| 301 | Terra Production Company | Okemah, OK 74859-5924 | Oil & Gas Operator | Apr 2020 |
| 302 | Tex/Con Oil & Gas Company | Houston, TX 77074 | Oil & Gas Operator | Feb 2001 |
| 303 | Texaco Expl. And Prod. Inc. | Houston, TX 77236 | Oil & Gas Operator | May 2025 |
| 304 | TGX Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2004 |
| 305 | Tide West Oil Company | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2021 |
| 306 | Titan Resources LTD | Limaville, OH 44640 | Oil & Gas Operator | May 2025 |
| 307 | Tomlinson Oil Co. Inc. | Great Bend, KS 67530 | Oil & Gas Operator | Jan 2025 |
| 308 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 309 | Totalfinaelf E&P USA Inc | Houston, TX 77024 | Oil & Gas Operator | Jul 2007 |
| 310 | Transok LLC | Oklahoma City, OK 73124-0300 | Oil & Gas Operator | Jul 2020 |
| 311 | Trigg Drilling Company Inc | Oklahoma City, OK 73105 | Oil & Gas Operator | Jan 2013 |
| 312 | Trigger'S Disposal LLC | Sayre, OK 73662-2913 | Oil Operator | Sep 2022 |
| 313 | Triple "S" Gas, Inc. | Louisville, KY 40255 | Oil & Gas Operator | Jul 2025 |
| 314 | Trissell Alva Lee | Willow, OK 73673-9602 | Oil Operator | Apr 2020 |
| 315 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 316 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 317 | Unbridled Resources, LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 318 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 319 | Union Texas Petroleum Corp. | Houston, TX 77252-2120 | Oil & Gas Operator | Dec 2014 |
| 320 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Jul 2025 |
| 321 | United Energy Operating, LLC | Edmond, OK 73083 | Oil & Gas Operator | Jul 2025 |
| 322 | United Oil Corporation | Denver, CO 80202-3813 | Oil & Gas Operator | Apr 2025 |
| 323 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Jul 2025 |
| 324 | V S Oil Company | Burkburnett, TX 76354 | Oil & Gas Operator | Jul 2025 |
| 325 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Jul 2025 |
| 326 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Mar 2025 |
| 327 | Venis Exploration Company | Aledo, TX 76008 | Oil & Gas Operator | Oct 2024 |
| 328 | W M Energy Corp | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2015 |
| 329 | Wacker Oil Inc | Houston, TX 77002 | Oil & Gas Operator | Aug 1996 |
| 330 | Wagner & Brown | Midland, TX 79702 | Oil & Gas Operator | Aug 2014 |
| 331 | Wallace Oil & Gas Inc | Oklahoma City, OK 73156 | Oil & Gas Operator | Jul 2025 |
| 332 | Ward Petroleum Corporation | Enid, OK 73702 | Oil & Gas Operator | Apr 2025 |
| 333 | Warren American Oil Company LLC | Tulsa, OK 74147 | Oil & Gas Operator | Jul 2025 |
| 334 | Weststar Oil & Gas Inc | Edmond, OK 73013 | Oil & Gas Operator | May 2025 |
| 335 | Wildcat Cement Co. | Shamrock, TX 79079 | Oil & Gas Operator | May 2015 |
| 336 | Williams Doyle Dba BCF Gas | Tulsa, OK 74114-7099 | Oil & Gas Operator | Jul 2023 |
| 337 | Williford Energy Company | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2025 |
| 338 | Windsor Energy Group LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Aug 2021 |
| 339 | Wynn-Crosby Operating LP | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 340 | Xanadu Exploration Company | Broken Arrow, OK 74014 | Oil & Gas Operator | May 2025 |
| 341 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 342 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |
| 343 | Yale Oil Association, Inc. | Oklahoma City, OK 73105 | Oil & Gas Operator | May 2025 |
| 344 | Yarhola Production Company | Drumright, OK 74030 | Oil & Gas Operator | May 2025 |