| 101 | Enerplus Resources USA Corporation | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 102 | Enogex Exploration Corp | Oklahoma City, OK 73124-0300 | Oil & Gas Operator | Jun 2000 |
| 103 | Enron Oil & Gas Company | Houston, TX 77210 | Oil & Gas Operator | Dec 1999 |
| 104 | Enserch Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | Apr 2015 |
| 105 | EOG Resources Inc | Midland, TX 79702 | Oil & Gas Operator | Dec 2025 |
| 106 | EP Energy E&P Company, LP | Houston, TX 77210 | Oil & Gas Operator | Jan 2023 |
| 107 | EP Operating Company LP | Midland, TX 79705-5510 | Oil & Gas Operator | Mar 1993 |
| 108 | Eps Resources Corp | Englewood, CO 80111 | Oil & Gas Operator | Dec 2009 |
| 109 | Equitable Resources Energy | Houston, TX 77056-2742 | Oil & Gas Operator | Sep 1997 |
| 110 | Equity Oil Company | Salt Lake City, UT 84110-095 | Oil & Gas Operator | Aug 2004 |
| 111 | Evergreen Operating Corp | Denver, CO 80202 | Oil & Gas Operator | Dec 2019 |
| 112 | Exxon Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2024 |
| 113 | Fiml Natural Resources LLC (FNR) | Denver, CO 80202-4438 | Oil & Gas Operator | Jul 2014 |
| 114 | Fina Oil And Chemical Company | Dallas, TX 75221 | Oil & Gas Operator | May 2019 |
| 115 | Finley Resources Inc | Fort Worth, TX 76113 | Oil & Gas Operator | Dec 2025 |
| 116 | First Zone Production | Salt Lake City, UT 84102 | Oil & Gas Operator | Dec 1997 |
| 117 | Flying Diamond Oil Corp | | Oil & Gas Operator | Dec 1983 |
| 118 | Flying J Inc | Roosevelt, UT 84066 | Oil & Gas Operator | Jul 1995 |
| 119 | Flying J Oil & Gas Inc | North Salt Lake, UT 84054 | Oil & Gas Operator | Dec 2009 |
| 120 | Forest Oil Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 121 | Foundation Energy Management, LLC | Addison, TX 75001 | Oil & Gas Operator | Dec 2025 |
| 122 | Fourpoint Resources, LLC | Denver, CO 80206 | Oil & Gas Operator | Sep 2025 |
| 123 | Freedom Energy Inc | Horseshoe Bay, TX 78657 | Oil & Gas Operator | Dec 2025 |
| 124 | Gas & Oil Management Inc | Englewood, CO 80112 | Oil & Gas Operator | Dec 1974 |
| 125 | Gas Producing Enterprises | Houston, TX 77046 | Oil & Gas Operator | Dec 1983 |
| 126 | Gasco Production Company | Denver, CO 80237 | Oil & Gas Operator | Dec 2015 |
| 127 | Gavilan Petroleum Inc | Park City, UT 84060 | Oil & Gas Operator | Dec 2006 |
| 128 | Gilmore Oil And Gas Co | Austin, TX 78768-4729 | Oil & Gas Operator | Jan 1997 |
| 129 | Graham Resources Inc | Denver, CO 80202 | Oil & Gas Operator | Apr 1988 |
| 130 | Graham Royalty LTD | Covington, LA 70434 | Oil & Gas Operator | Jul 2007 |
| 131 | Great Northern Gas Company | Denver, CO 80293-0602 | Oil & Gas Operator | Jun 2016 |
| 132 | Greenwood Holding Inc | Englewood, CO 80110 | Oil & Gas Operator | Jun 1993 |
| 133 | Greylock Production LLC | Charleston, WV 25311-1264 | Oil & Gas Operator | Oct 2025 |
| 134 | Guffey & Galey | | Oil & Gas Operator | Aug 1981 |
| 135 | Gulf Energy Corporation | Denver, CO 80237 | Oil & Gas Operator | Jun 1987 |
| 136 | Gulf Oil Corp. | Denver, CO 80201-0599 | Oil & Gas Operator | Dec 2014 |
| 137 | GW Petroleum Inc | Houston, TX 77002 | Oil & Gas Operator | Apr 1993 |
| 138 | Hadden, Pennell & Rohret | Lakewood, CO 80228 | Oil Operator | Nov 1994 |
| 139 | Harper Oil Co. | Denver, CO 80217 | Oil & Gas Operator | Jun 2025 |
| 140 | Hiko Bell Mining & Oil Co | Vernal, UT 84078 | Oil & Gas Operator | Oct 2003 |
| 141 | Hill, Gillman A | Englewood, CO 80112 | Oil & Gas Operator | Jun 1993 |
| 142 | Holden Energy Corporation | Ardmore, OK 73401 | Oil & Gas Operator | Mar 2015 |
| 143 | Hollandsworth & Travis Oil | Longview, TX 75606 | Oil Operator | May 2003 |
| 144 | Homeland Gas & Oil, Inc | Roosevelt, UT 84066-1574 | Oil & Gas Operator | Sep 2025 |
| 145 | Hot Rod Oil | Vernal, UT 84078 | Oil & Gas Operator | Oct 2025 |
| 146 | Houston Exploration Co, The | Houston, TX 77002 | Oil & Gas Operator | Apr 2017 |
| 147 | Hugoton Energy Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2019 |
| 148 | Humble Oil & Refining Co. | Houston, TX 77252 | Oil & Gas Operator | Jan 2000 |
| 149 | Huntford Resources Corp | Englewood, CO 80112 | Oil & Gas Operator | Nov 2001 |
| 150 | Husky Oil Company | Cody, WY 82414 | Oil & Gas Operator | Dec 1984 |
| 151 | Hyland Oil Corporation | | Oil & Gas Operator | Apr 1990 |
| 152 | Industrial Gas Services Inc | Wheat Ridge, CO 80033 | Oil & Gas Operator | Feb 2023 |
| 153 | Inland Production Company | Vernal, UT 84079 | Oil & Gas Operator | Dec 2004 |
| 154 | Interline Resources Corp | Casper, WY 82601 | Oil & Gas Operator | Oct 2009 |
| 155 | Intrepid Oil & Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Apr 2021 |
| 156 | Jacobs, R L Oil & Gas Co | Grand Junction, CO 81503 | Oil & Gas Operator | Oct 1986 |
| 157 | Javelin Energy Partners Management, LLC | Irving, TX 75038 | Oil & Gas Operator | Dec 2025 |
| 158 | Jenex Petroleum Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2025 |
| 159 | Kenneth D Luff | | Oil & Gas Operator | Dec 1983 |
| 160 | Kerr-McGee Oil & Gas Onshore LP | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 161 | KGH Operating Company | Billings, MT 59115 | Oil & Gas Operator | Sep 2025 |
| 162 | Koch Exploration Company, LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2019 |
| 163 | L B Industries Inc | Englewood, CO 80112 | Oil & Gas Operator | Jun 2003 |
| 164 | Lacy, R | Longview, TX 75606 | Oil Operator | Apr 1989 |
| 165 | Linmar Energy Corporation | Denver, CO 80237 | Oil & Gas Operator | Oct 1987 |
| 166 | Linmar Petroleum Company | Denver, CO 80237 | Oil & Gas Operator | Oct 1995 |
| 167 | Linn Operating, Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2017 |
| 168 | Linn Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Jan 2019 |
| 169 | Lockridge, John P | Denver, CO 80202 | Gas Operator | Mar 1999 |
| 170 | Lodestone Operating, Inc. | Portland, TX 78374 | Oil & Gas Operator | Dec 2025 |
| 171 | Lomax Exploration Company | Roosevelt, UT 84066 | Oil & Gas Operator | Jun 1995 |
| 172 | Lone MTN Production Co | Billings, MT 59108-0965 | Oil & Gas Operator | Jul 2019 |
| 173 | Luff Exploration Company | Denver, CO 80203 | Oil & Gas Operator | Oct 2025 |
| 174 | Mapco Inc | Billings, MT 59102 | Oil & Gas Operator | Dec 1983 |
| 175 | Mapco Oil & Gas Company | Tulsa, OK 74101-2115 | Oil & Gas Operator | Jan 1985 |
| 176 | Mapco Production Co | Billings, MT 59102 | Oil & Gas Operator | Apr 1994 |
| 177 | Mar/Reg Oil Company | Reno, NV 89511 | Oil & Gas Operator | Sep 2025 |
| 178 | Maralex Resources Inc | Ignacio, CO 81137 | Oil & Gas Operator | Oct 2025 |
| 179 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Oct 2025 |
| 180 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 181 | McCulliss Resources Co Inc | Littleton, CO 80161-3248 | Oil & Gas Operator | Jun 2009 |
| 182 | McElvain Energy Inc | Denver, CO 80265 | Oil & Gas Operator | Nov 2019 |
| 183 | McElvain Oil & Gas Properties Inc | Denver, CO 80265-2080 | Oil & Gas Operator | Jul 2011 |
| 184 | McKenzie Petroleum Company | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 185 | McKenzie Production Company | Houston, TX 77063 | Oil & Gas Operator | May 1995 |
| 186 | McLish & Luff | Denver, CO 80202 | Gas Operator | Nov 1972 |
| 187 | McLish, Holmes P | Denver, CO 80202 | Oil & Gas Operator | Dec 1983 |
| 188 | Medallion Exploration | Holladay, UT 84117 | Oil & Gas Operator | Dec 2015 |
| 189 | Middle Fork Energy Uinta, LLC | Denver, CO 80202 | Oil & Gas Operator | Sep 2025 |
| 190 | Miller, Dyer & Co LLC | Denver, CO 80202 | Oil & Gas Operator | May 2009 |
| 191 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 192 | Mountain Fuel Supply Co | Salt Lake City, UT 84139 | Oil & Gas Operator | May 1984 |
| 193 | Mountain Oil And Gas Inc | Roosevelt, UT 84066 | Oil & Gas Operator | Oct 2025 |
| 194 | Mountain Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Apr 2013 |
| 195 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Oct 2025 |
| 196 | Nadk, LLC | Orem, UT 84097 | Oil & Gas Operator | Nov 2025 |
| 197 | National Oil Company | Garden City, KS 67846 | Oil & Gas Operator | Jun 2024 |
| 198 | Natural Gas Corp Of Ca | Vernal, UT 84078 | Oil & Gas Operator | Jun 1989 |
| 199 | Newfield Production Company | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Jul 2022 |
| 200 | Northstar Gas Company Of Texas | Houston, TX 77057-2768 | Oil & Gas Operator | Nov 2025 |