| 1 | C S Petroleum Inc | Norman, OK 73070 | Oil & Gas Operator | Dec 2024 |
| 2 | C.F. Braun & Company | | Oil & Gas Operator | Dec 1986 |
| 3 | Cabot Petroleum Corporation | Englewood, CO 80111-2529 | Oil & Gas Operator | Dec 2004 |
| 4 | Cajun Minerals, Inc. | | Oil & Gas Operator | Mar 1997 |
| 5 | Cajun Operating, Inc. | | Oil & Gas Operator | Jun 2011 |
| 6 | Carl Oil & Gas Co. | Bakersfield, CA 93309 | Oil & Gas Operator | Dec 1995 |
| 7 | Carrollton Resources Corp. | | Oil & Gas Operator | Sep 2000 |
| 8 | Caskids Operating Company | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 9 | Century Mineral Corporation | | Oil & Gas Operator | Dec 1990 |
| 10 | Chesapeake Operating, Inc. | Oklahoma City, OK 73154 | Oil & Gas Operator | Jun 2025 |
| 11 | Chevron Pipe Line Company | Houston, TX 77001 | Oil Operator | Feb 2015 |
| 12 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Oct 2025 |
| 13 | Cholla Resources, Inc. | Denver, CO 80202 | Oil & Gas Operator | Jan 1997 |
| 14 | Cities Service Company | | Oil & Gas Operator | Mar 1983 |
| 15 | Cities Service Oil & Gas Corp | | Oil & Gas Operator | Mar 1988 |
| 16 | Cities Service Oil Co. | | Oil & Gas Operator | Dec 1986 |
| 17 | Click Corp | Monroe, LA 71207 | Oil & Gas Operator | Jan 2025 |
| 18 | CLK Energy Partners, LLC | | Oil & Gas Operator | Aug 2018 |
| 19 | Coalinga Corporation | Houston, TX 77002 | Oil & Gas Operator | May 1999 |
| 20 | Coastal Oil & Gas Corporation | Houston, TX 77252 | Oil & Gas Operator | Dec 2009 |
| 21 | Coastal States Gas Prod. Co. | | Oil & Gas Operator | Jun 1996 |
| 22 | Collet Oil Ventures, Inc. | Denver, CO 80217 | Oil & Gas Operator | Jun 2004 |
| 23 | Concord Operating Incorporated | Horseshoe Bay, TX 78657 | Oil & Gas Operator | Dec 2008 |
| 24 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 25 | Consolidated Energy Res., Inc. | | Oil Operator | Jun 1992 |
| 26 | Corum Production Co.-Tepco | | Oil & Gas Operator | Dec 1989 |
| 27 | Corum Production Company | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 28 | Cox Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2014 |
| 29 | Crosstex Lig, LLC | | Oil Operator | Mar 2014 |
| 30 | CSX Oil & Gas Corporation | Houston, TX 77210-4326 | Oil & Gas Operator | Mar 1993 |
| 31 | Cypress Gas Pipeline Company | | Oil Operator | Dec 1998 |
| 32 | Cypress Gas Pipeline, LLC | | Oil Operator | Sep 2019 |