Spanish oil and gas giant Repsol on Friday announced a large oil find in Alaska that it says holds approximately 1.2 billion barrels of recoverable light oil.
The discovery, made with its US partner Armstrong Energy, is Repsol's biggest since a gas find in Venezuela in 2009, a spokesman said.
The find is the "the largest US onshore conventional hydrocarbons discovery in 30 years", Repsol said in a statement.
"The contingent resources identified with the existing data in Repsol and Armstrong Energy's blocks in the Nanushuk play in Alaska could amount to approximately 1.2 billion barrels of recoverable light oil," it added.
Repsol has been actively exploring Alaska since 2008, The find was made in two wells in a region called the North Slope where Repsol has made other discoveries with Armstrong since 2011.
"The successive campaigns in the area have added significant new potential to what was previously viewed as a mature basin," Repsol said.
The company expects to begin production in the area in 2021, with a potential rate of around 120,000 barrels of oil per day.
Repsol produced 690,000 barrels of oil per day in 2016. It swung back to profit last year, posting a net profit of 1.7 billion euros ($1.8 billion), after recording a loss of 1.2 billion euros in 2015.
The company, together with Italy's ENI, in 2009 discovered the largest offshore gas field in Latin America, the giant Perla field off Venezuela which holds 17 trillion cubic feet of gas.