| 501 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 502 | Walter Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 503 | Warner Sisters, LLC | Thompsons Sta, TN 37179 | Oil Operator | Sep 2026 |
| 504 | Warwick-Artemis, LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Sep 2026 |
| 505 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 506 | Weeks Exploration Company | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 507 | Wejco, Inc. | Rising Star, TX 76471 | Oil & Gas Operator | Sep 2026 |
| 508 | Welder Exploration & Prod., Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Dec 2022 |
| 509 | Welderxp LTD. | San Antonio, TX 78212 | Oil & Gas Operator | Sep 2026 |
| 510 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 511 | Westport Oil And Gas Company Inc | Denver, CO 80202 | Oil & Gas Operator | Feb 2002 |
| 512 | WG Operating, Inc. | Tulsa, OK 74153 | Oil & Gas Operator | May 2012 |
| 513 | White Marlin Operating Company, LLC | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 514 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Sep 2026 |
| 515 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 516 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 517 | Wilbanks, Bruce A. | Midland, TX 79701 | Oil & Gas Operator | Aug 1996 |
| 518 | Wilco Properties, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Jan 2004 |
| 519 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Sep 2026 |
| 520 | Williams, Clayton Energy, L.L.C | Midland, TX 79705 | Oil & Gas Operator | May 1993 |
| 521 | Williams, Clayton W., Jr., Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 522 | Wilmoth Interests, Inc. | Marion Center, PA 15759 | Oil & Gas Operator | May 2026 |
| 523 | Wilson, Billy R. | New Braunfels, TX 78130 | Oil & Gas Operator | Sep 2026 |
| 524 | Winchester Energy, LLC | Houston, TX 77056 | Oil & Gas Operator | Sep 2026 |
| 525 | Winn Exploration Co., Inc. | Corpus Christ, TX 78401 | Oil & Gas Operator | Sep 2026 |
| 526 | Wnu Energy LLC | Pinedale, WY 82941 | Oil & Gas Operator | Jul 2026 |
| 527 | Wofford, C. J. | El Campo, TX 77437 | Oil & Gas Operator | Sep 2026 |
| 528 | Wolfe Oil Company | Stockdale, TX 78160 | Oil Operator | Sep 2026 |
| 529 | Wynn-Crosby Operating, LTD. | Dallas, TX 75201 | Oil & Gas Operator | Sep 2026 |
| 530 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Sep 2026 |
| 531 | Yarborough Oil & Gas L.P. | Midland, TX 79701 | Oil & Gas Operator | Oct 2000 |
| 532 | Yates Energy Corporation | Roswell, NM 88202 | Oil & Gas Operator | Sep 2026 |
| 533 | Zachry Exploration, LLC | San Antonio, TX 78224 | Oil & Gas Operator | Sep 2026 |
| 534 | Zarvona Energy LLC | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 535 | Zilkha Energy Company | Houston, TX 77046 | Oil & Gas Operator | Oct 2002 |
| 536 | Zinn Petroleum Co. | Houston, TX 77024 | Oil & Gas Operator | Nov 2021 |