| 601 | WCWB Energy, LLC | Midland, TX 79701 | Oil Operator | Sep 2015 |
| 602 | Westar Energy, Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 603 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 604 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 605 | WGR, Inc. | Houston, TX 77046 | Gas Operator | Jul 2007 |
| 606 | White'S Industrial Engine'S | Houston, TX 77070 | Oil & Gas Operator | Apr 2024 |
| 607 | Whiteman Industries, Inc. | Oklahoma City, OK 73101 | Oil & Gas Operator | Jan 2024 |
| 608 | Wilbanks, Bruce A. Company | Midland, TX 79702 | Oil & Gas Operator | Apr 2024 |
| 609 | Wildhorse Oil & Gas Corporation | Ardmore, OK 73402 | Oil & Gas Operator | May 2019 |
| 610 | Wildhorse Operating Company | Ardmore, OK 73402 | Oil & Gas Operator | Apr 2024 |
| 611 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Apr 2024 |
| 612 | Wilshire Oil Co. Of Texas | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2004 |
| 613 | Windsor Energy Group LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Aug 2021 |
| 614 | Windsor Permian LLC | Midland, TX 79701 | Oil & Gas Operator | Jun 2012 |
| 615 | Wiseman, B. W., Jr. | Midland, TX 79702 | Oil & Gas Operator | Dec 2002 |
| 616 | WTG Exploration | Midland, TX 79705 | Oil & Gas Operator | Apr 2024 |
| 617 | Xeric Oil & Gas Company | Midland, TX 79702 | Oil & Gas Operator | Jul 1997 |
| 618 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 619 | Xog Operating LLC | Midland, TX 79702 | Oil & Gas Operator | Apr 2024 |
| 620 | Xri Disposal Holdings, LLC | Midland, TX 79701 | Oil & Gas Operator | Apr 2024 |
| 621 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2024 |
| 622 | Yates Energy Corporation | Roswell, NM 88202 | Oil & Gas Operator | Apr 2024 |
| 623 | Yegen E C | Casper, WY 82604 | Oil & Gas Operator | Mar 2015 |
| 624 | Zachry Oil And Gas Properties | Midland, TX 79708 | Oil & Gas Operator | Apr 2024 |
| 625 | Zarvona Energy LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |