Oil begins flowing from 'cornerstone' North Sea field
300 million barrels of oil earmarked from Mariner field, 90 miles east of Shetland.
Oil has started flowing from one of the biggest and most challenging projects in the North Sea.
The Norwegian operator Equinor has started production in its Mariner field, which was discovered in 1981.
More than 70,000 barrels of oil are expected to be produced every day from the site, more than 90 miles east of Shetland.
Using the world's largest jack-up rig, the Noble Lloyd Noble, two wells have been drilled so far and up to 100 are expected over the field's 30-year lifetime.
Operators said 300 million barrels of oil had been earmarked as recoverable, but believe there is the potential to fill three billion.
Environmental campaigners, however, described the Mariner project as "bad news for life on earth".
Hedda Felin, senior vice-president of Equinor, said: "The start-up of the Mariner field marks a huge milestone for us.
"Mariner is our cornerstone - it contributes to our commitment to be a long-term, safe, energy partner for the UK".
Getting oil from the massive field has been a major challenge, having supposed to have come on-stream two years ago only to be delayed by a series of technical issues.
'We know we have got to stop burning oil and gas if we want to avoid climate breakdown, so every new field like this takes us the wrong direction'Dr Richard Dixon
But now its operators have described it as one of the most modern and digitally advanced installations anywhere in the world.
Using smart technology, staff will no longer need to log their work on paper and endure long journeys to and from the control room.
Trond Austrheim, Equinor's UK vice-president of production, said: "We see the Mariner field as our digital frontrunner.
"It will help us maximise safety and efficiency on board."
Friends of the Earth Scotland said the new project would contribute to a "climate breakdown".
The environment campaign group's director Dr Richard Dixon said: "The Mariner project is seriously bad news for life on earth.
"We know we have got to stop burning oil and gas if we want to avoid climate breakdown, so every new field like this takes us the wrong direction.
"Its time for the Scottish and UK governments to stop backing oil and gas expansion and instead redirect support and subsidies towards creating decent jobs in the renewable energy economy."
"With the world's nations expected to descend on Glasgow for a climate summit next year, pumping out new fossil fuels is the exact opposite of what Scotland should be doing."