Marathon Oil Announces Shenandoah Appraisal Well Results

Tue Mar 19, 2013 4:46pm EDT

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HOUSTON, March 19, 2013 (GLOBE NEWSWIRE) -- Marathon Oil Corporation (NYSE: MRO) today announced
the Shenandoah-2 well in the deepwater Gulf of Mexico has encountered more than 1,000 net feet of
oil pay in multiple high-quality Lower Tertiary-aged reservoirs.

The Shenandoah-2 well, located in Walker Ridge block 51, was drilled to a total depth of 31,405
feet in approximately 5,800 feet of water, more than 1 mile southwest and approximately 1,700 feet
structurally down-dip from the Shenandoah-1 discovery. Similar to the initial Shenandoah discovery
well, log and pressure data from the Shenandoah-2 well indicate excellent-quality reservoir and
fluid properties. The well was drilled to test the down-dip extent of the accumulation, and the
targeted sands were full to base with no oil-water contact.

The Shenandoah-1 discovery well was drilled in early 2009 on Walker Ridge Block 52 and encountered
more than 300 net feet of Inboard Lower Tertiary oil pay.

The operator and partners are incorporating the information obtained from Shenandoah-2 into
planning and anticipate further appraisal drilling to advance this potentially significant
resource discovery.

Marathon Oil holds a 10 percent working interest in Shenandoah. Partners include Anadarko
Petroleum Corporation as operator (30 percent working interest), ConocoPhillips (30 percent
working interest), Cobalt International Energy, L.P. (20 percent working interest), and Venari
Resources LLC (10 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
http://www.globenewswire.com/newsroom/ctr?d=10025796&l=6&a=http%3A%2F%2Fwww.marathonoil.com&u=http%3A%2F%2Fwww.marathonoil.com%2F
.

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This release contains forward-looking statements related to the possibility of a new resource base
and expectations for further appraisal drilling.  These statements are based on current
expectations, estimates and projections and are not guarantees of future performance.  Actual
results may differ materially from these expectations, estimates and projections and are subject
to certain risks, uncertainties and other factors, some of which are beyond the Company's control
and difficult to predict.  In accordance with the "safe harbor" provisions of the Private
Securities Litigation Reform Act of 1995, Marathon Oil Corporation has included in its Annual
Report on Form 10-K for the year ended December 31, 2012, cautionary language identifying other
important factors, though not necessarily all such factors, that could cause future outcomes to
differ materially from those set forth in the forward-looking statements.

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