Italian energy firm Eni has discovered oil in the Minsala Marine exploration prospect, located in the Marine XII Block offshore Democratic Republic of the Congo.
The company discovered the oil in the Minsala Marine 1 well, which was drilled to a total depth of 3,700m.
An accumulation of light oil was identified in the Lower Cretaceous age pre-salt sequence, passing via a 420m hydrocarbon column.
The Minsala Marine discovery is estimated to hold about one billion barrels of oil equivalent in place, of which 80% is oil.
Eni has already planned the appraisal plan for the discovery and begun studies for the commercial development of the hydrocarbons reserves.
The company, via its subsidiary Eni Congo, operates Marine XII with a 65% stake.
Eni chief executive Claudio Descalzi said: "It has been over four years since Eni started exploring the shallow water pre-salt plays of West Africa, and this campaign continues to deliver great results. We have already discovered about four billion barrels of oil equivalent in place, between Congo and Gabon.
"In Congo, this is the third discovery to be successfully drilled in the Marine XII permit pre-salt play, following the Litchjendily and Nene Marine discoveries, which are both already under development."
Eni, which has been operating in the Democratic Republic of the Congo since 1968, presently produces about 110,000 barrels of oil per day of equity production.