Cormorant oilfield

Oilfield in Shetland, Scotland

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Cormorant oilfield

Location of Cormorant oilfield

Country| Scotland, United Kingdom
Region| Shetland basin
Block| 211/26a
Offshore/onshore| Offshore
Coordinates| 61°06′9″N 1°4′22″E﻿ / ﻿61.10250°N 1.07278°E﻿ / 61.10250; 1.07278
Operator| TAQA Bratani
Field history
Discovery| September 1972
Start of production| 1979
Peak year| 1979
Production
Estimated oil in place| 90 million barrels (~1.2×10 ~~^~~ 7 t)
Estimated gas in place| 600×10 ~~^~~ 9 cu ft (17×10 ~~^~~ 9 m3)

The Cormorant oilfield is located 161 kilometres (100 mi) north east of Lerwick, Shetland, Scotland. It was discovered in September 1972 at a depth of 150 metres (490 ft). The oil reservoir is located at a depth of 2,895 metres (9,498 ft). Production started in December 1979 from the Cormorant Alpha platform and operates from two platforms and an underwater manifold centre.

## Description

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The Cormorant oilfield is located 161 kilometres (100 mi) north east of Lerwick, Shetland, Scotland, in block number 211/26a. It was discovered in September 1972 at a depth of 150 metres (490 ft). Estimated recovery is 90 million barrels (14×10 ~~^~~ 6 m3) of oil. The oil reservoir is located at a depth of 2,895 metres (9,498 ft). The discovery well, 211/26-1 was drilled by semi submersible rig Staflo.

Originally, it was operated by Shell and licensed to Shell/Esso. On 7 July 2008, it was purchased by Abu Dhabi National Energy Company.[1][2]

## Production

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Production operates from two Cormorant platforms. Details of the construction are given in the table.[3]

Cormorant platforms – construction  Installation  | Fabrication contractor  | Site  | Type  | Installation date

|
|
|
|

North Cormorant  | Redpath de Groot Caledonian, Union Industriellee et d'Enterprise  | Methil | Steel jacket  | July 1985
South Cormorant (Cormorant Alpha)  | McAlpine / Sea Tank  | Ardyne Point | Concrete  | May 1978

In addition, an Underwater Manifold Centre (controlled from the Cormorant platform) also produces oil. This started up in mid 1983. It has a design capacity for 50,000 barrels per day (7,900 m3/d). The UMC lost communications several years ago, but a project ongoing in 2006[update] is looking to produce from the UMC once again. Also a single satellite well (P1) is linked to the platform with a design capacity of 10,000 barrels per day (1,600 m3/d).

### Cormorant Alpha

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Production started in December 1979 from the Cormorant Alpha platform. This platform is a concrete gravity platform of the Sea Tank Co type. It has four legs and storage capacity for 1 million barrels (160,000 m3) of oil. The total sub-structure weight is 294,655 tonnes and it is designed to carry a topsides weight of 32,350 tonnes.

The topsides facilities included capability to drill, produce, meter and pump oil. It also has capability to re-inject water to maintain reservoir pressure. Peak production was 24,000 barrels per day (3,800 m3/d) in 1979. The platform is also the starting point for the Brent System pipeline, a major communications centre and the location of Brent Log \- air traffic control for Northern North Sea helicopter traffic.

The topsides for Cormorant Alpha were designed by Matthew Hall Engineering, which was awarded the contract in October 1974.[4] Initially there were facilities for 17 oil production wells, 18 water injection wells and one gas injection well. The production capacity was 60,000 barrels of oil per day and 900,000 standard cubic metres of gas per day. There was a single production train of three stages of separation with the first stage operating at a pressure of 30 barg. The 16 subsea storage cells had a capacity of 600,000 barrels. Electricity generation was powered by one 12 MW Rolls-Royce Avon gas turbine and four 2.5 MW Solar Mars gas turbines. The topside accommodation was for 200 people. There are 16 topsides modules and the topsides weight was 25,000 tonnes.[4]

Natural gas is exported from Cormorant Alpha via the Vesterled gas pipeline which connect into the FLAGS pipeline at Brent Alpha to St Fergus Gas Terminal.

## Accidents

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A Norwegian organisation states that the Cormorant A platform almost sank in 1977 during its construction in Norway.[citation needed][clarification needed] This was disputed in a TV documentary on 7 May 2007.[citation needed]

An explosion on 3 March 1983[5] killed two people outright and another died of burns later in hospital.[citation needed] The Cormorant Alpha crew waited inside the safe accommodation area for 2–3 days while the weather remained too bad for general helicopter evacuations, and eventually stood down and back to work a week or so later.[citation needed]

On 16 January 2013 and again on 2 March 2013, a hydrocarbon leak in one of the legs of the platform was reported. Personnel were evacuated from the platform and the Brent System was closed down, however no oil had been spilt into the sea.[6] Many environmental groups called for the UK and Scottish governments to regulate the industry and the "aging" platforms more closely.

## See also

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* Energy policy of the United Kingdom
* Energy use and conservation in the United Kingdom

## References

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1. ^ "Abu Dhabi national energy company pjsc (taqa) agrees to purchase north sea assets from shell u.k. ltd and esso exploration and production u.k. ltd". Al Bawaba. 7 July 2008. Retrieved 21 March 2009.
2. ^ Lin Noueihed (7 July 2008). "Abu Dhabi's Taqa buys Shell, Exxon North Sea interests". Reuters. Archived from the original on 3 February 2013. Retrieved 9 February 2010.
3. ^ Department of Trade and Industry (1994). The Energy Report. London: HMSO. p. 141\. ISBN 0115153802.
4. ^ a b Matthew Hall Engineering publicity brochure n.d. but c. 1990
5. ^ "A fiery explosion rocked a North Sea oil rig". United Press International, Inc. 3 March 1983. Archived from the original on 13 June 2018. Retrieved 26 October 2023.
6. ^ "UK Brent oil system still shut after Cormorant leak". Reuters. 3 March 2013. Retrieved 3 March 2013.[dead link]