Britannia, United Kingdom
The Britannia field, discovered in the mid 1970s, is the first in the UK sector of the North Sea to be operated jointly by two companies, Conoco and Chevron, through the formation of the new operating company, Britannia Operator Limited.
Britannia, situated 210km (130 miles) north-east of Aberdeen, covers approximately 112km² (70 square miles).
The subsea facilities are located on the seabed in 150m of water and produce approximately 25% of Britannia's reserves. Located 15km west of the platform, the subsea centre consists of a manifold adjacent to seven pre-drilled production wells. The manifold (33m long x 16m wide x 9m high) can handle gas and associated liquids from up to 14 wells, and is designed to produce up to 380,000,000ft³ of gas per day.
The manifold is linked to the platform by a series of flowlines, grouped together and surrounded by a 37in-diameter carrier pipe to form a flowline bundle. The carrier pipe provides a hot-water jacket to prevent hydrate and wax formation, as the gases and liquids travel from the subsea centre to the platform. The flowline bundle will be fabricated and towed 300km to the North Sea site, in two separate pieces, each 7.5km long.
The flowline bundle is the longest ever fabricated and the first to utilise the carrier pipe as a novel heating device, to prevent hydrate formation in the production line. Hot water is pumped from the platform to the manifold before it flows back, in a closed loop, through the carrier pipe. The subsea system is controlled from the platform, via two 15km flexible umbilicals, buried in the seabed on either side of the flowline bundle.
The eight-legged tubular-framed substructure supports the topsides, risers and caissons, and is located over the ten-slot well template, which was installed in 1995. Large mudmats were required to support the substructure's 20,700t weight, while the 20 foundation piles were driven 105m into the seabed using underwater hammers. At 123m in length (400ft) and 2.74m (9ft) in diameter, these are the largest piles in the history of the North Sea. The jacket is 158m tall and its base is 78x70m.
The seven major components comprising the platform topsides were built in Lowestoft and Teesside. These contain utility, drilling and production facilities, together with a 140-man accommodation unit. The heaviest unit is the integrated deck, weighing 11,000t, which required maximum use of the lift (this was one of the largest semi-submersible crane vessels available).
Gas from Britannia is processed at the Scottish Area Gas Evacuation (SAGE) terminal in St Fergus, which handles gas produced from a number of other North Sea fields.
Special attention has been given to the landfall, which occurs in an environmentally sensitive area of high dunes and a freshwater loch. Condensate is exported via a new 44km (27-mile) pipeline, to the existing Forties pipeline system and tanker-loading facilities, at Hound Point, in the Firth of Forth.
The 750t subsea production manifold has 14 slots and is located 15km away from the platform. A heated flowline bundle runs to platform and remote control from the platform is made possible by two electro-hydraulic umbilicals. Provisions for future expansion include the possible tie-in of a remote satellite well cluster from the west, and the future tie-in of an additional cluster, located mid-line.
The design and engineering of export pipelines includes a 14in-diameter pipe, for exporting condensate to the Forties Unity Platform and Forties Pipeline system. Gas export is through a 27in-diameter, 180bar line to St Fergus.
CORROLESS - VCI Corrosion Inhibitors, Hydrotest Additives and Coatings for Offshore Corrosion Protection
CORROLESS® has been a respected name in the specialist anticorrosion...
ORGA - Aids to Navigation and Helideck Lighting Packages
Operators of offshore oil and gas platforms require marking systems,...
Heerema Fabrication Group - Offshore Structure Engineering and Fabrication
Heerema Fabrication Group (HFG) specialises in the engineering...
Aquasign - Subsea Anti-Fouling Markers, Non-Toxic Underwater Signs, Nameplates and Oilfield RFID Signage
Aquasign specialises in the design and manufacture of anti-fouling...
LEWA - Metering Pumps, Process Diaphragm Pumps and Engineered Pumping Solutions
Key applications for the oil-and gas industry include:...
G.A. Valves Sales - Air Vent Valves, Vacuum Valves, Isolation Valves and Automatic Control Valves
Offering a wide range of base and exotic materials, G.A. Valves is...
FoundOcean - The Experts in Subsea Grouting for the Offshore Energy Construction Industry
FoundOcean is a world leader in subsea and offshore cementing for the...
Karmsund Maritime Offshore Supply - Development, Production, Supply and Sale of Patented Offshore Tools and Equipment
Karmsund Maritime Offshore deliver products and services to the oil and...
Rotrex Winches - Specialist Winch Systems
Rotrex Winches specialises in the hire, sales and service of...
Emerson Process Management - Ultrasonic Gas Detectors for the Onshore and Offshore Oil and Gas Industry
Groveley Detection Ltd (now Rosemount Measurement Ltd) has been supplying...