| 501 | Stine Oil Company | Mansfield, TX 76063 | Oil Operator | Mar 2016 |
| 502 | Stine, Ward L.Oil Company | Windthorst, TX 76389 | Oil & Gas Operator | Oct 1999 |
| 503 | Storm Oil | Burkburnett, TX 76354 | Oil & Gas Operator | Oct 2025 |
| 504 | Strange, D. D. | Archer City, TX 76351 | Oil & Gas Operator | Sep 2014 |
| 505 | Strawn DRLG. Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | Aug 2005 |
| 506 | Street, Spencer B., Jr. | Graham, TX 76450 | Oil & Gas Operator | Mar 1998 |
| 507 | Sunday Corporation | Olney, TX 76374 | Oil & Gas Operator | Oct 2025 |
| 508 | Sunrise Enterprises | Bowie, TX 76230 | Oil & Gas Operator | Dec 2016 |
| 509 | Sutterfield-Tisdale-Payne, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Jun 1998 |
| 510 | Swan PC, LP | Jacksboro, TX 76458 | Oil & Gas Operator | Oct 2025 |
| 511 | Swan Production Co. | Jacksboro, TX 76458 | Oil & Gas Operator | Nov 2009 |
| 512 | Swanson, Tommy Oil Co. | Electra, TX 76360 | Oil & Gas Operator | Mar 2017 |
| 513 | Sweetwater Drilling Co., Inc. | Fort Worth, TX 76116 | Oil & Gas Operator | Oct 2025 |
| 514 | Swenson, Clifford E. | Henrietta, TX 76365 | Oil & Gas Operator | Oct 2025 |
| 515 | T-N-T Engineering, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | Oct 2025 |
| 516 | Tahoe Exploration Inc. | Abilene, TX 79608 | Oil & Gas Operator | Mar 2016 |
| 517 | Talon Production, Inc. | Wichita Falls, TX 76301 | Oil & Gas Operator | Oct 2025 |
| 518 | Targa Midstream Services LLC | Houston, TX 77002 | Oil Operator | Mar 2023 |
| 519 | Taubert & Steed | Wichita Falls, TX 76301 | Oil & Gas Operator | Aug 2001 |
| 520 | Taylor, Ben J. Inc. | Fort Worth, TX 76185 | Oil & Gas Operator | Feb 2022 |
| 521 | Taylor, G. E. | Bridgeport, TX 76426 | Oil & Gas Operator | Jan 2001 |
| 522 | Taylor, G. E. Inc. | Bridgeport, TX 76426 | Oil & Gas Operator | Jul 2007 |
| 523 | TB Petroleum, LLC | Petrolia, TX 76377 | Oil & Gas Operator | Oct 2025 |
| 524 | Texakoma E & P, LLC | Plano, TX 75024 | Oil & Gas Operator | Oct 2025 |
| 525 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 526 | Texakoma Operating, L.P. | Plano, TX 75024 | Oil & Gas Operator | Mar 2025 |
| 527 | Texas Energy Operations, LC | Wichita Falls, TX 76301 | Oil & Gas Operator | Oct 2025 |
| 528 | Texoma Oil Tools, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Oct 2025 |
| 529 | Texxol Operating Company, Inc. | Fort Worth, TX 76108 | Oil & Gas Operator | Oct 2025 |
| 530 | Three-B Oil Company, The | Monahans, TX 79756 | Oil & Gas Operator | Oct 2025 |
| 531 | Tillman, Jack Equipment Co. | Holliday, TX 76366 | Oil & Gas Operator | Sep 2004 |
| 532 | Todd, J R Oil & Investments, Inc | Dallas, TX 75206 | Oil & Gas Operator | Jun 2002 |
| 533 | Trace Energy Management Inc | Weatherford, TX 76086 | Oil & Gas Operator | Oct 2025 |
| 534 | Tracker Mineral | Clyde, TX 79510 | Oil & Gas Operator | Oct 2025 |
| 535 | Tree Operating, LLC | Graham, TX 76450 | Oil & Gas Operator | Oct 2025 |
| 536 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Oct 2025 |
| 537 | Tri "M" Oil & Gas | Muenster, TX 76252 | Oil & Gas Operator | Oct 2025 |
| 538 | Triangle Energy Co. | Pampa, TX 79066 | Oil & Gas Operator | Nov 2000 |
| 539 | Trinity Bay Oil & Gas, Inc. | Lubbock, TX 79416 | Oil & Gas Operator | Oct 2025 |
| 540 | Trio Consulting & Management,LLC | Wichita Falls, TX 76307 | Oil & Gas Operator | Oct 2025 |
| 541 | Trio Consulting & MGMT LLC | Wichita Falls, TX 76301 | Oil Operator | Jun 2025 |
| 542 | Trio Operating Company, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2006 |
| 543 | TS & T Drilling, Inc. | Wichita Falls, TX 76301 | Oil & Gas Operator | Mar 2016 |
| 544 | Tuthill & Barbee | Amarillo, TX 79101 | Oil & Gas Operator | Nov 1994 |
| 545 | Twilco Operating LLC | Holliday, TX 76366 | Oil Operator | Oct 2025 |
| 546 | Twilight Energy LLC | Fort Worth, TX 76185 | Oil & Gas Operator | Oct 2025 |
| 547 | Twin Oaks Construction Company | Irving, TX 75063 | Oil & Gas Operator | Oct 2025 |
| 548 | Txu Gas Company | Dallas, TX 75201 | Oil & Gas Operator | Sep 2004 |
| 549 | Txu Lone Star Pipeline | Dallas, TX 75201 | Oil & Gas Operator | Oct 2003 |
| 550 | U. S. Operating, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Jul 2025 |
| 551 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 552 | Upham Oil & Gas Company | Mineral Wells, TX 76068 | Oil & Gas Operator | Oct 2025 |
| 553 | Uptex Operating Inc. | Dallas, TX 75201 | Oil & Gas Operator | May 2011 |
| 554 | Uptex Operating, L.P. | Dallas, TX 75201 | Oil & Gas Operator | May 2010 |
| 555 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Oct 2025 |
| 556 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 557 | Viola Production Inc | Dallas, TX 75251 | Oil & Gas Operator | Oct 2025 |
| 558 | Waggner, Fred | Wichita Falls, TX 76307 | Oil & Gas Operator | Oct 2025 |
| 559 | Waggner, Robert | Wichita Falls, TX 76307 | Oil & Gas Operator | Dec 2006 |
| 560 | Waggoner, W. T., Estate | Vernon, TX 76385 | Oil & Gas Operator | Feb 2018 |
| 561 | Walsh & Watts Inc | Aledo, TX 76008 | Oil & Gas Operator | Oct 2025 |
| 562 | Walter Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 563 | Warnock Operating Company, LLC | Graham, TX 76450 | Oil & Gas Operator | Jul 2013 |
| 564 | WBH Energy Partners LLC | Austin, TX 78703 | Oil & Gas Operator | Oct 2025 |
| 565 | Wells Oilfield Services, Inc. | Graham, TX 76450 | Oil & Gas Operator | Oct 2025 |
| 566 | Wendy Oil Company | Wichita Falls, TX 76307 | Oil & Gas Operator | Oct 2025 |
| 567 | Western Chief Oil & Gas Company | Graham, TX 76450 | Oil & Gas Operator | Jul 2009 |
| 568 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 569 | Westridge Oil & Gas Properties | Mineral Wells, TX 76068 | Oil & Gas Operator | Oct 2025 |
| 570 | WFW Production Company, Inc. | Muenster, TX 76252 | Oil & Gas Operator | Oct 2025 |
| 571 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 572 | William Fleming Productions, LLC | Wichita Falls, TX 76305 | Oil Operator | Feb 2025 |
| 573 | Williams, A. Oil | Wichita Falls, TX 76308 | Oil Operator | Oct 2025 |
| 574 | Willowbend Investments, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Oct 2025 |
| 575 | Wills Oil Company | Wichita Falls, TX 76308 | Oil & Gas Operator | Jun 1995 |
| 576 | Wills Oil Holdings, L.L.C. | Wichita Falls, TX 76308 | Oil & Gas Operator | Oct 2025 |
| 577 | Winco Petroleum Company | Richardson, TX 75080 | Oil & Gas Operator | Jan 2003 |
| 578 | Winfield Operating Company | Dallas, TX 75214 | Oil & Gas Operator | Oct 2025 |
| 579 | Winfrey Oil Co., Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | May 2016 |
| 580 | Wise Production Company | Bowie, TX 76230 | Oil & Gas Operator | Oct 2025 |
| 581 | Wise Supply Company | Bowie, TX 76230 | Oil & Gas Operator | Oct 2025 |
| 582 | Wise Well Service | Bowie, TX 76230 | Oil & Gas Operator | Jul 2017 |
| 583 | Wiser Oil Co | Denver, CO 80202 | Oil & Gas Operator | Dec 2023 |
| 584 | Wolf, Gene | Windthorst, TX 76389 | Oil & Gas Operator | Apr 2003 |
| 585 | Wolf, Gene L.L.C. | Windthorst, TX 76389 | Oil & Gas Operator | Oct 2025 |
| 586 | Wolfson, I. J. | Wichita Falls, TX 76301 | Oil & Gas Operator | Apr 2002 |
| 587 | Wolsey Well Service, Inc. | Windthorst, TX 76389 | Oil & Gas Operator | Jul 2006 |
| 588 | Wolsey Well Service, L.P. | Bowie, TX 76230 | Oil & Gas Operator | Jun 2014 |
| 589 | Woodbine Petroleum, Inc. | Dallas, TX 75204 | Oil & Gas Operator | Aug 2003 |
| 590 | Woods Operating Co., Inc. | Shreveport, LA 71136 | Oil & Gas Operator | Dec 2020 |
| 591 | World Producers, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 1994 |
| 592 | Xophi Energy, LLC | Arlington, TX 76006 | Oil & Gas Operator | Oct 2025 |
| 593 | Xplore Operating, LLC | Arlington, TX 76001 | Oil & Gas Operator | Oct 2025 |
| 594 | Yarberry Operating, LLC | Wichita Falls, TX 76308 | Oil & Gas Operator | Oct 2025 |
| 595 | Yarberry, E. E. | Wichita Falls, TX 76308 | Oil & Gas Operator | Oct 2015 |
| 596 | Yellowstone Petroleums Inc. | Canada, 00100 | Oil & Gas Operator | Jun 2025 |
| 597 | Yet Profits, L.L.C. | Wichita Falls, TX 76308 | Oil Operator | Oct 2025 |
| 598 | Zachris, Inc. | Mansfield, TX 76063 | Oil Operator | Oct 2021 |