| 101 | Carlson Petroleum Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 102 | Caskids Operating Company | Houston, TX 77027 | Oil & Gas Operator | May 2025 |
| 103 | Cavalier Oil & Gas, Inc. | Buchanan Dam, TX 78609 | Oil & Gas Operator | May 2025 |
| 104 | CB Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Nov 2017 |
| 105 | Century Exploration Houston, Inc | The Woodlands, TX 77380 | Oil & Gas Operator | Oct 2011 |
| 106 | Chandler Oil & Gas, LLC | Beeville, TX 78102 | Oil & Gas Operator | May 2025 |
| 107 | Chaparral Energy, L.L.C. | Oklahoma City, OK 73142 | Oil & Gas Operator | May 2025 |
| 108 | Chesapeake Operating LLC | Oklahoma City, OK 73154 | Oil & Gas Operator | May 2025 |
| 109 | Chesapeake Operating, Inc. | Oklahoma City, OK 73154 | Oil & Gas Operator | Jan 2025 |
| 110 | Chisholm Oil & Gas, LC | Buda, TX 78610 | Oil & Gas Operator | May 2025 |
| 111 | Christopher Oil & Gas Inc | Fulshear, TX 77441 | Oil & Gas Operator | Apr 2015 |
| 112 | Cibolo Energy Operating, Inc. | Bulverde, TX 78163 | Oil & Gas Operator | May 2025 |
| 113 | Cico Oil & Gas Company | Houston, TX 77057 | Oil & Gas Operator | Aug 2019 |
| 114 | Cimarex Energy Co. Of Colorado | Midland, TX 79706 | Oil & Gas Operator | May 2025 |
| 115 | Cimarron Engineering Corp. | Kingsville, TX 78364 | Oil & Gas Operator | May 2015 |
| 116 | Cimarron Engineering, LLC | Kingsville, TX 78364 | Oil & Gas Operator | May 2025 |
| 117 | Clay Exploration, Inc. | Spring, TX 77387 | Oil & Gas Operator | Jun 2019 |
| 118 | Clide Oil Corp. | Iraan, TX 79744 | Oil & Gas Operator | Nov 2015 |
| 119 | Cliffwood Production Co. | Houston, TX 77090 | Oil & Gas Operator | Aug 2013 |
| 120 | CNG Producing Company | New Orleans, LA 70112 | Oil & Gas Operator | Dec 2015 |
| 121 | Coastal Oil & Gas Corporation | Houston, TX 77252 | Oil & Gas Operator | Dec 2009 |
| 122 | Coastline Exploration, Inc. | Stafford, TX 77477 | Oil & Gas Operator | May 2025 |
| 123 | Coastline Operating, L.L.C. | Houston, TX 77027 | Oil & Gas Operator | Dec 2006 |
| 124 | Cobra Oil & Gas Corporation | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2025 |
| 125 | Collins Resources, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Mar 2011 |
| 126 | Colt Operating Corporation | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 127 | Concho Oil & Gas Corp. | Midland, TX 79701 | Oil & Gas Operator | May 2003 |
| 128 | Concho Resources Inc. | Oklahoma City, OK 73154 | Oil & Gas Operator | Mar 2004 |
| 129 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 130 | ConocoPhillips Company | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 131 | Convest Energy Corporation | Houston, TX 77057 | Oil & Gas Operator | Sep 2014 |
| 132 | Core E & P Corp. | Victoria, TX 77902 | Oil & Gas Operator | May 2025 |
| 133 | Coronado Energy E&P Company, LLC | Houston, TX 77252 | Oil & Gas Operator | Dec 2010 |
| 134 | Costilla Energy Inc | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 135 | Costilla Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 136 | Cougar Oil & Gas Co., Inc. | Houston, TX 77269 | Oil & Gas Operator | Mar 2008 |
| 137 | Cowrie Energy LLC | Austin, TX 78703 | Oil & Gas Operator | May 2025 |
| 138 | Crawford Energy Operating Co | Houston, TX 77056 | Oil & Gas Operator | Aug 2008 |
| 139 | Crawford Hughes Operating Co. | The Woodlands, TX 77380 | Oil & Gas Operator | May 2025 |
| 140 | Crimson Exploration Oper., Inc. | Houston, TX 77002 | Oil & Gas Operator | Dec 2019 |
| 141 | CTR Petroleum, Inc. | Corpus Chrsti, TX 78414 | Oil & Gas Operator | Mar 2015 |
| 142 | Cummins & Walker Oil Co., Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2021 |
| 143 | CXL Energy LLC | Canada, 00100 | Oil & Gas Operator | May 2025 |
| 144 | D C Energy, Inc. | Oklahoma City, OK 73134 | Oil & Gas Operator | Apr 2020 |
| 145 | D&H-S-S Production Co.,Inc | Corpus Chrsti, TX 78409 | Oil & Gas Operator | Aug 2003 |
| 146 | Dale Operating Company | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 147 | Dalen Resources Oil & Gas Co. | Dallas, TX 75206 | Oil & Gas Operator | Jun 2010 |
| 148 | Dartex Energy Corporation | Austin, TX 78746 | Oil & Gas Operator | May 2025 |
| 149 | Daylight Petroleum LLC | Houston, TX 77052 | Oil & Gas Operator | May 2025 |
| 150 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | Feb 2025 |
| 151 | Decker Operating Co., L.L.C. | Houston, TX 77008 | Oil & Gas Operator | May 2025 |
| 152 | Dekalb Energy Company | Oklahoma City, OK 73134 | Oil & Gas Operator | Oct 1996 |
| 153 | Delaware Davis Petroleum Corp. | Houston, TX 77056 | Oil & Gas Operator | Jan 2000 |
| 154 | Delray Oil, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 155 | Delta Exploration Company Inc | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 156 | Denali Oil & Gas Management, LLC | Houston, TX 77060 | Oil & Gas Operator | Dec 2012 |
| 157 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | May 2025 |
| 158 | Devon Gas Services, L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Nov 2015 |
| 159 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 160 | Dewbre Petroleum Corporation | Corpus Chrsti, TX 78404 | Oil & Gas Operator | May 2025 |
| 161 | Discovery Energy Corp. CC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | May 2025 |
| 162 | DMS Oil Company | Houston, TX 77042 | Oil & Gas Operator | Mar 2025 |
| 163 | Dominion Exploration & Production Inc | Houston, TX 77060 | Oil & Gas Operator | Apr 2015 |
| 164 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 165 | Dorado Drilling, Inc. | Gulfport, MS 39501 | Oil & Gas Operator | May 2025 |
| 166 | Double Eagle Petroleum Corp | Evansville, IN 47725 | Oil & Gas Operator | May 2025 |
| 167 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | May 2025 |
| 168 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |
| 169 | Duster Production, Inc. | Refugio, TX 78377 | Oil & Gas Operator | Oct 2011 |
| 170 | Dynamic Petroleum Res., Inc. | Houston, TX 77068 | Oil & Gas Operator | Jul 1994 |
| 171 | Dynamic Production, Inc. | Fort Worth, TX 76106 | Oil & Gas Operator | May 2025 |
| 172 | Eck Petroleum LLC | Kingman, KS 67068 | Oil Operator | Nov 2019 |
| 173 | Eclipse Petroleum Corporation | La Grange, TX 78945 | Oil & Gas Operator | Aug 2003 |
| 174 | Eclipse Services, Inc. * | La Grange, TX 78945 | Oil & Gas Operator | Jul 2003 |
| 175 | Edco Energy, Inc. | Austin, TX 78738 | Oil & Gas Operator | May 2003 |
| 176 | Edge Petroleum Oper. Co., Inc. | Houston, TX 77042 | Oil & Gas Operator | Nov 2010 |
| 177 | El Paso E&P Company, L.P. | Houston, TX 77002 | Oil & Gas Operator | Mar 2013 |
| 178 | El Paso Production Oil & Gas Co. | Houston, TX 77252 | Oil & Gas Operator | May 2025 |
| 179 | Eland Energy Inc | Dallas, TX 75248 | Oil & Gas Operator | Mar 2025 |
| 180 | Elliott Oil & Gas Company | The Woodlands, TX 77380 | Oil & Gas Operator | Sep 2006 |
| 181 | Elliott Oil & Gas Operating Co. | Magnolia, TX 77354 | Oil & Gas Operator | May 2025 |
| 182 | Elliott Oil Company, L.P. | Magnolia, TX 77354 | Oil & Gas Operator | May 2025 |
| 183 | Ellsworth, H. P. O&G Properties | Corpus Chrsti, TX 78413 | Oil & Gas Operator | May 2025 |
| 184 | Emerald Oil & Gas LC | Fort Worth, TX 76109 | Oil & Gas Operator | May 2025 |
| 185 | Encana Oil & Gas (USA) Inc. | Denver, CO 80202 | Oil & Gas Operator | Oct 2020 |
| 186 | Encino Exploration, Inc. | George West, TX 78022 | Oil & Gas Operator | May 2025 |
| 187 | Enduring Resources, LLC | Greenwood VLG, CO 80111 | Oil & Gas Operator | Mar 2025 |
| 188 | Energy Equity Company | Columbus, MT 59019 | Oil & Gas Operator | Mar 2025 |
| 189 | Enerquest Oil & Gas LLC | Oklahoma City, OK 73114 | Oil & Gas Operator | Feb 2025 |
| 190 | Enron Oil & Gas Company | Houston, TX 77210 | Oil & Gas Operator | Dec 1999 |
| 191 | Enserch Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | Apr 2015 |
| 192 | Ensign Operating LLC | Houston, TX 77086 | Oil & Gas Operator | Feb 2023 |
| 193 | EOG Resources, Inc. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 194 | EP Energy E&P Company, LP | Houston, TX 77210 | Oil & Gas Operator | May 2022 |
| 195 | EP Operating Limited Partnership | Dallas, TX 75201 | Oil & Gas Operator | Feb 1995 |
| 196 | Epic Permian Operating, LLC | Midland, TX 79705 | Oil & Gas Operator | Jan 2025 |
| 197 | Esenjay Exploration, Inc | Houston, TX 77042 | Oil & Gas Operator | Feb 2025 |
| 198 | Esenjay Petroleum Corp. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jul 1998 |
| 199 | Espada Operating LLC | San Antonio, TX 78209 | Oil Operator | May 2025 |
| 200 | Esperanza Energy Corp. | Prosper, TX 75078 | Oil & Gas Operator | Mar 2015 |