| 601 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 602 | Walker Energy Group | Houston, TX 77215-1089 | Oil & Gas Operator | Jun 1992 |
| 603 | Walker Explor & Prod Corp | Unknown, UT 99999 | Oil & Gas Operator | Dec 1989 |
| 604 | Wapiti Operating, LLC | Houston, TX 77043 | Oil & Gas Operator | Sep 2025 |
| 605 | Warren American Oil Co | Tulsa, OK 74147 | Oil & Gas Operator | Jul 2025 |
| 606 | Wasatch Oil & Gas Corp | Farmington, UT 84025-0699 | Oil & Gas Operator | Mar 2002 |
| 607 | Webb, Max D | Farmington, NM 87499 | Oil Operator | Dec 2022 |
| 608 | Weger Petroleum Corp | Dallas, TX 75251 | Oil Operator | Jan 1987 |
| 609 | Wem Operating, LLC | Provo, UT 84604 | Oil & Gas Operator | Jul 2025 |
| 610 | Wesco Operating, Inc. | Casper, WY 82602 | Oil & Gas Operator | Jul 2025 |
| 611 | Wesgra Corporation | Mexican Hat, UT 84531 | Oil & Gas Operator | Jun 2025 |
| 612 | Wessely Energy Company | Dallas, TX 75206 | Oil & Gas Operator | May 2001 |
| 613 | Western Alliance Petroleum | | Oil & Gas Operator | Dec 1987 |
| 614 | Western Natural Gas | | Oil & Gas Operator | Aug 1974 |
| 615 | Western Resources And Clean Energy, LLC | Manti, UT 84642 | Oil & Gas Operator | Aug 2025 |
| 616 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 617 | Weststar Exploration Co | Houston, TX 77027 | Oil & Gas Operator | Aug 2025 |
| 618 | Wexpro Company | Rock Springs, WY 82902-0458 | Oil & Gas Operator | Jul 2025 |
| 619 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2025 |
| 620 | Whitley, William W | Denver, CO 80209 | Oil & Gas Operator | Dec 1983 |
| 621 | Whitmar Exploration Company | Denver, CO 80202 | Oil & Gas Operator | Apr 2025 |
| 622 | Wildrose Resources Corp | Englewood, CO 80110-6007 | Oil & Gas Operator | Mar 2004 |
| 623 | Willard Pease Drilling Co | Grand Junction, CO 81501 | Oil & Gas Operator | Dec 1983 |
| 624 | William G Bush | Grand Junction, CO 81506 | Oil & Gas Operator | Jun 2012 |
| 625 | Williams Production RMT Company | Denver, CO 80202 | Oil & Gas Operator | Oct 2010 |
| 626 | Willstar Energy GP, LLC | Houston, TX 77279 | Oil & Gas Operator | Sep 2013 |
| 627 | Wilshire Oil Co. Of Texas | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2004 |
| 628 | Wind River Resources Corp | Park City, UT 84098 | Oil & Gas Operator | Jan 2020 |
| 629 | Winds Exploration And Production, LLC | Houston, TX 77032 | Gas Operator | Jan 2024 |
| 630 | Wintershall Oil & Gas Corp | Houston, TX 77027 | Oil & Gas Operator | Jul 1989 |
| 631 | Wold Oil Properties Inc | Denver, CO 80203 | Oil & Gas Operator | Feb 2018 |
| 632 | Wolverine Gas & Oil Company Of Utah, LLC | Grand Rapids, MI 49503-2616 | Oil & Gas Operator | Jul 2025 |
| 633 | Woosley, James P | Moab, UT 84532 | Oil & Gas Operator | May 2025 |
| 634 | Wrights Drilling | Cortez, CO 81321 | Oil & Gas Operator | Oct 1983 |
| 635 | XCL Assetco, LLC | Houston, TX 77007 | Oil & Gas Operator | Jun 2025 |
| 636 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Sep 2025 |
| 637 | Zinke & Trumbo LTD | Tulsa, OK 74105 | Oil & Gas Operator | Sep 2017 |
| 638 | Zoller & Danneberg Inc | Denver, CO 80203 | Oil & Gas Operator | May 1975 |