ConocoPhillips CEO James Mulva (left) and ExxonMobil CEO Rex Tillerson gather their things on Capitol Hill in Washington on Thursday, May 12, 2011, after testifying before the Senate Finance Committee. (AP Photo/Alex Brandon)

Photo by: Alex Brandon

ConocoPhillips CEO James Mulva (left) and ExxonMobil CEO Rex Tillerson gather their things on Capitol Hill in Washington on Thursday, May 12, 2011, after testifying before the Senate Finance Committee. (AP Photo/Alex Brandon)