| 501 | Stratagas, Inc. | Rowlett, TX 75088 | Oil & Gas Operator | May 2006 |
| 502 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | Apr 2026 |
| 503 | Strickland, H.W. | Henrietta, TX 76365 | Oil & Gas Operator | Dec 1999 |
| 504 | Stroud Energy, LTD. | Fort Worth, TX 76102 | Oil & Gas Operator | Jun 2006 |
| 505 | Suborp Energy, Inc. | Dallas, TX 75204 | Oil & Gas Operator | Sep 2000 |
| 506 | Sullivan, Hollis R. Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2009 |
| 507 | Sundance Resources, Inc. | Rio VIsta, TX 76093 | Oil & Gas Operator | Mar 2012 |
| 508 | Sunrise Enterprises | Bowie, TX 76230 | Oil & Gas Operator | Dec 2016 |
| 509 | Supreme Energy Company, Inc. | Abilene, TX 79601 | Oil & Gas Operator | Apr 2026 |
| 510 | Swan PC, LP | Jacksboro, TX 76458 | Oil & Gas Operator | Apr 2026 |
| 511 | Swan Production Co. | Jacksboro, TX 76458 | Oil & Gas Operator | Nov 2009 |
| 512 | Talon Oil & Gas LLC | Dallas, TX 75243 | Oil & Gas Operator | Dec 2010 |
| 513 | Talus Inc | Graham, TX 76450-1210 | Oil & Gas Operator | Feb 2017 |
| 514 | Targa Midstream Services LLC | Houston, TX 77002 | Oil Operator | Mar 2023 |
| 515 | Targo Oil & Gas, Inc. | Abilene, TX 79608 | Oil & Gas Operator | Apr 2026 |
| 516 | Tarpon Oil & Gas Co. | Fort Worth, TX 76147 | Oil & Gas Operator | Apr 2026 |
| 517 | Tarpon Oil Company | Fort Worth, TX 76107 | Oil & Gas Operator | Jun 2016 |
| 518 | Taubert & Steed | Wichita Falls, TX 76301 | Oil & Gas Operator | Aug 2001 |
| 519 | Taylor, Ben J. Inc. | Fort Worth, TX 76185 | Oil & Gas Operator | Feb 2022 |
| 520 | Taylor, G. E. | Bridgeport, TX 76426 | Oil & Gas Operator | Jan 2001 |
| 521 | Taylor, G. E. Inc. | Bridgeport, TX 76426 | Oil & Gas Operator | Jul 2007 |
| 522 | TC Oil And Gas, LLC | Denton, TX 76205 | Oil Operator | Apr 2026 |
| 523 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | Apr 2026 |
| 524 | Tech Resources, Inc. | Georgetown, TX 78628 | Oil & Gas Operator | Dec 2001 |
| 525 | Tejas Western Corp. | Granbury, TX 76048 | Oil & Gas Operator | Jul 2018 |
| 526 | Teleo Operating, LLC | Dallas, TX 75219 | Oil & Gas Operator | Apr 2009 |
| 527 | Telesis Operating Co. | Fort Worth, TX 76116 | Oil & Gas Operator | Apr 2026 |
| 528 | Tema Oil And Gas Company | Houston, TX 77084 | Oil & Gas Operator | Apr 2026 |
| 529 | Texaco E & P Inc. | Houston, TX 77099 | Oil & Gas Operator | Apr 2026 |
| 530 | Texakoma E & P, LLC | Plano, TX 75024 | Oil & Gas Operator | Apr 2026 |
| 531 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 532 | Texakoma Operating, L.P. | Plano, TX 75024 | Oil & Gas Operator | Mar 2025 |
| 533 | Texas American Resources Company | Austin, TX 78701 | Oil & Gas Operator | Apr 2026 |
| 534 | Texas Exploration & Prod. Co. | Gainesville, TX 76240 | Oil & Gas Operator | Apr 1996 |
| 535 | Texland Petroleum, L.P. | Fort Worth, TX 76107 | Oil & Gas Operator | Apr 2026 |
| 536 | Texoma Oil Tools, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Apr 2026 |
| 537 | Texu Inc. | Bridgeport, TX 76426 | Oil & Gas Operator | Jan 2007 |
| 538 | Texxol Operating Company, Inc. | Fort Worth, TX 76108 | Oil & Gas Operator | Apr 2026 |
| 539 | Theisen, VIncent A. | Wilmington, DE 19807 | Oil & Gas Operator | Sep 2003 |
| 540 | Threshold Development Company | Fort Worth, TX 76109 | Oil & Gas Operator | Aug 2016 |
| 541 | Torch Operating LLC | Fort Worth, TX 76135 | Oil & Gas Operator | Oct 2020 |
| 542 | Trace Energy Management Inc | Weatherford, TX 76086 | Oil & Gas Operator | Apr 2026 |
| 543 | Trans-Texas Energy Group LLC | Mineral Wells, TX 76068 | Oil & Gas Operator | Jul 2015 |
| 544 | Tree Operating, LLC | Graham, TX 76450 | Oil & Gas Operator | Apr 2026 |
| 545 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Apr 2026 |
| 546 | Trinity River Energy Oper, LLC | Houston, TX 77008 | Oil & Gas Operator | May 2018 |
| 547 | Trio Consulting & Management,LLC | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2026 |
| 548 | Trio Operating Company, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2006 |
| 549 | TS Oil, LLC | River Oaks, TX 76114 | Oil & Gas Operator | Apr 2026 |
| 550 | U. S. Operating, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Jul 2025 |
| 551 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 552 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 553 | Upham Oil & Gas Company | Mineral Wells, TX 76068 | Oil & Gas Operator | Apr 2026 |
| 554 | Upham, Chester R., Jr. | Mineral Wells, TX 76067 | Oil & Gas Operator | Aug 2001 |
| 555 | Upland Operating, LLC | Dallas, TX 75226 | Oil & Gas Operator | Apr 2026 |
| 556 | Upland Resources LLC | Canadian, TX 79014 | Oil & Gas Operator | Apr 2026 |
| 557 | Upp Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2026 |
| 558 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Apr 2026 |
| 559 | Van Operating, LTD. | Albany, TX 76430 | Oil & Gas Operator | Apr 2026 |
| 560 | Vantage Fort Worth Energy LLC | Pittsburgh, PA 15222 | Oil & Gas Operator | Apr 2026 |
| 561 | Viejo Services, LLC | Boyd, TX 76023 | Oil & Gas Operator | Apr 2026 |
| 562 | Waggoner, John S. | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2017 |
| 563 | Waggoner, W. T., Estate | Vernon, TX 76385 | Oil & Gas Operator | Feb 2018 |
| 564 | Waggoner-Baldridge Oper. Co, Inc | Dallas, TX 75206 | Oil & Gas Operator | Jan 1998 |
| 565 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 566 | Walsh & Watts Inc | Aledo, TX 76008 | Oil & Gas Operator | Apr 2026 |
| 567 | Walsh, F H Jr. Operating Co. Inc | Fort Worth, TX 76102 | Oil & Gas Operator | Oct 2019 |
| 568 | Walter Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | May 2009 |
| 569 | Watco Energy | Jacksboro, TX 76458 | Oil & Gas Operator | Apr 2026 |
| 570 | Waymar Oil & Gas Company | Texarkana, TX 75503 | Oil & Gas Operator | Jan 2007 |
| 571 | Wells Oilfield Services, Inc. | Graham, TX 76450 | Oil & Gas Operator | Apr 2026 |
| 572 | Wellstar Corporation | Northglenn, CO 80233 | Oil & Gas Operator | Feb 2026 |
| 573 | Wes-Mor Drilling, Inc. | Graham, TX 76450 | Oil & Gas Operator | Apr 2026 |
| 574 | Westerly Exploration, Inc. | Houston, TX 77256 | Oil & Gas Operator | Apr 2026 |
| 575 | Western Chief Oil & Gas Company | Graham, TX 76450 | Oil & Gas Operator | Jul 2009 |
| 576 | Western Chief Operating, L.L.C. | Graham, TX 76450 | Oil & Gas Operator | Apr 2026 |
| 577 | Western Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2026 |
| 578 | Westridge Oil & Gas Properties | Mineral Wells, TX 76068 | Oil & Gas Operator | Apr 2026 |
| 579 | Westside Energy Op. Co., LP | Oklahoma City, OK 73142 | Oil & Gas Operator | Jun 2008 |
| 580 | WG Operating, Inc. | Tulsa, OK 74153 | Oil & Gas Operator | May 2012 |
| 581 | Whiskey River Oil & Gas LLC | Dallas, TX 75230 | Oil & Gas Operator | Apr 2024 |
| 582 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Apr 2026 |
| 583 | Williams Petroleum Company, Inc. | Burkburnett, TX 76354 | Oil & Gas Operator | Apr 2026 |
| 584 | Williams Prod. Gulf Coast, L.P. | Benbrook, TX 76126 | Oil & Gas Operator | Jan 2012 |
| 585 | Willowbend Investments, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2026 |
| 586 | Wilson, Don H., Inc. | Elkhart, TX 75839 | Oil & Gas Operator | May 2019 |
| 587 | Winchester Energy, LLC | Houston, TX 77056 | Oil & Gas Operator | Apr 2026 |
| 588 | Winchester Exploration, Inc. | Arlington, TX 76013 | Oil & Gas Operator | Aug 2003 |
| 589 | Winchester Oil & Gas LLC | Rockdale, TX 76567 | Oil Operator | Apr 2026 |
| 590 | Winchester Production Company | Shreveport, LA 71129 | Oil & Gas Operator | Nov 2008 |
| 591 | Window Operating Co., The | Coleman, TX 76834 | Oil & Gas Operator | Apr 2026 |
| 592 | Winfield Operating Company | Dallas, TX 75214 | Oil & Gas Operator | Apr 2026 |
| 593 | Wise Exploration | Perrin, TX 76486 | Oil & Gas Operator | Apr 2026 |
| 594 | Wise Production Company | Bowie, TX 76230 | Oil & Gas Operator | Apr 2026 |
| 595 | Wise Supply Company | Bowie, TX 76230 | Oil & Gas Operator | Apr 2026 |
| 596 | Wise Well Service | Bowie, TX 76230 | Oil & Gas Operator | Jul 2017 |
| 597 | Wolfson Oil Co. | Dallas, TX 75230 | Oil & Gas Operator | Sep 1999 |
| 598 | Wolsey Oil Inc. | Bowie, TX 76230 | Oil & Gas Operator | Oct 2013 |
| 599 | Wolsey Well Service, Inc. | Windthorst, TX 76389 | Oil & Gas Operator | Jul 2006 |
| 600 | Wolsey Well Service, L.P. | Bowie, TX 76230 | Oil & Gas Operator | Jun 2014 |