| 401 | Strand Energy, L.C. | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 402 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | May 2025 |
| 403 | Stratlynn, Inc. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 404 | Stroud Energy, LTD. | Fort Worth, TX 76102 | Oil & Gas Operator | Jun 2006 |
| 405 | Stroud Oil Properties, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | May 2013 |
| 406 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 407 | T & T Production Co. | Victoria, TX 77902 | Oil & Gas Operator | Feb 1995 |
| 408 | T&T Energy LLC | Wooster, OH 44691 | Oil & Gas Operator | Dec 2024 |
| 409 | Tandem Energy Corporation | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 410 | Taos Resources Operating Co LLC | Houston, TX 77037 | Oil & Gas Operator | Dec 2019 |
| 411 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | May 2025 |
| 412 | Technical Energy Services, Inc. | Norman, OK 73070 | Oil & Gas Operator | Feb 2025 |
| 413 | Tex-Lee Operating Company | Giddings, TX 78942 | Oil & Gas Operator | May 2025 |
| 414 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | May 2025 |
| 415 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 416 | Texas American Resources Company | Austin, TX 78701 | Oil & Gas Operator | May 2025 |
| 417 | Texas Gulf Gas Corporation | Fayetteville, TX 78940 | Oil & Gas Operator | Jun 2005 |
| 418 | Texas Independent Explor., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 419 | Texas Land & Trading Co, Inc. | Austin, TX 78734 | Oil & Gas Operator | Mar 2008 |
| 420 | Texas Onshore Energy, Inc. | Austin, TX 78704 | Oil & Gas Operator | May 2025 |
| 421 | Texas Vanguard Oil Company | Austin, TX 78720 | Oil & Gas Operator | Jan 2014 |
| 422 | Tgo Operating, LLC | Midland, TX 79705 | Oil & Gas Operator | Dec 2008 |
| 423 | Three Forks Operating Co, LLC | Flatonia, TX 78941 | Oil & Gas Operator | May 2025 |
| 424 | Tomlinson, Thomas K. Inc. | Port Lavaca, TX 77979 | Oil & Gas Operator | Jul 2003 |
| 425 | Tor Energy, LLC | Temple, TX 76501 | Oil & Gas Operator | May 2025 |
| 426 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 427 | Total Minatome Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 1998 |
| 428 | Tracy Co. | Rockdale, TX 76567 | Oil & Gas Operator | Mar 2022 |
| 429 | Tracy Operating Co., LLC | Rockdale, TX 76567 | Oil & Gas Operator | May 2025 |
| 430 | Tradition Resources Oper, LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2017 |
| 431 | Trailblazer Energy Resources, LLC | Tulsa, OK 74136 | Oil & Gas Operator | May 2025 |
| 432 | Trans-Tex Operating LLC | Dallas, TX 75367 | Oil & Gas Operator | May 2025 |
| 433 | Treadstone Energy PRTNR Op, LLC | Katy, TX 77494 | Oil & Gas Operator | May 2025 |
| 434 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | May 2025 |
| 435 | Tri-C Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Aug 2009 |
| 436 | Trinity Resources, Inc. | Houston, TX 77277 | Oil & Gas Operator | May 2020 |
| 437 | Triple "S" Resources Inc | Sapulpa, OK 74066 | Oil & Gas Operator | Jun 1995 |
| 438 | Trivista Operating LLC | Giddings, TX 78942 | Oil & Gas Operator | May 2025 |
| 439 | TT Operating, LLC | Kilgore, TX 75663 | Oil & Gas Operator | May 2025 |
| 440 | U. S. Operating, Inc. | Dallas, TX 75252 | Oil & Gas Operator | May 2025 |
| 441 | Ubetco, Inc. | Rockdale, TX 76567 | Oil & Gas Operator | May 2025 |
| 442 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 443 | Union Pacific Austin Chalk Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 444 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 445 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 446 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 447 | Unitex Oil & Gas, L.L.C. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 448 | Ursa Operating Company LLC | Denver, CO 80265 | Oil & Gas Operator | Dec 2020 |
| 449 | USA Tubulars, Inc. | Valley Spring, TX 76885 | Oil & Gas Operator | Dec 1995 |
| 450 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | May 2025 |
| 451 | Validus Operating Inc. | Port Aransas, TX 78373 | Oil & Gas Operator | Oct 1998 |
| 452 | Verdun Oil & Gas LLC | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 453 | Veritas Energy LLC | San Antonio, TX 78231 | Oil & Gas Operator | May 2025 |
| 454 | Viceroy Petroleum GP, LLC | Rockdale, TX 76567 | Oil & Gas Operator | Feb 2010 |
| 455 | Viceroy Petroleum, LP | College Sta, TX 77845 | Oil & Gas Operator | May 2025 |
| 456 | W.L. Ranch Inc. | Caldwell, TX 77836 | Oil & Gas Operator | May 2025 |
| 457 | W.W.R. Holding, LLC | Coleman, TX 76834 | Oil & Gas Operator | Mar 2008 |
| 458 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | May 2025 |
| 459 | Warren Production Services | Caldwell, TX 77836 | Oil & Gas Operator | May 2025 |
| 460 | Water Works Engineering, Inc. | Rockdale, TX 76567 | Oil & Gas Operator | Jan 1998 |
| 461 | WCS Oil & Gas Corporation | Dallas, TX 75209 | Oil & Gas Operator | Aug 2021 |
| 462 | Wehunt Oil Company, Inc. | Dallas, TX 75376 | Oil & Gas Operator | Nov 2002 |
| 463 | Western Petroleum Resources, Inc | Dallas, TX 75219 | Oil & Gas Operator | May 2021 |
| 464 | Westlands Resources Corporation | Monrovia, CA 91016 | Oil & Gas Operator | May 2025 |
| 465 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | May 2025 |
| 466 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 467 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 468 | Wilco Properties, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Jan 2004 |
| 469 | Wildfire Energy Operating LLC | Houston, TX 77224 | Oil & Gas Operator | May 2025 |
| 470 | Wildhorse Resources MNGT Co, LLC | Oklahoma City, OK 73154 | Oil & Gas Operator | May 2019 |
| 471 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | May 2025 |
| 472 | Williams, Clayton Energy, L.L.C | Midland, TX 79705 | Oil & Gas Operator | May 1993 |
| 473 | Williams, Clayton W., Jr., Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 474 | Williams-Cody, Inc. | Houston, TX 77060 | Oil & Gas Operator | May 1994 |
| 475 | Wortham Oil & Gas | Conroe, TX 77301 | Oil & Gas Operator | May 2025 |
| 476 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 477 | Yeti Exploration, LLC | Fort Worth, TX 76107 | Oil & Gas Operator | May 2025 |
| 478 | Zarvona Energy LLC | Houston, TX 77002 | Oil & Gas Operator | May 2025 |