| 1 | Capitol Oil & Gas Corporation | Centennial, WY 82055 | Oil Operator | Feb 2006 |
| 2 | Central Operating Inc | Denver, CO 80202 | Oil & Gas Operator | Aug 2025 |
| 3 | Chaco Energy Company | Denver, CO 80201 | Oil & Gas Operator | Aug 2025 |
| 4 | Chemily Management Company | Cypress, TX 77429 | Oil & Gas Operator | Apr 2023 |
| 5 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Oct 2025 |
| 6 | Chipcore LLC | Casper, WY 82601 | Oil & Gas Operator | Aug 2025 |
| 7 | Chriscor Oil & Gas | Plana, TX 75075 | Oil & Gas Operator | Jul 1987 |
| 8 | Christensen Ranch | Newcastle, WY 82701 | Oil Operator | Aug 2021 |
| 9 | CKT Energy LLC | Dallas, TX 75379 | Oil & Gas Operator | Sep 2020 |
| 10 | Colorado Oil & Gas Corporation | | Oil & Gas Operator | May 2003 |
| 11 | Colt Resources Corporation | Billings, MT 59103 | Oil & Gas Operator | Feb 2013 |
| 12 | Columbine Exploration Corp | Englewood, CO 80111 | Oil & Gas Operator | Aug 1998 |
| 13 | Columbus Energy Corp. | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2008 |
| 14 | Common Energy Inc | Douglas, WY 82633 | Oil & Gas Operator | Aug 1995 |
| 15 | Consolidated Oil & Gas Inc | Wichita, KS 67202 | Oil & Gas Operator | Dec 2012 |
| 16 | Contango Resources LLC | Andrews, TX 79714 | Oil & Gas Operator | Oct 2025 |
| 17 | Contango Rocky Mountain Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2020 |
| 18 | Cook D L | Holliday, TX 76366 | Oil & Gas Operator | Dec 2008 |
| 19 | Cork Petroleum Corporation | Thermopolis, WY 82443 | Oil & Gas Operator | Apr 2012 |
| 20 | Coronado Oil Company | Denver, CO 80202 | Oil & Gas Operator | Dec 2019 |
| 21 | Cottonwood Oil Inc | Worland, WY 82401 | Oil & Gas Operator | Jun 1988 |
| 22 | Creek Oil Company | Colorado Springs, CO 80906 | Oil & Gas Operator | Aug 2001 |