| 1 | C.D. Operating Company, Inc. | Oklahoma City, OK 73116 | Oil & Gas Operator | Apr 2015 |
| 2 | Caddo Exploration, LLC | Norman, OK 73072 | Oil & Gas Operator | Mar 2025 |
| 3 | Calpine Natural Gas Company L.P. | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 4 | Canvas Energy LLC | Oklahoma City, OK 73142-1839 | Oil & Gas Operator | Mar 2025 |
| 5 | Canyon Exploration Co. | Amarillo, TX 79105 | Oil & Gas Operator | Feb 2025 |
| 6 | Carbon Economy LLC | Chickasha, OK 73023 | Oil & Gas Operator | Mar 2025 |
| 7 | Chaco Energy Company | Denver, CO 80201 | Oil & Gas Operator | Apr 2025 |
| 8 | Chesapeake Operating LLC | Oklahoma City, OK 73154 | Oil & Gas Operator | Jun 2025 |
| 9 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Jun 2025 |
| 10 | Cimarex Energy Co | Midland, TX 79706 | Oil & Gas Operator | Jun 2025 |
| 11 | Cimarex Energy Co. Of Colorado | Midland, TX 79706 | Oil & Gas Operator | Jun 2025 |
| 12 | Cimarron Operating Company | Oklahoma City, OK 73112-3967 | Oil & Gas Operator | May 2011 |
| 13 | Cisco Operating LLC | Plano, TX 75024 | Oil & Gas Operator | Mar 2025 |
| 14 | Citrus Energy Corporation | Castle Rock, CO 80104 | Oil & Gas Operator | Mar 2020 |
| 15 | Collins Dillard Dba Dilco Oil Company | Mangum, OK 73554-4029 | Oil & Gas Operator | Mar 2025 |
| 16 | Colt Resources Corporation | Billings, MT 59103 | Oil & Gas Operator | Feb 2013 |
| 17 | Combined Resources Corporation | Edmond, OK 73083 | Oil & Gas Operator | Jun 2025 |
| 18 | Complete Energy Services LLC | Gainesville, TX 76240 | Oil Operator | Aug 2022 |
| 19 | Concorde Resources Corporation | Eufaula, OK 74432 | Oil & Gas Operator | Feb 2025 |
| 20 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 21 | ConocoPhillips Company | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 22 | Cornelius Dale | Willow, OK 73673 | Oil Operator | Jan 2025 |
| 23 | Crawley Petroleum Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | Jun 2025 |
| 24 | Crescendo Resources, L.P. | Amarillo, TX 79188 | Oil & Gas Operator | Feb 2025 |
| 25 | Cross Timbers Operating Co | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 2025 |
| 26 | Cross Timbers Production Co | Oklahoma City, OK 73102-5605 | Oil & Gas Operator | Mar 2005 |
| 27 | Crouch Petroleum Company | Amarillo, TX 79110 | Oil & Gas Operator | Mar 2015 |