ENDEAVOUR International said yesterday it had drilled an appraisal well on the undeveloped Rochelle discovery in block 15/27 in the outer Moray Firth.
The Houston-based oil and gas company which focuses on the UK North Sea and US, holds a 55.6% interest in the well and is operator for the block.
Nexen is a joint-venture partner and holds the remaining 44.4% stake.
Endeavour said the appraisal well encountered 77 feet of net pay, with data and samples confirming 55ft of gas on top of 22ft of oil.
The US group added that plans were in progress to flow test the well.
It also said the results were much better than predicted in pre-drill estimates, and its best technical case could be more than 30million barrels of oil equivalent recoverable.
The company said it intended to move quickly towards the development of Rochelle.
Endeavour chief executive William Transier said: “Rochelle is the first successful appraisal project planned, executed, and operated by Endeavour.
“The Rochelle appraisal is an excellent example of maturing a fallow discovery towards development as envisaged by the regulatory authorities when they began seeking new entrants like Endeavour into the UK earlier this decade.”