| 401 | M & S Exploration | El Campo, TX 77437 | Oil & Gas Operator | Jul 2025 |
| 402 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 403 | Maggert Energy Corp. | Spring, TX 77387 | Gas Operator | Jun 1998 |
| 404 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2025 |
| 405 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 406 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2025 |
| 407 | Mark IV Energy | San Antonio, TX 78213 | Oil & Gas Operator | Apr 1993 |
| 408 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 409 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Jul 2025 |
| 410 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 411 | Maverick Prod. Co., Inc. | Houston, TX 77056 | Oil & Gas Operator | Jul 2025 |
| 412 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 413 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 414 | Mayne & Mertz, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2013 |
| 415 | MB Energy, LLC | San Antonio, TX 78233 | Oil & Gas Operator | Jul 2025 |
| 416 | McBee Company, The | Dallas, TX 75219 | Oil & Gas Operator | Dec 1997 |
| 417 | McCarter, A. Nelson | Houston, TX 77063 | Oil & Gas Operator | Aug 2003 |
| 418 | McCauley, F. R. | Houston, TX 77002 | Oil & Gas Operator | Apr 2000 |
| 419 | McCulliss Resources Co Inc | Littleton, CO 80161-3248 | Oil & Gas Operator | Jun 2009 |
| 420 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 421 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Jul 2025 |
| 422 | McLeod, George L. Inc. | Houston, TX 77079 | Oil & Gas Operator | Sep 2002 |
| 423 | McRae Exploration & Prod., Inc. | Houston, TX 77064 | Oil & Gas Operator | Feb 2017 |
| 424 | Medallion Oil Company | Houston, TX 77251 | Oil & Gas Operator | Jan 2012 |
| 425 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 426 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 427 | Metano Energy, LP | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2008 |
| 428 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 429 | Midas Resources, Inc. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Jul 2025 |
| 430 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 431 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 432 | Millennium Exploration Co. LLC | San Antonio, TX 78232 | Oil & Gas Operator | Jul 2025 |
| 433 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2025 |
| 434 | Miramar Petroleum, Inc. | Corpus Chrsti, TX 78463 | Oil & Gas Operator | Sep 2017 |
| 435 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 436 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |
| 437 | Mohican Oil & Gas, L.L.C. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Apr 2013 |
| 438 | Mojac Energy Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 1997 |
| 439 | Moose Oil & Gas Co. | Houston, TX 77002 | Oil & Gas Operator | Feb 2000 |
| 440 | Mosaic Oil LLC | Dallas, TX 75205 | Oil & Gas Operator | Jul 2025 |
| 441 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 442 | Mueller Exploration, Inc. | Portland, TX 78374 | Oil & Gas Operator | Jul 2025 |
| 443 | Mustang Energy Inc. | Porter, TX 77365 | Oil & Gas Operator | Mar 2008 |
| 444 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2025 |
| 445 | Nadsoilco LLC | Chicago, IL 60606 | Oil & Gas Operator | Jul 2025 |
| 446 | Nasser Oil & Gas, Inc. | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 1998 |
| 447 | National Onshore LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2008 |
| 448 | NBL Permian LLC | Houston, TX 77070 | Oil & Gas Operator | Aug 2018 |
| 449 | Ncey Holdings, LLC | Houston, TX 77056 | Oil & Gas Operator | Jun 2013 |
| 450 | Neumin Production Company | Point Comfort, TX 77978 | Oil & Gas Operator | Jul 2025 |
| 451 | New Century Exploration, Inc. | Spring, TX 77379 | Oil & Gas Operator | Jul 2025 |
| 452 | Newfield Exploration Company | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2017 |
| 453 | Newman, John A. | Joplin, MO 64804 | Oil & Gas Operator | Jan 2001 |
| 454 | Nolteco, Inc. | Longview, TX 75606 | Oil & Gas Operator | Jul 2025 |
| 455 | North Central Oil Corp | Houston, TX 77252 | Oil & Gas Operator | Dec 2005 |
| 456 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Jul 2025 |
| 457 | North Shore Energy, L.L.C. | Austin, TX 78750 | Oil & Gas Operator | Jul 2025 |
| 458 | Nupower Energy, LLC | Houston, TX 77058 | Oil & Gas Operator | Jul 2025 |
| 459 | O'Tool Oil & Gas, LLC | Dallas, TX 75219 | Oil & Gas Operator | Jul 2025 |
| 460 | Oblaen Resources LLC | Wallis, TX 77485 | Oil & Gas Operator | Jul 2025 |
| 461 | Okie Operating Company, LTD. | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2025 |
| 462 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | Jul 2025 |
| 463 | Omega Energy, LLC | Corpus Chrsti, TX 78418 | Oil & Gas Operator | Jul 2025 |
| 464 | Opal Energy, Inc. | Katy, TX 77494 | Oil & Gas Operator | Jun 2009 |
| 465 | Opex Energy, LLC | Houston, TX 77042 | Oil & Gas Operator | Mar 2008 |
| 466 | Orx Resources, L.L.C. | Houston, TX 77067 | Oil & Gas Operator | Jul 2025 |
| 467 | Osr Oil & Gas Company | Victoria, TX 77902 | Oil & Gas Operator | Jul 2000 |
| 468 | Owl Creek Production Co., Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2006 |
| 469 | Owl Creek Production Co., LLC | Denver, CO 80265 | Oil & Gas Operator | Jan 2006 |
| 470 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 471 | Pace Production Co. | San Angelo, TX 76902 | Oil & Gas Operator | Jul 2025 |
| 472 | Padon, Frank B. Oil Oper., Inc. | Houston, TX 77227 | Oil & Gas Operator | Nov 1998 |
| 473 | Paladin-Hayes, L.L.C. | Austin, TX 78746 | Oil & Gas Operator | Dec 1999 |
| 474 | Paloma Operating, LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2025 |
| 475 | Panhandle Producing Company | San Antonio, TX 78205 | Oil & Gas Operator | Oct 1993 |
| 476 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 477 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 478 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 479 | Patrick Pet. Corp. Of Michigan | Houston, TX 77227 | Oil & Gas Operator | Aug 1995 |
| 480 | Patterson Energy Corporation | Dallas, TX 75205 | Oil & Gas Operator | Jul 2025 |
| 481 | Patterson Petroleum LLC | Snyder, TX 79550 | Oil & Gas Operator | Oct 2007 |
| 482 | Patterson Petroleum LP | Snyder, TX 79550 | Oil & Gas Operator | Mar 2008 |
| 483 | Patterson Petroleum, Inc. | Snyder, TX 79550 | Oil & Gas Operator | Feb 2000 |
| 484 | Pecos Petroleum Company | Houston, TX 77057 | Oil & Gas Operator | Oct 1999 |
| 485 | Pegasus Operating, Inc. | Coldspring, TX 77331 | Oil & Gas Operator | Jul 2025 |
| 486 | Pegasus Petroleum Corporation | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Jul 2025 |
| 487 | Penn VIrginia Oil & Gas Corp | Houston, TX 77024 | Oil & Gas Operator | Dec 2023 |
| 488 | Penwell Energy, Inc. | Houston, TX 77057 | Oil & Gas Operator | Jul 2025 |
| 489 | Perlman,I.H.Oil & Gas Properties | Houston, TX 77056 | Oil & Gas Operator | Mar 2008 |
| 490 | Petech Enterprises, Inc. | Houston, TX 77066 | Oil & Gas Operator | Jan 2004 |
| 491 | Petra Oleum Corp. | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 492 | Petrodome Operating, LLC | Houston, TX 77265 | Oil & Gas Operator | Mar 2025 |
| 493 | Petrogas Operating Corporation | Garland, TX 75043 | Oil Operator | Feb 2010 |
| 494 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 495 | Petroleum Management Int'L, Inc. | Sugar Land, TX 77487 | Oil & Gas Operator | Oct 1993 |
| 496 | Petropro Energy Partners, L.P. | Houston, TX 77024 | Oil & Gas Operator | Jan 2013 |
| 497 | Petroreal Inc. | Temple, TX 76503 | Oil & Gas Operator | Jul 2025 |
| 498 | PG&E Resources Company | Houston, TX 77042 | Oil & Gas Operator | May 1995 |
| 499 | Pharaoh Oil & Gas, Inc. | MC Camey, TX 79752 | Oil & Gas Operator | Jul 2025 |
| 500 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |