| 1 | C.F. Braun & Company | | Oil & Gas Operator | Dec 1986 |
| 2 | Cairn Energy Partners, LLC | | Oil & Gas Operator | Feb 2023 |
| 3 | Cajun Minerals, Inc. | | Oil & Gas Operator | Mar 1997 |
| 4 | Callon Petroleum Company | Natchez, MS 39120 | Oil & Gas Operator | Jan 2000 |
| 5 | Cambridge Energy Corporation | | Oil & Gas Operator | Jul 2003 |
| 6 | Camex Operating Company | | Oil & Gas Operator | Dec 2024 |
| 7 | Campbell Wells Corporation | | Oil Operator | Dec 1995 |
| 8 | Cardinal Oil & Gas, Inc. | | Oil & Gas Operator | Jun 1995 |
| 9 | Caribbean Oil & Gas Corp | | Oil & Gas Operator | Mar 1980 |
| 10 | Carl Oil & Gas Co. | Bakersfield, CA 93309 | Oil & Gas Operator | Dec 1995 |
| 11 | Carl Oil & Gas Co.-CNG | | Oil & Gas Operator | Dec 1995 |
| 12 | Carrollton Resources Corp. | | Oil & Gas Operator | Sep 2000 |
| 13 | Castex Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 14 | Cel Properties LLC | | Oil & Gas Operator | Jan 2025 |
| 15 | Centergate Resources LLC | | Oil & Gas Operator | Dec 2024 |
| 16 | Century Exploration Houston, Inc | The Woodlands, TX 77380 | Oil & Gas Operator | Oct 2011 |
| 17 | Chaparral Energy, Inc. | Oklahoma City, OK 73114 | Oil & Gas Operator | Dec 2009 |
| 18 | Chaparral Energy, L.L.C. | Oklahoma City, OK 73142 | Oil & Gas Operator | Mar 2025 |
| 19 | Charles Holston, Inc. | | Oil Operator | Jan 2025 |
| 20 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Mar 2025 |
| 21 | Cico Oil & Gas Company | Houston, TX 77057 | Oil & Gas Operator | Aug 2019 |
| 22 | Clayton W. Williams, Jr. | | Oil & Gas Operator | Sep 1986 |
| 23 | Clover Energy Corp | | Oil & Gas Operator | May 1980 |
| 24 | Coda Energy, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Aug 1998 |
| 25 | Cody Energy LLC | Houston, TX 77024 | Oil & Gas Operator | Jun 2020 |
| 26 | Cody Energy, Inc. | Houston, TX 77077 | Oil & Gas Operator | Jan 2025 |
| 27 | Columbia Gulf Transmission Co. | | Oil Operator | Dec 2014 |
| 28 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 29 | Consolidated Resources Inc | | Oil & Gas Operator | May 2004 |
| 30 | Continental Operating Co. | Houston, TX 77024 | Oil & Gas Operator | Mar 2025 |
| 31 | Cordex Petroleums, Inc. | | Oil & Gas Operator | Jun 1996 |
| 32 | Cox Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2014 |
| 33 | Crimson Explor Operating, Inc. | | Oil & Gas Operator | Dec 2009 |
| 34 | Crown Central Petroleum Corp | Richmond, TX 77469 | Oil & Gas Operator | Dec 1999 |
| 35 | Crystal Oil And Land Company | | Oil & Gas Operator | May 1992 |
| 36 | CSX Oil & Gas Corporation | Houston, TX 77210-4326 | Oil & Gas Operator | Mar 1993 |
| 37 | CX Operating, Inc. | | Oil & Gas Operator | Oct 2023 |
| 38 | Czar Resources Inc | Houston, TX 77060 | Oil & Gas Operator | Oct 1992 |