| 501 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | May 2024 |
| 502 | Whittier Operating Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2007 |
| 503 | Wilcox Operating Corporation | Shreveport, LA 71115 | Oil & Gas Operator | May 2024 |
| 504 | Willstar Energy GP, LLC | Houston, TX 77279 | Oil & Gas Operator | Sep 2013 |
| 505 | WJW Operating Co.,LLC | Austin, TX 78738 | Oil & Gas Operator | May 2002 |
| 506 | Wolsey Well Service, Inc. | Windthorst, TX 76389 | Oil & Gas Operator | Jul 2006 |
| 507 | Wolsey Well Service, L.P. | Bowie, TX 76230 | Oil & Gas Operator | Jun 2014 |
| 508 | Wright Brothers Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | May 2024 |
| 509 | Wright Brothers Petroleum, LTD. | San Antonio, TX 78212 | Oil & Gas Operator | May 2002 |
| 510 | Wynn-Crosby Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2005 |
| 511 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 512 | Xog Operating LLC | Midland, TX 79702 | Oil & Gas Operator | May 2024 |
| 513 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2024 |