| 601 | Trumter Petroleum Corporation | Fort Worth, TX 76185 | Oil & Gas Operator | Aug 1998 |
| 602 | Trust Oil Co. | Pine, CO 80470 | Oil & Gas Operator | Jul 2026 |
| 603 | United Energy Partners, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2008 |
| 604 | Universal Resources Corp. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jan 2000 |
| 605 | Upco | Mineral Wells, TX 76068 | Gas Operator | Sep 2001 |
| 606 | Upda Operators, Inc. | Jacksboro, TX 76458 | Oil & Gas Operator | Dec 2009 |
| 607 | Upham Oil & Gas Company | Mineral Wells, TX 76068 | Oil & Gas Operator | Jul 2026 |
| 608 | Upham, Chester R., Jr. | Mineral Wells, TX 76067 | Oil & Gas Operator | Aug 2001 |
| 609 | Us. Fuels, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Jul 2026 |
| 610 | Vantage Fort Worth Energy LLC | Pittsburgh, PA 15222 | Oil & Gas Operator | Jul 2026 |
| 611 | Veritas Energy LLC | San Antonio, TX 78231 | Oil & Gas Operator | Jul 2026 |
| 612 | Viejo Services, LLC | Boyd, TX 76023 | Oil & Gas Operator | Jul 2026 |
| 613 | Vortt Exploration Company, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2019 |
| 614 | Voth Operating, Inc. | Muenster, TX 76252 | Oil & Gas Operator | Oct 2005 |
| 615 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 616 | Walter Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | May 2009 |
| 617 | Watusi Energy LLC | Midland, TX 79710 | Oil & Gas Operator | Jul 2026 |
| 618 | WB Mullin Operating LLC | Graham, TX 76450 | Oil & Gas Operator | Jul 2026 |
| 619 | WBR, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Sep 1995 |
| 620 | Wehunt Oil Company, Inc. | Dallas, TX 75376 | Oil & Gas Operator | Nov 2002 |
| 621 | Wells Oilfield Services, Inc. | Graham, TX 76450 | Oil & Gas Operator | Jul 2026 |
| 622 | Wes-Mor Drilling, Inc. | Graham, TX 76450 | Oil & Gas Operator | Jul 2026 |
| 623 | West Inland Energy, Inc. | Fort Worth, TX 76179 | Oil & Gas Operator | Jan 2026 |
| 624 | Western Chief Oil & Gas Company | Graham, TX 76450 | Oil & Gas Operator | Jul 2009 |
| 625 | Western Chief Operating, L.L.C. | Graham, TX 76450 | Oil & Gas Operator | Jul 2026 |
| 626 | Western Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2026 |
| 627 | Western Reserves Corporation | Abilene, TX 79608 | Oil & Gas Operator | Jan 2008 |
| 628 | Westico Energy Co. | Abilene, TX 79605 | Oil & Gas Operator | Nov 2004 |
| 629 | Westridge Oil & Gas Properties | Mineral Wells, TX 76068 | Oil & Gas Operator | Jul 2026 |
| 630 | Wharton Oil Co. | Vernon, TX 76384 | Oil & Gas Operator | Dec 2000 |
| 631 | Wheat, Buck Resources, Inc. | Eastland, TX 76448 | Oil & Gas Operator | Dec 2009 |
| 632 | White Knight Production LLC | Lafayette, LA 70505 | Oil & Gas Operator | Feb 2024 |
| 633 | Whitehead Prod. Co., Inc. | Humble, TX 77338 | Oil & Gas Operator | Apr 2026 |
| 634 | Wichita Falls Oil Expl. Co. | Holliday, TX 76366 | Oil & Gas Operator | Jul 2026 |
| 635 | Williams Petroleum Company, Inc. | Burkburnett, TX 76354 | Oil & Gas Operator | Jul 2026 |
| 636 | Willis Operating Co. | Graham, TX 76450 | Oil & Gas Operator | Jul 2026 |
| 637 | Willowbend Investments, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Jul 2026 |
| 638 | Wilson, Olan Max | Cisco, TX 76437 | Oil & Gas Operator | Jul 2026 |
| 639 | Wilson, W.W. Jr. Properties | Abilene, TX 79605 | Oil & Gas Operator | Jul 1995 |
| 640 | Wise Exploration | Perrin, TX 76486 | Oil & Gas Operator | Jul 2026 |
| 641 | Wise Production Company | Bowie, TX 76230 | Oil & Gas Operator | Jul 2026 |
| 642 | Wise Well Service | Bowie, TX 76230 | Oil & Gas Operator | Jul 2017 |
| 643 | World Producers, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 1994 |
| 644 | Xplore Operating, LLC | Arlington, TX 76001 | Oil & Gas Operator | Jul 2026 |
| 645 | Xstar Resources LLC | Jacksboro, TX 76458 | Oil & Gas Operator | Jul 2026 |
| 646 | Yellow Rose Oil & Gas Oper. Inc. | Cisco, TX 76437 | Oil & Gas Operator | Jul 2026 |
| 647 | Young, Clint Inc. | Graham, TX 76450 | Oil & Gas Operator | Jul 2026 |