The Magnus oilfield is a large oilfield in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

's zone of

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

. It is located north-east of the

Shetland Islands Shetland, also called the Shetland Islands and formerly Zetland, is a subarctic archipelago in Scotland lying between Orkney, the Faroe Islands and Norway. It is the northernmost region of the United Kingdom. The islands lie about to the n ...

. The field is located mainly in Block 211/12a. Resources are estimated to total of oil, of which are recoverable reserves.

History

The Magnus oilfield was discovered in March 1974 by BP. The discovery was made below the seabed in the younger sands of the

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the ...

by the

semi-submersible Semi-submersible may refer to a self-propelled vessel, such as: *Heavy-lift ship, which partially submerge to allow their cargo (another ship) to float into place for transport *Narco-submarine, some of which remained partially on the surface *Se ...

drilling rig A drilling rig is an integrated system that Drilling, drills wells, such as oil or water wells, or holes for piling and other construction purposes, into the earth's subsurface. Drilling rigs can be massive structures housing equipment used to ...

Sedco 703. Similarly to several other fields in the area, the field was named after the Viking saint–

Magnus of Orkney Saint Magnus Erlendsson, Earl of Orkney, sometimes known as Magnus the Martyr, was Earl of Orkney from 1106 to about 1115. Magnus's grandparents, Earl Thorfinn and his wife Ingibiorg Finnsdottir, had two sons, Erlend and Paul, who were twi ...

. It was announced on 24 January 2017 that BP will sell a 25% share of the field and turn over the operatorship to EnQuest. Fabrication of the Magnus structure began in 1973 at Highland Fabricators' yard at Nigg Bay in the Cromarty Firth. The jacket of the Magnus platform, the main oil export pipeline to the

Ninian Central Platform 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 sun ...

, and the

Northern Leg Gas Pipeline A flag is a piece of fabric (most often rectangular or quadrilateral) with a distinctive design and colours. It is used as a symbol, a signalling device, or for decoration. The term ''flag'' is also used to refer to the graphic design emp ...

to Brent A were installed by 1974. In May 1996, the production started at the South Magnus field. First oil from the field was achieved in August 1983. The

enhanced oil recovery Enhanced oil recovery (abbreviated EOR), also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. EOR can extract 30% to 60% or more of a reservoir's oil, compared to 20% to 40% using ...

project was proposed in 2000. It was implemented in 2003.

Reserves

Magnus field's reserves are estimated to contain of oil, of which are recoverable reserves.

Technical description

The field is developed by a single central combined drilling and production platform. The Magnus jacket is the largest single piece steel structure in the North Sea. It was designed, manufactured and installed by John Brown Offshore. The original system also included seven subsea producing wells which were later turned around to water injection duty. The topsides for Magnus were designed by Matthew Hall EngineeringMatthew Hall Engineering publicity brochure n.d. but c. 1990 which was also responsible for procurement, project management, construction management, offshore installation services and commissioning assistance. They were awarded the contract in December 1978. Initially there were facilities for 17 oil production wells, five water injection wells, and nine spare slots. The production capacity was 140,000

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 2.5 million standard cubic metres of gas per day. There are two production trains each with two stages of separation with the first stage operating at a pressure of 28 barg.

Natural gas liquids Natural-gas condensate, also called natural gas liquids, is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Some gas species within the raw natur ...

were extracted from the gas stream using a turbo-expander/re-compressor system. Electricity generation was powered by three 27 MW GE Frame 5 gas turbines. All the gas compressors were driven by electric motors, not by gas turbines. The topside accommodation was for 200 people. There were 19 topside modules and the topsides weight was 31,000 tonnes. The produced oil is transported by a long pipeline to the Ninian Central platform, and further to the

Sullom Voe Terminal The Sullom Voe Terminal is an oil and gas terminal at Sullom Voe in the Shetland Islands of Scotland. It handles production from oilfields in the North Sea and East Shetland Basin and stores oil before it is transported by tanker. Constructi ...

. Produced natural gas from Magnus, together with gas from the Thistle and Murchison fields, is transported by a long pipeline to Brent A and further through the FLAGS to

St Fergus St Fergus is a village in the Buchan area of Aberdeenshire, Scotland. St Fergus lies from the North Sea coast and north-west of Peterhead. The Parish of St Fergus includes the remains of Inverugie Castle and Ravenscraig Castle. The church i ...

Aberdeenshire Aberdeenshire ( sco, Aiberdeenshire; gd, Siorrachd Obar Dheathain) is one of the 32 council areas of Scotland. It takes its name from the County of Aberdeen which has substantially different boundaries. The Aberdeenshire Council area incl ...

Enhanced oil recovery project

To increase the recoverable oil from the field and to extend the field life, an enhanced oil recovery (EOR) project was implemented. The EOR project involved importing gas from the two West of Shetland fields Foinaven and

Schiehallion Schiehallion (; gd, Sìth Chailleann, ) is a prominent cone-shaped mountain in the Breadalbane region of the Scottish Highlands, in the county of Perthshire. It rises to and is classed as a Munro. Schiehallion has a rich botanical life, inte ...

to the Sullom Voe terminal where liquefied petroleum gas is added to natural gas. This gas stream is then transported by another pipeline to the Magnus platform where it is reinjected into the Magnus reservoir to aid pressure support and increased oil recovery. It is expected to increase the recoverable oil reserves by and extend the field life to beyond 2015. The project cost around £320 million.

References

{{reflist, 30em BP oil and gas fields North Sea oil fields Oil and gas industry in Shetland Oil fields of Scotland