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'Phantom volcanoes' may hide more oil and gas in the North Sea: study

FILE PHOTO: Drilling rigs are parked up in the Cromarty Firth near Invergordon, Scotland, Britain January 27, 2015. REUTERS/Russell Cheyne/File Photo

By Lefteris Karagiannopoulos

OSLO (Reuters) - An unexplored 7,000 square kilometre (2,700 square mile) swathe of the British North Sea, previously thought to contain empty chambers left by three extinct volcanoes, may hide oil and gas instead, the University of Aberdeen said on Tuesday.

For decades it was assumed that the Rattray volcanic province off northwest Scotland contained old magma chambers, ruling out the possibility of oil and gas discoveries.

However, the university's geologists now say these "phantom volcanoes" never existed at all.

The study's findings raise the prospect of future discoveries in the area, which has been left untouched over 50 years of exploration activity in the North Sea, said the university.

"What we found has completely overturned decades of accepted knowledge," Aberdeen University's Dr Nick Schofield said in a statement. "This gives us back a huge amount of gross rock volume that we never knew existed, in one of the world’s most prolific regions for oil and gas production."

Schofield said the team of geologists, including two colleagues from Heriot-Watt University and the University of Adelaide, had reassessed the area by combining 3D seismic data from Norway's Petroleum Geo-Services with well data.

"There is a huge area under there that hasn’t been looked at in detail for a long time, because of the previously incorrect geological model," Schofield said.

Exploration in the area may be challenging, said the geologists, but technology is improving and there are still big discoveries being made in the North Sea, such as the ones in the Central Graben and Viking Graben areas.

"As the old saying goes, often the best places to look for oil are in places near to where you've already found it," said Schofield. "The North Sea is a prime example of that."

The volcanoes were thought to have been formed millions of years ago, during seismic activity under the North Sea that almost created an ocean between Britain and Europe - an episode geologists have described as a failed "Jurassic Brexit" attempt.

(Reporting by Lefteris Karagiannopoulos; Editing by Jan Harvey)