| 301 | Rosa Petroleum | Evansville, WY 82636 | Oil Operator | Dec 1995 |
| 302 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 303 | Sage Butte PRB Operating, LLC | Denver, CO 80202 | Oil & Gas Operator | Jul 2026 |
| 304 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 305 | Samson Resources Company LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2021 |
| 306 | Sauer Bill Oil & Gas Company LLC | Casper, WY 82604 | Oil & Gas Operator | Jun 1999 |
| 307 | Sceptre Resources Inc | | Oil & Gas Operator | Dec 2007 |
| 308 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 309 | Sgcu GP LLC | Casper, WY 82602 | Oil Operator | Jul 2026 |
| 310 | Shenandoah Oil Corporation | | Oil & Gas Operator | Jun 1979 |
| 311 | Sierra Trading Corporation | | Oil & Gas Operator | Sep 1978 |
| 312 | Six Bar Oil LLC | Pine Haven, WY 82721 | Oil & Gas Operator | Jul 2026 |
| 313 | Skinner'S Resources & Expl Inc | | Oil & Gas Operator | Jun 2007 |
| 314 | Skull Creek A LLC | Douglas, WY 82633 | Oil & Gas Operator | Feb 2026 |
| 315 | Skyline Oil Company | Salt Lake City, UT 84111 | Oil & Gas Operator | Jan 1987 |
| 316 | Slaughter J M Oil Company | Fort Worth, TX 76116 | Oil & Gas Operator | Jan 2001 |
| 317 | Slawson Exploration Company Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Sep 2026 |
| 318 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Sep 2026 |
| 319 | Snowy Owl LLC | Gillette, WY 82717 | Oil & Gas Operator | Jul 2026 |
| 320 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 321 | Sonat Exploration Co. | Houston, TX 77251 | Oil & Gas Operator | Dec 2021 |
| 322 | South Coast Oil Corporation | Boulder, CO 80302 | Oil & Gas Operator | Oct 2015 |
| 323 | Southern Mineral Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2001 |
| 324 | Southern Union Exploration | | Oil Operator | Jan 1990 |
| 325 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 326 | Southport Exploration Inc | Tulsa, OK 74103-4015 | Oil & Gas Operator | Nov 1998 |
| 327 | Southwestern Production Corporation | Lakewood, CO 80228 | Oil & Gas Operator | Jul 2026 |
| 328 | Spirit Energy Inc | Edmond, OK 73034 | Oil & Gas Operator | Apr 1999 |
| 329 | St Michael Exploration | | Oil & Gas Operator | Jun 1987 |
| 330 | St. Mary Operating Company | Denver, CO 80203 | Oil & Gas Operator | Mar 2019 |
| 331 | Sterling Energy Corporation | Denver, CO 80202 | Oil & Gas Operator | Sep 1995 |
| 332 | Stone Energy Corporation | Denver, CO 80202-2828 | Oil & Gas Operator | Oct 2014 |
| 333 | Stone Energy LLC | Denver, CO 80202 | Oil & Gas Operator | May 2005 |
| 334 | Sunshine Valley Petroleum | Casper, WY 82605 | Oil & Gas Operator | Jul 2026 |
| 335 | T K Resources LLC | Gillette, WY 82716 | Oil & Gas Operator | Jul 2026 |
| 336 | T-Rex Oil Inc | Broomfield, CO 80021 | Oil Operator | Feb 2011 |
| 337 | T2 Operating Corporation | Denver, CO 80202 | Oil & Gas Operator | Jul 2026 |
| 338 | Target Oil Company | | Oil & Gas Operator | Mar 2007 |
| 339 | Tbi Exploration Inc | Englewood, CO 801556525 | Oil & Gas Operator | Jun 2011 |
| 340 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Dec 2025 |
| 341 | Terex Energy Corporation | Casper, WY 82602 | Oil & Gas Operator | Aug 2019 |
| 342 | Terrapet Corporation | | Oil & Gas Operator | Jun 2011 |
| 343 | Texaco Exploration & Prod | Midland, TX 79702 | Oil & Gas Operator | Aug 2002 |
| 344 | The Brinkerhoff Company | Denver, CO 80202 | Oil & Gas Operator | Dec 2017 |
| 345 | Thomas Operating Company Inc | Greeley, CO 80634 | Oil & Gas Operator | Aug 2008 |
| 346 | Three Forks Resources, LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | Sep 2026 |
| 347 | Tiger Oil Company | Dallas, TX 75221 | Oil & Gas Operator | May 2007 |
| 348 | Timberline Production Company LLC | Casper, WY 82601 | Oil & Gas Operator | Oct 2020 |
| 349 | Titan Exploration LLC | Denver, CO 80202 | Oil & Gas Operator | Jan 2026 |
| 350 | Torch E & P Company | Houston, TX 77010 | Oil & Gas Operator | Jan 2015 |
| 351 | Torch Oil & Gas Company | Houston, TX 77010 | Oil & Gas Operator | Aug 1997 |
| 352 | Transco Exploration Company | | Oil & Gas Operator | Jul 1989 |
| 353 | Transworld Systems Petroleum Inc | Denver, CO 80202 | Oil & Gas Operator | Sep 2025 |
| 354 | Tripower Resources LLC | Ardmore, OK 73402 | Oil & Gas Operator | Sep 2026 |
| 355 | Tristar Energy Corporation | Casper, WY 82602 | Oil & Gas Operator | Dec 2007 |
| 356 | Trout Kye Jr | | Oil & Gas Operator | Dec 2010 |
| 357 | True Oil LLC | Casper, WY 82602 | Oil & Gas Operator | Jul 2026 |
| 358 | Twin Arrow Inc | Rangely, CO 81648 | Oil & Gas Operator | Sep 2009 |
| 359 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 360 | U V Industries | | Oil & Gas Operator | Jan 1993 |
| 361 | Underwood Oil & Gas | Casper, WY 82602 | Oil & Gas Operator | Jul 2026 |
| 362 | Universal Fuels Company | | Oil & Gas Operator | Oct 1993 |
| 363 | Updike Resources Inc | Newcastle, WY 82701 | Oil & Gas Operator | Jun 1998 |
| 364 | Us Energy Corp. | Houston, TX 77057 | Oil & Gas Operator | Dec 2021 |
| 365 | USA Exploration & Production LLC | Mills, WY 82644 | Oil & Gas Operator | Sep 2012 |
| 366 | V A Resources LLC | Casper, WY 82601 | Oil Operator | Apr 2016 |
| 367 | Valkyrie Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Jul 2026 |
| 368 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | May 2026 |
| 369 | Vicorp Energy Inc | Denver, CO 80202-4927 | Oil & Gas Operator | Mar 2001 |
| 370 | Vortex Petroleum Inc | Centennial, CO 80111 | Oil Operator | Jan 2026 |
| 371 | Wave Petroleum Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Jul 2026 |
| 372 | Wellstar Corporation | Northglenn, CO 80233 | Oil & Gas Operator | Jul 2026 |
| 373 | Wessely Energy Corporation | | Oil & Gas Operator | Feb 1989 |
| 374 | Western American Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2024 |
| 375 | Western Interior Energy Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2016 |
| 376 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 377 | Weststar Oil & Gas Inc | Edmond, OK 73013 | Oil & Gas Operator | Jul 2026 |
| 378 | Wexpro Company | Rock Springs, WY 82902-0458 | Oil & Gas Operator | Jun 2026 |
| 379 | White Rock Oil & Gas, LLC | Plano, TX 75024 | Oil & Gas Operator | Sep 2026 |
| 380 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 381 | Wichita River Oil Corporation | Englewood, CO 80111 | Oil & Gas Operator | Apr 2009 |
| 382 | Wildfire Partners Inc | Ardmore, OK 73402 | Oil & Gas Operator | Dec 2009 |
| 383 | Winco Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Dec 1997 |
| 384 | Windsor Energy Group LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Aug 2021 |
| 385 | Wold Energy Partners LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2022 |
| 386 | Wold Oil Properties Inc | Denver, CO 80203 | Oil & Gas Operator | Feb 2018 |
| 387 | Woods Petroleum Corporation | Oklahoma City, OK 73112 | Oil & Gas Operator | Mar 2015 |
| 388 | WPX Energy Rocky Mountain LLC | Tulsa, OK 74101 | Oil & Gas Operator | May 2026 |
| 389 | WRC Energy LLC | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2026 |
| 390 | Wyoil Corp | Buffalo, WY 82834 | Oil Operator | Aug 2025 |
| 391 | Wyoming Mineral Exploration LLC | Casper, WY 82602 | Oil Operator | Dec 2006 |
| 392 | Wyoming Oil & Minerals Inc | Casper, WY 82601 | Oil & Gas Operator | Jun 2001 |
| 393 | Xoil Inc | Aurora, CO 80016 | Oil & Gas Operator | Jul 2023 |
| 394 | XPR Wyoming LLC | | Oil & Gas Operator | Jun 2026 |