David E. Roberts

Non-Executive Chairman of the Board; Former Chief Executive Officer, Gavilan Resources, LLC

David E. Roberts, has served as a director since November 2011 and currently serves as the Non-Executive Chairman of the Board. From February 2017 until his retirement in 2020, Mr. Roberts served as the Chief Executive Officer of Gavilan Resources, LLC, a private company formed in partnership with Blackstone that is focused on oil and natural gas development and production opportunities in South Texas. Prior to this role, Mr. Roberts served as President and CEO of Penn West Exploration, a Canadian oil and gas exploration and production company from June 2013 to October 2016. He served as Executive Vice President and Chief Operating Officer of Marathon Oil Corporation, an independent upstream company with international operations in exploration and production, oil sands mining and integrated gas, from 2008 through December 2012. He held other key management positions with Marathon from 2006 through 2008, including Executive Vice President in charge of Marathon’s worldwide upstream operations and Senior Vice President of business development. Prior to his time at Marathon, Mr. Roberts held leadership roles at BG Group, an integrated natural gas company, and served as advisor to the Vice Chairman of Chevron Corporation from 2001 to 2003.