| 301 | Logan Oil, LLC | | Oil & Gas Operator | May 2010 |
| 302 | Louisiana Land & Exploration Co. | Houston, TX 77210 | Oil & Gas Operator | Sep 2013 |
| 303 | LPB Oil Company | | Oil & Gas Operator | Apr 1991 |
| 304 | Lyle Cashion Company | | Oil & Gas Operator | Sep 1989 |
| 305 | Lynx Operating Co., Inc. | Dallas, TX 75206 | Oil & Gas Operator | Oct 2025 |
| 306 | Mammoth Service Group, LLC | | Oil & Gas Operator | Jun 2025 |
| 307 | Manchester Oil Co | | Oil Operator | Jan 2000 |
| 308 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Aug 2025 |
| 309 | Marion Corporation | | Oil & Gas Operator | Jan 2001 |
| 310 | Marlin Exploration, LLC | | Oil & Gas Operator | Jul 2025 |
| 311 | Marshall Production Co Inc | | Oil & Gas Operator | Jun 1989 |
| 312 | Marshall Young Oil Co | | Oil & Gas Operator | Jan 2007 |
| 313 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 314 | McGoldrick Oil Company | Shreveport, LA 71129 | Oil & Gas Operator | Jul 2020 |
| 315 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Oct 2025 |
| 316 | Meason Oper. Co. For Cinco Energy Corp. | | Oil & Gas Operator | Sep 2000 |
| 317 | Meason Operating Company | Natchez, MS 39121 | Oil & Gas Operator | Dec 2011 |
| 318 | Meng Oper. & Expl. Co. | | Oil & Gas Operator | Dec 1989 |
| 319 | Merit Field LLC | | Oil & Gas Operator | Dec 2001 |
| 320 | Meyer, Ruskin H. Et Al | | Oil Operator | Oct 1980 |
| 321 | Midco Energy, Inc. | | Oil & Gas Operator | Dec 1992 |
| 322 | Midroc Oil Company Et Al | | Oil Operator | Nov 1984 |
| 323 | Midroc Operating Company | | Oil & Gas Operator | Apr 2013 |
| 324 | Midstate Energy Inc | | Oil & Gas Operator | Aug 2017 |
| 325 | Miller Exploration Company | Tulsa, OK 74136-1020 | Oil & Gas Operator | Mar 2015 |
| 326 | Miss Basin Oil & Gas Company | | Oil Operator | Jan 1985 |
| 327 | Miss Lou Oil Producers, Inc. | | Oil & Gas Operator | Dec 1998 |
| 328 | Miss-Lou Operating LLC | | Oil & Gas Operator | Jul 2025 |
| 329 | Missala Inc | | Oil & Gas Operator | Dec 1995 |
| 330 | Mississippi Valley Gas Co | | Oil & Gas Operator | Aug 1984 |
| 331 | Mitchell And R. E. Mitchel | | Oil Operator | Feb 2000 |
| 332 | Mitchell Resources, Inc. | Addison, TX 75001 | Oil & Gas Operator | Aug 2003 |
| 333 | Mize Energy Producers, LLC | | Oil & Gas Operator | Jul 2025 |
| 334 | Mize Operations, LLC. | | Oil & Gas Operator | Dec 2018 |
| 335 | Mobil Oil Expl & Prod S E | | Oil & Gas Operator | Dec 1979 |
| 336 | Moon-Hines-Tigrett Operating Co., Inc. | | Oil & Gas Operator | Jun 2025 |
| 337 | Morris Operating Co | Lovington, NM 88260 | Oil & Gas Operator | Oct 2025 |
| 338 | Morrow Oil & Gas Co. | Terry, MS 39170 | Oil & Gas Operator | Jul 2025 |
| 339 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 340 | MS United, LLC | | Oil & Gas Operator | Apr 2025 |
| 341 | MT. Crescent Operating Company, LLC | | Oil & Gas Operator | Jul 2025 |
| 342 | Mullen Exploration Inc | | Oil & Gas Operator | Dec 2002 |
| 343 | Mullen-Hathorn-Bass | | Oil & Gas Operator | Mar 1985 |
| 344 | Murphy Oil USA Inc | New Orleans, LA 70161 | Oil & Gas Operator | Jan 1993 |
| 345 | Natchez Operating, LLC | | Oil & Gas Operator | Nov 2023 |
| 346 | Natchez Pipe & Equip. Co., Inc | | Oil Operator | Nov 1981 |
| 347 | Nevanen Energy, Inc. | | Oil & Gas Operator | Dec 2022 |
| 348 | New & Brasher | | Oil Operator | Mar 1982 |
| 349 | New Horizon Resources LLC | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 350 | New York Petroleum Corp. | | Oil & Gas Operator | Nov 1982 |
| 351 | Northland Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Apr 2003 |
| 352 | Norton Oil Co. | | Oil & Gas Operator | Jun 1984 |
| 353 | O'Brien Resources LLC | Shreveport, LA 71136 | Oil Operator | Nov 2017 |
| 354 | O'Malley Production Co. Inc. | | Oil & Gas Operator | Mar 1988 |
| 355 | Odom, Claude | | Oil Operator | Jul 1983 |
| 356 | Odyssey Petroleum Corp. | | Oil & Gas Operator | Jun 2011 |
| 357 | Ogden Oil Co., Inc. | | Oil Operator | May 1981 |
| 358 | Oglesby Oil Company | | Oil & Gas Operator | Nov 2023 |
| 359 | Oglesby Prod & Expl Co Inc | | Oil & Gas Operator | Nov 1987 |
| 360 | Oilfield Services And Supply Co. Inc. | | Oil Operator | Sep 1989 |
| 361 | Oilwell Acquisition Co. | | Oil & Gas Operator | Jun 1999 |
| 362 | Orion Energy Partners LP | Denver, CO 80202 | Oil & Gas Operator | Nov 2010 |
| 363 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 364 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Aug 2025 |
| 365 | Owco Production Co., Inc. | | Oil Operator | Aug 1997 |
| 366 | Owl Creek Production Co., Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2006 |
| 367 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |
| 368 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 369 | P.R.P., Inc. | | Oil & Gas Operator | Jun 2025 |
| 370 | Pacesetter Energy, Inc. | Flower Mound, TX 75028 | Oil & Gas Operator | May 2008 |
| 371 | Palmer Petroleum Inc. | Shreveport, LA 71105 | Oil & Gas Operator | Jun 2025 |
| 372 | Paloma Natural Gas, LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2024 |
| 373 | Par Minerals Corporation | Shreveport, LA 71101 | Oil & Gas Operator | Oct 2025 |
| 374 | Par-Co Drilling Inc. | | Oil Operator | Dec 2023 |
| 375 | Paradigm Energy-Mississippi, LLC | | Oil Operator | Jun 2025 |
| 376 | Parish Operating LLC | | Oil Operator | Jun 2025 |
| 377 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 378 | Peak Energy Co Inc | | Oil & Gas Operator | Mar 1985 |
| 379 | Penn VIrginia Oil & Gas Corp | Houston, TX 77024 | Oil & Gas Operator | Dec 2023 |
| 380 | Pennzoil Expl & Prod Co -TX | | Oil & Gas Operator | May 1993 |
| 381 | Pennzoil Expl & Prod Co. -MS | | Oil Operator | Jan 1988 |
| 382 | Pennzoil Producing Company | | Oil & Gas Operator | Oct 1992 |
| 383 | Petra, Inc. | | Oil & Gas Operator | Apr 1987 |
| 384 | Petro Harvester Operating Company, LLC | | Oil & Gas Operator | Nov 2022 |
| 385 | Petro Producers Corporation | | Oil & Gas Operator | Mar 1993 |
| 386 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 387 | Petrocan, Inc. | | Oil & Gas Operator | Apr 1998 |
| 388 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 389 | Petroleum Development LLC | | Oil Operator | Jul 2018 |
| 390 | Petroleum Management, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Oct 2025 |
| 391 | Petrotx Operating, LLC | Kingwood, TX 77339 | Oil & Gas Operator | Oct 2025 |
| 392 | PF Operating Company | Wichita Falls, TX 76302 | Oil & Gas Operator | Aug 2003 |
| 393 | Phoenix Operating, Inc | | Oil & Gas Operator | Jul 2025 |
| 394 | Phoenix Petroleum Corp. | | Gas Operator | Aug 1985 |
| 395 | Pine Ridge Operating, L.P. | Waelder, TX 78959 | Oil & Gas Operator | Oct 2025 |
| 396 | Pistol Ridge Partners, LLC | | Oil & Gas Operator | Jun 2025 |
| 397 | Pita Oil & Gas, LLC | | Oil Operator | Jul 2004 |
| 398 | Pittman, Joe N. | | Oil & Gas Operator | Apr 1985 |
| 399 | Pitts, W. C. | | Oil Operator | Jan 1988 |
| 400 | Placid Oil Company | Houston, TX 77227 | Oil & Gas Operator | Mar 2008 |