"Production from the Lianzi field will begin in 2015 and investments will cost $2 billion," Katia Mounthault-Tatu, a Chevron spokeswoman, told Reuters.

State revenues from the field, which holds proven reserves of 70 million barrels, will be split 50-50 between Congo and Angola, the two countries confirmed in an agreement on Friday.

Congo produced 105 million barrels of crude oil last year. Angola pumps around 1.8 million barrels per day.