| 301 | Atkinson WM H Estate | Oklahoma City, OK 73156 | Oil & Gas Operator | Nov 2001 |
| 302 | Atlanko Oil & Gas Inc | Tulsa, OK 74135-7846 | Oil & Gas Operator | Aug 2025 |
| 303 | Atlantic Richfield Company | Plano, TX 75074 | Oil & Gas Operator | Dec 2016 |
| 304 | Atlas Oil Inc | Oklahoma City, OK 73154-0467 | Oil & Gas Operator | Aug 2008 |
| 305 | Atlas Operating LLC | Houston, TX 77056 | Oil & Gas Operator | Dec 2025 |
| 306 | Atls Production Company LLC | Fort Worth, TX 76102-7426 | Gas Operator | Sep 2020 |
| 307 | Atteberry Engineering | Edmond, OK 73013-6624 | Oil & Gas Operator | Mar 2008 |
| 308 | Atwell, David L. | Duncan, OK 73533 | Oil & Gas Operator | Jul 2003 |
| 309 | Austex Energy, Inc. | Granbury, TX 76048 | Oil & Gas Operator | Apr 1993 |
| 310 | Austin Production Company, Inc. | Dallas, TX 75219 | Oil & Gas Operator | Mar 2015 |
| 311 | Austin Robert L | Stafford, KS 67578 | Oil & Gas Operator | Dec 1999 |
| 312 | Autumn Exploration LTD | Tulsa, OK 74136 | Oil & Gas Operator | Apr 2015 |
| 313 | Avalanche Oil & Gas LLC | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2025 |
| 314 | Avalon Exploration Inc | Tulsa, OK 74119-5401 | Oil & Gas Operator | Dec 2019 |
| 315 | Avalon Operating LLC | Tulsa, OK 74119-5401 | Oil & Gas Operator | Sep 2025 |
| 316 | Avant Jack E | Skiatook, OK 74070 | Oil Operator | Jan 2013 |
| 317 | Avatar Energy LLC | Dallas, TX 75220-2230 | Oil & Gas Operator | Jul 2016 |
| 318 | Aven Gas & Oil Inc | Oklahoma City, OK 73113-0491 | Oil & Gas Operator | Nov 2021 |
| 319 | Avers Harvey G Energy Expl | | Oil & Gas Operator | May 2013 |
| 320 | Avondale Operating Co | Tulsa, OK 74145-7627 | Oil & Gas Operator | Apr 2019 |
| 321 | Avra Oil Co | Dallas, TX 75248 | Oil & Gas Operator | Dec 2025 |
| 322 | Aw Hembree Co | Shawnee, OK 74802-1725 | Oil & Gas Operator | Aug 2025 |
| 323 | Axem Resources Inc | Denver, CO 80202-4617 | Oil & Gas Operator | Jul 2013 |
| 324 | Axeon Energy Operations LLC | Evergreen, CO 80439-7624 | Oil Operator | Jul 2015 |
| 325 | Axia Energy III LLC | Highlands Ranch, CO 80129 | Oil & Gas Operator | Aug 2025 |
| 326 | Axis Energy Corporation | Roswell, NM 88202 | Oil & Gas Operator | Dec 2025 |
| 327 | Aycox Robert D | Healdton, OK 73438 | Oil Operator | Sep 2022 |
| 328 | Ayluma Operating Inc | Dewar, OK 74437 | Oil & Gas Operator | Oct 2024 |
| 329 | Azar Marsha | Chicago, IL 60618 | Oil Operator | Jan 2025 |
| 330 | Aztec Exploration Inc | Oklahoma City, OK 73143 | Oil & Gas Operator | May 2013 |
| 331 | Azure Energy LTD | Tulsa, OK 74135-7825 | Oil & Gas Operator | Sep 2025 |