| 401 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 402 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 403 | WCS Oil & Gas Corporation | Dallas, TX 75209 | Oil & Gas Operator | Aug 2021 |
| 404 | Weber Energy Corporation | Dallas, TX 75219 | Oil & Gas Operator | Feb 2017 |
| 405 | Welder Exploration & Prod., Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Dec 2022 |
| 406 | Welhausen Operating Company, LP | Beeville, TX 78104 | Oil & Gas Operator | Nov 2016 |
| 407 | Wen-Be | Jourdanton, TX 78026 | Oil & Gas Operator | Feb 2026 |
| 408 | Western Field Exploration, Inc. | Dilley, TX 78017 | Oil & Gas Operator | Feb 2026 |
| 409 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Feb 2026 |
| 410 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 411 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 412 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Feb 2026 |
| 413 | Williams, Clayton Energy, L.L.C | Midland, TX 79705 | Oil & Gas Operator | May 1993 |
| 414 | Williams, Clayton W., Jr., Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 415 | Windsor Exploration Company | Dallas, TX 75204 | Oil & Gas Operator | Jan 1994 |
| 416 | Wolco Energy, Inc. | Dallas, TX 75220 | Oil & Gas Operator | May 1997 |
| 417 | World Energy Corporation | Laredo, TX 78041 | Oil & Gas Operator | Aug 2003 |
| 418 | Wright Brothers Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Feb 2026 |
| 419 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Feb 2026 |
| 420 | Yarborough Oil & Gas L.P. | Midland, TX 79701 | Oil & Gas Operator | Oct 2000 |
| 421 | Young, Clint Inc. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 422 | Young, John H., Inc. | Houston, TX 77027 | Oil & Gas Operator | Feb 2026 |
| 423 | Zaf Oil | San Antonio, TX 78230 | Oil & Gas Operator | Aug 2002 |
| 424 | Zaza Energy, LLC | Houston, TX 77010 | Oil & Gas Operator | Feb 2026 |