| 401 | Texas Independent Explor., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 402 | Texas Southern Petroleum Corp. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | May 2025 |
| 403 | Thunder Oil & Gas, LLC | Ardmore, OK 73402 | Oil & Gas Operator | Feb 2025 |
| 404 | Tidal Petroleum, Inc. | Schertz, TX 78154 | Oil & Gas Operator | May 2025 |
| 405 | TK Operating | Cross Plains, TX 76443 | Oil & Gas Operator | May 2025 |
| 406 | Trans-Pecos Resources, Inc. | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 407 | Tri-C Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Aug 2009 |
| 408 | Triad Energy Corporation | Houston, TX 77057 | Oil & Gas Operator | Oct 2011 |
| 409 | Triple L Oil Company | Corpus Chrsti, TX 78469 | Oil & Gas Operator | Jan 1998 |
| 410 | Tristar Exploration, Inc | Pflugerville, TX 78660 | Oil & Gas Operator | May 2025 |
| 411 | Tschoepe, Arthur J. | Leakey, TX 78873 | Oil & Gas Operator | Jun 2001 |
| 412 | TX Petroleum Company | Corpus Chrsti, TX 78412 | Oil & Gas Operator | Apr 1996 |
| 413 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 414 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 415 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 416 | United Texas Petroleum Inc. | McKinney, TX 75070 | Oil & Gas Operator | May 2025 |
| 417 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | May 2025 |
| 418 | Valley Petrochemicals, LLC | Pharr, TX 78577 | Oil Operator | May 2025 |
| 419 | Vanco Oil & Gas Corp. | Abilene, TX 79604 | Oil & Gas Operator | May 2025 |
| 420 | Ventex Operating Corp. | Addison, TX 75001 | Oil & Gas Operator | May 2025 |
| 421 | Verado Energy, Inc. | Allen, TX 75013 | Oil & Gas Operator | May 2025 |
| 422 | Veritas Energy LLC | San Antonio, TX 78231 | Oil & Gas Operator | May 2025 |
| 423 | Virtex Petroleum Company, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Jan 2008 |
| 424 | Wallis Energy, Inc. | Austin, TX 78746 | Oil & Gas Operator | May 2025 |
| 425 | Ward, E. B. | Alice, TX 78333 | Oil & Gas Operator | Jun 2001 |
| 426 | Warren American Oil Co | Tulsa, OK 74147 | Oil & Gas Operator | Mar 2025 |
| 427 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 428 | Weaver & Sharp | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Mar 1997 |
| 429 | Welder Exploration & Prod., Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Dec 2022 |
| 430 | Welderxp LTD. | San Antonio, TX 78212 | Oil & Gas Operator | May 2025 |
| 431 | Western Gulf Oil & Gas, LLC | Bishop, TX 78343 | Oil & Gas Operator | May 2025 |
| 432 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | May 2025 |
| 433 | Winn Exploration Co., Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 434 | Winslow, Harry C. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 435 | Wiser Oil Co | Denver, CO 80202 | Oil & Gas Operator | Dec 2023 |
| 436 | Wright Brothers Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | May 2025 |
| 437 | Wright Brothers Petroleum, LTD. | San Antonio, TX 78212 | Oil & Gas Operator | May 2002 |
| 438 | WTXR Operating (Texas), Inc. | Carrollton, TX 75007 | Oil Operator | May 2025 |
| 439 | Xog Operating LLC | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 440 | Zelaya Oil And Gas, LLC | Premont, TX 78375 | Oil & Gas Operator | May 2025 |