| 501 | Stone, J. G. Oil Co. | Victoria, TX 77904 | Oil & Gas Operator | Sep 2018 |
| 502 | Strata Operating, Inc. | Corpus Chrsti, TX 78466 | Oil & Gas Operator | Apr 2024 |
| 503 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | Apr 2024 |
| 504 | Sue-Ann Operating, L.C. | Victoria, TX 77903 | Oil & Gas Operator | Apr 2024 |
| 505 | Sue-Ann Production Company | Victoria, TX 77903 | Oil & Gas Operator | Mar 2008 |
| 506 | Suemaur Expl. & Prod., LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2024 |
| 507 | Suemaur Exploration, Inc. | Corpus Chrsti, TX 78470 | Oil & Gas Operator | Mar 2008 |
| 508 | Suncoast Technical Services Inc | Dallas, TX 75251 | Oil & Gas Operator | Apr 2024 |
| 509 | Sundown Energy LP | Dallas, TX 75248 | Oil & Gas Operator | Apr 2024 |
| 510 | Sundown Energy, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Dec 2023 |
| 511 | Sure Flow Oil & Gas Company | Victoria, TX 77902 | Oil & Gas Operator | Mar 2008 |
| 512 | Sure Flow Oil & Gas, Inc. | Victoria, TX 77902 | Oil & Gas Operator | Apr 2024 |
| 513 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 514 | Swope Corp. | Austin, TX 78735 | Oil & Gas Operator | Apr 2024 |
| 515 | Sydri Operating, LLC | Dallas, TX 75231 | Oil & Gas Operator | Apr 2024 |
| 516 | T & T Production Co. | Victoria, TX 77902 | Oil & Gas Operator | Feb 1995 |
| 517 | T - C Oil Company | Refugio, TX 78377 | Oil & Gas Operator | Jan 2012 |
| 518 | T-C Oil Company, LLC | Refugio, TX 78377 | Oil & Gas Operator | Apr 2024 |
| 519 | Talon Development Company | Boerne, TX 78006 | Oil & Gas Operator | Sep 2007 |
| 520 | Taos Resources Operating Co LLC | Houston, TX 77037 | Oil & Gas Operator | Dec 2019 |
| 521 | TBC Petroleum | Cuero, TX 77954 | Oil & Gas Operator | Sep 2023 |
| 522 | Team Operating, L.L.C. | Pinehurst, TX 77362 | Oil & Gas Operator | Apr 2024 |
| 523 | Tejas Operating LLC | Houston, TX 77056 | Oil & Gas Operator | Apr 2024 |
| 524 | Tepee Petroleum Company, Inc. | Houston, TX 77098 | Oil & Gas Operator | Feb 2014 |
| 525 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Apr 2024 |
| 526 | Texas Fuel Company | Galveston, TX 77550 | Oil & Gas Operator | Apr 2024 |
| 527 | Texcal Energy (GP) LLC | Denver, CO 80202 | Oil & Gas Operator | Mar 2016 |
| 528 | Texlan Oil Company, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Nov 1994 |
| 529 | Texstar North America, Inc. | Waynesboro, MS 39367 | Oil & Gas Operator | Aug 1994 |
| 530 | Three Mile Joint Venture | Houston, TX 77027 | Oil & Gas Operator | Jul 1995 |
| 531 | Thunderbird Energy, Inc. | Norman, OK 73069 | Oil & Gas Operator | Apr 2024 |
| 532 | Tidal Petroleum, Inc. | Schertz, TX 78154 | Oil & Gas Operator | Apr 2024 |
| 533 | Tidemark Petroleum, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2002 |
| 534 | Tiger Resources, L.L.C. | Houston, TX 77070 | Oil & Gas Operator | Feb 2004 |
| 535 | Titan Resources I, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2000 |
| 536 | Top Op, L.L.C. | Houston, TX 77077 | Oil & Gas Operator | May 2020 |
| 537 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 538 | Trans-Pecos Resources, Inc. | Houston, TX 77056 | Oil & Gas Operator | Apr 2024 |
| 539 | Transtexas Gas Corporation | Houston, TX 77265 | Oil & Gas Operator | Aug 2005 |
| 540 | Tri-C Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Aug 2009 |
| 541 | Tri-C Resources, LLC | Houston, TX 77024 | Oil & Gas Operator | Apr 2024 |
| 542 | Tri-Union Development Corp. | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 543 | Triad Energy Corporation | Houston, TX 77057 | Oil & Gas Operator | Oct 2011 |
| 544 | Triangle Three Resources L.L.C. | Dallas, TX 75240 | Oil & Gas Operator | Apr 2024 |
| 545 | Trident Corporation | Woodsboro, TX 78393 | Oil & Gas Operator | Apr 2024 |
| 546 | Trinity Resources, Inc. | Houston, TX 77277 | Oil & Gas Operator | May 2020 |
| 547 | Triple L Oil Company | Corpus Chrsti, TX 78469 | Oil & Gas Operator | Jan 1998 |
| 548 | Triton Oil & Gas Corp. | Houston, TX 77002 | Oil & Gas Operator | Nov 2014 |
| 549 | Truth Resources LP | Conroe, TX 77304 | Oil Operator | Sep 2021 |
| 550 | Tschoepe, Arthur J. | Leakey, TX 78873 | Oil & Gas Operator | Jun 2001 |
| 551 | TT Operating, LLC | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2024 |
| 552 | Tucker Operating Co., Inc. | Victoria, TX 77903 | Oil & Gas Operator | Apr 2024 |
| 553 | TX Petroleum Company | Corpus Chrsti, TX 78412 | Oil & Gas Operator | Apr 1996 |
| 554 | Ultra Oil & Gas, Inc. | Centerton, AR 72719 | Oil & Gas Operator | Apr 2024 |
| 555 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 556 | Unicorn Energy, Inc. | Elgin, TX 78621 | Oil & Gas Operator | Apr 2024 |
| 557 | Union Crude Company | Baytown, TX 77521 | Oil & Gas Operator | Apr 2018 |
| 558 | Union Gas Operating Company | Houston, TX 77014 | Oil & Gas Operator | Apr 2024 |
| 559 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 560 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2024 |
| 561 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 562 | United Operating, LLC *** | Midland, TX 79710 | Oil & Gas Operator | Apr 2024 |
| 563 | Unoso Operating Company L.L.C. | Georgetown, TX 78633 | Oil & Gas Operator | Apr 2024 |
| 564 | Upda Operators, Inc. | Jacksboro, TX 76458 | Oil & Gas Operator | Dec 2009 |
| 565 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Apr 2024 |
| 566 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Apr 2024 |
| 567 | Valerius, Inc. & Zine, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Jul 1994 |
| 568 | Valerius, Robert D. Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Aug 2003 |
| 569 | Valley Gathering Company | Midland, TX 79702 | Oil & Gas Operator | Feb 1997 |
| 570 | Vantage Operating, LLC | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2024 |
| 571 | Venus Oil Company | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2002 |
| 572 | Verus Energy, Inc | Houston, TX 77098 | Oil & Gas Operator | Sep 2004 |
| 573 | Victoria Operating, Inc. | Victoria, TX 77903 | Oil & Gas Operator | Apr 2024 |
| 574 | Viola Production Inc | Dallas, TX 75251 | Oil & Gas Operator | Apr 2024 |
| 575 | Viper S.W.D., LLC | El Campo, TX 77437 | Oil & Gas Operator | Apr 2024 |
| 576 | Virtex Petroleum Company, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Jan 2008 |
| 577 | Wadi Petroleum Inc | Houston, TX 77014 | Oil & Gas Operator | May 2018 |
| 578 | Waelder Oil & Gas, Inc. | Fort Smith, AR 72903 | Oil & Gas Operator | Jan 2024 |
| 579 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 580 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 581 | Wallis Energy, Inc. | Austin, TX 78746 | Oil & Gas Operator | Apr 2024 |
| 582 | Walter Exploration Company | Dallas, TX 75206 | Oil & Gas Operator | Apr 2024 |
| 583 | Walter Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | May 2009 |
| 584 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 585 | Weibye, Carolyn S. | Houston, TX 77098 | Oil & Gas Operator | Apr 2024 |
| 586 | Welder Operating, Inc. | San Antonio, TX 78205 | Oil & Gas Operator | Mar 2001 |
| 587 | Welder-Heyer Energy, Inc. | San Antonio, TX 78205 | Oil & Gas Operator | Feb 2001 |
| 588 | West Petroleum Corp. | San Antonio, TX 78205 | Oil & Gas Operator | Oct 2009 |
| 589 | Western Gulf Oil & Gas Inc. | Dallas, TX 75360 | Oil & Gas Operator | Jul 2000 |
| 590 | Westhall Associates, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Aug 1997 |
| 591 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 592 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 593 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Apr 2024 |
| 594 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 595 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Feb 2024 |
| 596 | Wilcox Operating Corporation | Shreveport, LA 71115 | Oil & Gas Operator | Apr 2024 |
| 597 | Wild Cat Operating Company | Victoria, TX 77903 | Oil & Gas Operator | Mar 2008 |
| 598 | Williams-Cody, Inc. | Houston, TX 77060 | Oil & Gas Operator | May 1994 |
| 599 | Williamson Oil & Gas, Inc. | Shreveport, LA 71166 | Oil & Gas Operator | Dec 2023 |
| 600 | Wilson Hydrocarbon Inc. | Houston, TX 77066 | Oil & Gas Operator | Apr 2024 |