| 501 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 502 | Swift Energy Operating, LLC | Houston, TX 77079 | Oil & Gas Operator | Jun 2017 |
| 503 | Sydri Operating, LLC | Dallas, TX 75231 | Oil & Gas Operator | Sep 2026 |
| 504 | Talisman Energy USA Inc. | The Woodlands, TX 77381 | Oil & Gas Operator | May 2016 |
| 505 | Tana Oil And Gas Corporation | Irving, TX 75062 | Oil & Gas Operator | Mar 2000 |
| 506 | Tanos Production, Inc. | Houston, TX 77077 | Oil & Gas Operator | Aug 2003 |
| 507 | Tare Resources, LLC | Corpus Chrsti, TX 78426 | Oil & Gas Operator | Sep 2026 |
| 508 | Targa Midstream Services LLC | Tulsa, OK 74103 | Oil Operator | Mar 2023 |
| 509 | Teal Operating, LLC | Dallas, TX 75225 | Oil & Gas Operator | Oct 2021 |
| 510 | Terrafina Energy, LLC | San Antonio, TX 78280 | Oil & Gas Operator | Sep 2026 |
| 511 | Teton Petroleum Corporation | Kerrville, TX 78028 | Oil & Gas Operator | Sep 2026 |
| 512 | Texaco E & P Inc. | Houston, TX 77099 | Oil & Gas Operator | Sep 2026 |
| 513 | Texas Energen Inc. | Austin, TX 78731 | Oil & Gas Operator | Sep 2026 |
| 514 | Texas Independent Explor LTD. | Houston, TX 77024 | Oil & Gas Operator | Sep 2026 |
| 515 | Texas Independent Explor., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 516 | Texas Lone Star Petroleum Corp. | Corpus Christ, TX 78401 | Oil & Gas Operator | Dec 2013 |
| 517 | Texas Secondary Oil Corporation | Devine, TX 78016 | Oil & Gas Operator | Sep 2026 |
| 518 | Texas Southern Petroleum Corp. | Corpus Christ, TX 78410 | Oil & Gas Operator | Sep 2026 |
| 519 | Texas, Les & Co. | Brenham, TX 77833 | Oil & Gas Operator | Sep 2026 |
| 520 | Texas, Les C., LTD. | Houston, TX 77095 | Oil & Gas Operator | Dec 2006 |
| 521 | Texcal Energy (GP) LLC | Denver, CO 80202 | Oil & Gas Operator | Mar 2016 |
| 522 | Texegy Operating Company LLC | Corpus Christ, TX 78401 | Oil & Gas Operator | Dec 2024 |
| 523 | Texona Petroleum Corporation | Houston, TX 77084 | Oil & Gas Operator | Aug 2003 |
| 524 | Texoz E&P I, Inc. | Houston, TX 77077 | Oil & Gas Operator | Sep 2026 |
| 525 | Texron Operating, LLC | Bulverde, TX 78163 | Oil & Gas Operator | Sep 2026 |
| 526 | Thalmann Oilfield | Carrizo SPGS, TX 78834 | Oil Operator | Sep 2026 |
| 527 | Thomas Exploration & Devel., Inc | Jourdanton, TX 78026 | Oil & Gas Operator | Sep 2026 |
| 528 | Three J Energy, Inc. | Seguin, TX 78155 | Oil & Gas Operator | Sep 2026 |
| 529 | Tidal Petroleum, Inc. | Schertz, TX 78154 | Oil & Gas Operator | Sep 2026 |
| 530 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 531 | Toreador Exploration & Prod Inc | Dallas, TX 75240 | Oil & Gas Operator | Feb 2008 |
| 532 | Tracker Oil & Gas, Inc. | Bastrop, TX 78602 | Oil & Gas Operator | Sep 2026 |
| 533 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Sep 2026 |
| 534 | Tri-C Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Aug 2009 |
| 535 | Tri-Union Development Corp. | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 536 | Triangle Three Resources L.L.C. | Dallas, TX 75248 | Oil & Gas Operator | Sep 2026 |
| 537 | Trident Corporation | Woodsboro, TX 78393 | Oil & Gas Operator | Sep 2026 |
| 538 | Trinity Operating (Usg), LLC | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 539 | Triple L Oil Company | Corpus Christ, TX 78469 | Oil & Gas Operator | Jan 1998 |
| 540 | Trium, LTD. | Laredo, TX 78041 | Oil Operator | Sep 2026 |
| 541 | Tucker Petroleum, Inc. | Corpus Chrsti, TX 78468 | Oil & Gas Operator | Sep 2026 |
| 542 | TX Petroleum Company | Corpus Christ, TX 78412 | Oil & Gas Operator | Apr 1996 |
| 543 | U.S. Enercorp, LLC | San Antonio, TX 78217 | Oil & Gas Operator | Jul 2004 |
| 544 | U.S. Enercorp, LTD. | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2019 |
| 545 | U.S.A. Plugging Company | Pearsall, TX 78061 | Oil & Gas Operator | Sep 2026 |
| 546 | Ultra Oil & Gas, Inc. | Centerton, AR 72719 | Oil & Gas Operator | Sep 2026 |
| 547 | Umma Resources, LLC | Portland, TX 78374 | Gas Operator | Sep 2026 |
| 548 | Union Gas Operating Company | Spring, TX 77391 | Oil & Gas Operator | Sep 2026 |
| 549 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Sep 2026 |
| 550 | Valley Gathering Company | Midland, TX 79702 | Oil & Gas Operator | Feb 1997 |
| 551 | Varas Energy Operating Company, LLC | Houston, TX 77005 | Oil & Gas Operator | Sep 2026 |
| 552 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Apr 2026 |
| 553 | Verdun Oil & Gas LLC | Houston, TX 77024 | Oil & Gas Operator | Sep 2026 |
| 554 | Verdun Oil Ef II LLC | Houston, TX 77024 | Oil & Gas Operator | Sep 2026 |
| 555 | Vermillion Production, Inc. | Pearsall, TX 78061 | Oil & Gas Operator | Sep 2026 |
| 556 | Victoria Operating, Inc. | Victoria, TX 77903 | Oil & Gas Operator | Sep 2026 |
| 557 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Apr 2026 |
| 558 | Virtex Operating Company, Inc. | Corpus Christ, TX 78401 | Oil & Gas Operator | Oct 2023 |
| 559 | Virtex Petroleum Company, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Jan 2008 |
| 560 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2026 |
| 561 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 562 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 563 | Walking X Oil Co. | Whiteface, TX 79379 | Oil & Gas Operator | Sep 2026 |
| 564 | Walter Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 565 | Wandoo Energy, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | Dec 2025 |
| 566 | Wapiti Operating, LLC | Houston, TX 77043 | Oil & Gas Operator | Sep 2026 |
| 567 | Welder Exploration & Prod., Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Dec 2022 |
| 568 | Welhausen Operating Co., Inc. | Beeville, TX 78104 | Oil & Gas Operator | Aug 2003 |
| 569 | Welhausen Operating Company, LP | Beeville, TX 78104 | Oil & Gas Operator | Nov 2016 |
| 570 | Wen-Be | Jourdanton, TX 78026 | Oil & Gas Operator | Sep 2026 |
| 571 | Western Pride Resources, Inc. | Jacksboro, TX 76458 | Oil & Gas Operator | Jan 2011 |
| 572 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 573 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Sep 2026 |
| 574 | Whitesands Operating, L.L.C. | Corpus Chrsti, TX 78466 | Oil & Gas Operator | Mar 2025 |
| 575 | Whitesands Resources, L.L.C. | Corpus Chrsti, TX 78466 | Oil Operator | Jun 2019 |
| 576 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 577 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 578 | Wilco Properties, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Jan 2004 |
| 579 | Wiley Lease Co., LTD. | Jourdanton, TX 78026 | Oil Operator | Sep 2026 |
| 580 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Sep 2026 |
| 581 | Williams, Clayton Energy, L.L.C | Midland, TX 79705 | Oil & Gas Operator | May 1993 |
| 582 | Williams, Clayton W., Jr., Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 583 | Wind River Resources Inc | Tulsa, OK 74136-6381 | Oil & Gas Operator | Jun 2010 |
| 584 | Wing Corporation | Houston, TX 77002 | Oil & Gas Operator | Jun 2000 |
| 585 | Winn Exploration Co., Inc. | Corpus Christ, TX 78401 | Oil & Gas Operator | Sep 2026 |
| 586 | Wood, C.W. | Calliham, TX 78007 | Oil & Gas Operator | Sep 2023 |
| 587 | WR Resources, LLC | Jourdanton, TX 78026 | Oil & Gas Operator | Sep 2026 |
| 588 | Wynn-Crosby Operating, LTD. | Dallas, TX 75201 | Oil & Gas Operator | Sep 2026 |
| 589 | Xplor Energy Operating Co. | Houston, TX 77079 | Oil & Gas Operator | Jan 2012 |
| 590 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Sep 2026 |
| 591 | York & Price Petroleum Corp. | San Antonio, TX 78218 | Oil & Gas Operator | Jul 2004 |