| 501 | Sun Exploration, Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2026 |
| 502 | SV Energy Company, LLC | Corpus Christ, TX 78401 | Oil & Gas Operator | Mar 2017 |
| 503 | SW Operating, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Sep 2000 |
| 504 | Sydson Energy, Inc. | Houston, TX 77019 | Oil & Gas Operator | Jul 2026 |
| 505 | Syj Oil & Gas, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2026 |
| 506 | T - C Oil Company | Refugio, TX 78377 | Oil & Gas Operator | Jan 2012 |
| 507 | T-C Oil Company, LLC | Refugio, TX 78377 | Oil & Gas Operator | Jul 2026 |
| 508 | T.D. Operating Company, Inc. | New Braunfels, TX 78130 | Oil & Gas Operator | Nov 1999 |
| 509 | Talisman Energy USA Inc. | The Woodlands, TX 77381 | Oil & Gas Operator | May 2016 |
| 510 | Talon Development Company | Boerne, TX 78006 | Oil & Gas Operator | Sep 2007 |
| 511 | Tare Resources, LLC | Corpus Chrsti, TX 78426 | Oil & Gas Operator | Jul 2026 |
| 512 | Tasca Exploration Company | Houston, TX 77257 | Oil & Gas Operator | Jun 2002 |
| 513 | TC Oil And Gas, LLC | Denton, TX 76205 | Oil Operator | Jul 2026 |
| 514 | Tepee Petroleum Company, Inc. | Houston, TX 77098 | Oil & Gas Operator | Feb 2014 |
| 515 | Texacal, Inc. | Newport Beach, CA 92660 | Oil & Gas Operator | Jul 2026 |
| 516 | Texaco E & P Inc. | Houston, TX 77099 | Oil & Gas Operator | Jul 2026 |
| 517 | Texas Independent Explor., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 518 | Texas Southern Petroleum Corp. | Corpus Christ, TX 78410 | Oil & Gas Operator | Jul 2026 |
| 519 | Texas Sunset Energy And Ent Inc | Victoria, TX 77904 | Oil Operator | Aug 2003 |
| 520 | Texas, Les & Co. | Brenham, TX 77833 | Oil & Gas Operator | Jul 2026 |
| 521 | Texron Operating, LLC | Bulverde, TX 78163 | Oil & Gas Operator | Jul 2026 |
| 522 | Thunder Oil & Gas, LLC | Ardmore, OK 73402 | Oil & Gas Operator | May 2026 |
| 523 | Tidal Petroleum, Inc. | Schertz, TX 78154 | Oil & Gas Operator | Jul 2026 |
| 524 | Tidewater Minerals Corporation | Orange Grove, TX 78372 | Oil & Gas Operator | Jul 2026 |
| 525 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 526 | Trailblazer Oil & Gas LLC | Goliad, TX 77963 | Oil & Gas Operator | Jul 2026 |
| 527 | Trans-Pecos Resources, Inc. | Houston, TX 77056 | Oil & Gas Operator | Jul 2026 |
| 528 | Transfuel Resources Co | Houston, TX 77215 | Oil & Gas Operator | Aug 2013 |
| 529 | Trident Corporation | Woodsboro, TX 78393 | Oil & Gas Operator | Jul 2026 |
| 530 | Trinity River Energy Oper, LLC | Houston, TX 77008 | Oil & Gas Operator | May 2018 |
| 531 | Triple L Oil Company | Corpus Christ, TX 78469 | Oil & Gas Operator | Jan 1998 |
| 532 | Tschoepe, Arthur J. | Leakey, TX 78873 | Oil & Gas Operator | Jun 2001 |
| 533 | Tsoco | Tuleta, TX 78162 | Oil & Gas Operator | Apr 2017 |
| 534 | Tsoco & W. M. Null | Pettus, TX 78146 | Oil & Gas Operator | Aug 2002 |
| 535 | Tucker Petroleum, Inc. | Corpus Chrsti, TX 78468 | Oil & Gas Operator | Jul 2026 |
| 536 | TX Petroleum Company | Corpus Christ, TX 78412 | Oil & Gas Operator | Apr 1996 |
| 537 | U.S. Enercorp, LLC | San Antonio, TX 78217 | Oil & Gas Operator | Jul 2004 |
| 538 | U.S. Exploration Company | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 539 | Ultra Oil & Gas, Inc. | Centerton, AR 72719 | Oil & Gas Operator | Jul 2026 |
| 540 | Union Gas Operating Company | Spring, TX 77391 | Oil & Gas Operator | Jul 2026 |
| 541 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 542 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Jul 2026 |
| 543 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 544 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 545 | United Texas Petroleum Inc. | McKinney, TX 75070 | Oil & Gas Operator | Jul 2026 |
| 546 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Jul 2026 |
| 547 | Valley Gathering Company | Midland, TX 79702 | Oil & Gas Operator | Feb 1997 |
| 548 | Vaquero Operating | FT Stockton, TX 79735 | Oil & Gas Operator | Jul 2026 |
| 549 | Ventex Operating Corp. | Addison, TX 75001 | Oil & Gas Operator | Jul 2026 |
| 550 | Ventura Oil & Gas Company | San Antonio, TX 78205 | Oil & Gas Operator | Mar 2002 |
| 551 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Apr 2026 |
| 552 | Viper S.W.D., LLC | El Campo, TX 77437 | Oil & Gas Operator | Jul 2026 |
| 553 | Vision Oil And Gas LLC | Laredo, TX 78041 | Oil & Gas Operator | Jul 2026 |
| 554 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2026 |
| 555 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 556 | Wallis Energy, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jul 2026 |
| 557 | Warwick-Artemis, LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Jul 2026 |
| 558 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 559 | Welder Exploration & Prod., Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Dec 2022 |
| 560 | Welder Operating, Inc. | San Antonio, TX 78205 | Oil & Gas Operator | Mar 2001 |
| 561 | Welder-Heyer Energy, Inc. | San Antonio, TX 78205 | Oil & Gas Operator | Feb 2001 |
| 562 | Welderxp LTD. | San Antonio, TX 78212 | Oil & Gas Operator | Jul 2026 |
| 563 | West Petroleum Corp. | San Antonio, TX 78205 | Oil & Gas Operator | Oct 2009 |
| 564 | West Tuleta Operating Corp. | Tuleta, TX 78162 | Oil & Gas Operator | May 2019 |
| 565 | Western Gulf Oil & Gas Inc. | Dallas, TX 75360 | Oil & Gas Operator | Jul 2000 |
| 566 | Western Gulf Oil & Gas, LLC | Bishop, TX 78343 | Oil & Gas Operator | Jul 2026 |
| 567 | Westhall Associates, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Aug 1997 |
| 568 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 569 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Jul 2026 |
| 570 | Whitesands Operating, L.L.C. | Corpus Chrsti, TX 78466 | Oil & Gas Operator | Mar 2025 |
| 571 | Wilbanks, Bruce A. Company | Midland, TX 79702 | Oil & Gas Operator | Jul 2026 |
| 572 | Winn Exploration Co., Inc. | Corpus Christ, TX 78401 | Oil & Gas Operator | Jul 2026 |
| 573 | Wiser Oil Co | Denver, CO 80202 | Oil & Gas Operator | Dec 2023 |
| 574 | Wofford, C. J. | El Campo, TX 77437 | Oil & Gas Operator | Jul 2026 |
| 575 | Wolverine Exploration Company | Houston, TX 77002 | Oil & Gas Operator | May 2019 |
| 576 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2026 |
| 577 | York & Price Petroleum Corp. | San Antonio, TX 78218 | Oil & Gas Operator | Jul 2004 |
| 578 | Young, John H., Inc. | Houston, TX 77027 | Oil & Gas Operator | Jul 2026 |
| 579 | Yuma Petroleum Company | Houston, TX 77027 | Oil & Gas Operator | Aug 2002 |
| 580 | Zachry Exploration, LLC | San Antonio, TX 78224 | Oil & Gas Operator | Jul 2026 |
| 581 | Zachry, H. B. Company | San Antonio, TX 78205 | Oil & Gas Operator | Apr 1994 |
| 582 | Zinn Petroleum Co. | Houston, TX 77024 | Oil & Gas Operator | Nov 2021 |