| 1 | C & K Petroleum Inc | Denver, CO 80202 | Oil & Gas Operator | Apr 1984 |
| 2 | C & VC, Inc. | | Oil & Gas Operator | Sep 1991 |
| 3 | C.F. Braun & Company | | Oil & Gas Operator | Dec 1986 |
| 4 | Callon Offshore Production, Inc. | Natchez, MS 39121 | Oil & Gas Operator | Dec 2005 |
| 5 | Callon Petroleum Company | Natchez, MS 39120 | Oil & Gas Operator | Jan 2000 |
| 6 | Callon Petroleum Operating Co | Houston, TX 77042 | Oil & Gas Operator | Jul 2024 |
| 7 | Calpine Natural Gas Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2002 |
| 8 | Calpine Natural Gas Company L.P. | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 9 | Calpine Natural Gas L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2006 |
| 10 | Campbell Energy Corp. | | Oil & Gas Operator | May 1992 |
| 11 | Caribe Resources, Inc. | | Oil & Gas Operator | Jan 1985 |
| 12 | Carl Oil & Gas Co. | Bakersfield, CA 93309 | Oil & Gas Operator | Dec 1995 |
| 13 | Castex Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 14 | Castlerock Oil Company, Inc. | Addison, TX 75001 | Oil & Gas Operator | Feb 2006 |
| 15 | Cayman Exploration Corp. | Tulsa, OK 74119-1323 | Oil & Gas Operator | Jun 2001 |
| 16 | Cayman Resources Corporation | Tulsa, OK 74119-1323 | Oil & Gas Operator | Jun 2001 |
| 17 | Cedyco Corporation | Houston, TX 77227 | Oil & Gas Operator | Nov 2008 |
| 18 | Cenergy Exploration Company | Dallas, TX 75231 | Oil & Gas Operator | Sep 2000 |
| 19 | Century Exploration Company | | Oil & Gas Operator | Dec 2003 |
| 20 | Century Exploration N.O. LLC | | Oil & Gas Operator | Jun 2017 |
| 21 | Century Exploration N.O., Inc. | | Oil & Gas Operator | Sep 2011 |
| 22 | Century Mineral Corporation | | Oil & Gas Operator | Dec 1990 |
| 23 | Century Offshore MGMT. Corp. | | Oil & Gas Operator | Dec 1999 |
| 24 | Chain Oil & Gas, Inc. | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 25 | Cheniere Petroleum Corporation | | Oil & Gas Operator | Feb 1989 |
| 26 | Chevron Pipe Line Company | Houston, TX 77001 | Oil Operator | Feb 2015 |
| 27 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Oct 2025 |
| 28 | Chroma Operating, Inc. | Washington, DC 20036 | Oil & Gas Operator | Jun 2016 |
| 29 | Claron Corporation | Houston, TX 77219 | Oil & Gas Operator | Oct 2025 |
| 30 | Clayton Williams Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Apr 2017 |
| 31 | Clements Energy, Inc. | | Oil & Gas Operator | Oct 1987 |
| 32 | Cliffs Drilling Company | | Oil & Gas Operator | Dec 1984 |
| 33 | CNG Producing Company | New Orleans, LA 70112 | Oil & Gas Operator | Dec 2015 |
| 34 | Coalinga Corporation | Houston, TX 77002 | Oil & Gas Operator | May 1999 |
| 35 | Cockrell Oil Corporation | Houston, TX 77002-7348 | Oil & Gas Operator | Feb 2001 |
| 36 | Columbia Gas Dev. Corp. | | Oil & Gas Operator | Apr 1996 |
| 37 | Columbia Minerals Corp., Inc. | | Oil & Gas Operator | May 1996 |
| 38 | Commerce Energy, Inc. | | Oil & Gas Operator | Dec 1999 |
| 39 | Comstock Offshore, LLC | | Oil & Gas Operator | Nov 2004 |
| 40 | Concord Operating Incorporated | Horseshoe Bay, TX 78657 | Oil & Gas Operator | Dec 2008 |
| 41 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 42 | ConocoPhillips Company | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 43 | Conquest Exploration Co. | | Oil & Gas Operator | Mar 1992 |
| 44 | Continental Oil & Gas Co. Inc. | | Oil & Gas Operator | Jul 1997 |
| 45 | Costilla Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 46 | Cox Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2014 |
| 47 | Cox Operating, L.L.C. | | Oil & Gas Operator | Jan 2024 |
| 48 | Crawford Energy Operating Co | Houston, TX 77056 | Oil & Gas Operator | Aug 2008 |
| 49 | Crawford Hughes Operating Co. | The Woodlands, TX 77380 | Oil & Gas Operator | Oct 2025 |
| 50 | Crest Resources & Expl. Corp. | Houston, TX 77079 | Oil & Gas Operator | Dec 1998 |
| 51 | Crystal Oil Company | Shreveport, LA 71120 | Oil & Gas Operator | Jul 1995 |
| 52 | Cxy Energy, Inc. | Dallas, TX 75251 | Oil & Gas Operator | Nov 2000 |