| 301 | Superior Oil Co. | Denver, CO 80217-5444 | Oil & Gas Operator | Feb 2001 |
| 302 | Synergy Oil & Gas, L.P. | Houston, TX 77024 | Oil & Gas Operator | May 2012 |
| 303 | Taurus Petroleum | | Oil & Gas Operator | Jul 1987 |
| 304 | Terra Resources, Inc. | Casper, WY 82601 | Oil & Gas Operator | Jun 1990 |
| 305 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Oct 2025 |
| 306 | Texaco Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2017 |
| 307 | Texaco Producing Inc. | Rock Springs, WY 82901 | Oil & Gas Operator | Dec 2000 |
| 308 | Texas Eastern Transm. Corp. | | Oil & Gas Operator | Dec 2002 |
| 309 | Texoil Company | | Oil & Gas Operator | Dec 2000 |
| 310 | The B&C Corp-Imp Amer MGT Co | | Oil & Gas Operator | Aug 1981 |
| 311 | The Dow Chemical Company | | Oil & Gas Operator | Dec 1997 |
| 312 | Tiger Oil Company | Dallas, TX 75221 | Oil & Gas Operator | May 2007 |
| 313 | Tiger Oil International, Inc | | Oil & Gas Operator | Dec 1978 |
| 314 | Tiger Petroleum | | Oil Operator | Sep 2002 |
| 315 | Tipco | Shreveport, LA 71104-3047 | Oil & Gas Operator | May 1988 |
| 316 | Toce Energy, L.L.C. | | Oil & Gas Operator | Dec 2017 |
| 317 | Toce Oil Company | | Oil & Gas Operator | Dec 2014 |
| 318 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 319 | Total Minatome Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 1998 |
| 320 | Tradition Resources Oper, LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2017 |
| 321 | Transcontinental Gas P/L Corp. | | Oil & Gas Operator | Dec 2009 |
| 322 | Transcontinental Gas Pipeline Co LLC | | Oil Operator | Jan 2025 |
| 323 | Tribal Oil Company | | Oil & Gas Operator | Dec 1981 |
| 324 | Triumph Energy, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Nov 2015 |
| 325 | TXP Operating Company | | Oil & Gas Operator | Jul 1992 |
| 326 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 327 | Union Gas Operating Company | Houston, TX 77014 | Oil & Gas Operator | Oct 2025 |
| 328 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 329 | United Gas Pipe Line Co. | | Oil Operator | Aug 1993 |
| 330 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Oct 2025 |
| 331 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Jun 2025 |
| 332 | Vermilion Resources, Inc. | Houston, TX 77060 | Oil & Gas Operator | Sep 2009 |
| 333 | Vernon E. Faulconer | | Oil & Gas Operator | Dec 1996 |
| 334 | Vernon E. Faulconer, Inc. | Tyler, TX 75711 | Oil & Gas Operator | Dec 2024 |
| 335 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 336 | Vistatex Energy LLC | Houston, TX 77057 | Oil & Gas Operator | Jun 2025 |
| 337 | W & T Oil Properties, Inc. | | Oil & Gas Operator | Nov 1989 |
| 338 | W. A. Moncrief | | Oil & Gas Operator | Jun 2010 |
| 339 | W. A. Moncrief, Jr. | Fort Worth, TX 76102 | Oil & Gas Operator | Aug 2025 |
| 340 | W. G. Darsey, III | | Oil & Gas Operator | Nov 1981 |
| 341 | W. L. Estis | | Oil & Gas Operator | Dec 1999 |
| 342 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 343 | Walter Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 344 | Wapiti Operating, LLC | Houston, TX 77043 | Oil & Gas Operator | Oct 2025 |
| 345 | Warhorse Oil & Gas, LLC | | Oil & Gas Operator | Dec 2018 |
| 346 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 347 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Oct 2025 |
| 348 | White River Operating LLC | Gilmer, TX 75644 | Oil & Gas Operator | Jul 2025 |
| 349 | Whitton Company, Inc. | | Oil & Gas Operator | Jul 2020 |
| 350 | Windfohr Oil Company | | Oil & Gas Operator | May 1980 |
| 351 | Wle, Inc. | | Oil & Gas Operator | Feb 2012 |
| 352 | Woods Petroleum Corporation | Oklahoma City, OK 73112 | Oil & Gas Operator | Mar 2015 |
| 353 | Yasny Corporation | | Oil Operator | Nov 1991 |
| 354 | Zadeck Energy Group Inc | | Oil & Gas Operator | Dec 2011 |
| 355 | Zone Energy, LLC | Houston, TX 77251 | Oil & Gas Operator | Jan 2025 |