| 101 | Byron Oil Industries Inc | Ballwin, MO 63011 | Oil & Gas Operator | Apr 2019 |
| 102 | C & J Field Services | | Oil & Gas Operator | May 2025 |
| 103 | Cabot Oil & Gas Corporation | Houston, TX 77024 | Oil & Gas Operator | Apr 2025 |
| 104 | Caerus Piceance LLC | | Oil & Gas Operator | Feb 2025 |
| 105 | Caerus Washco LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2019 |
| 106 | Calpine Natural Gas L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2006 |
| 107 | Cannon Resources Inc | | Oil & Gas Operator | Sep 2003 |
| 108 | Carbon Energy Corporation (USA) | Denver, CO 80290 | Oil & Gas Operator | Jul 2004 |
| 109 | Carrizo Niobrara LLC | | Oil & Gas Operator | Aug 2017 |
| 110 | Carrizo Oil & Gas, Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 111 | Cascade Oil And Gas, Inc | | Oil & Gas Operator | Jun 2005 |
| 112 | Cascade Petroleum LLC | | Oil & Gas Operator | Nov 2015 |
| 113 | Catamount Energy Partners LLC | Denver, CO 80202 | Gas Operator | Jun 2025 |
| 114 | Cci Paradox Upstream LLC | | Oil & Gas Operator | Feb 2024 |
| 115 | CCRP Operating Inc | Denver, CO 80202 | Oil & Gas Operator | Aug 2024 |
| 116 | CDM Oil & Gas | | Oil & Gas Operator | Oct 2018 |
| 117 | CDX Rockies LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2005 |
| 118 | Cedar Ridge LLC | | Oil & Gas Operator | Oct 2006 |
| 119 | Ceh Operating LLC | | Oil & Gas Operator | Jun 2025 |
| 120 | Celsius Energy Company | Denver, CO 80202-1558 | Oil & Gas Operator | Mar 2000 |
| 121 | Central Operating Inc | Denver, CO 80202 | Oil & Gas Operator | Jun 2025 |
| 122 | Central Resources Inc | Denver, CO 80203 | Oil & Gas Operator | Dec 2019 |
| 123 | CFG Energy, Inc | | Oil & Gas Operator | Apr 2006 |
| 124 | CGT Inc | | Oil & Gas Operator | May 2015 |
| 125 | Chaco Energy Company | Denver, CO 80201 | Oil & Gas Operator | May 2025 |
| 126 | Chandler & Associates LLC | | Oil & Gas Operator | Jul 2001 |
| 127 | Chandler DJ Basin LLC | | Oil & Gas Operator | Jul 2012 |
| 128 | Charles P Dunning LLC | | Oil & Gas Operator | Apr 2025 |
| 129 | Chemco Inc | | Oil & Gas Operator | Sep 2023 |
| 130 | Chesapeake Operating LLC | Oklahoma City, OK 73154 | Oil & Gas Operator | Jul 2025 |
| 131 | Chevron Midcontinent, L.P. | Midland, TX 79706 | Oil & Gas Operator | Jul 2025 |
| 132 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Jul 2025 |
| 133 | Choctaw II Oil & Gas, LTD. | Houston, TX 77002 | Oil & Gas Operator | Jan 2002 |
| 134 | Cholla Petroleum Inc | Dallas, TX 75225 | Oil & Gas Operator | Jul 2025 |
| 135 | Cholla Production LLC | Littleton, CO 80127 | Oil & Gas Operator | Mar 2025 |
| 136 | Churchill Energy Inc | | Oil & Gas Operator | Sep 2020 |
| 137 | Cig Resources Company | Colorado Spring, CO 80944-1087 | Oil & Gas Operator | Jun 2018 |
| 138 | Cinnamon Creek Oil & Gas Inc | | Oil Operator | Jun 2025 |
| 139 | Cirque Resources LP | Denver, CO 80202 | Oil & Gas Operator | Aug 2016 |
| 140 | Citation Oil & Gas Corp. | Houston, TX 77269 | Oil & Gas Operator | Jul 2025 |
| 141 | City & County Of Denver | | Oil & Gas Operator | Sep 2023 |
| 142 | Civitas North LLC | | Oil & Gas Operator | May 2025 |
| 143 | CLX Oil & Gas LLC | | Oil & Gas Operator | Feb 2005 |
| 144 | CM Production LLC | | Oil & Gas Operator | Aug 2020 |
| 145 | Coachman Energy Operating Company LLC | Englewood, CO 80111 | Oil & Gas Operator | May 2024 |
| 146 | Coastal Oil & Gas Corporation | Houston, TX 77252 | Oil & Gas Operator | Dec 2009 |
| 147 | Coleman Oil & Gas Inc | Farmington, NM 87499 | Oil & Gas Operator | Jan 2023 |
| 148 | Colorado Energy Minerals Inc | | Oil Operator | Dec 2010 |
| 149 | Colorado Interstate Gas Company LLC | Colorado Springs, CO 80944 | Oil & Gas Operator | May 2025 |
| 150 | Colorado Oil & Gas Corporation | | Oil & Gas Operator | May 2003 |
| 151 | Colton Limited Liability Co | | Oil & Gas Operator | Sep 2023 |
| 152 | Combined Resources Corporation | Edmond, OK 73083 | Oil & Gas Operator | Jul 2025 |
| 153 | Condor Energy Technology LLC | | Oil & Gas Operator | Jul 2018 |
| 154 | ConocoPhillips Company | Midland, TX 79701 | Oil & Gas Operator | Jul 2025 |
| 155 | Conquest Oil Company | Big Spring, TX 79721 | Oil & Gas Operator | Aug 2024 |
| 156 | Consolidated Resources Inc | | Oil & Gas Operator | May 2004 |
| 157 | Continental Resources, Inc. | Oklahoma City, OK 73126 | Oil & Gas Operator | Jul 2025 |
| 158 | Copper Land Resources LLC | | Oil Operator | May 2025 |
| 159 | Coral Production Corporation | Denver, CO 80201 | Oil & Gas Operator | Apr 2025 |
| 160 | Costilla Energy Inc | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 161 | CPX Piceance Holdings LLC | | Oil & Gas Operator | Jul 2024 |
| 162 | Crestone Peak Resources Operating LLC | | Oil & Gas Operator | May 2025 |
| 163 | Crimson Exploration Oper., Inc. | Houston, TX 77002 | Oil & Gas Operator | Dec 2019 |
| 164 | Crumley* Jack | | Oil Operator | Aug 2018 |
| 165 | Cub Creek Energy LLC | | Oil & Gas Operator | Oct 2023 |
| 166 | Curton Capital Corp | | Oil Operator | Sep 2015 |
| 167 | CWC Oil & Gas, LLC | Abilene, TX 79608 | Oil & Gas Operator | Jul 2025 |
| 168 | CWC Petro LLC | | Gas Operator | Dec 2024 |
| 169 | Cyanostar Energy, Inc | Tulsa, OK 74103-4122 | Oil & Gas Operator | Sep 2001 |
| 170 | Cypress Production, Inc. | Azle, TX 76020 | Oil & Gas Operator | Jul 2025 |
| 171 | D & G Roustabout Service | | Oil & Gas Operator | Jan 2024 |
| 172 | D90 Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 173 | Dakota Exploration LLC | Tulsa, OK 74136 | Oil & Gas Operator | Apr 2025 |
| 174 | Daniels Petroleum Co | Denver, CO 80202 | Oil & Gas Operator | Mar 2003 |
| 175 | Darrah Oil Company LLC | Wichita, KS 67201 | Oil & Gas Operator | Jul 2025 |
| 176 | Dart Oil Co | Parker, CO 80134 | Oil & Gas Operator | Dec 2024 |
| 177 | Davis, LLC* Edward Mike | | Oil & Gas Operator | Sep 2015 |
| 178 | Dawson Resources Inc | Franktown, CO 80116 | Oil & Gas Operator | Mar 2015 |
| 179 | Declar Oil & Gas Inc | | Oil & Gas Operator | Dec 2012 |
| 180 | Dejour Energy (USA) Corporation | | Oil & Gas Operator | Jun 2014 |
| 181 | Delek Energy Systems Us Inc | Denver, CO 80202 | Oil & Gas Operator | Oct 2011 |
| 182 | Desert Eagle Operating LLC | | Gas Operator | May 2025 |
| 183 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 184 | Diamond Oil And Gas, Inc. | Kalamazoo, MI 49001 | Oil & Gas Operator | Jul 2025 |
| 185 | Diamond Operating, Inc. | | Oil & Gas Operator | Feb 2022 |
| 186 | Diamondback Oil Partners LLP | Arvada, CO 80004 | Oil & Gas Operator | Dec 2016 |
| 187 | Direct Petroleum Exploration Inc | | Oil & Gas Operator | Aug 2010 |
| 188 | Diversified Energy LLC | Parker, CO 80138 | Oil & Gas Operator | Jun 2025 |
| 189 | Diversified Operating Corp. | Golden, CO 80401 | Oil & Gas Operator | Oct 2012 |
| 190 | DJ Production Services Inc | | Oil & Gas Operator | Sep 2012 |
| 191 | DJ Resources Inc | Bowie, TX 76230 | Oil & Gas Operator | Nov 2017 |
| 192 | Dominion Oklahoma Texas Exploration & Production | Houston, TX 77060 | Oil & Gas Operator | Dec 2006 |
| 193 | Donnelly Casing Pulling Co | | Oil Operator | Aug 2020 |
| 194 | Dover Atwood Corporation | Massillon, OH 44646 | Oil & Gas Operator | Dec 2024 |
| 195 | Drindak* Jon | | Oil Operator | Aug 2013 |
| 196 | Dugan Production Corp | Farmington, NM 87499 | Oil & Gas Operator | May 2025 |
| 197 | Duke Gas Company LLC | | Gas Operator | May 2025 |
| 198 | Dunamis Energy Operating LLC | | Oil & Gas Operator | Apr 2025 |
| 199 | Duncan Energy Company | Denver, CO 80202 | Oil & Gas Operator | Mar 2008 |
| 200 | Duncan Oil Inc | Denver, CO 80210 | Oil & Gas Operator | Jun 2016 |