1975 (North sector) 1976 (Central sector) 1977 (South sector)
Start of production
1983 (South) 1988 (North) 1989 (Central)
The Brae field is a Scottishoil 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 were operated by Marathon Oil from their inception until 2019 and are now operated by TAQA Bratani. They 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
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
12,000-13,500ft
12,000ft
Oil column
1,500ft
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
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] and may later have been extended to 20,000 tonnes[6]. Fabrication details are shown in the table.[4][3]
Starts in 2025 planned completion by end of 2028.[6][12][13].
Decomissioning
Several of the platforms used in the Brae field have reached a CoP (Cessation of Production) point, and are actively beeing or are scheduled for decomission and dismantling and removal.[14]
Decomissioning of Brae East
Report[6] by contractor RockRose Energy concludes that the decomission expects to consist of 20,326 tonnes of installations and 2,663 tonnes of pipeline. Of the installations, 100% (20,326 tonnes) is expected to be removed, and of the pipeline roughly 38,5% (740 tonnes) will be removed, thus leaving 1,923 tonnes of pipeline in situ. 90% of all materials of installations are calculated to be recycled, 5-10% to be reused and less than 5% to be disposed. Of the pipeline, 25% will be disposed and 75% will be recycled.
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.
