| 501 | Terra Resources, Inc. | Casper, WY 82601 | Oil & Gas Operator | Jun 1990 |
| 502 | Terral D Hinds | | Oil Operator | Mar 2012 |
| 503 | Tex/Con Oil & Gas Company | Houston, TX 77074 | Oil & Gas Operator | Feb 2001 |
| 504 | Texaco Producing Inc. | Rock Springs, WY 82901 | Oil & Gas Operator | Dec 2000 |
| 505 | Texas General Petroleum Corp | | Oil & Gas Operator | Aug 1984 |
| 506 | Texas Oil & Gas Corporation | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 507 | The Goro Corporation | | Oil & Gas Operator | Jul 1978 |
| 508 | The Hunter Company, Inc. | | Oil & Gas Operator | Sep 1985 |
| 509 | The Romanoff Corporation | | Oil & Gas Operator | Nov 1989 |
| 510 | Thornton & Brooks, Inc. | | Oil & Gas Operator | Oct 1990 |
| 511 | Tide West Oil Company | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2021 |
| 512 | TMR Exploration, Inc. | Bossier City, LA 71171 | Oil & Gas Operator | Feb 2026 |
| 513 | Tola Production Company | Dallas, TX 75367 | Oil & Gas Operator | Feb 2026 |
| 514 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 515 | Trans-Gulf Petroleum Corp | | Oil & Gas Operator | Sep 1999 |
| 516 | Trans-Pacific Oil & Gas Inc. | | Oil & Gas Operator | Mar 1982 |
| 517 | Transco Exploration Company | | Oil & Gas Operator | Jul 1989 |
| 518 | Tri-Par Exploration, Inc. | | Oil Operator | Oct 2001 |
| 519 | Trinity River Energy Oper, LLC | Houston, TX 77008 | Oil & Gas Operator | May 2018 |
| 520 | Tristar Energy 1 | | Oil Operator | Sep 1987 |
| 521 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 522 | Van Zanten, Inc. | | Gas Operator | Jan 1990 |
| 523 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Sep 2025 |
| 524 | Vaughn Petroleum, Inc. | Dallas, TX 75219 | Oil & Gas Operator | May 2004 |
| 525 | Vernon E. Faulconer | | Oil & Gas Operator | Dec 1996 |
| 526 | Vernon E. Faulconer, Inc. | Tyler, TX 75711 | Oil & Gas Operator | Dec 2024 |
| 527 | Vine Energy Operating LP | | Gas Operator | Oct 2021 |
| 528 | Vine Oil & Gas LP | | Gas Operator | Apr 2021 |
| 529 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |
| 530 | Vista Corporation | | Oil & Gas Operator | Jan 2011 |
| 531 | Vista Resources LLC | Teague, TX 75860 | Oil & Gas Operator | Feb 2026 |
| 532 | W D L Enterprises, Inc | | Oil & Gas Operator | Apr 1983 |
| 533 | Weatherly Oil & Gas, LLC | Dallas, TX 75206 | Oil & Gas Operator | Feb 2026 |
| 534 | Wesla Oil & Gas Co., Inc. | | Oil & Gas Operator | Jun 2001 |
| 535 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 536 | White & Ellis Drilling, Inc. | Wichita, KS 67206 | Oil & Gas Operator | Sep 2025 |
| 537 | Whitton Company, Inc. | | Oil & Gas Operator | Jul 2020 |
| 538 | Wicker Oil Co | | Oil & Gas Operator | Feb 1992 |
| 539 | Wildcat Midstream Caddo LLC | | Oil Operator | May 2017 |
| 540 | Wildhorse Resources, LLC | Houston, TX 77279 | Oil & Gas Operator | Feb 2015 |
| 541 | Will-Drill Operating, L.L.C. | Shreveport, LA 71105 | Oil & Gas Operator | Feb 2026 |
| 542 | Will-Drill Production Co., Inc. | Shreveport, LA 71105 | Oil & Gas Operator | Feb 2026 |
| 543 | William D. Pittman | | Oil & Gas Operator | Jun 1991 |
| 544 | Win Oil Company | Russell, KS 67665 | Oil & Gas Operator | Jul 2021 |
| 545 | Winbeau Oil & Gas Co. | | Oil & Gas Operator | Oct 2013 |
| 546 | Winchester Production Company | Shreveport, LA 71129 | Oil & Gas Operator | Nov 2008 |
| 547 | WNR Enterprises', Inc. | | Oil & Gas Operator | Feb 1997 |
| 548 | Wynn-Crosby Operating, LTD. | Dallas, TX 75201 | Oil & Gas Operator | Feb 2026 |
| 549 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Feb 2026 |
| 550 | Youngblood Enterprises | | Gas Operator | Dec 1983 |
| 551 | Youngblood Enterprises, Inc. | | Oil & Gas Operator | Jan 1992 |
| 552 | Zadeck Energy Group, Inc. | | Oil & Gas Operator | Dec 2011 |
| 553 | Zeagler Enterprises, Inc. | | Oil & Gas Operator | Jun 2008 |