| 301 | McCord-Goodrich Oil Company | | Oil & Gas Operator | Oct 1991 |
| 302 | McCormick Operating Company | | Oil & Gas Operator | Mar 1984 |
| 303 | McCormick Operating PRTNSHP | | Oil & Gas Operator | Sep 1985 |
| 304 | McFarland Energy, Inc. | New Orleans, LA 70160 | Oil & Gas Operator | Dec 2009 |
| 305 | McMoran Exploration Company | | Oil & Gas Operator | May 1985 |
| 306 | McMoran Production Co. | | Oil & Gas Operator | May 1985 |
| 307 | McRae Exploration & Prod., Inc. | Houston, TX 77064 | Oil & Gas Operator | Feb 2017 |
| 308 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 309 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 310 | Meridian Oil Offshore Inc. | | Oil & Gas Operator | Aug 1996 |
| 311 | Merritt Operating, Inc. | Mineola, TX 75773 | Oil & Gas Operator | Mar 2025 |
| 312 | Mesa Gulf Coast LLC | | Oil & Gas Operator | Dec 2020 |
| 313 | Micron Minerals Company | | Oil & Gas Operator | Sep 1988 |
| 314 | Mid-America Resources Corporation | | Oil Operator | Jan 2019 |
| 315 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 316 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 317 | Mobil E&P N.A.-WM Scully Et Al | | Oil & Gas Operator | Dec 1993 |
| 318 | Mobil E&P North America Inc. | | Oil & Gas Operator | Jan 1994 |
| 319 | Mobil Oil E & P Southeast Inc | | Oil & Gas Operator | Sep 2013 |
| 320 | Mongrue Oil Company, Inc. | | Oil & Gas Operator | Oct 1999 |
| 321 | Monterey Pipeline Co. | | Oil Operator | Aug 1993 |
| 322 | Moon Operating, Inc. | Longview, TX 75601 | Oil & Gas Operator | Mar 2003 |
| 323 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 324 | Mullins & Prichard | | Oil & Gas Operator | May 1992 |
| 325 | Mustang Energy L C | | Oil & Gas Operator | Jan 2013 |
| 326 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 327 | Nasser Oil & Gas, Inc. | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 1998 |
| 328 | National Energy Group, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 329 | Needham Resources, Inc. | | Oil & Gas Operator | Jan 1998 |
| 330 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Nov 2024 |
| 331 | Nerco Oil & Gas, Inc. | | Oil & Gas Operator | Dec 1996 |
| 332 | Nicklos Oil & Gas Co. | Houston, TX 77252 | Oil & Gas Operator | Nov 1986 |
| 333 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Mar 2025 |
| 334 | Nomeco Oil & Gas Co. | Jackson, MI 49204 | Oil & Gas Operator | Dec 1994 |
| 335 | Norcen Explorer, Inc. | Houston, TX 77079 | Oil & Gas Operator | May 1998 |
| 336 | Northcott Exploration Co. Inc. | | Oil & Gas Operator | Dec 1987 |
| 337 | Nugulf Operating, L.L.C. | | Oil & Gas Operator | Dec 2024 |
| 338 | O'Sullivan Oil & Gas Co., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2000 |
| 339 | Ody Oil Corp. | | Oil & Gas Operator | Oct 1994 |
| 340 | Oil Country Management, Inc. | | Oil & Gas Operator | Jan 2005 |
| 341 | Oil Lift, Incorporated | Metairie, LA 70002 | Oil & Gas Operator | Apr 2020 |
| 342 | Olipdp II, LLC | Lafayette, LA 70503 | Oil & Gas Operator | Mar 2025 |
| 343 | Omni Operating Company | Osage, WY 82723 | Oil & Gas Operator | Sep 2001 |
| 344 | Orx Resources, Inc. | | Oil & Gas Operator | Dec 2009 |
| 345 | Orx Resources, L.L.C. | Houston, TX 77067 | Oil & Gas Operator | Mar 2025 |
| 346 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 347 | Osr Oil & Gas Corp | Midland, TX 79710 | Oil & Gas Operator | Dec 2024 |
| 348 | Osyka Permian, LLC | Houston, TX 77079 | Oil & Gas Operator | Mar 2025 |
| 349 | P & A Well Service | | Oil & Gas Operator | Jan 1994 |
| 350 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 351 | Pacific Atlantic Oil Co. | | Oil & Gas Operator | Dec 2003 |
| 352 | Pacific Enterprises Oil Co USA | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 353 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 354 | Palace Operating Company | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2009 |
| 355 | Pan-Ok Production Company | | Oil & Gas Operator | Nov 2024 |
| 356 | Parker & Parsley Devpt L P | | Oil & Gas Operator | Oct 1997 |
| 357 | Partners Oil Company | Tulsa, OK 74135 | Oil & Gas Operator | Aug 1995 |
| 358 | Patrick Petroleum Corp. | | Oil & Gas Operator | Oct 1984 |
| 359 | Patterson Resources, Inc. | | Oil & Gas Operator | Apr 1984 |
| 360 | Paxton Oil Company | | Oil & Gas Operator | Dec 2024 |
| 361 | Peachtree Production Co. | | Oil & Gas Operator | Mar 1981 |
| 362 | Pecos Western Corporation | | Gas Operator | Feb 1992 |
| 363 | Pel-Tex Oil Company, Inc. | | Oil & Gas Operator | Jul 1995 |
| 364 | Pel-Tex, Inc. | | Oil & Gas Operator | Jul 1985 |
| 365 | Pelican Dome Exploration Inc | Harahan, LA 70123 | Oil & Gas Operator | Aug 2000 |
| 366 | Pend Oreille Oil & Gas Company | | Oil & Gas Operator | Sep 1989 |
| 367 | Pennzenergy Explor & Prod LLC | | Oil & Gas Operator | Dec 1999 |
| 368 | Pennzoil E & P Co - Clark Oil | | Oil & Gas Operator | Apr 1980 |
| 369 | Pennzoil Exploration & Production Co. | Carthage, TX 75633 | Oil & Gas Operator | Mar 2008 |
| 370 | Perdido Energy Louisiana, LLC | | Oil & Gas Operator | Dec 2024 |
| 371 | Perenco LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2005 |
| 372 | Petro-Lewis Corp. | | Oil & Gas Operator | Feb 1994 |
| 373 | Petrodome Operating, LLC | Houston, TX 77265 | Oil & Gas Operator | Nov 2024 |
| 374 | Petrogulf Corporation | Denver, CO 80202 | Oil & Gas Operator | Mar 2025 |
| 375 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 376 | Petroleum Properties MGMT Corp | | Oil & Gas Operator | Aug 1990 |
| 377 | Petroquest Energy, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Feb 2001 |
| 378 | Petroquest Energy, L.L.C. | Lafayette, LA 70505 | Oil & Gas Operator | Mar 2025 |
| 379 | Petrus Oil Company., L.P. | | Oil & Gas Operator | Dec 1989 |
| 380 | Petsec Energy Inc. | | Oil & Gas Operator | Sep 2012 |
| 381 | Phalanx Petroleum LLC | | Oil & Gas Operator | Jan 2025 |
| 382 | Phillips Oil Company | Casper, WY 82602 | Oil & Gas Operator | Sep 1986 |
| 383 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 384 | Phoenix Exploration Company LP | | Oil & Gas Operator | Sep 2011 |
| 385 | Pioneer Natural Res. (GPC), Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 1998 |
| 386 | Pioneer Natural Resources USA Inc | Irving, TX 75039 | Oil & Gas Operator | Nov 2024 |
| 387 | Placid Oil Company | Houston, TX 77227 | Oil & Gas Operator | Mar 2008 |
| 388 | Plymouth Resource Group LLC | | Oil & Gas Operator | Dec 1999 |
| 389 | Plymouth Resources Group II Inc | | Oil & Gas Operator | May 2007 |
| 390 | Pogo Producing Company | Houston, TX 77002 | Oil & Gas Operator | Jan 2008 |
| 391 | Pontchartrain Oil & Gas Corp 2 | | Oil & Gas Operator | Dec 1984 |
| 392 | Precio Energy, LLC | Beaumont, TX 77726 | Oil & Gas Operator | Mar 2025 |
| 393 | Presidio Energy, Inc. | | Oil & Gas Operator | Jan 1992 |
| 394 | Presidio Exploration, Inc. | Englewood, CO 80155 | Oil & Gas Operator | May 1999 |
| 395 | Prime Natural Resources, Inc. | Houston, TX 77042 | Oil & Gas Operator | Jun 2007 |
| 396 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 397 | Production Funds Inc | | Oil & Gas Operator | Nov 2001 |
| 398 | Prosper Energy Corporation | | Oil & Gas Operator | Oct 1988 |
| 399 | Proven Fuel Exploration, Inc. | | Oil & Gas Operator | Mar 2022 |
| 400 | PXP Gulf Coast Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |