Alwyn North oil and gas field

Alwyn North oil and gas field
Alwyn North oil and gas field
	Location of Alwyn North oil and gas field
Country	United Kingdom
Region	North Sea
Location/blocks	3/9a 3/4a
Offshore/onshore	Offshore
Coordinates	60°48′33″N1°41′01″E / 60.8093°N 1.6836°E
Operators	Total Oil Marine, TotalFinaElf
Owner	Elf Exploration UK and Total Oil Marine; TotalFinaElf
Field history
Start of production	1987
Peak of production	4.36 million tonnes per year
Peak year	1989
Production
Recoverable oil	200 million barrels (~2.7×107 t)
Recoverable gas	27×109 m3 (950×109 cu ft)
Producing formations	Jurassic sandstone

Last updated July 20, 2023

Alwyn North is a major oil and gas field in the United Kingdom sector of the northern North Sea, 160 km east of the Shetland Islands. The field was developed through two bridge-linked offshore platforms and a number of subsea satellite wellheads. Alwyn North has been producing oil and gas since 1987 and is still (2023) in operation.

The field

The field was discovered in June 1975 principally in Block 3/9a of the northern North Sea with a small extension into Block 3/4a.^[1] The reservoir is a Jurassic sandstone, comprising a Brent (oil) formation at a depth of 3,100 m and a Statfjord (gas) formation at 3,400 m.^[2] The estimated recoverable oil is 200 million barrels and recoverable gas is 27 billion cubic metres. The oil has an API gravity of 39° and a sulfur content of 0.5%. The name Alwyn has Scottish connotations and can be easily pronounced in English and French – the French operator Is Total.^[1]

Development

The Alwyn North field was developed by a joint venture comprising Elf Exploration UK plc (66.66 %) and Total Oil Marine plc (33.33%). The field was initially developed by two bridge-linked offshore platforms: the drilling platform NAA and a production platform NAB. Key parameters of the platforms are:^[2]

Key parameters of the NAA and NAB platforms
Platform	NAA	NAB
Type	Steel jacket self-buoyant launch	Steel jacket self-buoyant launch
Function	Drilling & accommodation	Processing
Topsides design	Foster Wheeler Ltd	McDermott Engineering
Fabrication yard	RGC Methil/UIE Clydebank	RGC Methil/UIE Clydebank
Legs	8	8
Piles	32	24
Operating topsides weight	21,000 tonnes	17,500 tonnes
Well slots	40	–
Jacket installation	Summer 1985	Summer 1986
Coordinates	60.809278N 1.683611E	60.810117N 1.743450E
Water depth	126 m	126 m
Topsides installation	1985/6	Early 1987
Start up	Autumn 1986 (drilling)	Autumn 1987 (production)

Oil and gas processing

The process plant has an oil treatment capacity of 99,000 stock tank barrels per day and a gas handling capacity of 9 million cubic metres per day.^[2] Oil from the NAA oil wells is routed across the bridge to the oil separator, where vapour and water are removed, oil then flows to the oil dehydrator where more water is removed and through the export pumps to the Ninian Central installation via a 16 km 12-inch pipeline, and from there to the Sullom Voe terminal. Gas from the gas wellheads flows to the gas condensate separator and is then comingled with compressed off-gas from the oil plant. The combined flow is then routed to the glycol-based gas dehydration system to reduce the water dewpoint. Gas is then refrigerated using Freon to remove liquids, gas flows to Frigg TP1 installation via a 112 km 24-inch gas export line.^[3] Liquids removed in the gas plant are routed to the inlet of the oil separator.^[2]

Produced water from the oil train separators is treated to remove oil prior to overboard discharge. The oily water system has a capacity of 100,000 barrels per day.

Filtered and deoxygenated seawater is injected into the reservoir to assist with production, the plant is designed to treat and inject 130,000 barrels of water per day.^[2]

The peak oil production was 4.36 million tonnes per year in 1989; the peak gas production was 2.8 billion m³ (in 1989).^[1]

Gas injection commenced in late 1999 into the Brent East-South area then from September 2000 into the Brent North West area. By mid 2002 1.68 Gsm³ of gas had been injected. This increased oil production in four wells between a 2 to 10 fold.^[4]

Satellite fields

The subsea wellheads from the Nuggets (Northern Underwater Gas Gathering Export and Treatment System), Forvie, Islay and Jura fields are routed to Alwyn North for fluid processing.^[5]^[6]^[7]

Alwyn North satellite fields
Name	Forvie	Islay	Jura	Nuggets
Owner	Total	Total	Total
Block	3/15	3/15	3/15	3/18c, 3/19a, 3/19b, 3/20a
Reservoir fluids	Condensate	HT HP gas	Gas	Gas
Discovered	2002	2008	November 2006	1973
Reserves		17 million barrels oil equivalent	30 million barrels oil equivalent	500 billion cubic feet
Wells		1	2	5
Export	Alwyn N	Alwyn N	Forvie N manifold	Alwyn N
First oil/gas	2006	2012	2008	2003
Water depth	120 m	112 m	113 m	120 m

Related Research Articles

The Brent field was an oil and gas field located in the East Shetland Basin of the North Sea, 186 kilometres (116 mi) north-east of Lerwick in the Shetland Islands, Scotland, at the water depth of 140 metres (460 ft). The field operated by Shell UK Limited was discovered in 1971 and was once one of the most productive parts of the UK's offshore assets but has reached the stage where production is no longer economically viable. Decommissioning of the Brent field is complete with the exception of Brent C, which is producing from another field. The discovery well 211/26-1 was drilled in 1971 by the semi-submersible drilling rig "Staflo". This was a major surprise at the time as the nearest land in Scotland and Norway is composed of granite and other non reservoir metamorphic rocks.

The Dunlin oilfield is situated 195 km northeast of Lerwick, Shetland, Scotland, in block number 211/23a and 211/24a. It was originally operated by Shell but was sold in 2008 and is now operated by Fairfield Energy and partners MCX.

Platform Name - Tern Alpha.

The Ninian Central Platform is an oil platform in the North Sea. When constructed in Loch Kishorn, Scotland in 1978 the 600,000 tonne platform was the world's largest man-made movable object before being towed to its current position and sunk to the sea floor.

The Clair oilfield is an offshore oil field in Scottish territorial waters 75 kilometres (47 mi) west of Shetland in water depths of up to 140 metres (460 ft). The field is the largest oilfield on the UK Continental Shelf with an estimated 8 billion barrels of oil-in-place, according to the BP Plc’s website. It extends over an area of some 220 square kilometres (85 sq mi), covering five licence blocks.

The Harding oilfield is a small oil field operated by TAQA, in the North Sea block 9/23b, approximately 200 miles (320 km) North-East of Aberdeen and in 110 metres (360 ft) of water.

The Everest gasfield is located in the Central North Sea, 233 kilometres (145 mi) east of Aberdeen, Scotland. It lies in the United Kingdom Continental Shelf blocks 22/9, 22/10a and 22/14a. The gasfield was discovered by Amoco in 1982 with first gas produced in 1993.

The Schiehallion oilfield is a deepwater offshore oilfield approximately 175 kilometres (110 mi) west of the Shetland Islands in the North Atlantic Ocean. The Schiehallion and adjacent Loyal field were jointly developed by BP on behalf of the Schiehallion field partners; BP, Shell, Amerada Hess, Murphy Oil, Statoil and OMV, and the Loyal field partners; BP and Shell.

An oil production plant is a facility which processes production fluids from oil wells in order to separate out key components and prepare them for export. Typical oil well production fluids are a mixture of oil, gas and produced water. An oil production plant is distinct from an oil depot, which does not have processing facilities.

The Hutton oil field, located on the UK continental shelf, was the location for the first ever production Tension Leg Platform (TLP).

Tyra Field is the largest gas condensate field in the Danish Sector of the North Sea. It was discovered in 1968 and production started in 1984. The field is owned by Dansk Undergrunds Consortium, a partnership between Total, Noreco and Nordsofonden, and operated by Total. The reservoir depth is about 2,000 metres (6,600 ft) and it covers area of 90 kilometres (56 mi) in the water depth of 37–40 metres (121–131 ft).

The Buzzard Oil Field is an oil field located in the North Sea Blocks 19/10, 19/5a, 20/6 and 20/1s. It was discovered in 2001 by PanCanadian, and developed initially by PanCanadian's successor EnCana and then by Nexen. The oil field was initially operated and owned by Nexen which is now a subsidiary of China's CNOOC.

Gannet is an oil and gas field located in the United Kingdom's continental shelf in the North Sea. It is 180 km (110 mi) east of Aberdeen, and the water depth at the Gannet offshore installation is 95 m (312 ft). 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 (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 Beryl oil field is a major crude oil production field in the UK sector of the northern North Sea, 335 km north east of Aberdeen. Production of oil started in 1976 and the field is still producing oil and gas (2021).

The Heather oil field is a significant crude oil producing field in the UK sector of the northern North Sea, 458 km north-north-east of Aberdeen. Production of oil started in 1978 and ceased in 2019. The Heather Alpha installation is currently (2021) undergoing decommissioning.

The Tartan oil field is a significant crude oil producing field in the UK sector of the North Sea, 187 km north-east of Aberdeen. Production of oil started in 1981 and ceased in 2020, the Tartan Alpha installation is currently (2021) undergoing decommissioning.

The Clyde oil field is a crude oil producing field in the UK sector of the North Sea, 290 km east-south-east of Aberdeen. Production of oil started in 1987 and the field is still operational (2021).

The Maureen oil field is a partially depleted crude oil field in the UK sector of the central North Sea, 262 km north-east of Aberdeen. Oil was produced from the field reservoir by the Maureen A platform between 1983 and 1999. Proposals to further exploit the residual hydrocarbons in the field have yet to be implemented.

The Balmoral oil field is a depleted crude oil field in the UK sector of the central North Sea, 225 km north-east of Aberdeen. Oil was produced from the field reservoir by the Balmoral Floating Production Vessel (FPV) between 1986 and 2020. The Balmoral FPV also processed oil from six minor oil fields in the area. Oil production from the field has ceased.

The Ravenspurn gas fields are two adjacent natural gas fields located in the UK sector of the southern North Sea about 65 km east of Flambrough Head, Yorkshire.

References

1 2 3 Department of Trade and Industry (1994). The Energy Report. London: HMSO. pp. 52 and map 6. ISBN 0115153802.
1 2 3 4 5 Oilfield Publications Limited (1985). The North Sea Platform Guide. Ledbury: Oilfield Publications Limited. pp. 1 to 11.
↑ Total E&P UK (2014). "Total E&P UK 30 years of technological innovation" (PDF). totalenergies.uk. Archived (PDF) from the original on 2021-10-27. Retrieved 12 October 2021.
↑ Burns, L.J., G.J. Richardson, R.N. Kimber (2002). "Tertiary Miscible Gas Injection in the Alwyn North Brent Reservoirs". European Petroleum Conference, Aberdeen, United Kingdom, October 2002.
↑ "TotalFinaElf Gas Field Project Offshore Technology". offshore-technology.com. Archived from the original on 2004-09-22. Retrieved 12 October 2021.
↑ "Jura Field, North Sea Northern Offshore Technology". offshore-technology.com. Archived from the original on 2007-11-27. Retrieved 12 October 2021.
↑ "North Sea Forvie field overcomes technical challenges of long-distance pipe-in-pipe". offshore-mag.com. 2006. Archived from the original on 2021-10-29. Retrieved 12 October 2021.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[:0-1] 1 2 3 Department of Trade and Industry (1994). The Energy Report. London: HMSO. pp. 52 and map 6. ISBN 0115153802.

[:1-2] 1 2 3 4 5 Oilfield Publications Limited (1985). The North Sea Platform Guide. Ledbury: Oilfield Publications Limited. pp. 1 to 11.

[3] Total E&P UK (2014). "Total E&P UK 30 years of technological innovation" (PDF). totalenergies.uk. Archived (PDF) from the original on 2021-10-27. Retrieved 12 October 2021.

[4] Burns, L.J., G.J. Richardson, R.N. Kimber (2002). "Tertiary Miscible Gas Injection in the Alwyn North Brent Reservoirs". European Petroleum Conference, Aberdeen, United Kingdom, October 2002.

[5] "TotalFinaElf Gas Field Project Offshore Technology". offshore-technology.com. Archived from the original on 2004-09-22. Retrieved 12 October 2021.

[6] "Jura Field, North Sea Northern Offshore Technology". offshore-technology.com. Archived from the original on 2007-11-27. Retrieved 12 October 2021.

[7] "North Sea Forvie field overcomes technical challenges of long-distance pipe-in-pipe". offshore-mag.com. 2006. Archived from the original on 2021-10-29. Retrieved 12 October 2021.

[1]

[2]

[3]

[4]

[5]

[6]

[7]