| 401 | Speller Oil Corporation | Oklahoma City, OK 73112 | Oil & Gas Operator | Dec 2025 |
| 402 | Spence Energy Company | Dallas, TX 75360 | Oil & Gas Operator | Mar 2026 |
| 403 | Spicer Oil Company, Inc. | Dallas, TX 75225 | Oil & Gas Operator | Dec 2008 |
| 404 | Spicewood Operating Company, LLC | Austin, TX 78746 | Oil & Gas Operator | Mar 2026 |
| 405 | Spindletop Oil & Gas Co. | Dallas, TX 75230 | Oil & Gas Operator | Mar 2026 |
| 406 | St Johns Operating #1 LP | Houston, TX 77060 | Oil & Gas Operator | Aug 2023 |
| 407 | Stallion Oil Company | Lafayette, LA 70505 | Oil & Gas Operator | Jun 2004 |
| 408 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | Mar 2026 |
| 409 | STS Petroleum LLC | Houston, TX 77289 | Oil & Gas Operator | Mar 2026 |
| 410 | Sulphur River Exploration, Inc. | Dallas, TX 75244 | Oil & Gas Operator | Mar 2026 |
| 411 | SW Operating, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Sep 2000 |
| 412 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 413 | T Investments Inc | Oklahoma City, OK 73118-1401 | Oil & Gas Operator | Mar 2011 |
| 414 | T-Bar-X Limited Company | Houston, TX 77057 | Oil & Gas Operator | Dec 2005 |
| 415 | Tag Operating Company, Inc. | Houston, TX 77092 | Oil & Gas Operator | Mar 2026 |
| 416 | Tahiti PTRS Enrgy Solutions Corp | Long Beach, CA 90807 | Oil Operator | Mar 2026 |
| 417 | Taleeho Energy Co. | Normangee, TX 77871 | Oil & Gas Operator | Jun 2003 |
| 418 | Tamarack Petroleum Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | Mar 2026 |
| 419 | Tanos Exploration II, LLC | Tyler, TX 75701 | Oil & Gas Operator | Sep 2023 |
| 420 | TC Oil And Gas, LLC | Denton, TX 76205 | Oil Operator | Mar 2026 |
| 421 | TDT Production, Inc. | Capitola, CA 95010 | Oil & Gas Operator | Aug 2003 |
| 422 | Tech Resources, Inc. | Georgetown, TX 78628 | Oil & Gas Operator | Dec 2001 |
| 423 | Teco Operating Company | Athens, TX 75751 | Oil & Gas Operator | Jun 2001 |
| 424 | Tepee Petroleum Company, Inc. | Houston, TX 77098 | Oil & Gas Operator | Feb 2014 |
| 425 | Texaco E & P Inc. | Houston, TX 77099 | Oil & Gas Operator | Mar 2026 |
| 426 | Texas Royalty Corp. | Austin, TX 78746 | Oil & Gas Operator | Mar 2026 |
| 427 | Texla Operating Co | Jonesville, TX 75659 | Oil & Gas Operator | Mar 2026 |
| 428 | Texlan Oil Company, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Nov 1994 |
| 429 | TGNR Gulf Coast LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2026 |
| 430 | Thomfield Energy LLC | Kilgore, TX 75663 | Oil Operator | Mar 2026 |
| 431 | Threshold Development Company | Fort Worth, TX 76109 | Oil & Gas Operator | Aug 2016 |
| 432 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 433 | Trailblazer Energy Resources, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2026 |
| 434 | Trans-Tex Operating LLC | Dallas, TX 75367 | Oil & Gas Operator | Mar 2026 |
| 435 | Travis Operating, LLC | Kingwood, TX 77345 | Oil & Gas Operator | Mar 2026 |
| 436 | Treadstone Energy Partners, LLC | Houston, TX 77070 | Oil & Gas Operator | Jun 2016 |
| 437 | Triad Energy Corporation | Houston, TX 77057 | Oil & Gas Operator | Oct 2011 |
| 438 | Trinity River Energy Oper, LLC | Houston, TX 77008 | Oil & Gas Operator | May 2018 |
| 439 | Tristar Exploration, Inc | Pflugerville, TX 78660 | Oil & Gas Operator | Mar 2026 |
| 440 | Trivium Operating, LLC | Fort Worth, TX 76107 | Oil & Gas Operator | Mar 2026 |
| 441 | Tuleta Energy Partners, LLC | Norman, OK 73072 | Oil & Gas Operator | Mar 2026 |
| 442 | Tyler Oil & Gas Inc. | Tyler, TX 75702 | Oil & Gas Operator | Sep 2004 |
| 443 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 444 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 445 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 446 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Mar 2026 |
| 447 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 448 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 449 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 450 | Universal Resources Corp. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jan 2000 |
| 451 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Mar 2026 |
| 452 | Vess Oil Corporation | Dallas, TX 75201 | Oil & Gas Operator | Mar 2026 |
| 453 | Vinland Texas Services LLC | Electra, TX 76360 | Oil & Gas Operator | Jun 2024 |
| 454 | Vital Petroleum LLC | Tomball, TX 77375 | Oil Operator | Mar 2026 |
| 455 | W&T Offshore, Inc. | Houston, TX 77057 | Oil & Gas Operator | Mar 2026 |
| 456 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2026 |
| 457 | Weatherly Oil & Gas, LLC | Dallas, TX 75206 | Oil & Gas Operator | Mar 2026 |
| 458 | Weeks Exploration Company | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 459 | West Mountain Operating Co, Inc. | Longview, TX 75604 | Oil & Gas Operator | Feb 2019 |
| 460 | Western Energy Group, LLC | Leander, TX 78641 | Oil & Gas Operator | Mar 2026 |
| 461 | Wheeler Operating Corporation | Fort Worth, TX 76109 | Oil & Gas Operator | Mar 2026 |
| 462 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2026 |
| 463 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 464 | Wildco Resources, Inc. | Tyler, TX 75713 | Oil & Gas Operator | Mar 2026 |
| 465 | Wildfire Energy Operating LLC | Houston, TX 77224 | Oil & Gas Operator | Mar 2026 |
| 466 | Williams Prod. Gulf Coast, L.P. | Benbrook, TX 76126 | Oil & Gas Operator | Jan 2012 |
| 467 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Mar 2026 |
| 468 | Williams, Clayton W., Jr., Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 469 | Wilson Operating Service Inc | Brownfield, TX 79316 | Oil & Gas Operator | Aug 2003 |
| 470 | Wilson, Don H., Inc. | Elkhart, TX 75839 | Oil & Gas Operator | May 2019 |
| 471 | Wing Corporation | Houston, TX 77002 | Oil & Gas Operator | Jun 2000 |
| 472 | Wisenbaker Production Company | Tyler, TX 75702 | Oil & Gas Operator | Oct 2011 |
| 473 | Wiser Oil Co | Denver, CO 80202 | Oil & Gas Operator | Dec 2023 |
| 474 | WJW Operating Co.,LLC | Austin, TX 78738 | Oil & Gas Operator | May 2002 |
| 475 | Woodbine Production Corporation | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2026 |
| 476 | Wortham Oil & Gas | Conroe, TX 77301 | Oil & Gas Operator | Mar 2026 |
| 477 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Mar 2026 |
| 478 | York & Price Petroleum Corp. | San Antonio, TX 78218 | Oil & Gas Operator | Jul 2004 |
| 479 | ZTC Petro Investments LP | Houston, TX 77056 | Oil & Gas Operator | May 2020 |