A total of 450m barrels of oil could be beneath Co Antrim.
Based on a seismic survey carried out by Surrey firm Infrastrata over the last two years, geosciences engineers Merlin Energy Resources has said there are "significant potential resources".
Infrastrata said it has funding to bankroll exploration of the site and expects to test drill the 'Larne-Lough Neagh basin', running from the tip of Lough Neagh to Larne, with months.
But an industry expert has warned that while an oil discovery could transform the economy and make fortunes for investors, profitable drilling is far from guaranteed at this early stage.
"It can take years from getting a licence to discovering oil and there can be problems along the way," Stewart Dalby, editor of Oilbarrel.com, an investor website for small cap oil gas companies and previously Ireland correspondent for the Financial Times.
"It is expensive. First you have to get a licence, then you have to find a likely spot to drill on the licence. Then there are various surveys to be done most importantly seismic surveys. Then you need to estimate whether there is a source rock, a reservoir rock and a seal. Then you need to drill. Only drilling will tell you if the oil is there.
"Before you drill you need to find the money to drill. Infrastata is small company with limited funds. Even if oil is found, not all of it may be recoverable. All that said, Infrastrata's statement is exciting. Because the stakes are so high, oil could transform the Northern Ireland economy and make fortunes for investors.
"This amount of oil, if it is there, would not get them leaping in the air at BP but it could be significant for Northern Ireland.
"But beware the jargon. It could be all or nothing and prospective means just that. It is not proven. It is just a prospect."
Andrew Hindle, CEO of Infrastrata, said that the Larne-Lough Neagh Basin has been largely overlooked by the oil and gas industry, with only one exploration well being drilled in the centre of the basin covered back in 1971.
The licence was awarded in March 2011 by Deti, covering 663 sq kms. The initial term is five years with a decision on drilling a well required within three years.