The Bluefin discovery joins more than 30 already since 2015 in the Stabroek block, an 6.6 million acre (26,800 square kilometers) area that has been the site of more than 11 billion barrels of recoverable oil and gas.

The Bluefin well, located in the southeastern portion of the Stabroek block and drilled in 4,244 feet of water by the Stena Drillmax drillship, encountered approximately 197 feet of hydrocarbon-bearing sandstone, Exxon said.

The company did not estimate recoverable reserves from the discovery.   

"Our exploration program continues to improve our understanding of the block's potential to drive viable oil-and-gas development," said the head of Exxon's Guyana operations, Alistair Routledge.

A consortium led by Exxon began crude output in Guyana in 2019, and has ramped up production to some 650,000 barrels per day this year. The other members of the consortium are Hess Corp and CNOOC Ltd.

The group is considering its first offshore natural gas production in Guyana, close to the country's maritime border with Suriname, which could come from its seventh project in the South American nation.

(Reporting by Kiana Wilburg, writing by Marianna Parraga)