| 601 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 602 | Wallis Energy, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jul 2025 |
| 603 | Wandoo Energy, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | Jul 2025 |
| 604 | Wapiti Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Jul 2006 |
| 605 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 606 | Weber Energy Corporation | Dallas, TX 75219 | Oil & Gas Operator | Feb 2017 |
| 607 | Weeks Exploration Company | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 608 | West Texas Syndicate LLC. | Corpus Chrsti, TX 78414 | Oil Operator | Jul 2025 |
| 609 | Westhall Associates, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Aug 1997 |
| 610 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 611 | Wharton Oil Co. | Vernon, TX 76384 | Oil & Gas Operator | Dec 2000 |
| 612 | Wheeler Operating Corporation | Fort Worth, TX 76101 | Oil & Gas Operator | Jul 2025 |
| 613 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Jul 2025 |
| 614 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 615 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 616 | WHL Oil Corp. | Houston, TX 77227 | Oil & Gas Operator | Sep 1998 |
| 617 | Wild Cat Operating Company | Victoria, TX 77903 | Oil & Gas Operator | Mar 2008 |
| 618 | Wilson Hydrocarbon Inc. | Houston, TX 77066 | Oil & Gas Operator | Jul 2025 |
| 619 | Wineland Oil - LLC | Hays, KS 67601 | Oil Operator | Mar 2025 |
| 620 | Wing Corporation | Houston, TX 77002 | Oil & Gas Operator | Jun 2000 |
| 621 | Winn Exploration Co., Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2025 |
| 622 | Wnu Energy LLC | Pinedale, WY 82941 | Oil & Gas Operator | May 2025 |
| 623 | Wofford, C. J. | El Campo, TX 77437 | Oil & Gas Operator | Jul 2025 |
| 624 | Wynn-Crosby Operating, LTD. | Dallas, TX 75201 | Oil & Gas Operator | Jul 2025 |
| 625 | Xplor Energy Operating Co. | Houston, TX 77079 | Oil & Gas Operator | Jan 2012 |
| 626 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |
| 627 | Yates Energy Corporation | Roswell, NM 88202 | Oil & Gas Operator | Jul 2025 |
| 628 | Young, John H., Inc. | Houston, TX 77027 | Oil & Gas Operator | Jul 2025 |
| 629 | Zachry Exploration, Inc. | San Antonio, TX 78205 | Oil & Gas Operator | Jul 2025 |
| 630 | Zaza Energy, LLC | Houston, TX 77010 | Oil & Gas Operator | Jul 2025 |
| 631 | Zinn Petroleum Co. | Houston, TX 77024 | Oil & Gas Operator | Nov 2021 |