| 601 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2024 |
| 602 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 603 | Walter Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 604 | Warhorse Oil & Gas, LLC | | Oil & Gas Operator | Dec 2018 |
| 605 | Watson Energy, L.L.C. | | Oil & Gas Operator | Jun 2005 |
| 606 | WCC Energy Group LLC | | Oil & Gas Operator | Dec 2023 |
| 607 | Weaver Expl & Brock Pet Corp | | Oil & Gas Operator | Apr 1983 |
| 608 | Weaver Exploration Company | | Oil & Gas Operator | Jun 1991 |
| 609 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 610 | White Marlin Operating Company, LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 611 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Apr 2024 |
| 612 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Feb 2024 |
| 613 | Whitton Company, Inc. | | Oil & Gas Operator | Jul 2020 |
| 614 | WHK, Inc. | | Oil & Gas Operator | Oct 1993 |
| 615 | Williams-Cody, Inc. | Houston, TX 77060 | Oil & Gas Operator | May 1994 |
| 616 | Wintershall Corporation | | Oil & Gas Operator | Oct 1989 |
| 617 | Wintershall Oil & Gas Corp | Houston, TX 77027 | Oil & Gas Operator | Jul 1989 |
| 618 | Wolverine Exploration Company | Houston, TX 77002 | Oil & Gas Operator | May 2019 |
| 619 | WRT Energy Corporation | Oklahoma City, OK 73118 | Oil & Gas Operator | May 1998 |
| 620 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2024 |
| 621 | Zadeck Energy Group Inc | | Oil & Gas Operator | Jun 2013 |
| 622 | Zinke & Trumbo, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2007 |