| 1 | C & VC, Inc. | | Oil & Gas Operator | Sep 1991 |
| 2 | Canlan Oil Company | | Oil & Gas Operator | Mar 1992 |
| 3 | Cardinal Oil & Gas, Inc. | | Oil & Gas Operator | Jun 1995 |
| 4 | Carl Oil & Gas Co. | Bakersfield, CA 93309 | Oil & Gas Operator | Dec 1995 |
| 5 | Castex Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 6 | Cedyco Corporation | Houston, TX 77227 | Oil & Gas Operator | Nov 2008 |
| 7 | Central Mineral Management Inc | | Oil & Gas Operator | Jul 1990 |
| 8 | Century Exploration Houston, Inc | The Woodlands, TX 77380 | Oil & Gas Operator | Oct 2011 |
| 9 | Chevron Pipe Line Company | Houston, TX 77001 | Oil Operator | Feb 2015 |
| 10 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Oct 2025 |
| 11 | Chroma Operating, Inc. | Washington, DC 20036 | Oil & Gas Operator | Jun 2016 |
| 12 | Cimarex Energy Co. Of Colorado | Midland, TX 79706 | Oil & Gas Operator | Oct 2025 |
| 13 | Claron Corporation | Houston, TX 77219 | Oil & Gas Operator | Oct 2025 |
| 14 | Clayton Williams Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Apr 2017 |
| 15 | Clovelly Oil Co. LLC | | Oil & Gas Operator | Nov 2024 |
| 16 | Clovelly Oil Co., Inc. | | Oil & Gas Operator | Nov 2008 |
| 17 | Comstock Oil & Gas -- La, Inc. | | Oil & Gas Operator | Mar 2005 |
| 18 | Continental Operating Co. | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 19 | Corpus Christi Oil & Gas Co. | | Oil & Gas Operator | Dec 1991 |
| 20 | Costilla Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 21 | Cox Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2014 |