| 201 | Transhorizon Energy Inc | Cheyenne, WY 82003 | Oil & Gas Operator | Jul 2023 |
| 202 | Tressler John R & IVa M | | Oil Operator | Apr 1989 |
| 203 | Trigg Drilling Company Inc | Oklahoma City, OK 73105 | Oil & Gas Operator | Jan 2013 |
| 204 | Trinity Resources, Inc. | Houston, TX 77277 | Oil & Gas Operator | May 2020 |
| 205 | Trout Kye Jr | | Oil & Gas Operator | Dec 2010 |
| 206 | True Oil LLC | Casper, WY 82602 | Oil & Gas Operator | Jul 2025 |
| 207 | Turner Smith & Associates | Englewood, CO 80111 | Oil & Gas Operator | May 1994 |
| 208 | Tyrex Oil Company | Casper, WY 82602 | Oil & Gas Operator | May 1997 |
| 209 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 210 | United Natural Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2020 |
| 211 | United Natural Resources Corp | | Oil Operator | Jan 1986 |
| 212 | Us Ore Corporation | Pacific Beach, CA 92109 | Oil Operator | Feb 2014 |
| 213 | Valkyrie Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Jul 2025 |
| 214 | Wagner & Brown Limited Partnership | Midland, TX 79701 | Oil & Gas Operator | Feb 2013 |
| 215 | Warrego Oil & Gas LLC | Lander, WY 82520 | Oil Operator | May 2018 |
| 216 | Washakie Oil Company | | Oil & Gas Operator | Dec 1989 |
| 217 | Washington Energy Exploration | | Oil & Gas Operator | Dec 1997 |
| 218 | Wesco Operating, Inc. | Casper, WY 82602 | Oil & Gas Operator | Jul 2025 |
| 219 | Wesco Production LLC | | Oil & Gas Operator | Jun 2025 |
| 220 | Wexpro Company | Rock Springs, WY 82902-0458 | Oil & Gas Operator | Jul 2025 |
| 221 | Wind River Energy Commission | | Oil Operator | Jul 2025 |
| 222 | Wold Oil & Gas | | Oil & Gas Operator | Oct 1996 |
| 223 | Wold Oil Properties Inc | Denver, CO 80203 | Oil & Gas Operator | Feb 2018 |
| 224 | Wood River Oil & Refining Co | | Oil & Gas Operator | Dec 1998 |
| 225 | Wynn-Crosby Operating, LTD. | Dallas, TX 75201 | Oil & Gas Operator | Sep 2025 |
| 226 | Zavanna Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2025 |