| 601 | Whitmar Exploration Company | Denver, CO 80202 | Oil & Gas Operator | Dec 2023 |
| 602 | Wildrose Resources Corp | Englewood, CO 80110-6007 | Oil & Gas Operator | Mar 2004 |
| 603 | Willard Pease Drilling Co | Grand Junction, CO 81501 | Oil & Gas Operator | Dec 1983 |
| 604 | William G Bush | Grand Junction, CO 81506 | Oil & Gas Operator | Jun 2012 |
| 605 | Williams Production RMT Company | Denver, CO 80202 | Oil & Gas Operator | Oct 2010 |
| 606 | Willstar Energy GP, LLC | Houston, TX 77279 | Oil & Gas Operator | Sep 2013 |
| 607 | Wilshire Oil Co. Of Texas | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2004 |
| 608 | Wind River Resources Corp | Park City, UT 84098 | Oil & Gas Operator | Jan 2020 |
| 609 | Winds Exploration And Production, LLC | Houston, TX 77032 | Gas Operator | Jan 2024 |
| 610 | Wintershall Oil & Gas Corp | Houston, TX 77027 | Oil & Gas Operator | Jul 1989 |
| 611 | Wold Oil Properties Inc | Denver, CO 80203 | Oil & Gas Operator | Feb 2018 |
| 612 | Wolverine Gas & Oil Company Of Utah, LLC | Grand Rapids, MI 49503-2616 | Oil & Gas Operator | Jan 2024 |
| 613 | Wrights Drilling | Cortez, CO 81321 | Oil & Gas Operator | Oct 1983 |
| 614 | XCL Assetco, LLC | Houston, TX 77007 | Oil & Gas Operator | Jan 2024 |
| 615 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2024 |
| 616 | Zinke & Trumbo LTD | Tulsa, OK 74105 | Oil & Gas Operator | Sep 2017 |
| 617 | Zoller & Danneberg Inc | Denver, CO 80203 | Oil & Gas Operator | May 1975 |