| 601 | Wessely Energy Company | Dallas, TX 75206 | Oil & Gas Operator | May 2001 |
| 602 | Western Alliance Petroleum | | Oil & Gas Operator | Dec 1987 |
| 603 | Western Natural Gas | | Oil & Gas Operator | Aug 1974 |
| 604 | Western Resources And Clean Energy, LLC | Manti, UT 84642 | Oil & Gas Operator | Mar 2026 |
| 605 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 606 | Weststar Exploration Co | Houston, TX 77027 | Oil & Gas Operator | Jan 2026 |
| 607 | Wexpro Company | Rock Springs, WY 82902-0458 | Oil & Gas Operator | Mar 2026 |
| 608 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | May 2026 |
| 609 | Whitley, William W | Denver, CO 80209 | Oil & Gas Operator | Dec 1983 |
| 610 | Whitmar Exploration Company | Denver, CO 80202 | Oil & Gas Operator | Feb 2026 |
| 611 | Wildrose Resources Corp | Englewood, CO 80110-6007 | Oil & Gas Operator | Mar 2004 |
| 612 | Willard Pease Drilling Co | Grand Junction, CO 81501 | Oil & Gas Operator | Dec 1983 |
| 613 | William G Bush | Grand Junction, CO 81506 | Oil & Gas Operator | Jun 2012 |
| 614 | Williams Production RMT Company | Denver, CO 80202 | Oil & Gas Operator | Oct 2010 |
| 615 | Willstar Energy GP, LLC | Houston, TX 77279 | Oil & Gas Operator | Sep 2013 |
| 616 | Wilshire Oil Co. Of Texas | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2004 |
| 617 | Wind River Resources Corp | Park City, UT 84098 | Oil & Gas Operator | Jan 2020 |
| 618 | Winds Exploration And Production, LLC | Houston, TX 77032 | Gas Operator | Jan 2025 |
| 619 | Wintershall Oil & Gas Corp | Houston, TX 77027 | Oil & Gas Operator | Jul 1989 |
| 620 | Wold Oil Properties Inc | Denver, CO 80203 | Oil & Gas Operator | Feb 2018 |
| 621 | Wolverine Gas & Oil Company Of Utah, LLC | Grand Rapids, MI 49503-2616 | Oil & Gas Operator | Feb 2026 |
| 622 | Woosley, James P | Moab, UT 84532 | Oil & Gas Operator | Feb 2026 |
| 623 | Wrights Drilling | Cortez, CO 81321 | Oil & Gas Operator | Oct 1983 |
| 624 | XCL Assetco, LLC | Houston, TX 77007 | Oil & Gas Operator | Feb 2026 |
| 625 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2026 |
| 626 | Zinke & Trumbo LTD | Tulsa, OK 74105 | Oil & Gas Operator | Sep 2017 |
| 627 | Zoller & Danneberg Inc | Denver, CO 80203 | Oil & Gas Operator | May 1975 |