| 201 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 202 | Taylor Oil #13 LLC | Lander, WY 82520 | Oil Operator | Nov 2024 |
| 203 | Tbi Exploration Inc | Englewood, CO 801556525 | Oil & Gas Operator | Jun 2011 |
| 204 | Tbi Production Company | Lakewood, CO 80228 | Oil & Gas Operator | Oct 2004 |
| 205 | TCF Inc | | Gas Operator | Dec 1993 |
| 206 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Dec 2024 |
| 207 | Terry Production Co | Stroud, OK 74079-0475 | Oil & Gas Operator | Aug 2008 |
| 208 | Texaco Exploration & Prod | Midland, TX 79702 | Oil & Gas Operator | Aug 2002 |
| 209 | The Brinkerhoff Company | Denver, CO 80202 | Oil & Gas Operator | Dec 2017 |
| 210 | Tidemark Exploration | Tulsa, OK 74170 | Oil & Gas Operator | May 2005 |
| 211 | Timberline Energy Inc | Franklin, PA 16323-0269 | Oil & Gas Operator | Dec 2023 |
| 212 | Timberline Production Company LLC | Casper, WY 82601 | Oil & Gas Operator | Oct 2020 |
| 213 | Toc-Rocky Mountain Inc | | Oil & Gas Operator | Oct 2013 |
| 214 | Transhorizon Energy Inc | Cheyenne, WY 82003 | Oil & Gas Operator | Jul 2023 |
| 215 | Tressler John R & IVa M | | Oil Operator | Apr 1989 |
| 216 | Trigg Drilling Company Inc | Oklahoma City, OK 73105 | Oil & Gas Operator | Jan 2013 |
| 217 | Trinity Resources, Inc. | Houston, TX 77277 | Oil & Gas Operator | May 2020 |
| 218 | Trout Kye Jr | | Oil & Gas Operator | Dec 2010 |
| 219 | True Oil LLC | Casper, WY 82602 | Oil & Gas Operator | Mar 2025 |
| 220 | Turner Smith & Associates | Englewood, CO 80111 | Oil & Gas Operator | May 1994 |
| 221 | Tyrex Oil Company | Casper, WY 82602 | Oil & Gas Operator | May 1997 |
| 222 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 223 | United Natural Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2020 |
| 224 | United Natural Resources Corp | | Oil Operator | Jan 1986 |
| 225 | Us Ore Corporation | Pacific Beach, CA 92109 | Oil Operator | Feb 2014 |
| 226 | Valkyrie Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Mar 2025 |
| 227 | Wagner & Brown Limited Partnership | Midland, TX 79701 | Oil & Gas Operator | Feb 2013 |
| 228 | Warrego Oil & Gas LLC | Lander, WY 82520 | Oil Operator | May 2018 |
| 229 | Washakie Oil Company | | Oil & Gas Operator | Dec 1989 |
| 230 | Washington Energy Exploration | | Oil & Gas Operator | Dec 1997 |
| 231 | Wesco Operating, Inc. | Casper, WY 82602 | Oil & Gas Operator | Mar 2025 |
| 232 | Wesco Production LLC | | Oil & Gas Operator | Feb 2025 |
| 233 | Wexpro Company | Rock Springs, WY 82902-0458 | Oil & Gas Operator | Feb 2025 |
| 234 | Wind River Energy Commission | | Oil Operator | Mar 2025 |
| 235 | Wold Oil & Gas | | Oil & Gas Operator | Oct 1996 |
| 236 | Wold Oil Properties Inc | Denver, CO 80203 | Oil & Gas Operator | Feb 2018 |
| 237 | Wood River Oil & Refining Co | | Oil & Gas Operator | Dec 1998 |
| 238 | Wynn-Crosby Operating, LTD. | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 239 | Zavanna Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Jan 2025 |