William D. (Bill) Sullivan

Mr. Sullivan was appointed to our Board of Directors upon completion of our private equity offering on March 15, 2006. Since May 2004, Mr. Sullivan has served as a director and since May 2009 as a non-executive Chairman of the board of directors of SM Energy Company, a publicly traded exploration and production company (formerly known as St. Mary Land & Exploration Company). Mr. Sullivan has served as director of Targa Resources GP, LLC (the general partner of Targa Resource Partners LP) since February 14, 2007. Targa is principally in the gas and gas liquids gathering, processing and logistics services business. Mr. Sullivan has served as a director of TETRA Technologies, Inc. since August 2007. TETRA is principally in the oilfield services business. Mr. Sullivan has served as a director of Compressco Partners GP, LLC, the general partner of Compressco Partners, L.P., since Compressco Partners completed its initial public offering in June 2011. Compressco Partners is a provider of wellhead compression-based production enhancement services and is a majority owned subsidiary of TETRA. From 1981 through August 2003, Mr. Sullivan was employed in various capacities by Anadarko Petroleum Corporation, most recently as Executive Vice President, Exploration and Production. Mr. Sullivan has a Bachelor of Science degree in Mechanical Engineering, with high honors, from Texas A&M University.