| 1 | Cajun Minerals, Inc. | | Oil & Gas Operator | Mar 1997 |
| 2 | Cajun Operating, Inc. | | Oil & Gas Operator | Jun 2011 |
| 3 | Cambridge Energy Corporation | | Oil & Gas Operator | Jul 2003 |
| 4 | Camex Operating Company | | Oil & Gas Operator | Dec 2024 |
| 5 | Camex, Inc. | | Oil & Gas Operator | Jun 1992 |
| 6 | Canlan Oil Company | | Oil & Gas Operator | Mar 1992 |
| 7 | Cardinal Oil & Gas, Inc. | | Oil & Gas Operator | Jun 1995 |
| 8 | Caribbean Oil & Gas Corp | | Oil & Gas Operator | Mar 1980 |
| 9 | Caribe Resources, Inc. | | Oil & Gas Operator | Jan 1985 |
| 10 | Carrizo Oil & Gas, Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 11 | Cashco Energy Corporation | | Oil & Gas Operator | Feb 1982 |
| 12 | Cashco Oil Company | Houston, TX 77024 | Oil & Gas Operator | Aug 2003 |
| 13 | Caskids Operating Company | Houston, TX 77027 | Oil & Gas Operator | Feb 2026 |
| 14 | Caspen Oil, Inc. | Denver, CO 80226 | Oil & Gas Operator | Jul 1993 |
| 15 | Castex Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 16 | Cedyco Corporation | Houston, TX 77227 | Oil & Gas Operator | Nov 2008 |
| 17 | Celeron Oil & Gas Company | | Oil & Gas Operator | Dec 1987 |
| 18 | Cenco, Inc. | | Oil & Gas Operator | Mar 2022 |
| 19 | Century Exploration Company | | Oil & Gas Operator | Dec 2003 |
| 20 | Century Offshore MGMT. Corp. | | Oil & Gas Operator | Dec 1999 |
| 21 | Charles Holston, Inc. | | Oil Operator | Jan 2025 |
| 22 | Charles Reeves, Jr., Inc. | | Oil & Gas Operator | Mar 1990 |
| 23 | Cheniere Petroleum Corporation | | Oil & Gas Operator | Feb 1989 |
| 24 | Chesapeake Operating, Inc. | Oklahoma City, OK 73154 | Oil & Gas Operator | Sep 2025 |
| 25 | Chevron Pipe Line Company | Houston, TX 77001 | Oil Operator | Feb 2015 |
| 26 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Feb 2026 |
| 27 | Chroma Operating, Inc. | Washington, DC 20036 | Oil & Gas Operator | Jun 2016 |
| 28 | Cibolo Energy Operating, Inc. | Bulverde, TX 78163 | Oil & Gas Operator | Feb 2026 |
| 29 | Cimarex Energy Co | Midland, TX 79706 | Oil & Gas Operator | Feb 2026 |
| 30 | Cities Service Oil & Gas Corp | | Oil & Gas Operator | Mar 1988 |
| 31 | CNG Producing Company | New Orleans, LA 70112 | Oil & Gas Operator | Dec 2015 |
| 32 | Coastal Production Inc. | | Oil & Gas Operator | Aug 2000 |
| 33 | Cody Energy LLC | Houston, TX 77024 | Oil & Gas Operator | Jun 2020 |
| 34 | Cody Energy, Inc. | Houston, TX 77077 | Oil & Gas Operator | Dec 2025 |
| 35 | Columbia Gas Dev. Corp. | | Oil & Gas Operator | Apr 1996 |
| 36 | Concord Resources, LLC | | Oil & Gas Operator | Nov 2000 |
| 37 | Conley P Smith Operating Co. | | Oil & Gas Operator | Jun 1995 |
| 38 | Conoco Inc | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 39 | Consolidated Energy Res., Inc. | | Oil Operator | Jun 1992 |
| 40 | Continental Operating Co. | Houston, TX 77024 | Oil & Gas Operator | Feb 2026 |
| 41 | Continental Resources, Inc. | Oklahoma City, OK 73126 | Oil & Gas Operator | Feb 2026 |
| 42 | Contour Energy E & P, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 43 | Contour Energy E & P, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Aug 2003 |
| 44 | Cornell Oil Company | | Oil & Gas Operator | May 1985 |
| 45 | Coronado Energy E&P Company, LLC | Houston, TX 77252 | Oil & Gas Operator | Dec 2010 |
| 46 | Costilla Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 47 | Cotton Petroleum Corporation | Tulsa, OK 74102 | Oil & Gas Operator | Jan 2005 |
| 48 | Cougar Exploration, Inc. | | Oil & Gas Operator | Jun 1988 |
| 49 | Cox Oil & Gas Inc | Dallas, TX 75201 | Oil & Gas Operator | Mar 2014 |
| 50 | Crosstex Lig, LLC | | Oil Operator | Mar 2014 |
| 51 | Crosstex Processing SVCS, LLC | | Oil Operator | Mar 2014 |
| 52 | Crystal Oil And Land Company | | Oil & Gas Operator | May 1992 |
| 53 | Cxy Energy, Inc. | Dallas, TX 75251 | Oil & Gas Operator | Nov 2000 |
| 54 | Cymri Corporation, The | Houston, TX 77057 | Oil & Gas Operator | Mar 2008 |
| 55 | Cypress Gas Pipeline Company | | Oil Operator | Dec 1998 |
| 56 | Cypress Gas Pipeline, LLC | | Oil Operator | Sep 2019 |
| 57 | Cypress Production, Inc. | Azle, TX 76020 | Oil & Gas Operator | Feb 2026 |