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Geologists say there could be reserves of oil and gas in areas around Scotland's coast which have previously been dismissed.

A team from the University of Aberdeen has been studying rock formations around Rockall - a tiny outcrop 300 miles off the Western Isles.

Earlier attempts to search for oil in the area have been largely unsuccessful and so very little exploration has taken place.

Only 12 wells have ever been drilled in the Rockall Basin compared with about 4,000 in the North Sea.

A small amount of gas was found in one well but the rest were unsuccessful.

But after studying new seismic data, geologists say past drilling has essentially been concentrated in the wrong areas.

'Volcanic intrusions'

Geologist Dr Nick Schofield said: "The Rockall Basin is one of the most challenging environments on earth when it comes to hydrocarbon explorations, but our analysis has revealed that one of the barriers to success may have been a misunderstanding of the subsurface geology.

"By analysing seismic data, and using what we have learned through our work in the Faroe-Shetland Basin, we found that the character of areas where operators hoped to find oil may have been misleading."

In simple terms, subsea bumps were previously thought to be the most likely location for finding trapped oil but none has been discovered there.

Now it is believed the oil may have been pushed further away from Rockall by "volcanic intrusions".

The new data has come from a series of seismic surveys carried out for the Oil and Gas Authority to try to stimulate the sector.

The discovery does not guarantee that large reserves of oil will be found in the area but suggests it is worth further exploration.

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Nick Richardson from the Oil and Gas Authority said: "The seismic acquisition programme and subsequent work by Aberdeen and Heriot Watt universities are an important part of our strategy to revitalise exploration.

"The findings of Dr Schofield's paper demonstrate the value in applying the latest geological knowledge and understanding to seismic data to increase industry's awareness of the opportunities that still exist in frontier areas."

However, with the oil price still below $60 a barrel, and with the hostile nature of that part of the Atlantic, geologists think it is unlikely there will be an immediate rush to drill more wells.

Mike Tholen, from industry body Oil and Gas UK, told BBC Scotland: "You're probably looking at two or three years to really pursue something if we see it now, but we're talking about years rather than decades.

"This is a new horizon and a new opportunity. Rigs are affordable at the minute (and) companies are looking hard at prospectivity around the world."

More analysis of the seismic data is expected to take place over the next 18 months.