Cormorant oilfield explained

Cormorant oilfield
Location Map:North Sea
Coordinates:61.1025°N 1.0728°W
Relief:yes
Country:Scotland, United Kingdom
Region:Shetland basin
Block:211/26a
Offonshore:Offshore
Operator:TAQA Bratani
Discovery:September 1972
Start Production:1979
Peak Year:1979
Est Oil Bbl:90
Est Gas Bft:600

The Cormorant oilfield is located north east of Lerwick, Shetland, Scotland. It was discovered in September 1972 at a depth of 150m (490feet). The oil reservoir is located at a depth of 2895m (9,498feet). Production started in December 1979 from the Cormorant Alpha platform and operates from two platforms and an underwater manifold centre.

Description

The Cormorant oilfield is located north east of Lerwick, Shetland, Scotland, in block number 211/26a. It was discovered in September 1972 at a depth of 150m (490feet). Estimated recovery is of oil. The oil reservoir is located at a depth of 2895m (9,498feet). 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

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 CormorantRedpath de Groot Caledonian, Union Industriellee et d'EnterpriseMethilSteel jacketJuly 1985
South Cormorant (Cormorant Alpha)McAlpine / Sea TankArdyne PointConcreteMay 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 50000oilbbl/d. The UMC lost communications several years ago, but a project 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 10000oilbbl/d.

Cormorant Alpha

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 1Moilbbl 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 24000oilbbl/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.

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

A Norwegian organisation states that the Cormorant A platform almost sank in 1977 during its construction in Norway.June 2024. This was disputed in a TV documentary on 7 May 2007.June 2024.

An explosion on 3 March 1983[5] killed two people outright and another died of burns later in hospital. 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.

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

Notes and References

  1. News: 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 . 2008-07-07 . 2009-03-21.
  2. News: Abu Dhabi's Taqa buys Shell, Exxon North Sea interests . . Lin Noueihed . 2008-07-07 . 2010-02-09.
  3. Book: Department of Trade and Industry . The Energy Report . HMSO . 1994 . 0115153802 . London . 141.
  4. Matthew Hall Engineering publicity brochure n.d. but c. 1990
  5. Web site: A fiery explosion rocked a North Sea oil rig. 3 March 1983. United Press International, Inc. 26 October 2023. 13 June 2018. https://web.archive.org/web/20180613040605/https://www.upi.com/Archives/1983/03/03/A-fiery-explosion-rocked-a-North-Sea-oil-rig/2506415515600/. live.
  6. News: . UK Brent oil system still shut after Cormorant leak . 2013-03-03 . 2013-03-03.