| 101 | Calco Inc | | Oil & Gas Operator | Feb 1991 |
| 102 | Cambria Oil Company | Casper, WY 82601 | Oil & Gas Operator | Dec 1996 |
| 103 | Camwest II LP | McKinney, TX 75070 | Oil & Gas Operator | Jul 2007 |
| 104 | Camwest Limited Partnership | Denver, CO 80202 | Oil & Gas Operator | Apr 2004 |
| 105 | Carbon Creek Energy LLC | Sheridan, WY 82801 | Oil & Gas Operator | May 2025 |
| 106 | Cardinal Wyoming LLC | | Oil & Gas Operator | May 2025 |
| 107 | Carol-Holly Oil Corporation | Denver, CO 80237 | Oil & Gas Operator | Jun 2025 |
| 108 | Carrizo Oil & Gas, Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 109 | Caza Exploration Company | | Oil Operator | Nov 1991 |
| 110 | Cedar Resources Corporation | Gillette, WY 82717 | Gas Operator | Dec 2010 |
| 111 | Cedar Ridge Operating Co LLC | Durango, CO 81303 | Gas Operator | Dec 2009 |
| 112 | Celeron Oil & Gas Company | | Oil & Gas Operator | Dec 1987 |
| 113 | Celsius Energy Company | Denver, CO 80202-1558 | Oil & Gas Operator | Mar 2000 |
| 114 | Cenergy Resources LLC | | Oil & Gas Operator | May 2025 |
| 115 | Cenex | | Oil & Gas Operator | Dec 1996 |
| 116 | Central Resources Inc | Denver, CO 80203 | Oil & Gas Operator | Dec 2019 |
| 117 | Century Energy | Gillette, WY 82717 | Oil & Gas Operator | Dec 1996 |
| 118 | Century Oil & Gas Corporation | | Oil & Gas Operator | Dec 1987 |
| 119 | Century Oil And Gas LLC | Katy, TX 77494 | Oil & Gas Operator | May 2025 |
| 120 | CH4 Energy LLC | Fort Worth, TX 76102 | Oil & Gas Operator | May 2006 |
| 121 | Chaco Energy Company | Denver, CO 80201 | Oil & Gas Operator | May 2025 |
| 122 | Chambers Jerry | Denver, CO 80237 | Oil & Gas Operator | Dec 1993 |
| 123 | Chandler Energy LLC | Denver, CO 80202 | Oil & Gas Operator | Jan 2009 |
| 124 | Chaparral Energy, L.L.C. | Oklahoma City, OK 73142 | Oil & Gas Operator | Jul 2025 |
| 125 | Chaparral Resources Inc | Denver, CO 80293 | Oil & Gas Operator | Jan 1996 |
| 126 | Charger Resources, LLC | Hurst, TX 76054 | Oil & Gas Operator | Aug 2015 |
| 127 | Chemily Management Company | Cypress, TX 77429 | Oil & Gas Operator | Apr 2023 |
| 128 | Chesapeake Operating LLC | Oklahoma City, OK 73154 | Oil & Gas Operator | Jul 2025 |
| 129 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Jul 2025 |
| 130 | Chipcore LLC | Casper, WY 82601 | Oil & Gas Operator | May 2025 |
| 131 | Chriscor Oil & Gas | Plana, TX 75075 | Oil & Gas Operator | Jul 1987 |
| 132 | CHS McPherson Refinery Inc | Platteville, CO 80651 | Oil & Gas Operator | Apr 1994 |
| 133 | Ciris Energy Inc | Centennial, CO 80112 | Gas Operator | Dec 2016 |
| 134 | Citation Oil & Gas Corp. | Houston, TX 77269 | Oil & Gas Operator | Jul 2025 |
| 135 | CKT Energy LLC | Dallas, TX 75379 | Oil & Gas Operator | Sep 2020 |
| 136 | CLC Operations Inc | Midland, TX 79701 | Oil & Gas Operator | Mar 1997 |
| 137 | CMS Oil And Gas Company | Jackson, MI 49201 | Oil & Gas Operator | Oct 2002 |
| 138 | CNX Gas Company LLC | Canonsburg, PA 15317 | Oil & Gas Operator | May 2025 |
| 139 | Coal Creek Minerals LLC | Northglenn, CO 80234 | Gas Operator | Feb 2012 |
| 140 | Coastal Oil & Gas Corporation | Houston, TX 77252 | Oil & Gas Operator | Dec 2009 |
| 141 | Cobra Oil & Gas Corporation | Wichita Falls, TX 76307 | Oil & Gas Operator | Jul 2025 |
| 142 | Coleman Oil & Gas Inc | Farmington, NM 87499 | Oil & Gas Operator | Jan 2023 |
| 143 | Coltrane Charles | | Oil Operator | Dec 1980 |
| 144 | Columbus Energy Corp. | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2008 |
| 145 | Columbus Production Inc | | Oil & Gas Operator | Mar 2005 |
| 146 | Comdisco Exploration Inc | | Oil Operator | Dec 1990 |
| 147 | Comet Energy Services LLC | Traverse City, MI 49686 | Oil & Gas Operator | Oct 2011 |
| 148 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 149 | ConocoPhillips Company | Midland, TX 79701 | Oil & Gas Operator | Jul 2025 |
| 150 | Consolidated Oil & Gas Inc | Wichita, KS 67202 | Oil & Gas Operator | Dec 2012 |
| 151 | Contango Resources LLC | Andrews, TX 79714 | Oil & Gas Operator | Jul 2025 |
| 152 | Continental Industries LC | Casper, WY 82602 | Oil & Gas Operator | Feb 2008 |
| 153 | Continental Production Co LLC | Greenwood VIllage, CO 80155 | Oil & Gas Operator | Aug 2012 |
| 154 | Continental Resources, Inc. | Oklahoma City, OK 73126 | Oil & Gas Operator | Jul 2025 |
| 155 | Convest Energy Corporation | Houston, TX 77057 | Oil & Gas Operator | Sep 2014 |
| 156 | Cook D L | Holliday, TX 76366 | Oil & Gas Operator | Dec 2008 |
| 157 | Coquina Oil Corporation | Houston, TX 77227 | Oil & Gas Operator | Mar 2015 |
| 158 | Coral Production Corporation | Denver, CO 80201 | Oil & Gas Operator | Apr 2025 |
| 159 | Cordero Mining Co | Gillette, WY 82717 | Oil Operator | Nov 2009 |
| 160 | Cordero Oil And Gas LLC | Gillette, WY 82716 | Oil Operator | Nov 2021 |
| 161 | Corrida Oil Inc | Denver, CO 80217 | Oil & Gas Operator | Jun 1990 |
| 162 | Costilla Energy Inc | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 163 | Cotton Petroleum Corporation | Tulsa, OK 74102 | Oil & Gas Operator | Jan 2005 |
| 164 | Cowboy Clean Fuels LLC | Laramie, WY 82072 | Gas Operator | Apr 2025 |
| 165 | Cox Edwin L & Berry R | | Oil & Gas Operator | Oct 1987 |
| 166 | Cox Kendall Jay | Recluse, WY 28775 | Oil & Gas Operator | Aug 2016 |
| 167 | Cramer Oil Company | Denver, CO 80202 | Oil Operator | Aug 2012 |
| 168 | Crawley Petroleum Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | Jul 2025 |
| 169 | Creek Oil Company | Colorado Springs, CO 80906 | Oil & Gas Operator | Aug 2001 |
| 170 | Crest Resources Inc | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2025 |
| 171 | Crystal Exploration & Production Company | Shreveport, LA 71120 | Oil & Gas Operator | Feb 1995 |
| 172 | Crystal Oil Company | Shreveport, LA 71120 | Oil & Gas Operator | Jul 1995 |
| 173 | Czar Resources Inc | Houston, TX 77060 | Oil & Gas Operator | Oct 1992 |
| 174 | D K Cook Heirs LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2011 |
| 175 | D90 Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 176 | Dalen Resources Oil & Gas Co. | Dallas, TX 75206 | Oil & Gas Operator | Jun 2010 |
| 177 | Damson Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Mar 2005 |
| 178 | Daube Company The | Ardmore, OK 73401 | Oil & Gas Operator | May 2025 |
| 179 | Davey Corporation | Golden, CO 80401 | Oil & Gas Operator | Jun 2025 |
| 180 | Davis Exploration | | Oil Operator | Dec 2007 |
| 181 | Davis Oil Company | Denver, CO 80202 | Oil & Gas Operator | Jun 1988 |
| 182 | DCD Inc | Gillette, WY 82716 | Oil & Gas Operator | Aug 2003 |
| 183 | Deca Energy Corporation | | Oil & Gas Operator | Aug 1986 |
| 184 | Decalta International Corp | Denver, CO 80202 | Oil & Gas Operator | Mar 2015 |
| 185 | Dekalb Energy Company | Oklahoma City, OK 73134 | Oil & Gas Operator | Oct 1996 |
| 186 | Denbury Onshore, LLC | Plano, TX 75024 | Oil & Gas Operator | Jul 2025 |
| 187 | Devon Energy Operating Corp | Oklahoma City, OK 73102 | Oil & Gas Operator | Apr 2013 |
| 188 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Jul 2025 |
| 189 | Devon SFS Operating Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2008 |
| 190 | Diamond Oil & Gas LLC | Casper, WY 82604 | Oil & Gas Operator | May 2025 |
| 191 | Diasu Oil & Gas Co., Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2016 |
| 192 | Dietrich Resources Corporation | | Oil & Gas Operator | Jun 2007 |
| 193 | DKM Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Sep 2011 |
| 194 | DNR Oil And Gas, Inc. | Englewood, CO 80155 | Oil & Gas Operator | Jun 2025 |
| 195 | Dol Resources Inc | Rowlett, TX 75088 | Oil & Gas Operator | Jun 2025 |
| 196 | Dome Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Dec 2016 |
| 197 | Dominion Exploration & Production Inc | Houston, TX 77060 | Oil & Gas Operator | Apr 2015 |
| 198 | Duncan Energy Company | Denver, CO 80202 | Oil & Gas Operator | Mar 2008 |
| 199 | Duncan Oil Inc | Denver, CO 80210 | Oil & Gas Operator | Jun 2016 |
| 200 | Dyco Petroleum Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |