| 501 | Wilco Properties, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Jan 2004 |
| 502 | Williams, Clayton Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | May 2025 |
| 503 | Williams, Clayton Energy, L.L.C | Midland, TX 79705 | Oil & Gas Operator | May 1993 |
| 504 | Williams, Clayton W., Jr., Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 505 | Wilmoth Interests, Inc. | Marion Center, PA 15759 | Oil & Gas Operator | Mar 2025 |
| 506 | Wilson, Billy R. | New Braunfels, TX 78130 | Oil & Gas Operator | May 2025 |
| 507 | Winchester Energy, LLC | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 508 | Winn Exploration Co., Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 509 | Wnu Energy LLC | Pinedale, WY 82941 | Oil & Gas Operator | Apr 2025 |
| 510 | Wofford, C. J. | El Campo, TX 77437 | Oil & Gas Operator | May 2025 |
| 511 | Wynn-Crosby Operating, LTD. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 512 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 513 | Yarborough Oil & Gas L.P. | Midland, TX 79701 | Oil & Gas Operator | Oct 2000 |
| 514 | Yates Energy Corporation | Roswell, NM 88202 | Oil & Gas Operator | May 2025 |
| 515 | Zachry Exploration, LLC | San Antonio, TX 78224 | Oil & Gas Operator | May 2025 |
| 516 | Zarvona Energy LLC | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 517 | Zilkha Energy Company | Houston, TX 77046 | Oil & Gas Operator | Oct 2002 |
| 518 | Zinn Petroleum Co. | Houston, TX 77024 | Oil & Gas Operator | Nov 2021 |