| 401 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 402 | Sinclair Oil & Gas Company | Salt Lake Cty, UT 84130 | Oil & Gas Operator | May 2025 |
| 403 | Slawson Exploration Company Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | May 2025 |
| 404 | Slohcin, Inc. | Shelby, MT 59474 | Oil Operator | Apr 2025 |
| 405 | Slow Poke Production-George L. Dobson Dba | Cut Bank, MT 59427 | Gas Operator | Mar 2025 |
| 406 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | May 2025 |
| 407 | Smith, Loren E. And Foster, Chas. P. | Broomfield, CO 80020 | Oil Operator | Mar 2025 |
| 408 | Soap Creek Associates, Inc. | Broomfield, CO 80020-2995 | Oil Operator | Mar 2025 |
| 409 | Solomon Exploration Inc. | Havre, MT 59501 | Gas Operator | Feb 2025 |
| 410 | Somont Oil Co., Inc. | Spring, TX 77379 | Oil & Gas Operator | Mar 2025 |
| 411 | Sonkar, Inc. | Sunburst, MT 59482 | Oil Operator | Apr 2025 |
| 412 | Southwestern Energy Prod Co | Houston, TX 77032 | Oil & Gas Operator | Jun 2015 |
| 413 | Spectrum Energy Inc | Scottsdale, AZ 85257 | Oil & Gas Operator | Oct 2003 |
| 414 | St. Mary Land & Exploration Co | Denver, CO 80201 | Oil & Gas Operator | Jun 2010 |
| 415 | Staghorn Energy, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2025 |
| 416 | Stalking Horse Energy, LLC | Denver, CO 80246 | Oil Operator | Mar 2025 |
| 417 | Stearns Oil Company LLC | Willison, ND 58801 | Oil & Gas Operator | Mar 2025 |
| 418 | Stephens & Johnson Operating Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2025 |
| 419 | Stephens, Autry C. | Midland, TX 79701 | Oil & Gas Operator | Mar 2023 |
| 420 | Stivers Inc | Graham, TX 76450 | Oil & Gas Operator | May 2003 |
| 421 | Stone Energy Corporation | Denver, CO 80202-2828 | Oil & Gas Operator | Oct 2014 |
| 422 | Stone Energy LLC | Denver, CO 80202 | Oil & Gas Operator | May 2005 |
| 423 | Storm Cat Energy USA Operating Corp | Denver, CO 80202 | Gas Operator | Jun 2017 |
| 424 | Stovall Oil Company | Casper, WY 82602 | Oil & Gas Operator | Aug 1998 |
| 425 | Stratex Oil And Gas, Inc. | Watertown, CT 06795 | Oil & Gas Operator | Jun 2016 |
| 426 | Striper Oil, Inc. | Dallas, TX 75379 | Oil & Gas Operator | Apr 2002 |
| 427 | Summit Gas Resources Inc | Sheridan, WY 82801 | Gas Operator | Dec 2023 |
| 428 | Summit Resources, Inc. | Houston, TX 77077 | Oil & Gas Operator | Sep 2016 |
| 429 | Sun Coulee, LLC | Martinsdale, MT 59053 | Oil Operator | Mar 2025 |
| 430 | Sunburst Exploration, Inc. | | Oil & Gas Operator | Jul 2000 |
| 431 | Swanson Oil & Gas LLC | Williston, ND 58802 | Oil Operator | Mar 2025 |
| 432 | Synergy Offshore LLC | Houston, TX 77024 | Oil & Gas Operator | Feb 2022 |
| 433 | T.W.O. (Taylor Well Operating) | Missoula, MT 59803 | Oil & Gas Operator | Mar 2025 |
| 434 | T2 Operating Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 435 | Tanglewood Oil & Gas LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Oct 2017 |
| 436 | Taqa USA, Inc. | Centennial, CO 80111 | Oil & Gas Operator | Jul 2020 |
| 437 | Targe Energy Exploration And Production, LLC | Denver, CO 80202 | Gas Operator | Oct 2013 |
| 438 | Tempel Contracting, Inc. | Joplin, MT 59531 | Gas Operator | Feb 2025 |
| 439 | Tensas Delta Expl Co., LLC | Shreveport, LA 71101-5323 | Oil & Gas Operator | Jul 2021 |
| 440 | Terrol Energy, Inc. | Hygiene, CO 80533 | Oil & Gas Operator | Dec 2006 |
| 441 | Texaco Expl. And Prod. Inc. | Houston, TX 77236 | Oil & Gas Operator | Mar 2025 |
| 442 | Texakoma Exploration & Production LLC | Plano, TX 75024 | Oil & Gas Operator | Mar 2025 |
| 443 | Thomas Operating Company Inc | Greeley, CO 80634 | Oil & Gas Operator | Aug 2008 |
| 444 | Thompson Oil Co. | Corsicana, TX 75151 | Oil & Gas Operator | Feb 2025 |
| 445 | Three Forks Resources LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | May 2025 |
| 446 | Tipperary Oil & Gas Corp | Denver, CO 80202 | Oil & Gas Operator | May 2014 |
| 447 | TMR Exploration, Inc. | Bossier City, LA 71171 | Oil & Gas Operator | May 2025 |
| 448 | TNT Oil, LLC | Conrad, MT 59425 | Oil Operator | Nov 2017 |
| 449 | Toi Operating | Sidney, MT 59270 | Oil Operator | Sep 2019 |
| 450 | Tomahawk Oil Company, Inc. | Roundup, MT 59072 | Oil Operator | Mar 2025 |
| 451 | Topaz Oil & Gas Inc | Fort Collins, CO 80627 | Gas Operator | Nov 2019 |
| 452 | Triangle USA Petroleum Corporation | Denver, CO 80202 | Oil & Gas Operator | Jul 2021 |
| 453 | Trout Kye Jr | | Oil & Gas Operator | Dec 2010 |
| 454 | True Oil LLC | Casper, WY 82602 | Oil & Gas Operator | Apr 2025 |
| 455 | Tyler Oil Company | Billings, MT 59104-3203 | Oil & Gas Operator | Nov 2019 |
| 456 | Tyler Rockies Exploration LTD | Tyler, TX 75710-0119 | Oil & Gas Operator | Mar 2025 |
| 457 | Tyrex Oil Company | Casper, WY 82602 | Oil & Gas Operator | May 1997 |
| 458 | U Bee Tea Production LLC | Culbertson, MT 59218 | Oil & Gas Operator | Mar 2025 |
| 459 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 460 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | May 2025 |
| 461 | United States Energy Corp. | Longview, TX 75601 | Oil & Gas Operator | Mar 2025 |
| 462 | Upton Resources U.S.A. Inc. | | Oil & Gas Operator | Oct 2013 |
| 463 | Ursa Major (Crow Og), LLC | Billings, MT 59101 | Gas Operator | Aug 2017 |
| 464 | Vaalco Energy (USA), Inc. | Houston, TX 77042 | Oil & Gas Operator | Dec 2016 |
| 465 | Vecta Oil & Gas LTD | Dallas, TX 75235 | Oil & Gas Operator | Mar 2025 |
| 466 | Vess Oil Corporation | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 467 | Vesta Inc | Great Falls, MT 59403 | Gas Operator | Mar 1997 |
| 468 | Viking Resources Corp | Deerfield, OH 44411-0160 | Oil & Gas Operator | Dec 2007 |
| 469 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Feb 2025 |
| 470 | Ward Petroleum Corporation | Enid, OK 73702 | Oil & Gas Operator | Feb 2025 |
| 471 | Wbi Energy Transmission, Inc. | Glendive, MT 59330-0131 | Gas Operator | Nov 1999 |
| 472 | Wbi Production, Inc. | Glendive, MT 59330-0131 | Gas Operator | Mar 2001 |
| 473 | Wesco Operating, Inc. | Casper, WY 82602 | Oil & Gas Operator | Mar 2025 |
| 474 | West Gas Inc | | Oil & Gas Operator | Dec 2017 |
| 475 | Westech Energy Corporation | Denver, CO 80237 | Oil & Gas Operator | Mar 2011 |
| 476 | Western Meadowlark Resources LLC | Denver, CO 80206 | Oil & Gas Operator | Mar 2025 |
| 477 | Western Natural Gas Company | Shelby, MT 59474 | Oil & Gas Operator | Feb 2025 |
| 478 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 479 | Wheless Industries, Inc. | Shreveport, LA 71101-5301 | Oil & Gas Operator | Sep 2002 |
| 480 | White Rock Oil & Gas, LLC | Plano, TX 75024 | Oil & Gas Operator | May 2025 |
| 481 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 482 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 483 | Williston Industrial Supply Corporation | Williston, ND 58801 | Oil & Gas Operator | Mar 2012 |
| 484 | Woods, Pete Or Maxine | Chester, MT 59522 | Oil & Gas Operator | Feb 2025 |
| 485 | Wyoming Resources Corporation | Rapid City, SD 57702 | Oil & Gas Operator | Oct 2018 |
| 486 | Xeno, Inc | Calgary, AB T2P 2S5 | Gas Operator | Dec 2001 |
| 487 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 488 | Xoil Inc | Aurora, CO 80016 | Oil & Gas Operator | Jul 2023 |
| 489 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 490 | Yellowstone Petroleums Inc. | Canada, 00100 | Oil & Gas Operator | Feb 2025 |
| 491 | Zenergy Operating Company, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Dec 2016 |
| 492 | Zimco (Robt A Zimmerman) | Wolf Point, MT 59201 | Oil Operator | Apr 2009 |