| 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 & R Petroleum Co. | Duncan, OK 73533-1341 | Oil & Gas Operator | Sep 2024 |
| 4 | C & Y Casing Pulling Company | Duncan, OK 73533 | Oil & Gas Operator | Sep 2024 |
| 5 | Cactus Operating Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Nov 2000 |
| 6 | Cal-Tex Operating Co. | Manchaca, TX 78652 | Oil & Gas Operator | May 2020 |
| 7 | Caprock, Inc. | Ralls, TX 79357 | Oil & Gas Operator | Mar 2013 |
| 8 | Caulkins Oil Company | Aztec, NM 87410 | Oil & Gas Operator | Sep 2024 |
| 9 | Cibola Energy Corporation | Albuquerque, NM 87103 | Oil & Gas Operator | Oct 2017 |
| 10 | Citation Oil & Gas Corp. | Houston, TX 77269 | Oil & Gas Operator | Dec 2024 |
| 11 | Clark Operating Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Dec 2024 |
| 12 | CLV Oil & Gas Inc | Tulsa, OK 74169-0713 | Oil & Gas Operator | Apr 2020 |
| 13 | Coast Petroleum Company | | Oil Operator | Nov 1998 |
| 14 | Coho Oil & Gas Inc | Coppell, TX 75019-8288 | Oil & Gas Operator | Mar 2015 |
| 15 | Coker Oil Company | Duncan, OK 73533-0818 | Oil Operator | Jan 2014 |
| 16 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 17 | Consolidated Exploration Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Apr 2015 |
| 18 | Continental Oil & Refining Co | Catoosa, OK 74015-0831 | Oil & Gas Operator | Aug 2024 |
| 19 | Cotton County Ventures | Estes Park, CO 80517 | Oil Operator | Nov 2003 |
| 20 | County Line Stripper Wells LLC | Chelsea, OK 74016 | Oil & Gas Operator | Jun 2024 |
| 21 | Crescent Exploration, LLC | Edmond, OK 73013 | Oil & Gas Operator | Mar 2015 |
| 22 | Crown Petroleum Company | Duncan, OK 73534-0938 | Oil & Gas Operator | Jan 2011 |