| 501 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2025 |
| 502 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 503 | Wallis Energy, Inc. | Austin, TX 78746 | Oil & Gas Operator | Dec 2025 |
| 504 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 505 | Wayne E. Glenn Associates, Inc. | Dickinson, TX 77539 | Oil & Gas Operator | Jan 2016 |
| 506 | Welder Exploration & Prod., Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Dec 2022 |
| 507 | Western Global Oil, Inc | Deerfld Beach, FL 33442 | Oil Operator | Dec 2025 |
| 508 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 509 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Dec 2025 |
| 510 | White Stride LLC | Piedmont, OK 73078 | Oil & Gas Operator | Dec 2025 |
| 511 | Whittier Operating Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2007 |
| 512 | Wilcox Operating Corporation | Shreveport, LA 71115 | Oil & Gas Operator | Dec 2025 |
| 513 | Willstar Energy GP, LLC | Houston, TX 77279 | Oil & Gas Operator | Sep 2013 |
| 514 | WJW Operating Co.,LLC | Austin, TX 78738 | Oil & Gas Operator | May 2002 |
| 515 | Wolsey Well Service, Inc. | Windthorst, TX 76389 | Oil & Gas Operator | Jul 2006 |
| 516 | Wolsey Well Service, L.P. | Bowie, TX 76230 | Oil & Gas Operator | Jun 2014 |
| 517 | Wright Brothers Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Dec 2025 |
| 518 | Wright Brothers Petroleum, LTD. | San Antonio, TX 78212 | Oil & Gas Operator | May 2002 |
| 519 | Wynn-Crosby Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2005 |
| 520 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 521 | Xog Operating LLC | Midland, TX 79702 | Oil & Gas Operator | Dec 2025 |
| 522 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Dec 2025 |
| 523 | Zachry, H. B. Company | San Antonio, TX 78205 | Oil & Gas Operator | Apr 1994 |