| 301 | Pure Petroleum LLC | Gillette, WY 82717 | Oil & Gas Operator | Aug 2011 |
| 302 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Apr 2025 |
| 303 | Quinoco Petroleum Inc | | Oil & Gas Operator | Dec 1990 |
| 304 | Ranch Oil Company | West Linn, OR 97068 | Oil & Gas Operator | Jun 2025 |
| 305 | Rathbun Roger | | Oil & Gas Operator | Dec 1993 |
| 306 | Rathpro Inc | Douglas, WY 82633 | Oil & Gas Operator | Feb 1994 |
| 307 | RB Operating Company | Shawnee, OK 74802-1488 | Oil & Gas Operator | Apr 2015 |
| 308 | Reading & Bates Petroleum | | Oil & Gas Operator | Apr 1989 |
| 309 | Remuda Energy Development LLC | Billings, MT 59104 | Oil & Gas Operator | May 2025 |
| 310 | Renos Land & Minerals Company | Casper, WY 82601 | Oil & Gas Operator | Oct 2021 |
| 311 | Resources Investment Corp | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 312 | Reunion Energy Company | Houston, TX 77056 | Oil & Gas Operator | May 1996 |
| 313 | Richardson Operating Company | Denver, CO 80237 | Oil & Gas Operator | Jun 2025 |
| 314 | Rim Operating, Inc. | Englewood, CO 80112 | Oil & Gas Operator | Jul 2025 |
| 315 | Rki Exploration & Production LLC | Tulsa, OK 74172 | Oil & Gas Operator | Jul 2025 |
| 316 | Rme Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Nov 2016 |
| 317 | Robert Hawkins Inc | Kevin, MT 59454 | Oil & Gas Operator | May 2025 |
| 318 | Rochelle Oil & Gas | Gillette, WY 82717 | Oil & Gas Operator | Mar 2024 |
| 319 | Rockies Resources Holdings LLC | Lakewood, CO 80228 | Oil & Gas Operator | May 2025 |
| 320 | Rocky Mountain Gas Inc | Sheridan, WY 82801 | Gas Operator | Nov 2009 |
| 321 | Rosa Petroleum | Evansville, WY 82636 | Oil Operator | Dec 1995 |
| 322 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 323 | Sage Butte PRB Operating, LLC | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 324 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 325 | Samson Resources Company LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2021 |
| 326 | Sauer Bill Oil & Gas Company LLC | Casper, WY 82604 | Oil & Gas Operator | Jun 1999 |
| 327 | Sceptre Resources Inc | | Oil & Gas Operator | Dec 2007 |
| 328 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 329 | Sgcu GP LLC | Casper, WY 82602 | Oil Operator | May 2025 |
| 330 | Shenandoah Oil Corporation | | Oil & Gas Operator | Jun 1979 |
| 331 | Sierra Trading Corporation | | Oil & Gas Operator | Sep 1978 |
| 332 | Skinner'S Resources & Expl Inc | | Oil & Gas Operator | Jun 2007 |
| 333 | Skull Creek A LLC | Douglas, WY 82633 | Oil & Gas Operator | Apr 2025 |
| 334 | Skyline Oil Company | Salt Lake City, UT 84111 | Oil & Gas Operator | Jan 1987 |
| 335 | Slaughter J M Oil Company | Fort Worth, TX 76116 | Oil & Gas Operator | Jan 2001 |
| 336 | Slawson Exploration Company Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Jul 2025 |
| 337 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Jul 2025 |
| 338 | Snowy Owl LLC | Gillette, WY 82717 | Oil & Gas Operator | May 2025 |
| 339 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 340 | Sonat Exploration Co. | Houston, TX 77251 | Oil & Gas Operator | Dec 2021 |
| 341 | South Coast Oil Corporation | Boulder, CO 80302 | Oil & Gas Operator | Oct 2015 |
| 342 | Southern Mineral Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2001 |
| 343 | Southern Union Exploration | | Oil Operator | Jan 1990 |
| 344 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 345 | Southport Exploration Inc | Tulsa, OK 74103-4015 | Oil & Gas Operator | Nov 1998 |
| 346 | Southwestern Production Corporation | Lakewood, CO 80228 | Oil & Gas Operator | Jun 2025 |
| 347 | Spirit Energy Inc | Edmond, OK 73034 | Oil & Gas Operator | Apr 1999 |
| 348 | St Michael Exploration | | Oil & Gas Operator | Jun 1987 |
| 349 | St. Mary Operating Company | Denver, CO 80203 | Oil & Gas Operator | Mar 2019 |
| 350 | Sterling Energy Corporation | Denver, CO 80202 | Oil & Gas Operator | Sep 1995 |
| 351 | Stone Energy Corporation | Denver, CO 80202-2828 | Oil & Gas Operator | Oct 2014 |
| 352 | Stone Energy LLC | Denver, CO 80202 | Oil & Gas Operator | May 2005 |
| 353 | Sunshine Valley Petroleum | Casper, WY 82605 | Oil & Gas Operator | May 2025 |
| 354 | T-Rex Oil Inc | Broomfield, CO 80021 | Oil Operator | Feb 2011 |
| 355 | T2 Operating Corporation | Denver, CO 80202 | Oil & Gas Operator | Jul 2025 |
| 356 | Target Oil Company | | Oil & Gas Operator | Mar 2007 |
| 357 | Tbi Exploration Inc | Englewood, CO 801556525 | Oil & Gas Operator | Jun 2011 |
| 358 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Apr 2025 |
| 359 | Terex Energy Corporation | Casper, WY 82602 | Oil & Gas Operator | Aug 2019 |
| 360 | Terrapet Corporation | | Oil & Gas Operator | Jun 2011 |
| 361 | Texaco Exploration & Prod | Midland, TX 79702 | Oil & Gas Operator | Aug 2002 |
| 362 | The Brinkerhoff Company | Denver, CO 80202 | Oil & Gas Operator | Dec 2017 |
| 363 | Thomas Operating Company Inc | Greeley, CO 80634 | Oil & Gas Operator | Aug 2008 |
| 364 | Three Forks Resources LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | Jul 2025 |
| 365 | Tiger Oil Company | Dallas, TX 75221 | Oil & Gas Operator | May 2007 |
| 366 | Timberline Production Company LLC | Casper, WY 82601 | Oil & Gas Operator | Oct 2020 |
| 367 | Titan Exploration LLC | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 368 | Torch E & P Company | Houston, TX 77010 | Oil & Gas Operator | Jan 2015 |
| 369 | Torch Oil & Gas Company | Houston, TX 77010 | Oil & Gas Operator | Aug 1997 |
| 370 | Transco Exploration Company | | Oil & Gas Operator | Jul 1989 |
| 371 | Transworld Systems Petroleum Inc | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 372 | Tripower Resources LLC | Ardmore, OK 73402 | Oil & Gas Operator | Jul 2025 |
| 373 | Tristar Energy Corporation | Casper, WY 82602 | Oil & Gas Operator | Dec 2007 |
| 374 | Trout Kye Jr | | Oil & Gas Operator | Dec 2010 |
| 375 | True Oil LLC | Casper, WY 82602 | Oil & Gas Operator | Jun 2025 |
| 376 | Twin Arrow Inc | Rangely, CO 81648 | Oil & Gas Operator | Sep 2009 |
| 377 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 378 | U V Industries | | Oil & Gas Operator | Jan 1993 |
| 379 | Underwood Oil & Gas | Casper, WY 82602 | Oil & Gas Operator | Jun 2025 |
| 380 | Universal Fuels Company | | Oil & Gas Operator | Oct 1993 |
| 381 | Updike Resources Inc | Newcastle, WY 82701 | Oil & Gas Operator | Jun 1998 |
| 382 | Us Energy Corp. | Houston, TX 77057 | Oil & Gas Operator | Dec 2021 |
| 383 | USA Exploration & Production LLC | Mills, WY 82644 | Oil & Gas Operator | Sep 2012 |
| 384 | V A Resources LLC | Casper, WY 82601 | Oil Operator | Apr 2016 |
| 385 | Valkyrie Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2025 |
| 386 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Mar 2025 |
| 387 | Vicorp Energy Inc | Denver, CO 80202-4927 | Oil & Gas Operator | Mar 2001 |
| 388 | Vortex Petroleum Inc | Centennial, CO 80111 | Oil Operator | Apr 2025 |
| 389 | Wave Petroleum Operating LLC | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 390 | Wellstar Corporation | Northglenn, CO 80233 | Oil & Gas Operator | May 2025 |
| 391 | Wessely Energy Corporation | | Oil & Gas Operator | Feb 1989 |
| 392 | Western American Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2024 |
| 393 | Western Interior Energy Inc. | Denver, CO 80202 | Oil & Gas Operator | Jul 2020 |
| 394 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 395 | Weststar Oil & Gas Inc | Edmond, OK 73013 | Oil & Gas Operator | May 2025 |
| 396 | Wexpro Company | Rock Springs, WY 82902-0458 | Oil & Gas Operator | May 2025 |
| 397 | White Rock Oil & Gas, LLC | Plano, TX 75024 | Oil & Gas Operator | Jul 2025 |
| 398 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 399 | Wichita River Oil Corporation | Englewood, CO 80111 | Oil & Gas Operator | Apr 2009 |
| 400 | Wildfire Partners Inc | Ardmore, OK 73402 | Oil & Gas Operator | Dec 2009 |