| 501 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 502 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 503 | Walter Exploration Company | Dallas, TX 75206 | Oil & Gas Operator | Mar 2025 |
| 504 | Walter Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | May 2009 |
| 505 | Walter Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 506 | Wandoo Energy, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | Mar 2025 |
| 507 | Weathers Exploration, Inc. | Tyler, TX 75702 | Oil & Gas Operator | Mar 2025 |
| 508 | Weeks Exploration Company | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 509 | Westhall Associates, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Aug 1997 |
| 510 | Wheeler Operating Corporation | Fort Worth, TX 76101 | Oil & Gas Operator | Mar 2025 |
| 511 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Mar 2025 |
| 512 | Whitehead Prod. Co., Inc. | Humble, TX 77338 | Oil & Gas Operator | Dec 2024 |
| 513 | Wilco Properties, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Jan 2004 |
| 514 | Wing Corporation | Houston, TX 77002 | Oil & Gas Operator | Jun 2000 |
| 515 | Wofford, C. J. | El Campo, TX 77437 | Oil & Gas Operator | Mar 2025 |
| 516 | Wright Brothers Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Mar 2025 |
| 517 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Mar 2025 |
| 518 | Yuma E & P Company, Inc. | Houston, TX 77027 | Oil & Gas Operator | Mar 2025 |
| 519 | Yuma Petroleum Company | Houston, TX 77027 | Oil & Gas Operator | Aug 2002 |
| 520 | Zachry Exploration, Inc. | San Antonio, TX 78205 | Oil & Gas Operator | Mar 2025 |
| 521 | Zachry Exploration, LLC | San Antonio, TX 78224 | Oil & Gas Operator | Mar 2025 |
| 522 | Zachry Exploration, LTD. | San Antonio, TX 78205 | Oil & Gas Operator | Jan 2009 |
| 523 | Zinn Petroleum Co. | Houston, TX 77024 | Oil & Gas Operator | Nov 2021 |