| 301 | McMoran Production Co. | | Oil & Gas Operator | May 1985 |
| 302 | MCZ, Inc. | Houston, TX 77026 | Oil & Gas Operator | Sep 1990 |
| 303 | Medders Oil Company | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2026 |
| 304 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 305 | Merlin J Verret | | Gas Operator | Jun 1986 |
| 306 | Mideast Gas Systems, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 2005 |
| 307 | Midstates Petroleum Company LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2018 |
| 308 | Midstates Petroleum Corp. | | Oil & Gas Operator | Dec 2008 |
| 309 | Miller Oil Field Services, Inc | | Oil Operator | Feb 1990 |
| 310 | Minatome Corpora | | Oil & Gas Operator | Sep 1987 |
| 311 | Miss-Lou Operating LLC | | Oil & Gas Operator | Dec 2025 |
| 312 | Miss-Lou Petroleum LLC | | Oil & Gas Operator | Jun 2011 |
| 313 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 314 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 315 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 316 | Mobil Oil E & P Southeast Inc | | Oil & Gas Operator | Sep 2013 |
| 317 | Moore McCormack Energy, Inc. | | Oil & Gas Operator | Jul 1988 |
| 318 | Moran Exploration, Inc. | | Oil & Gas Operator | Jan 1985 |
| 319 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 320 | Murchison Oil & Gas Inc | Plano, TX 75024 | Oil & Gas Operator | Aug 2020 |
| 321 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 322 | National Exploration Company | | Oil & Gas Operator | Mar 1982 |
| 323 | National Offshore LP | Oklahoma City, OK 73154 | Oil & Gas Operator | Mar 2008 |
| 324 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Aug 2025 |
| 325 | Nerco Oil & Gas Inc | | Oil & Gas Operator | Dec 1996 |
| 326 | Neumin Production Company | Point Comfort, TX 77978 | Oil & Gas Operator | Feb 2026 |
| 327 | New Century Exploration, Inc. | Spring, TX 77379 | Oil & Gas Operator | Feb 2026 |
| 328 | Newhaven Operating Inc | | Oil & Gas Operator | Dec 1998 |
| 329 | Newport Operators, LLC | | Oil & Gas Operator | Jan 2019 |
| 330 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Feb 2026 |
| 331 | Norcen Explorer, Inc. | Houston, TX 77079 | Oil & Gas Operator | May 1998 |
| 332 | Northland Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Apr 2003 |
| 333 | NRG Resources, Inc. | Houston, TX 77057 | Oil & Gas Operator | Jun 1987 |
| 334 | Nucorp Energy, Inc. | | Oil & Gas Operator | Jan 1985 |
| 335 | Occidental Energy Company, Inc. | Houston, TX 77282 | Oil & Gas Operator | Jul 2021 |
| 336 | Ody Oil Corp. | | Oil & Gas Operator | Oct 1994 |
| 337 | Oil Well Buyers Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 2024 |
| 338 | Oleum Inc | | Oil & Gas Operator | Mar 1996 |
| 339 | Oleum Operating Company, L.C. | Longview, TX 75606 | Oil & Gas Operator | Dec 2021 |
| 340 | Oleum Operating La LLC | | Oil & Gas Operator | Nov 2022 |
| 341 | Olipdp II, LLC | Lafayette, LA 70503 | Oil & Gas Operator | Feb 2026 |
| 342 | Olympic Petroleum Co | Tulsa, OK 74114 | Oil & Gas Operator | Jun 1998 |
| 343 | Olympic Production Company | | Oil & Gas Operator | Jul 1994 |
| 344 | Omeara Bros. | | Oil & Gas Operator | Oct 1982 |
| 345 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 346 | Orion Oil & Gas, LLC | Houston, TX 77042 | Oil & Gas Operator | Oct 2007 |
| 347 | Orx Resources, L.L.C. | Houston, TX 77067 | Oil & Gas Operator | Feb 2026 |
| 348 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 349 | Output Acquisition Corp. | | Oil & Gas Operator | Jul 2010 |
| 350 | Oxtex Inc | | Oil & Gas Operator | Oct 1989 |
| 351 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 352 | P. B. Operating Company | | Oil & Gas Operator | Feb 1978 |
| 353 | Panaco, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Aug 2025 |
| 354 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 355 | Parker & Parsley Devpt L P | | Oil & Gas Operator | Oct 1997 |
| 356 | Parker & Parsley Petroleum Co. | | Oil & Gas Operator | Dec 1990 |
| 357 | Paul M. Toce | | Oil & Gas Operator | Jul 1984 |
| 358 | Pedernales Production, LP | Houston, TX 77057 | Oil & Gas Operator | Mar 2022 |
| 359 | Pelto Oil Company | Houston, TX 77002 | Oil & Gas Operator | Nov 1998 |
| 360 | Penn VIrginia Oil & Gas Corp | Houston, TX 77024 | Oil & Gas Operator | Dec 2023 |
| 361 | Penn VIrginia Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Nov 2022 |
| 362 | Peoples Energy Prod.-TX, L.P. | Houston, TX 77002 | Oil & Gas Operator | Sep 2007 |
| 363 | Permeator Corp. | | Oil Operator | Sep 1990 |
| 364 | Peterman-Sturlese Et Al | | Oil & Gas Operator | Sep 1987 |
| 365 | Petro Harvester Operating Company, LLC | | Oil & Gas Operator | Nov 2022 |
| 366 | Petro-Assets Corporation | | Oil & Gas Operator | Feb 2000 |
| 367 | Petro-Lewis Corp. | | Oil & Gas Operator | Feb 1994 |
| 368 | Petrocana,Inc. | | Oil & Gas Operator | Aug 1993 |
| 369 | Petrodome Operating, LLC | Houston, TX 77265 | Oil & Gas Operator | May 2025 |
| 370 | Petroleum Corp Of Delaware The | | Oil & Gas Operator | May 1991 |
| 371 | Petroleum Resources MGMT Corp. | | Oil & Gas Operator | Mar 2002 |
| 372 | Petrotex Engineering Company | Cypress, TX 77429 | Oil & Gas Operator | Feb 2026 |
| 373 | Petrotex Louisiana Company | | Oil & Gas Operator | Aug 1998 |
| 374 | Petrus Oil Company, L.P. | | Oil & Gas Operator | Dec 1989 |
| 375 | Pharaoh Oil & Gas, Inc. | MC Camey, TX 79752 | Oil & Gas Operator | Feb 2026 |
| 376 | Phillips Oil Company | Casper, WY 82602 | Oil & Gas Operator | Sep 1986 |
| 377 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 378 | Phoenix Oil & Gas LTD., L.L.P. | Houston, TX 77010 | Oil & Gas Operator | Jun 2004 |
| 379 | Pickens Company, Inc., The | Dallas, TX 75225 | Oil & Gas Operator | Jan 2025 |
| 380 | Pintail Oil & Gas, LLC | Midland, TX 79702 | Oil & Gas Operator | Dec 2019 |
| 381 | Pioneer Exploration, LLC | Houston, TX 77090 | Oil & Gas Operator | Dec 2025 |
| 382 | Plumb Operating Company, Inc. | | Oil & Gas Operator | Dec 1989 |
| 383 | Pmo | Garland, TX 75040 | Oil & Gas Operator | Feb 2018 |
| 384 | Polaris Enterprises Inc | Houston, TX 77057 | Oil & Gas Operator | Oct 1998 |
| 385 | Prairie Producing Company | | Oil & Gas Operator | Dec 1992 |
| 386 | Precision Holdings, LLC | | Oil & Gas Operator | Dec 2015 |
| 387 | Presidio Exploration, Inc. | Englewood, CO 80155 | Oil & Gas Operator | May 1999 |
| 388 | Prudential Oil & Gas, Inc. | | Oil & Gas Operator | Jul 1987 |
| 389 | Quest Exploration L.L.C. | | Oil & Gas Operator | Jul 2014 |
| 390 | Quinoco Petroleum Inc | | Oil & Gas Operator | Dec 1990 |
| 391 | Quintana Petroleum Corporation | Denver, CO 80265 | Oil & Gas Operator | Mar 1998 |
| 392 | R L Kelly, SR. | | Oil Operator | Feb 2009 |
| 393 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 394 | Realco Oil & Gas, Inc. | | Oil & Gas Operator | Sep 2007 |
| 395 | Reef Exploration Inc | Denver, CO 80202 | Oil & Gas Operator | Feb 2007 |
| 396 | Reef Exploration, L.P. | Richardson, TX 75080 | Oil & Gas Operator | Feb 2026 |
| 397 | Reliance Energy, L.L.C. | | Oil & Gas Operator | Dec 2024 |
| 398 | Reserve Oil Inc. | | Oil & Gas Operator | Jan 1980 |
| 399 | Resources Investment Corp | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 400 | Reunion Energy Company | Houston, TX 77056 | Oil & Gas Operator | May 1996 |