Brae oilfield

Brae oil field
Brae oilfield is located in North Sea
Brae oilfield
Location of Brae oil field
CountryScotland, United Kingdom
RegionNorth Sea
Location/block16/7a
Offshore/onshoreoffshore
Coordinates58°42′N 1°18′E / 58.7°N 1.3°E / 58.7; 1.3[1]
OperatorTAQA
PartnersBP, Centrica, GDF Suez, Nippon Oil, TAQA
Field history
Discovery1975 (North sector)
1976 (Central sector)
1977 (South sector)
Start of production1983 (South)
1988 (North)
1989 (Central)

The Brae field is a Scottish oil field. The name comes from a Scots language word for hillside. The field was discovered in 1974 by well 16/7-1 drilled by a semi-submersible rig Odin Drill for operator Pan Ocean.[2]

The Fields are operated by TAQA Bratani and are located in UKCS block 16/7a. Three accumulations total about 70 million tonnes of oil liquids and a further 22 cubic kilometres of gas. The main platforms currently produce from underlying reserves, with regular infill drilling to identify and exploit undrained pockets in the Brae stratigraphy. A number of subsea tieback fields in the area produce through facilities on the platforms, extending their viability into the future. Gas is exported to St Fergus, Scotland via the SAGE pipeline system and oil is exported via the Forties system.

Field reservoirs

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The hydrocarbon reservoirs in the Brae field have the following properties.[3][4]

Brae field reservoir properties
Field Brae South Brae Central Brae North
Reservoir Upper Jurassic sands Upper Jurassic
Depth 12,000-13,500 ft 12,000 ft
Oil column 1,500 ft
API gravity 37° 33° 47° (NGL)
Sulfur 0.64 % 0.64 %
Gas Oil Ratio 1,400 scf/bbl 5,000 scf/bbl
Carbon dioxide Up to 35% 8 %
Pressure & temperature 7,200 psi, 240 °F 7,000 psi, 240 °F
Bubble point pressure 3,688 psi
Recoverable reserves, oil 267 million bbl; 40 million tonnes 65 million bbl; 9.0 million tonnes 204 million bbl; 21 million tonnes
Recoverable reserves, NGL 33 million bbl NGL 6 million bbl
Recoverable reserves, gas 155 billion cubic feet 682 billion cubic feet; 22 billion cubic metres

Topside facilities

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The topsides for Brae Alpha (Brae South) were designed by Matthew Hall Engineering[5] which was awarded the contract in August 1979. Initially there were facilities for 19 oil production wells, 14 water injection wells, two gas injection wells and 11 spare slots. The production capacity was 100,000 barrels of oil per day, 12,000 barrels of Natural Gas Liquids (NGL) per day and 4.25 million standard cubic metres of gas per day. There are two production trains each with three stages of separation with the first stage operating at the exceptionally high initial pressure, for that time, of 248 bar. Electricity generation was powered by four 25 MW Rolls-Royce SK-30 gas turbines. The topside accommodation was for 240 people. There were 14 topside modules and the topsides weight was 31,000 tonnes.[5]

The topsides for Brae Bravo (Brae North) were designed by Matthew Hall Engineering which was awarded the contract in October 1983.[5] Initially there were facilities for 12 oil production wells, three gas injection wells and 19 spare slots. The production capacity was 75,000 barrels of liquid hydrocarbons per day, and 11.3 million standard cubic metres of gas per day. There is a single production train with four stages of separation with the first stage operating at a pressure of 103. Electricity generation was powered by three 24 MW Rolls-Royce/GEC ERB-124C gas turbines. The topside accommodation was for 240 people. There were 21 topside modules and the topsides weight was 33,000 tonnes.[5]

The topsides for East Brae were designed by Matthew Hall Engineering which was awarded the contract in October 1988.[5] Initially there were facilities for 13 oil wells, and four gas injection wells and 13 spare slots. The production capacity was 120,000 barrels of liquid hydrocarbon per day, and 17.6 million standard cubic metres of gas per day. There is a single production train with three stages of separation with the first stage operating at a pressure of 102 bar. Electric power is provided from Brae A and Brae B by subsea cable. The topside accommodation was for 160 people. The topsides weight was 18,500 tonnes.[5] Fabrication details are shown in the table.[4][3]

Brae platforms – construction
Installation Fabrication contractor Site Installation date
Brae Alpha McDermott Scotland Ardersier April 1982
Brae Bravo McDermott Scotland Ardersier June 1987
Brae East Trafalgar House Offshore Fabricators Methil May 1993
Brae platforms key  facts
Platform Brae Alpha Brae Bravo
Type Steel jacket Steel jacket
Function Drilling, production, accommodation Drilling, production, accommodation
Coordinates 58°41’33”N 01°16’54”E 58°47’32”N 01°20’51”E
Water depth 112 m 99.5 m
Jacket weight 18,600 tonnes 22,000 tonnes
Legs 8 8
Piles 36 36
Topsides weight 32,000 tonnes 40,000 tones
Accommodation 240 240
Well slots 46 34
Wells planned 14 producers, 14 water injection, 2 gas injection 12 production; 3 gas injection
Installation June 1982 1987
Production start July 1983 1988

See also

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References

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  1. ^ "Northern/Central North Sea Map". Archived from the original on 4 April 2009. Retrieved 8 August 2009.
  2. ^ Pye, Malcolm (2018). "The Discovery and Development of the Brae Area Fields, U.K. South Viking Graben". Rift-Related Coarse-Grained Submarine Fan Reservoirs; the Brae Play, South Viking Graben, North Sea. pp. 155–162. doi:10.1306/13652181M1153810. ISBN 9780891813958.
  3. ^ a b Oilfield Publications Limited (1985). The North Sea Platform Guide. Ledbury: Oilfield Publications Limited. pp. 69–81.
  4. ^ a b Department of Trade and Industry (1994). The Energy Report. London: HMSO. p. 140. ISBN 0115153802.
  5. ^ a b c d e f Matthew Hall Engineering publicity brochure n.d. but c. 1990
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