| 401 | Vista Petroleum Corp | Houston, TX 77277 | Oil & Gas Operator | Dec 1996 |
| 402 | Wacker Oil Inc | Houston, TX 77002 | Oil & Gas Operator | Aug 1996 |
| 403 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2024 |
| 404 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 405 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 406 | Walter Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 407 | Wellstar Corporation | Northglenn, CO 80233 | Oil & Gas Operator | Feb 2024 |
| 408 | Western Energy Group, LLC | Leander, TX 78641 | Oil & Gas Operator | Apr 2024 |
| 409 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 410 | White Marlin Operating Company, LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 411 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Apr 2024 |
| 412 | Whitson, James A., Jr. | Houston, TX 77063 | Oil & Gas Operator | Nov 2011 |
| 413 | Williams Prod. Gulf Coast, L.P. | Benbrook, TX 76126 | Oil & Gas Operator | Jan 2012 |
| 414 | Wilson, Charles B., Jr., Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2000 |
| 415 | Wortham Oil & Gas | Conroe, TX 77301 | Oil & Gas Operator | Apr 2024 |
| 416 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2024 |
| 417 | Zachry Exploration, LLC | San Antonio, TX 78224 | Oil & Gas Operator | Apr 2024 |
| 418 | Zackson Resources, Inc. | Houston, TX 77063 | Oil & Gas Operator | Apr 2024 |
| 419 | Zenergy Inc | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2024 |
| 420 | Zinke & Trumbo, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2007 |
| 421 | Zinn Petroleum Co. | Houston, TX 77024 | Oil & Gas Operator | Nov 2021 |