Gannet is an oil and gas field located in the United Kingdom's continental shelf in the North Sea. It is east of Aberdeen, and the water depth at the Gannet offshore installation is . The field is located in Blocks 22/21, 22/25, 22/26 and 21/30. It is half-owned by Royal Dutch Shell (50%) and partly by

ExxonMobil ExxonMobil Corporation (commonly shortened to Exxon) is an American multinational oil and gas corporation headquartered in Irving, Texas. It is the largest direct descendant of John D. Rockefeller's Standard Oil, and was formed on November 30, ...

(50%) and has been operated by Shell UK Ltd since ‘first oil’ in November 1993. The Gannet A installation is the host platform for subsea tiebacks designated Gannet B to G. Like most Shell fields in the central and northern North Sea the field is named after a sea bird the gannet.

The Gannet reservoirs

The Gannet reservoirs are located at a depth of between and extend over several blocks. They comprises good quality turbiditic sands of a Tertiary age (

Tay Tay may refer to: People and languages * Tay (name), including lists of people with the given name, surname and nickname * Tay people, an ethnic group of Vietnam ** Tày language *Atayal language, an Austronesian language spoken in Taiwan (ISO 639 ...

Rogaland Rogaland () is a Counties of Norway, county in Western Norway, bordering the North Sea to the west and the counties of Vestland to the north, Vestfold og Telemark to the east and Agder to the east and southeast. In 2020, it had a population of 47 ...

Forties Forties can mean: *1940s, the years 1940–1949 *40s, the years 40-49 AD *The years 40-49 of any century - see List of decades *Long Forties, area in the North Sea *The Forties shipping forecast area (roughly corresponding to the Long Forties) *Fo ...

, Lista and Andrew Formations) and were discovered in 1973. The formation comprises a mixture of hydrocarbon reservoirs. :

Design

The topsides for Gannet were designed by Matthew Hall EngineeringMatthew Hall Engineering publicity brochure undated but c. 1990 which was also responsible for procurement and construction and commissioning assistance. They were awarded the contract in July 1989. Initially there were facilities for 15 oil production wells, two gas production wells and seven spare slots; there was also provision for 39 subsea risers. The production capacity was 56,000

barrels A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...

of oil per day and 4.0 million standard cubic metres of gas per day. There are four production trains for both oil and gas processing. Electricity generation is powered by two 21-megawatt Rolls-Royce RB211 gas turbines. The topside accommodation was for 40 people. The integrated deck topsides (9600 tonnes) are supported by a four leg steel jacket (lift weight 8400 tonnes). The topsides were fabricated by Redpath Offshore North; and the jacket by RGC Offshore at

Methil Methil (Scottish Gaelic: Meadhchill) is an eastern coastal town in Scotland. It was first recorded as "Methkil" in 1207, and belonged to the Bishop of St Andrews. Two Bronze Age cemeteries have been discovered which date the settlement as ov ...

Operation

Oil from the platform wellheads and subsea wells is routed to one of the three horizontal first stage 3-phase separators.Process Overall Flow Scheme, undated Oil from the separators is combined and fed to common second, third and fourth stage 3-phase separators. Processed oil is exported by pipeline to the Fulmar A installation and thence via

Norpipe Norpipe is a subsea oil and natural gas pipelines system in the North Sea. It supplies oil from the Norwegian Ekofisk and associated fields in the North Sea to the United Kingdom and natural gas to Germany. Oil pipeline The Norpipe oil pipelin ...

to Teesside. Gas from the second, third and fourth stage separators is compressed to the operating pressure of the first stage separators with which it is combined and further compressed. Gas from the Gannet A gas wellheads and from the Gannet B and C subsea wells flows to one of the two vertical separators. Gas is co-mingled with the off-gas from the oil separators is dehydrated through counter-current contact with Triethylene glycol. Gas is compressed for export to St Fergus via the Fulmar gas pipeline. There are also facilities for gas injection into Gannet A, B and C reservoirs and for gas lift to oil production wells on reservoirs, A, C, D, E, F and G. Produced water is treated prior to overboard disposal. Oil export capacity is 88,000 barrels per day. Gas compression and dehydration capacity is 246 million standard cubic feet per day. Gannet A has a gas lift capacity of 130 million standard cubic feet per day and a produced water handling capability of 60,000

per day. Shell have indicated that there is greater than 25% ullage of the total system capability available in the plant for additional third party processing and transportation. Peak production was: Gannet A 1 million tonnes per year (1999); Gannet B 0.8 billion cubic metres per year (1996); Gannet C 1.6 million tonnes per year (1993); Gannet D 0.5 million tonnes per year (1994).

East of Gannet and Montrose Fields MPA(NC)

In 2014 of sea to the east of Gannet and the neighbouring

Montrose oil field The Montrose oil field is a significant crude oil producing field in the UK sector of the central North Sea, 210 km east of Aberdeen. Production of oil started in 1976 and a major upgrade in 2016 extended the field life to beyond 2030. Th ...

was declared a Nature Conservation Marine Protected Area under the title East of Gannet and Montrose Fields MPA(NC). The sands and gravels that form most of the seabed within the MPA are the preferred habitat for

ocean quahog The ocean quahog (''Arctica islandica'') is a species of edible clam, a marine bivalve mollusk in the family Arcticidae. This species is native to the North Atlantic Ocean, and it is harvested commercially as a food source. This species is ...

, which bury themselves deep into the sand to escape predation. When buried ocean quahog can survive long periods of time without food or oxygen, and are one of the longest living creatures on Earth, having a lifespan of more than 400 years. The MPA also includes a band of offshore deep-sea mud which form a habitat for many species of worm and mollusc, who live buried in the mud.

References

{{Marine Protected Areas in Scotland North Sea energy Natural gas platforms Oil and gas industry in Scotland Oil fields of Scotland Nature Conservation Marine Protected Areas of Scotland Shell plc oil and gas fields ExxonMobil oil and gas fields

The Gannet reservoirs

Design

Operation

East of Gannet and Montrose Fields MPA(NC)

See also

References