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Quad 204 (Schiehallion)

Quad 204 is the multi-billion-pound redevelopment of the Schiehallion and Loyal fields, located 175 kilometres west of the Shetland Islands

Schiehallion and the adjacent Loyal fields were first developed in the mid-1990s and have produced nearly 400 million barrels of oil since production started in 1998. After 15 years of operating in harsh conditions and producing nearly 400 million barrels of oil, the original Schiehallion floating, production, storage and offload (FPSO) vessel required replacement to enable continued production from the fields. Technological advances also increased understanding of the fields and BP saw the greater potential the Schiehallion Area holds.

With the fields’ redevelopment through the Quad 204 project, BP and co-venturers expect to unlock a further estimated 450 million barrels of resources, extending the life of the fields out to 2035 and beyond. Production from the project is expected to ramp up to a plateau level of 130,000 barrels per day.

The Quad 204 project has involved construction of a purpose-built FPSO, the Glen Lyon, which is expected to process 130,000 barrels of oil a day at peak production. The project has also seen a complete upgrade of the subsea infrastructure and the start of a major drilling campaign with up to 20 new wells planned.

Glen Lyon was constructed at the Hyundai Heavy Industries shipyard in Ulsan, South Korea. It left Asian waters in early December 2015 and, following a short stop in Norway, arrived on field West of Shetland in June 2016. This was quite a journey considering the FPSO does not have its own means of propulsion. Tugs were used to tow it, first, the 15,300 nautical miles from South Korea to Norway and then the 286 nautical miles to the West of Shetland.

Without the skills and expertise of the UK supply chain, delivery of the Quad 204 project would not have been possible. Rosyth-based Babcock fabricated 73 subsea structures for the project – one of the largest subsea fabrication orders placed in the UK. Other key UK contractors included Technip for the supply of flexible risers and offshore installation; Aker Subsea for subsea control systems and Amec Foster Wheeler for hook-up and commissioning support.

The Quad 204 project presents one of the most complex engineering challenges BP and its partners have ever undertaken.


Glen Lyon FPSO fast facts

Just over a year after first oil, the Glen Lyon FPSO has successfully completed its ramp-up by producing 132,200 barrels of oil on 23 June – exceeding the maximum design rate target of 130,000 barrels a day.

The world’s largest harsh water floating, production, storage and offloading (FPSO) vessel, with superior seakeeping and long-term processing capabilities.
Process plant designed to handle 130,000 barrels of oil and 220 million cubic feet of gas per day.
Storage capacity of up to 800,000 barrels of oil.
270 metres long by 52 metres wide, weighs around 100,000 tonnes and accommodates up to 140 people.
Anchored to the seabed via a turret mooring system allowing the vessel to rotate and position head to the prevailing environment.
Moored by 20 mooring lines, each almost a mile (1.6km) in length.
Connected to subsea by 21 new subsea risers, including 15 new production risers, 3 gas risers and 3 water injection risers.
The Schiehallion and neighbouring Loyal fields have produced nearly 400 million barrels of oil since production started in 1998 and an estimated 450 million barrels of resource is still available.