| 601 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 602 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2025 |
| 603 | United Company | Lubbock, TX 79408 | Oil & Gas Operator | Jun 1995 |
| 604 | United Energy Trading LLC | Tulsa, OK 74133 | Oil & Gas Operator | Jan 2025 |
| 605 | Upland Production Company | Edmond, OK 73083 | Oil & Gas Operator | Apr 2025 |
| 606 | V-F Petroleum Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 607 | Valla Energy Corporation | Odessa, TX 79762 | Oil & Gas Operator | Aug 2003 |
| 608 | Vanguard Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Feb 2021 |
| 609 | Vanguard Permian LLC | Houston, TX 77057 | Oil & Gas Operator | Nov 2018 |
| 610 | Vencer Energy, LLC | Abilene, TX 79602 | Oil & Gas Operator | Dec 2023 |
| 611 | Venus Exploration, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2013 |
| 612 | Venus Oil Company | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2002 |
| 613 | Veritas Energy LLC | San Antonio, TX 78231 | Oil & Gas Operator | Apr 2025 |
| 614 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Jan 2025 |
| 615 | Vital Energy, Inc. | Tulsa, OK 74120 | Oil & Gas Operator | Apr 2025 |
| 616 | Walker, Kent | Midland, TX 79704 | Oil & Gas Operator | Jun 2004 |
| 617 | Walsh & Watts Inc | Aledo, TX 76008 | Oil & Gas Operator | Apr 2025 |
| 618 | Walton Properties LTD. | Midland, TX 79702 | Oil & Gas Operator | Feb 2004 |
| 619 | Warren, Earl T. | San Angelo, TX 76906 | Oil & Gas Operator | Apr 2025 |
| 620 | WCWB Energy, LLC | Midland, TX 79701 | Oil Operator | Sep 2015 |
| 621 | Westar Energy, Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 622 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 623 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 624 | WG Oil, LLC | Wichita Falls, TX 76308 | Oil Operator | Apr 2025 |
| 625 | WGR, Inc. | Houston, TX 77046 | Gas Operator | Jul 2007 |
| 626 | White'S Industrial Engine'S | Houston, TX 77070 | Oil & Gas Operator | Apr 2025 |
| 627 | Whiteman Industries, Inc. | Oklahoma City, OK 73101 | Oil & Gas Operator | Jun 2024 |
| 628 | Wilbanks, Bruce A. Company | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 629 | Wilco Properties, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Jan 2004 |
| 630 | Wildhorse Oil & Gas Corporation | Ardmore, OK 73402 | Oil & Gas Operator | May 2019 |
| 631 | Wildhorse Operating Company | Ardmore, OK 73402 | Oil & Gas Operator | Apr 2025 |
| 632 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Apr 2025 |
| 633 | Wilshire Oil Co. Of Texas | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2004 |
| 634 | Windsor Energy Group LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Aug 2021 |
| 635 | Windsor Permian LLC | Midland, TX 79701 | Oil & Gas Operator | Jun 2012 |
| 636 | Wiseman, B. W., Jr. | Midland, TX 79702 | Oil & Gas Operator | Dec 2002 |
| 637 | WTG Exploration | Midland, TX 79705 | Oil & Gas Operator | Apr 2025 |
| 638 | Xeric Oil & Gas Company | Midland, TX 79702 | Oil & Gas Operator | Jul 1997 |
| 639 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 640 | Xog Operating LLC | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 641 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2025 |
| 642 | Yates Energy Corporation | Roswell, NM 88202 | Oil & Gas Operator | Apr 2025 |
| 643 | Yegen E C | Casper, WY 82604 | Oil & Gas Operator | Mar 2015 |
| 644 | Zachry Oil And Gas Properties | Midland, TX 79708 | Oil & Gas Operator | Apr 2025 |
| 645 | Zarvona Energy LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |