-Shetland Basin (F49), the giant Clair field was discovered in 1977. The complex fractured reservoir prevented early development, and it is only now, with the application of technological advances, that this field is being brought into production. Around 15 years after the discovery of Clair, BP found the Foinaven and Schiehallion fields, also in the Faeroe-Shetland Basin. These two fields are now in production, using Floating, Production, Storage and Offloading (FPSO) vessels, with the oil transported by shuttle tanker.