1 Exhibit 21.1 CMS NOMECO OIL & GAS CO. CORPORATE STRUCTURE (ALL ENTITIES 100% OWNED UNLESS OTHERWISE INDICATED) CMS NOMECO Oil & Gas Co. CMS NOMECO Colombia Oil Company NOMECO Ecuador Oil Company NOMECO Thailand Oil Company Comeco Petroleum Holdings, Inc. - 50% Shareholder CMS NOMECO Pipeline Company Explotaciones CMS NOMECO Inc. CMS NOMECO Services Company CMS NOMECO Peru Company CMS NOMECO China Oil Co. CMS NOMECO Equatorial Guinea Oil & Gas Co. NOMECO Australia Pty. Limited NOMECO Exploration (Thailand) Limited CMS NOMECO Holdings Ltd. CMS NOMECO International Ltd. CMS NOMECO Ecuador LDC CMS NOMECO Argentina LDC CMS NOMECO Venezuela LDC CMS NOMECO Alba LDC CMS NOMECO E.G. LDC CMS NOMECO International Inc. Walter International Tunisia, Inc. CMS NOMECO International Equatorial Guinea, Inc. Walter International Transportation, Inc. CMS NOMECO International Venezuela, Inc. Walter Congo Holdings, Inc. Walter International Congo, Inc. 2 Terra Energy, Ltd. Terra Pipeline Company Kristin Corporation Energy Acquisition Operating Corporation Wellcorps LLC (55%) Thunder Bay Pipeline Company, LLC (50%)