| 1 | C & H Oil Company | Ratliff City, OK 73481-0130 | Oil & Gas Operator | Apr 2015 |
| 2 | C & J Exploration LLC | Colorado Springs, CO 80920-3946 | Oil & Gas Operator | Oct 2022 |
| 3 | C & L Oil And Gas Corporation | Norman, OK 73069-8224 | Oil & Gas Operator | Feb 2024 |
| 4 | C & R Petroleum Co. | Duncan, OK 73533-1341 | Oil & Gas Operator | Feb 2024 |
| 5 | C & Y Casing Pulling Company | Duncan, OK 73534-0037 | Oil & Gas Operator | Feb 2024 |
| 6 | Cactus Operating Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Nov 2000 |
| 7 | Cal-Tex Operating Co. | Manchaca, TX 78652 | Oil & Gas Operator | May 2020 |
| 8 | Caprock, Inc. | Ralls, TX 79357 | Oil & Gas Operator | Mar 2013 |
| 9 | Capstone Oilfield Disposal Service LLC | Hennessey, OK 73742-0698 | Oil Operator | Dec 2019 |
| 10 | Caulkins Oil Company | Aztec, NM 87410 | Oil & Gas Operator | Dec 2023 |
| 11 | Central Ok Reclamation LLC | | Oil & Gas Operator | Jun 2014 |
| 12 | Cibola Energy Corp | Albuquerque, NM 87103 | Oil & Gas Operator | Oct 2017 |
| 13 | Clark Operating Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | May 2024 |
| 14 | Climax Oil Co LLC | | Oil Operator | Jan 2024 |
| 15 | CLV Oil & Gas Inc | Tulsa, OK 74169-0713 | Oil & Gas Operator | Apr 2020 |
| 16 | Coast Petroleum Company | | Oil Operator | Nov 1998 |
| 17 | Coho Oil & Gas Inc | Coppell, TX 75019-8288 | Oil & Gas Operator | Mar 2015 |
| 18 | Coker Oil Company | Duncan, OK 73533-0818 | Oil Operator | Jan 2014 |
| 19 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 20 | Consolidated Exploration Company | Oklahoma City, OK 73116 | Oil & Gas Operator | Apr 2015 |
| 21 | Continental Oil & Refining Co | Catoosa, OK 74015-0831 | Oil & Gas Operator | Oct 2023 |
| 22 | Continental Resources, Inc. | Oklahoma City, OK 73126 | Oil & Gas Operator | May 2024 |
| 23 | Convest Energy Corporation | Houston, TX 77057 | Oil & Gas Operator | Sep 2014 |
| 24 | Cotton County Ventures | Estes Park, CO 80517 | Oil Operator | Nov 2003 |
| 25 | County Line Stripper Wells LLC | | Oil & Gas Operator | Sep 2023 |
| 26 | Crescent Exploration, LLC | Edmond, OK 73013 | Oil & Gas Operator | Mar 2015 |
| 27 | Crown Petroleum Company | Duncan, OK 73534-0938 | Oil & Gas Operator | Jan 2011 |