AN extra three to eight billion barrels of oil could be extracted from the North Sea oilfields, but only with significant investment, according to a Durham University expert.

Professor Jon Gluyas, head of the department of Earth sciences, at Durham University, who spent 28 years in the oil industry, said there was still a wealth of oil in the fields off the Scottish coast, despite them being in decline.

But he added that investment was needed in ageing infrastructure and new techniques, such as using carbon dioxide injection to enhance oil recovery from the field, to be successful.

He also said that an independent Scotland would have to think about how it would meet the “eye-watering” costs of well abandonment once the oil has been extracted.

Professor Gluyas said: “Somewhere between three billion and eight billion barrels of oil could be extracted on top of what is already planned if we can enhance its recovery using carbon dioxide to improve the recovery from existing fields. This would also help us meet our national emissions reduction target by capturing the CO2 from power plants and injecting it deep below the sea bed as part of the enhanced oil recovery programme.”