| 501 | TK Drilling Corp. | Tulsa, OK 74133 | Oil & Gas Operator | Jan 2026 |
| 502 | TK Operating | Cross Plains, TX 76443 | Oil & Gas Operator | Apr 2026 |
| 503 | TKL Oil Properties Inc | Konawa, OK 74849 | Oil & Gas Operator | Oct 2025 |
| 504 | TKP Petroleum, Inc. | Lubbock, TX 79464 | Oil & Gas Operator | Apr 2026 |
| 505 | TLH Production LLC | Abilene, TX 79602 | Oil & Gas Operator | Apr 2026 |
| 506 | TMBR/Sharp Drilling, Inc. | Midland, TX 79703 | Oil & Gas Operator | Feb 2004 |
| 507 | TMR Exploration, Inc. | Bossier City, LA 71171 | Oil & Gas Operator | Sep 2025 |
| 508 | TNC Energy, LLC | Lubbock, TX 79401 | Oil & Gas Operator | Nov 2016 |
| 509 | TNCH, LLC | Colorado City, TX 79512 | Oil Operator | Apr 2026 |
| 510 | TNR Petroleum, Inc. | Austin, TX 78747 | Oil & Gas Operator | Sep 1999 |
| 511 | TNT Energy Inc. | Brownwood, TX 76801 | Oil & Gas Operator | May 2013 |
| 512 | TNT Oil Co. | Hamlin, TX 79520 | Oil & Gas Operator | Apr 2026 |
| 513 | TNT Petroleum Company, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Feb 1996 |
| 514 | Toc Energy Resources, LLC | Fort Worth, TX 76101 | Oil & Gas Operator | Apr 2026 |
| 515 | Todd, J R Oil & Investments, Inc | Dallas, TX 75206 | Oil & Gas Operator | Jun 2002 |
| 516 | Tog Operating, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2026 |
| 517 | Toklan Oil And Gas Corporation | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2026 |
| 518 | Tola Production Company | Dallas, TX 75367 | Oil & Gas Operator | Apr 2026 |
| 519 | Tollett Oil | Graham, TX 76450 | Oil Operator | Nov 2024 |
| 520 | Tom Coble Oil & Gas LP | Amarillo, TX 79105 | Oil & Gas Operator | Apr 2026 |
| 521 | Tom E. Johnson Exploration LLC | Midland, TX 79702 | Oil & Gas Operator | Dec 2019 |
| 522 | Tom Operating And Minerals LLC | Andrews, TX 79714 | Gas Operator | Apr 2026 |
| 523 | Tom-Tom Operating, LLC | Dallas, TX 75209 | Oil & Gas Operator | Apr 2026 |
| 524 | Toma Oil & Gas, Inc. | Corpus Chrsti, TX 78411 | Oil & Gas Operator | Oct 1997 |
| 525 | Tomar Petroleum Inc | Dallas, TX 75225 | Oil & Gas Operator | Mar 2001 |
| 526 | Tomco Oil & Gas Inc. | Comanche, TX 76442 | Oil & Gas Operator | Apr 2026 |
| 527 | Tomel Production, LLC | Dallas, TX 75360 | Oil & Gas Operator | Apr 2026 |
| 528 | Tomlinson, John Oil Operator | Batson, TX 77519 | Oil & Gas Operator | Mar 2008 |
| 529 | Tomlinson, Thomas K. Inc. | Port Lavaca, TX 77979 | Oil & Gas Operator | Jul 2003 |
| 530 | Tompkins, Kevin D. | Kilgore, TX 75663 | Oil Operator | Apr 2026 |
| 531 | Tomsha LLC | Bryson, TX 76427 | Oil Operator | Apr 2026 |
| 532 | Toney, W.L. | Borger, TX 79007 | Oil & Gas Operator | Oct 2012 |
| 533 | Tong Petrotech Inc. | Houston, TX 77079 | Oil & Gas Operator | Apr 2026 |
| 534 | Tonk Creek Oil Company | Aspermont, TX 79502 | Oil & Gas Operator | Apr 2026 |
| 535 | Tonto Petroleum Corporation | Post, TX 79356 | Oil & Gas Operator | Jan 2007 |
| 536 | Toomey Oil Company Inc | Tulsa, OK 74120 | Oil & Gas Operator | Jan 2026 |
| 537 | Top O'Texas Energy, L.P. | Pampa, TX 79066 | Oil & Gas Operator | Apr 2026 |
| 538 | Top O'Texas Production Co. | Pampa, TX 79065 | Oil & Gas Operator | May 2024 |
| 539 | Top O'Texas Production, Inc. | Odessa, TX 79764 | Oil & Gas Operator | Feb 1997 |
| 540 | Top Op, L.L.C. | Houston, TX 77077 | Oil & Gas Operator | May 2020 |
| 541 | Topat Oil Corporation | Midland, TX 79701 | Oil & Gas Operator | Sep 2017 |
| 542 | Topaz Oil Company | Diboll, TX 75941 | Oil & Gas Operator | Apr 1994 |
| 543 | Topper Oil Company | Borger, TX 79007 | Oil & Gas Operator | Apr 2026 |
| 544 | Tor Energy, LLC | Temple, TX 76501 | Oil & Gas Operator | Apr 2026 |
| 545 | Torch Energy Services, Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2011 |
| 546 | Torch Oil & Gas Company | Houston, TX 77010 | Oil & Gas Operator | Aug 1997 |
| 547 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 548 | Torch Operating LLC | Fort Worth, TX 76135 | Oil & Gas Operator | Oct 2020 |
| 549 | Toreador Exploration & Prod Inc | Dallas, TX 75240 | Oil & Gas Operator | Feb 2008 |
| 550 | Torrent Oil LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2026 |
| 551 | Tortuga Operating Company | Houston, TX 77055 | Oil & Gas Operator | Apr 2026 |
| 552 | Tot Richards Family LP | Abilene, TX 79601 | Oil & Gas Operator | Apr 2026 |
| 553 | Total E&P USA, Inc. | Houston, TX 77210 | Oil & Gas Operator | May 2025 |
| 554 | Total Minatome Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 1998 |
| 555 | Totalfinaelf E&P USA Inc | Houston, TX 77024 | Oil & Gas Operator | Jul 2007 |
| 556 | Touchstone Resources USA, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2006 |
| 557 | Tower Resources Inc | Conroe, TX 77304 | Oil & Gas Operator | Apr 2026 |
| 558 | Townes, Don | Clarksville, TX 75426 | Oil & Gas Operator | Apr 2026 |
| 559 | Townsend Company | Abilene, TX 79608 | Oil & Gas Operator | Dec 2021 |
| 560 | Townsend, R. F. Trustee | Dallas, TX 75201 | Oil & Gas Operator | Dec 1994 |
| 561 | TPC Exploration, LLC | May, TX 76857 | Oil & Gas Operator | Apr 2026 |
| 562 | Tpet Management Inc. | Dallas, TX 75204 | Oil & Gas Operator | Dec 1997 |
| 563 | Tpet, Inc. | Dallas, TX 75204 | Oil & Gas Operator | Mar 2008 |
| 564 | TR Offshore, LLC | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Apr 2026 |
| 565 | TR Operating LLC | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 566 | Trace Energy Management Inc | Weatherford, TX 76086 | Oil & Gas Operator | Apr 2026 |
| 567 | Trace Operating, LLC | Fort Worth, TX 76116 | Oil & Gas Operator | Apr 2026 |
| 568 | Tracer Energy, Inc. | Graham, TX 76450 | Oil & Gas Operator | Nov 1998 |
| 569 | Tracer Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | Apr 2026 |
| 570 | Tracker Mineral | Clyde, TX 79510 | Oil & Gas Operator | Apr 2026 |
| 571 | Tracker Oil & Gas, Inc. | Bastrop, TX 78602 | Oil & Gas Operator | Apr 2026 |
| 572 | Tracker Resource Dev III, LLC | Englewood, CO 80112 | Oil & Gas Operator | Jul 2021 |
| 573 | Trackstar Energies LLC | Colorado Springs, CO 80919-3233 | Oil Operator | Mar 2023 |
| 574 | Tracy Co. | Rockdale, TX 76567 | Oil & Gas Operator | Mar 2022 |
| 575 | Tracy Operating Co., LLC | Rockdale, TX 76567 | Oil & Gas Operator | Apr 2026 |
| 576 | Tracy Production | Lindale, TX 75771 | Oil & Gas Operator | Apr 2026 |
| 577 | Tradestar Energy, Inc. | Hot Springs, AR 71913 | Oil Operator | Feb 2021 |
| 578 | Tradition Resources LLC | Houston, TX 77002 | Oil & Gas Operator | Jan 2014 |
| 579 | Tradition Resources Oper, LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2017 |
| 580 | Trail Mountain, Inc. | Artesia, NM 88210 | Oil & Gas Operator | Jan 2016 |
| 581 | Trail Ridge Energy Partners, LLC | Grapevine, TX 76051 | Oil & Gas Operator | Feb 2026 |
| 582 | Trail Ridge Energy PRTNS II LLC | Grapevine, TX 76051 | Oil & Gas Operator | Jun 2017 |
| 583 | Trailblazer Energy LLC | Plano, TX 75075 | Oil & Gas Operator | Feb 2026 |
| 584 | Trailblazer Energy Resources, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Apr 2026 |
| 585 | Trailblazer Oil & Gas LLC | Goliad, TX 77963 | Oil & Gas Operator | Apr 2026 |
| 586 | Trailhead Exploration, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 2026 |
| 587 | Trans Terra Corp., International | Amarillo, TX 79159 | Oil & Gas Operator | Feb 2009 |
| 588 | Trans Texas Minerals Company | Austin, TX 78714 | Oil & Gas Operator | Aug 1999 |
| 589 | Trans-Pecos Resources, Inc. | Houston, TX 77056 | Oil & Gas Operator | Apr 2026 |
| 590 | Trans-Tex Operating LLC | Dallas, TX 75367 | Oil & Gas Operator | Apr 2026 |
| 591 | Trans-Texas Energy Group LLC | Mineral Wells, TX 76068 | Oil & Gas Operator | Jul 2015 |
| 592 | Transamerica Energy Corp. | Atlanta, GA 30356 | Oil & Gas Operator | Apr 2026 |
| 593 | Transamerican Natural Gas Corp. | Houston, TX 77032 | Oil & Gas Operator | Aug 2000 |
| 594 | Transatlantic Petr (USA) Corp. | Dallas, TX 75206 | Oil & Gas Operator | Apr 2026 |
| 595 | Transcontinental Minerals Corp. | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2008 |
| 596 | Transcontinental Shale L.L.C. | Austin, TX 78717 | Oil & Gas Operator | Feb 2016 |
| 597 | Transfuel Resources Co | Houston, TX 77215 | Oil & Gas Operator | Aug 2013 |
| 598 | Transoil, Inc. | Oklahoma City, OK 73129 | Oil & Gas Operator | Apr 2026 |
| 599 | Transpacific Energy, LLC | Katy, TX 77450 | Oil & Gas Operator | Apr 2026 |
| 600 | Transpetco I | Shreveport, LA 71101 | Oil & Gas Operator | May 2009 |