| 301 | Thomas Turman | | Oil & Gas Operator | Dec 1991 |
| 302 | Thornton Page Natural Gas | | Oil & Gas Operator | Dec 2024 |
| 303 | THT Operating Company | | Oil & Gas Operator | Jul 1990 |
| 304 | TMR Exploration, Inc. | Bossier City, LA 71171 | Oil & Gas Operator | Sep 2025 |
| 305 | Toc, Inc. (TN) | | Oil Operator | Apr 1995 |
| 306 | Tradestar Energy, Inc. | Hot Springs, AR 71913 | Oil Operator | Feb 2021 |
| 307 | Transfuel Resources Co | Houston, TX 77215 | Oil & Gas Operator | Aug 2013 |
| 308 | Tredegar Properties, Inc. | | Oil Operator | Jun 1990 |
| 309 | Trendsetter Production Co, Inc | | Oil & Gas Operator | Jul 2008 |
| 310 | Trich Production, Inc. | Longview, TX 75606 | Oil & Gas Operator | Jan 2025 |
| 311 | Trichel Contracting Company | | Oil & Gas Operator | Sep 1987 |
| 312 | Trident Oil & Gas Corp. | | Oil & Gas Operator | Sep 2000 |
| 313 | Trinidad Petroleum Corporation | | Oil & Gas Operator | Apr 1990 |
| 314 | Triple J Investments Inc | Longview, TX 75606 | Oil & Gas Operator | Feb 2023 |
| 315 | Tundra Energy | | Oil Operator | Jan 2025 |
| 316 | Tundra Operating LLC | Spring, TX 77386 | Oil Operator | May 2017 |
| 317 | TWC Oil Company, Inc. | | Oil Operator | Jan 2025 |
| 318 | Twiner Oil & Gas Corporation | | Oil & Gas Operator | Oct 1988 |
| 319 | United Gas Pipe Line Co. | | Oil Operator | Aug 1993 |
| 320 | Universal Producers, Inc. | | Oil Operator | Jun 2001 |
| 321 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Jan 2026 |
| 322 | Vision Natural Res-La, LLC | | Oil Operator | Dec 2024 |
| 323 | Voyager Energy, LLC | | Oil & Gas Operator | Dec 2010 |
| 324 | W & C Oil & Gas | | Oil Operator | Feb 1996 |
| 325 | W D L Enterprises, Inc | | Oil & Gas Operator | Apr 1983 |
| 326 | W&T Offshore, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2026 |
| 327 | W. H. Hunt, Et Al | | Oil & Gas Operator | Jul 1990 |
| 328 | W. L. Rambo | | Oil Operator | Apr 1981 |
| 329 | W. L. Rambo, Inc. | | Oil & Gas Operator | Aug 1985 |
| 330 | W. Trich & Hallwell, Inc. | | Oil & Gas Operator | Oct 1988 |
| 331 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 332 | Walter W. Heard, Jr. | | Oil & Gas Operator | Dec 1995 |
| 333 | Wenert Trich | | Oil & Gas Operator | Oct 1988 |
| 334 | Westar Oil & Minerals | | Oil Operator | Feb 1999 |
| 335 | White Oil Company | Cement, OK 73017-0515 | Oil Operator | Jun 2002 |
| 336 | White River Operating LLC | Gilmer, TX 75644 | Oil & Gas Operator | Jan 2026 |
| 337 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 338 | Wicker Oil Co | | Oil & Gas Operator | Feb 1992 |
| 339 | Wildcat Equipment Co. Inc. | | Oil Operator | Dec 1987 |
| 340 | Wildcat Well Services, LTD. | | Oil Operator | Oct 1989 |
| 341 | Williams-Robinson | | Oil Operator | Mar 1988 |
| 342 | Windham Oil Corp. | | Oil & Gas Operator | Dec 2024 |
| 343 | Woodpecker Corp. | | Oil & Gas Operator | Dec 2024 |
| 344 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2026 |
| 345 | Zad, Inc. | | Oil Operator | May 2001 |
| 346 | Zercon Oil & Gas, Inc. | | Oil Operator | Oct 2003 |
| 347 | Zilkha Energy Company | Houston, TX 77046 | Oil & Gas Operator | Oct 2002 |