POWER OF ATTORNEY
The undersigned hereby authorizes and designates each of Reginald D. Hedgebeth, Anna
Jones and Sam A. Mazzu III (the "Attorneys") as his fully authorized attorney for the purpose of
signing and filing on behalf of the undersigned all forms which are permitted or required to be filed
pursuant to Section 16(a) of the Securities Exchange Act of 1934 (the "Forms") concerning the
undersigned's interest in securities of Marathon Oil Corporation ("MOC") and/or the undersigned's
status with respect to MOC. The Forms shall include, but are not limited to, Form IDs and any
other documents necessary or appropriate to obtain codes and passwords enabling the
undersigned to make electronic filings with the SEC, and Forms 3, 4 and 5.
This Power of Attorney authorizes each of the Attorneys to sign and file the Forms on
behalf of the undersigned from the date hereof until the undersigned is no longer required to file
Forms 3, 4 and 5 with respect to the undersigned's holdings of and transactions in securities
issued by MOC, unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing Attorneys. This Power of Attorney is automatically revoked with respect to each
Attorney individually upon cessation of such Attorney's employment with MOC.
Dated: May 30, 2018
/s/ Dennis H. Reilley
