| 1 | Callaway Oil & Gas LLC | Gillette, WY 82717 | Oil & Gas Operator | Aug 2024 |
| 2 | Capitan Operating LLC | Reno, NV 89502 | Oil & Gas Operator | Jan 2013 |
| 3 | Carol-Holly Oil Corporation | Denver, CO 80237 | Oil & Gas Operator | Sep 2024 |
| 4 | Cenex | | Oil & Gas Operator | Dec 1996 |
| 5 | Central Resources Inc | Denver, CO 80203 | Oil & Gas Operator | Dec 2019 |
| 6 | Century Oil & Gas Corporation | | Oil & Gas Operator | Dec 1987 |
| 7 | Chaco Energy Company | Denver, CO 80201 | Oil & Gas Operator | Sep 2024 |
| 8 | Chaparral Resources Inc | Denver, CO 80293 | Oil & Gas Operator | Jan 1996 |
| 9 | Chapman Oil Company | Midland, TX 79702 | Oil & Gas Operator | Sep 2024 |
| 10 | Cheetah Oil Inc | Casper, WY 82602 | Oil & Gas Operator | Dec 2007 |
| 11 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Nov 2024 |
| 12 | Christmann John J | Lubbock, TX 79401 | Oil & Gas Operator | Dec 1994 |
| 13 | CHS McPherson Refinery Inc | Platteville, CO 80651 | Oil & Gas Operator | Apr 1994 |
| 14 | Cig Exploration | Denver, CO 80201 | Oil & Gas Operator | Sep 1999 |
| 15 | Citation Oil & Gas Corp. | Houston, TX 77269 | Oil & Gas Operator | Nov 2024 |
| 16 | Clark Oil Producing Company | | Oil & Gas Operator | Oct 1979 |
| 17 | Cloud Peak Operating LLC | Casper, WY 82601 | Oil Operator | Aug 2024 |
| 18 | Coaleum Corporation | Dallas, TX 75205 | Oil & Gas Operator | Jan 2001 |
| 19 | Coastal Oil & Gas Corporation | Houston, TX 77252 | Oil & Gas Operator | Dec 2009 |
| 20 | Columbus Energy Corp. | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2008 |
| 21 | Consolidated Oil & Gas Inc | Wichita, KS 67202 | Oil & Gas Operator | Dec 2012 |
| 22 | Contango Resources LLC | Houston, TX 77002 | Oil & Gas Operator | Nov 2024 |
| 23 | Contango Rocky Mountain Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2020 |
| 24 | Continental Industries LC | Casper, WY 82602 | Oil & Gas Operator | Feb 2008 |
| 25 | Continental Production Co LLC | Greenwood VIllage, CO 80155 | Oil & Gas Operator | Aug 2012 |
| 26 | CR Energy | | Oil & Gas Operator | Dec 1992 |
| 27 | Creek Oil Company | Colorado Springs, CO 80906 | Oil & Gas Operator | Aug 2001 |
| 28 | Crowheart Energy LLC | Baggs, WY 82321 | Oil & Gas Operator | Aug 2024 |