Foinaven

Location and Geology

The Foinaven oilfield is situated approximately 190 kilometres (120 miles) west of the Shetland Islands, in the blocks 204/19 and 204/24a of the UK Continental Shelf. It is part of the West of Shetland area, which also includes fields such as Schiehallion, Loyal, Solan, Clair, and Lancaster. The field is located in deep water, with depths ranging from 400 to 600 metres (1,300 to 2,000 feet).

Discovery and Development

The Foinaven oil field was discovered in 1992. The development of the field was sanctioned in 1994, marking the first deep-water oil development beyond the UK Continental Shelf. Oil production began in November 1997, with the first phase involving 21 wells and completed by 2000.

Production and Facilities

• Operator and Partners: The field is operated by BP in partnership with RockRose Energy, and Shell UK Exploration and Production is also a co-venturer.
• FPSO: The production is facilitated by the Floating Production Storage and Offloading (FPSO) system, Petrojarl Foinaven. This FPSO, operated by Teekay Petrojarl and later by Golar-Nor (UK) Limited, has an overall length of 240 metres (790 feet) and an oil storage capacity of 300,000 barrels (48,000 cubic metres). The FPSO was converted from a vessel named Anadyr, built in Finland for the Russian Navy, and was rebuilt and extended at the Astano yard in Ferrol, Spain.
• Production Capacity: The FPSO has two oil and gas separation trains, each with a capacity close to 47,500 barrels per day. The water injection capacity is 165,000 barrels per day. The system includes sophisticated electrical, instrumentation, control, fire, and gas systems.
• Subsea Infrastructure: The field features three subsea drill centers, two water injection well sites, a gas disposal center, and control umbilical distribution assemblies. The subsea layout includes manifolds, rigid steel flowlines, flexible risers, and innovative diverless connectors. The drilling centers are located approximately 3.5 kilometres from the FPSO.

Production Process

• Oil Production: Oil is produced through subsea wells, which are connected via manifolds and flowlines to the FPSO. The FPSO processes the oil and stores it before it is exported by shuttle tankers primarily to the Flotta oil terminal in Orkney and smaller amounts to the Tranmere Oil Terminal on Merseyside.
• Gas Production: Associated gas is either used for enhanced oil recovery in the field or exported through a 20-inch pipeline to the Sullom Voe Terminal. Some of this gas is used as fuel in the Fortum-operated Sullom Voe power station, and the remainder is enriched with liquefied petroleum gas and exported to the Magnus platform for enhanced oil recovery.

Reserves and Production History

• Recoverable Reserves: The estimated recoverable oil reserves of Foinaven range between 250 and 600 million barrels (40 million to 95 million cubic metres).
• Production Achievements: To date, approximately 390 million barrels of oil have been recovered from the Foinaven area.

Suspension and Future Plans

• FPSO Removal: In April 2021, BP suspended production from the Foinaven field as the Petrojarl Foinaven FPSO neared the end of its 25-year design life. The FPSO was removed in 2022 and is to be scrapped at Frederikshavn in Denmark.
• Future Options: BP and its partners are evaluating options for the development of the estimated remaining resources of up to 200 million barrels from the Foinaven field and surrounding area. These options include full or partial redevelopment or full decommissioning of the field.

Decommissioning

• Decommissioning Activities: The Petrojarl Foinaven FPSO will be utilized for initial decommissioning activities such as flushing and de-oiling of the subsea infrastructure. Following this, the FPSO will be removed, and other specialist vessels will handle subsequent decommissioning stages of the mooring systems, risers, and dynamic umbilicals.

Technological Innovations

• Horizontal Drilling: The project has utilized horizontal drilling technology, which has allowed for the exposure of larger sections of the reservoir to the well bore, increasing flow rates. This technology reduced the number of production wells required from 28 to 14.
• Diverless Connectors: Innovative diverless connectors (DMaC) were used for the subsea installation and hook-up, addressing the challenges of working in deep water beyond the reach of divers.

In summary, the Foinaven oil project is a significant deep-water oil development that has been a pioneer in several technological and operational aspects, and its future is currently under review as BP and its partners consider various options for its continued operation or decommissioning.