Marathon Replaces 124 Percent of 2003 Production

Marathon Oil replaced 124 percent of its 2003 worldwide crude oil and natural gas production, excluding dispositions, at a finding and development cost of $8.78 per barrel of oil equivalent (boe). Reserve additions excluding acquisitions and dispositions were 106 million barrels of oil equivalent (mmboe), resulting in a reserve replacement ratio of 76 percent. Of the 106 mmboe reserve additions, approximately 62 mmboe were international, equivalent to 113 percent of 2003 international production, and 44 mmboe were added in the United States, equivalent to 52 percent of 2003 U.S. production.

At year-end, Marathon had estimated proved reserves of 1,042 mmboe. During 2003, Marathon sold 274 mmboe of proved reserves as part of the company's successful plan to sell non-core assets and added 67 mmboe of proved reserves through an acquisition of assets in Russia.

During 2003, approximately 35 percent of Marathon's total proved reserves were prepared, reviewed or validated by third-party petroleum engineering consultants and the results were consistent with Marathon's proved reserves. Additionally, approximately 70 percent of Marathon's proved reserves were developed at year-end 2003. Of the just over 300 mmboe of proved undeveloped reserves at year-end 2003, only 10 percent have been included as proved reserves for more than two years.

During 2004, Marathon expects to replace approximately 180 percent of production at a finding and development cost of under $5 per boe. This would result in a projected 2002 through 2004 three-year-average reserve replacement of approximately 190 percent at a competitive finding and development cost of less than $6.00 per boe.