Forties oil field

Year:1970 onwards

Duration:58 years

Cost:Unknown

Country: The North Sea

What did this project achieve?

Engineer a network of wells, rigs and platforms to extract oil from the North Sea

The Forties oil field is the largest in the North Sea. 110 miles east of the Scottish city of Aberdeen, it first produced oil in 1975.

In 1965 British Petroleum (BP) had already found natural gas in the region then in 1970 discovered oil. The find contained an estimated 1.8bn barrels.

After 5 years of exploration and construction, Forties field was officially inaugurated by the Queen in November 1975. The scheme was expected to produce 400,000 barrels of crude oil a day, sent through a 32in (81cm) pipeline to refineries near Aberdeen.

By 1978 the field was providing the UK with about a fifth of its annual oil needs. Production peaked at 500,000 barrels a day – well above early predictions.

BP owned and ran the scheme until 2003 when it sold its 96% interest to the US-based Apache Corporation for $812m.

At the time of the sale the field's output was 40,000 barrels a day with production expected to stop by 2013. Apache invested in exploration and infrastructure to boost output to 60,000 barrels by the end of 2004.

Further investment since then means the US company could have extended the field's lifetime by up to 20 years.

Difference the oil fields have made

The discovery of the Forties field marked the birth of the wider offshore oil industry. The find brought oil explorers to the region from all over the world.

Oil produced by the field generates billions in tax for the UK government every year.

The wealth created by offshore oil and natural gas contributed to the formation of the Scottish National Party and calls for an independent Scotland.

How the work was done

Engineers working in the Forties field have built 103 oil wells. Of these, 81 are producer wells – producing oil directly - and 22 are injector wells.

Injector wells pump seawater into a reservoir of oil to create pressure so the oil can be extracted from the field.

The 109 wells are all linked to 5 steel structure platforms: Forties Alpha, Forties Bravo, Forties Charlie, Forties Delta and Forties Echo

Engineers designed Forties Charlie platform to act as the central hub and gathering platform for all production at the field. Oil from the platform is pumped to onshore refineries near Aberdeen.

Alpha and Delta platforms were constructed as processing and separation facilities. The Echo platform is solely a processing facility.

The Bravo platform handles production fluid from the field. Production fluid is a mixture of oil, gas and water.

Recent work at Forties saw engineers construct the Forties Alpha satellite platform. Weighing about 17,000 tonnes, the structure is connected to the existing Alpha platform by a 90m bridge.

The new facility was designed to boost Alpha platform's capacity to produce oil and gas.

"​‌

When I first joined BP and someone mentioned Forties it was synonymous with the North Sea and the UK

Bob Dudley

BP chief executive. Quoted in the Guardian, October 2014.

Fascinating facts

The sale of the Forties field to Apache Corporation was controversial. Critics said it was like 'selling off the family silver'.

The US company has invested £2.8bn in Forties since it bought the field in 2003.

The field produced the equivalent of 190m barrels of oil between 2003 and 2013.

People who made it happen

  • Principal oil companies: BP, Apache Corporation
  • Forties Alpha satellite platform built by OGN Group

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