Corallian Energy and partners will give a “large European E&P company” more time to decide whether it wants to farm into a licence in the inner Moray Firth.
The acreage contains the 174 million barrel Dunrobin prospect.
Corallian said in April that it would stop marketing licence P2478 to the wider industry while the unspecified E&P firm assessed the prospect.
The exclusivity period initially ran until September 30, but has now been extended to the end of January 2021.
Corallian operates and holds 45% of the licence, Upland Resources has 40% and Baron Oil has 15%.
Upland chief executive Bolhassan Di said: “We are very pleased to announce along with our JV partners this extension to our Work Sharing and Confidentiality Agreement with a large international E&P Company.
“This four-month extension is a good show of confidence in the Dunrobin prospect and it is encouraging that all parties have reached this agreement in order for further evaluations to take place.”