Marathon Oil Corporation (NYSE: MRO) announced today that the pre-salt Diaman-1B exploration well offshore Gabon has encountered 160-180 net feet (50-55 meters) of hydrocarbon pay in the deepwater pre-salt play. Preliminary analysis suggests that the hydrocarbons are natural gas with condensate content, pending results of ongoing analyses of well data. The Diaman-1B well was drilled to a total depth of 18,323 feet in approximately 5,673 feet of water in the Diaba License G4-223.

The Diaman-1B successfully confirms the existence of a working petroleum system and is the first discovery drilled in the deepwater portion of the pre-salt play. Diaman-1B is located over 60 miles away from the nearest other pre-salt commercial discovery. The operator and partners are currently evaluating the well results and incorporating them into an overall evaluation of the Diaman-1B discovery. The well will be temporarily abandoned pending further analysis of the data.

Marathon Oil holds a 21.25 percent non-operated working interest in the Diaba License. Partners include TOTAL Gabon as operator (42.5 percent working interest), Cobalt International Energy, L.P. (21.25 percent working interest), and Gabonese Republic (15 percent working interest).

Marathon Oil Corporation is an international exploration and production company. Based in Houston, Texas, the Company had net proved reserves at the end of 2012 of 2 billion barrels of oil equivalent in North America, Europe and Africa. For more information, please visit our website at http://www.marathonoil.com.