| 501 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 502 | TR Offshore, LLC | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Apr 2024 |
| 503 | Trans-Pecos Resources, Inc. | Houston, TX 77056 | Oil & Gas Operator | Apr 2024 |
| 504 | Traton Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Mar 2019 |
| 505 | Tri-C Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Aug 2009 |
| 506 | Triple L Oil Company | Corpus Chrsti, TX 78469 | Oil & Gas Operator | Jan 1998 |
| 507 | Truth Resources LP | Conroe, TX 77304 | Oil Operator | Sep 2021 |
| 508 | Tschoepe, Arthur J. | Leakey, TX 78873 | Oil & Gas Operator | Jun 2001 |
| 509 | Tucker Operating Co., Inc. | Victoria, TX 77903 | Oil & Gas Operator | Apr 2024 |
| 510 | Tuthill & Barbee | Amarillo, TX 79101 | Oil & Gas Operator | Nov 1994 |
| 511 | TX Petroleum Company | Corpus Chrsti, TX 78412 | Oil & Gas Operator | Apr 1996 |
| 512 | Txco Resources Inc. | San Antonio, TX 78280 | Oil & Gas Operator | Apr 2024 |
| 513 | Txla Energy, Inc. | Houston, TX 77018 | Oil & Gas Operator | Apr 2024 |
| 514 | Ultra Oil & Gas, Inc. | Centerton, AR 72719 | Oil & Gas Operator | Apr 2024 |
| 515 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 516 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 517 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 518 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 519 | Universal Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2002 |
| 520 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Apr 2024 |
| 521 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Apr 2024 |
| 522 | Valerius, Inc. & Zine, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Jul 1994 |
| 523 | Valerius, Robert D. Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Aug 2003 |
| 524 | Van Oil Co Inc | Fort Worth, TX 76102 | Oil Operator | Dec 1997 |
| 525 | Vanguard Permian LLC | Houston, TX 77057 | Oil & Gas Operator | Nov 2018 |
| 526 | Vantage Operating, LLC | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2024 |
| 527 | Vector Energy Corporation | Houston, TX 77060 | Oil & Gas Operator | Apr 2024 |
| 528 | Ventex Operating Corp. | Addison, TX 75001 | Oil & Gas Operator | Apr 2024 |
| 529 | Venus Oil Company | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2002 |
| 530 | Victoria Operating, Inc. | Victoria, TX 77903 | Oil & Gas Operator | Apr 2024 |
| 531 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Jan 2024 |
| 532 | Viper S.W.D., LLC | El Campo, TX 77437 | Oil & Gas Operator | Apr 2024 |
| 533 | Virtex Operating Company, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2023 |
| 534 | Virtex Petroleum Company, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Jan 2008 |
| 535 | Vision Oil And Gas LLC | Laredo, TX 78041 | Oil & Gas Operator | Apr 2024 |
| 536 | Vtex Energy, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2024 |
| 537 | Wadi Operating, LLC | Houston, TX 77079 | Oil & Gas Operator | Apr 2024 |
| 538 | Wadi Petroleum Inc | Houston, TX 77014 | Oil & Gas Operator | May 2018 |
| 539 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2024 |
| 540 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 541 | Wallis Energy, Inc. | Austin, TX 78746 | Oil & Gas Operator | Apr 2024 |
| 542 | Walter Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 543 | Warren American Oil Co | Tulsa, OK 74147 | Oil & Gas Operator | Feb 2024 |
| 544 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 545 | Welder Exploration & Prod., Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Dec 2022 |
| 546 | Western Gulf Oil & Gas Inc. | Dallas, TX 75360 | Oil & Gas Operator | Jul 2000 |
| 547 | Western Gulf Oil & Gas, LLC | Bishop, TX 78343 | Oil & Gas Operator | Apr 2024 |
| 548 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 549 | White Marlin Operating Company, LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 550 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Apr 2024 |
| 551 | Whitehead Prod. Co., Inc. | Humble, TX 77338 | Oil & Gas Operator | Jan 2024 |
| 552 | Whitfield Energy | Midland, TX 79702 | Oil & Gas Operator | Jan 1999 |
| 553 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 554 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Feb 2024 |
| 555 | Whittington Operating Company | Houston, TX 77069 | Oil & Gas Operator | Apr 2024 |
| 556 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Apr 2024 |
| 557 | Wilson Hydrocarbon Inc. | Houston, TX 77066 | Oil & Gas Operator | Apr 2024 |
| 558 | Winn Exploration Co., Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2024 |
| 559 | Wood Energy Corporation | Baytown, TX 77520 | Oil & Gas Operator | Jun 1999 |
| 560 | WRT Energy Corporation | Oklahoma City, OK 73118 | Oil & Gas Operator | May 1998 |
| 561 | Wynn-Crosby Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2005 |
| 562 | Wynne Petroleum Co. | Fort Worth, TX 76116 | Oil & Gas Operator | Nov 1997 |
| 563 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 564 | Xog Operating LLC | Midland, TX 79702 | Oil & Gas Operator | Apr 2024 |
| 565 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2024 |