Shell said well 21/12-3 in the central North Sea, 80 miles off Scotland, had tested oil at a rate of 8,200 barrels a day.
It was now evaluating a range of possible infrastructure solutions, such as a subsea tie-back to its existing Kittiwake platform seven miles away.
But Lasmo and British Borneo will not participate, having sold on their combined 26 per cent stake to Burlington Resources of the US. The area had not been considered exciting after two previous wells failed to show any sign of hydrocarbons.
The new find is a considerable boost to Burlington which has only developed a very small presence in the North Sea and Ireland over the last 12 months.
It is also important for Ireland's exploration minnow, Dana Petroleum, which holds an 11.4 per cent stake. Shell and Esso each own 31.3 per cent.
Meanwhile BG has made a significant gas discovery off the coast of Trinidad. BG has been developing a liquefied natural gas project in Trinidad and needed new gas supplies to help fuel it.