| 501 | Southeastern Resources Corp. | Mansfield, TX 76063 | Oil & Gas Operator | Feb 2004 |
| 502 | Southern Alliance Oil Corp. | Grapevine, TX 76099 | Oil & Gas Operator | Feb 2026 |
| 503 | Southern Mineral Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2001 |
| 504 | Southlake Exploration, Inc. | Southlake, TX 76092 | Oil & Gas Operator | Feb 2026 |
| 505 | Spade Energy L.L.C. | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2026 |
| 506 | Spartan Oil Corporation | Abilene, TX 79601 | Oil & Gas Operator | Aug 2003 |
| 507 | Speller Oil Corporation | Oklahoma City, OK 73112 | Oil & Gas Operator | Dec 2025 |
| 508 | Spence Energy Company | Dallas, TX 75360 | Oil & Gas Operator | Feb 2026 |
| 509 | Spitfire Partners, LLC | Dallas, TX 75225 | Oil Operator | Feb 2026 |
| 510 | Squyres Oil Co., Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Nov 2024 |
| 511 | Stamper Operating Co., Inc. | Jacksboro, TX 76458 | Oil & Gas Operator | Feb 2026 |
| 512 | Stasney Well Service, LLC | Albany, TX 76430 | Oil & Gas Operator | Feb 2026 |
| 513 | Steinberger, Gerald | Windthorst, TX 76389 | Oil & Gas Operator | Sep 2007 |
| 514 | Stephens & Johnson Operating Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | Feb 2026 |
| 515 | Stewart, James G. | Graham, TX 76450 | Oil & Gas Operator | Sep 2019 |
| 516 | Stovall Operating Co. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 517 | Strawn DRLG. Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | Aug 2005 |
| 518 | Stream Energy, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Nov 2025 |
| 519 | Street, Spencer B., Jr. | Graham, TX 76450 | Oil & Gas Operator | Mar 1998 |
| 520 | Stubblefield Energy Company | Abilene, TX 79604 | Oil & Gas Operator | Feb 2026 |
| 521 | Subsea Operating Co. | Albany, TX 76430 | Oil & Gas Operator | Feb 2026 |
| 522 | Sullivan, Hollis R. Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2009 |
| 523 | Sunday Corporation | Olney, TX 76374 | Oil & Gas Operator | Feb 2026 |
| 524 | Supreme Energy Company, Inc. | Abilene, TX 79601 | Oil & Gas Operator | Feb 2026 |
| 525 | Susanna Corporation | Breckenridge, TX 76424 | Oil & Gas Operator | Feb 2026 |
| 526 | Sweetwater Drilling Co., Inc. | Fort Worth, TX 76116 | Oil & Gas Operator | Feb 2026 |
| 527 | Synergy Operating Co., LLC | Dallas, TX 75225 | Oil & Gas Operator | Feb 2026 |
| 528 | T & M Oil Company | Midlothian, TX 76065 | Oil & Gas Operator | Feb 2026 |
| 529 | T-N-T Engineering, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | Feb 2026 |
| 530 | Tahoe Exploration Inc. | Abilene, TX 79608 | Oil & Gas Operator | Mar 2016 |
| 531 | Talon Production, Inc. | Wichita Falls, TX 76301 | Oil & Gas Operator | Feb 2026 |
| 532 | Tamarron Resources, Inc. | Azle, TX 76020 | Oil & Gas Operator | Feb 2026 |
| 533 | Targa Midstream Services LLC | Houston, TX 77002 | Oil Operator | Mar 2023 |
| 534 | Tarpon Oil Company | Fort Worth, TX 76107 | Oil & Gas Operator | Jun 2016 |
| 535 | Taylor, Dutch | Graham, TX 76450 | Oil & Gas Operator | Jan 2016 |
| 536 | TC Oil And Gas, LLC | Denton, TX 76205 | Oil Operator | Feb 2026 |
| 537 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | Feb 2026 |
| 538 | Telesis Operating Co. | Fort Worth, TX 76116 | Oil & Gas Operator | Feb 2026 |
| 539 | Tempo Resources GP, LLC | Mineral Wells, TX 76068 | Oil & Gas Operator | Apr 2013 |
| 540 | Tenison Oil Company | Abilene, TX 79605 | Oil & Gas Operator | Nov 2025 |
| 541 | Terry'S Roustabout Service, Inc. | Throckmorton, TX 76483 | Oil & Gas Operator | Oct 2002 |
| 542 | Tex-Am-Energy Inc. | Dallas, TX 75205 | Oil & Gas Operator | Mar 2008 |
| 543 | Tex-R Energy, Inc. | Abilene, TX 79608 | Oil & Gas Operator | Feb 2021 |
| 544 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 545 | Texxol Operating Company, Inc. | Fort Worth, TX 76108 | Oil & Gas Operator | Feb 2026 |
| 546 | Thompson, Richard W. Inc. | Plano, TX 75024 | Oil & Gas Operator | Feb 2026 |
| 547 | Thornton, Michael D. | Breckenridge, TX 76424 | Oil & Gas Operator | Nov 1995 |
| 548 | Three P Operating Co.,GP, L.L.C. | Newcastle, TX 76372 | Oil & Gas Operator | Feb 2026 |
| 549 | Three P Operating Company | Newcastle, TX 76372 | Oil & Gas Operator | Nov 2007 |
| 550 | Threshold Development Company | Fort Worth, TX 76109 | Oil & Gas Operator | Aug 2016 |
| 551 | Throckmorton Oil, Inc. | Throckmorton, TX 76483 | Oil & Gas Operator | Mar 2008 |
| 552 | Tiara Resources, Inc. | Fort Worth, TX 76179 | Oil & Gas Operator | Apr 1998 |
| 553 | Titan Energy, Inc. | Austin, TX 78703 | Oil & Gas Operator | Feb 2026 |
| 554 | Tom-Tom Operating, LLC | Dallas, TX 75209 | Oil & Gas Operator | Feb 2026 |
| 555 | Tot Richards Family LP | Abilene, TX 79601 | Oil & Gas Operator | Feb 2026 |
| 556 | Trace Energy Management Inc | Weatherford, TX 76086 | Oil & Gas Operator | Feb 2026 |
| 557 | Tracer Energy, Inc. | Graham, TX 76450 | Oil & Gas Operator | Nov 1998 |
| 558 | Tracer Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 559 | Tracker Resource Dev III, LLC | Englewood, CO 80112 | Oil & Gas Operator | Jul 2021 |
| 560 | Treco Oil Company | Albany, TX 76430 | Oil & Gas Operator | Feb 2026 |
| 561 | Trio Consulting & Management,LLC | Wichita Falls, TX 76307 | Oil & Gas Operator | Feb 2026 |
| 562 | Trio Operating Company, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2006 |
| 563 | Trust Oil Co. | Pine, CO 80470 | Oil & Gas Operator | Feb 2026 |
| 564 | Tucker Resources, Inc. | Wichita Falls, TX 76301 | Oil & Gas Operator | Aug 2003 |
| 565 | Tuthill & Barbee | Amarillo, TX 79101 | Oil & Gas Operator | Nov 1994 |
| 566 | Tyco Operating Co. | Archer City, TX 76351 | Oil & Gas Operator | Feb 2026 |
| 567 | U. D. Man, Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Feb 2026 |
| 568 | Uhc Petroleum Corporation | Rocksprings, TX 78880 | Oil & Gas Operator | Feb 2026 |
| 569 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Feb 2026 |
| 570 | United Texas Petroleum Inc. | McKinney, TX 75070 | Oil & Gas Operator | Feb 2026 |
| 571 | Uphill Consulting LLC | Pearland, TX 77584 | Oil & Gas Operator | Feb 2026 |
| 572 | Us. Fuels, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Feb 2026 |
| 573 | V & H Oil, L.P. | Muenster, TX 76252 | Oil & Gas Operator | Feb 2026 |
| 574 | V-F Petroleum Inc. | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 575 | Vaca Operating Company LLC | Pacific PLSDS, CA 90272 | Oil & Gas Operator | Aug 2017 |
| 576 | Van Operating, LTD. | Albany, TX 76430 | Oil & Gas Operator | Feb 2026 |
| 577 | Vantage Fort Worth Energy LLC | Pittsburgh, PA 15222 | Oil & Gas Operator | Feb 2026 |
| 578 | Veneto Exploration, LLC | Richardson, TX 75083 | Oil & Gas Operator | Feb 2026 |
| 579 | Viejo Services, LLC | Boyd, TX 76023 | Oil & Gas Operator | Feb 2026 |
| 580 | Vortt Exploration Company, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2019 |
| 581 | Walsh & Watts Inc | Aledo, TX 76008 | Oil & Gas Operator | Feb 2026 |
| 582 | Walter Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | May 2009 |
| 583 | Walton, W. W. | Breckenridge, TX 76424 | Oil & Gas Operator | Sep 1994 |
| 584 | WB Mullin Operating LLC | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 585 | Wells Oilfield Services, Inc. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 586 | Wes-Mor Drilling, Inc. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 587 | West,Gordon T.Jr. & Rugeley,Stan | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2019 |
| 588 | Western Chief Oil & Gas Company | Graham, TX 76450 | Oil & Gas Operator | Jul 2009 |
| 589 | Western Chief Operating, L.L.C. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 590 | Western Reserves Corporation | Abilene, TX 79608 | Oil & Gas Operator | Jan 2008 |
| 591 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 592 | Wheat, Buck Resources, Inc. | Eastland, TX 76448 | Oil & Gas Operator | Dec 2009 |
| 593 | White Rock Exploration, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Jul 2021 |
| 594 | White, Jack Operating | Breckenridge, TX 76424 | Oil & Gas Operator | Feb 2026 |
| 595 | White, Oscar | Tuscola, TX 79562 | Oil & Gas Operator | Feb 2026 |
| 596 | Whiteside, H. W. | Abilene, TX 79604 | Oil & Gas Operator | Nov 1998 |
| 597 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 598 | Whitt Oil & Gas, Inc. | Albany, TX 76430 | Oil & Gas Operator | Feb 2026 |
| 599 | Wichita Falls Oil Expl. Co. | Holliday, TX 76366 | Oil & Gas Operator | Feb 2026 |
| 600 | Wichita Operating Company, Inc. | Spring, TX 77393 | Oil & Gas Operator | May 2009 |