| 601 | Western Sky Oil & Gas | Abilene, TX 79604 | Oil & Gas Operator | Aug 2003 |
| 602 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 603 | Westoil LLC | Austin, TX 78747 | Oil & Gas Operator | Jul 2025 |
| 604 | Weststar Oil & Gas Inc | Edmond, OK 73013 | Oil & Gas Operator | May 2025 |
| 605 | Westwin Energy I, LP | Midland, TX 79701 | Oil & Gas Operator | Aug 2003 |
| 606 | Westwood Energy, Inc. | Abilene, TX 79608 | Oil & Gas Operator | May 2013 |
| 607 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 608 | Williams Oil Company | Midland, TX 79710 | Oil & Gas Operator | Jul 2025 |
| 609 | Williams, A. Oil | Wichita Falls, TX 76308 | Oil Operator | Jul 2025 |
| 610 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Jul 2025 |
| 611 | Wilson Brothers Leasing Co., Inc | Midland, TX 79705 | Oil & Gas Operator | Mar 2015 |
| 612 | Wilson Energy LLC | Marietta, OH 45750 | Oil & Gas Operator | Dec 2024 |
| 613 | Wilson Exploration Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 1996 |
| 614 | Wilson, W. Corp. | Midland, TX 79705 | Oil & Gas Operator | Mar 1999 |
| 615 | Wilson, WM. B. Exploration Inc. | Midland, TX 79701 | Oil & Gas Operator | Jan 1996 |
| 616 | Winchester Energy, LLC | Houston, TX 77056 | Oil & Gas Operator | Jul 2025 |
| 617 | Wiser Oil Co | Denver, CO 80202 | Oil & Gas Operator | Dec 2023 |
| 618 | Wolverine Exploration Company | Houston, TX 77002 | Oil & Gas Operator | May 2019 |
| 619 | WVH Operating LLC | Aledo, TX 76008 | Oil Operator | Jul 2025 |
| 620 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 621 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |
| 622 | Zachry Oil And Gas Properties | Midland, TX 79708 | Oil & Gas Operator | Jul 2025 |