| 501 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 502 | Metis Energy LLC | Houston, TX 77019 | Oil & Gas Operator | Jan 2026 |
| 503 | Metro Energy Group, Inc. | Bossier City, LA 71112 | Oil & Gas Operator | May 2013 |
| 504 | Metroplex Barnett Shale LLC | Houston, TX 77001 | Gas Operator | Sep 2008 |
| 505 | Metzner, Norma J. Estate | Wichita Falls, TX 76307 | Oil & Gas Operator | Oct 1998 |
| 506 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Apr 2026 |
| 507 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 508 | Mextex Operating Company | Austin, TX 78734 | Oil & Gas Operator | Apr 2026 |
| 509 | Meyer Oil Co., Inc. | Skellytown, TX 79080 | Oil & Gas Operator | Feb 2026 |
| 510 | MFP Petroleum LP | Oklahoma City, OK 73142-3017 | Gas Operator | Jan 2026 |
| 511 | MFP Petroleum LTD. Partnership | Oklahoma City, OK 73142 | Oil & Gas Operator | Nov 2017 |
| 512 | Mge Resources, Inc. | Perryton, TX 79070 | Oil & Gas Operator | Jan 2026 |
| 513 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 514 | MGM Oil & Gas Company | Midland, TX 79702 | Oil & Gas Operator | Apr 2026 |
| 515 | MGM Oil & Gas Inc. | Ballinger, TX 76821 | Oil & Gas Operator | Apr 2026 |
| 516 | MGM Well Service, Inc. | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Oct 2004 |
| 517 | MHM Oil Co. | Dallas, TX 75240 | Oil & Gas Operator | Oct 2002 |
| 518 | MHM Pipeline Co., Inc. | Dallas, TX 75252 | Oil & Gas Operator | Apr 2026 |
| 519 | Mi-Co Oil & Gas LLC | Caddo, TX 76429 | Oil Operator | Apr 2026 |
| 520 | Michael Petr. & Hurd Ent., LTD. | Houston, TX 77056 | Oil & Gas Operator | Oct 1993 |
| 521 | Michael Petroleum Corporation | Houston, TX 77040 | Oil & Gas Operator | Dec 2001 |
| 522 | Michaelson Producing Company | MC Camey, TX 79752 | Oil & Gas Operator | Apr 2026 |
| 523 | Micro Operating, Inc. | Tomball, TX 77375 | Oil & Gas Operator | Apr 2026 |
| 524 | Mid Continent Resources, Inc. | Houston, TX 77060 | Oil & Gas Operator | Apr 2026 |
| 525 | Mid Texas Natural Gas | Kyle, TX 78640 | Oil & Gas Operator | May 2019 |
| 526 | Mid-Con Energy Operating, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | May 2020 |
| 527 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2026 |
| 528 | Mid-Continent Energy Operating Company | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2026 |
| 529 | Mid-Continent Energy, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2020 |
| 530 | Mid-Continental Exploration,Inc. | Sanger, TX 76266 | Oil & Gas Operator | Apr 2026 |
| 531 | Mid-Gulf, Inc. | Brenham, TX 77834 | Oil & Gas Operator | Mar 2008 |
| 532 | Mid-States Operating Company | Midland, TX 79702 | Oil & Gas Operator | Apr 2026 |
| 533 | Mid-Tex Energy Inc. | Costa Mesa, CA 92626 | Oil & Gas Operator | Jan 1999 |
| 534 | Mid-Tex Operating, Inc. | Austin, TX 78748 | Oil & Gas Operator | Apr 2026 |
| 535 | Mid-Tex Resources | Merkel, TX 79536 | Oil & Gas Operator | Feb 2001 |
| 536 | Midas Resources, Inc. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Apr 2026 |
| 537 | Midcoast G & P (East Texas) L.P. | Houston, TX 77002 | Oil & Gas Operator | Apr 2026 |
| 538 | Midcon Offshore, Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 539 | Middle Bay Oil Company, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 1998 |
| 540 | Middle Bay Production Co. Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2014 |
| 541 | Middleton Oil Company | Houston, TX 77006 | Oil & Gas Operator | Apr 2026 |
| 542 | Mideast Gas Systems, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 2005 |
| 543 | Midenergy Operating, LLC | Houston, TX 77024 | Oil & Gas Operator | Apr 2026 |
| 544 | Midgard Energy Company | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2014 |
| 545 | Midkiff, John | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 546 | Midland Energy, Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2026 |
| 547 | Midland Oil And Gas, Inc. | Midland, TX 79705 | Oil & Gas Operator | Apr 2026 |
| 548 | Midland Operating, Inc. | Midland, TX 79710 | Oil & Gas Operator | Dec 2025 |
| 549 | Midland Res. Oper. Co., Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 1998 |
| 550 | Midland Southwest Cold Lake Inc | Midland, TX 79702 | Oil & Gas Operator | Jun 1997 |
| 551 | Midland TMG Inc. | Midland, TX 79705 | Oil & Gas Operator | Apr 2017 |
| 552 | Midnite Oil Co. | Wichita Falls, TX 76310 | Oil & Gas Operator | Apr 2026 |
| 553 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 554 | Midsco | Cross Plains, TX 76443 | Oil & Gas Operator | Apr 2026 |
| 555 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2026 |
| 556 | Midstates Petroleum Company LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2018 |
| 557 | Midville Energy, LLC. | Midland, TX 79705 | Oil & Gas Operator | Jul 2024 |
| 558 | Midway Drilling Co. | Richmond, TX 77469 | Oil & Gas Operator | Apr 2026 |
| 559 | Midway Energy Partners Operating LLC | Midland, TX 79701 | Oil Operator | Apr 2026 |
| 560 | Midway Operating Company, L.L.C. | Woodward, OK 73802 | Oil & Gas Operator | Apr 2026 |
| 561 | Midwestern Energy | Mankato, MN 56003 | Oil & Gas Operator | Apr 2026 |
| 562 | Midwestern Exploration Company | Edmond, OK 73013 | Oil & Gas Operator | May 2025 |
| 563 | Miesch Exploration Corporation | Dallas, TX 75229 | Oil & Gas Operator | Nov 2002 |
| 564 | Mike Oil LLC | Colorado City, TX 79512 | Oil Operator | Apr 2026 |
| 565 | Miken Oil, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2026 |
| 566 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 567 | Milam, Inc. | Oklahoma City, OK 73118 | Oil & Gas Operator | Apr 2026 |
| 568 | Miles Production Co. | Argyle, TX 76226 | Oil & Gas Operator | Mar 2008 |
| 569 | Milestone Operating, Inc. | Montgomery, TX 77316 | Oil & Gas Operator | Apr 2026 |
| 570 | Millennium Exploration Co. LLC | San Antonio, TX 78232 | Oil & Gas Operator | Apr 2026 |
| 571 | Millennium Minerals Corporation | Fredericksbrg, TX 78624 | Oil Operator | Apr 2026 |
| 572 | Millennium Offshore Group, Inc. | Houston, TX 77007 | Oil & Gas Operator | Sep 2005 |
| 573 | Millennium Operating Company | Houston, TX 77057 | Oil & Gas Operator | Apr 2026 |
| 574 | Millennium Petro-Physics, Inc. | Corpus Chrsti, TX 78480 | Oil & Gas Operator | Apr 2026 |
| 575 | Millennium Resources, LLC. | Big Lake, TX 76932 | Oil & Gas Operator | Sep 2012 |
| 576 | Millennium Resources, LP | Midland, TX 79708 | Oil Operator | Apr 2026 |
| 577 | Miller Energy Inc | Houston, TX 77024 | Oil & Gas Operator | Oct 2016 |
| 578 | Miller Oil & Gas, LLC | Snyder, TX 79549 | Oil & Gas Operator | Apr 2026 |
| 579 | Miller Oil Company | Corsicana, TX 75110 | Oil & Gas Operator | Dec 2015 |
| 580 | Miller Operating Company LLC | Lafayette, LA 70598 | Oil & Gas Operator | Apr 2026 |
| 581 | Miller Petroleum LLC | Graham, TX 76450 | Oil Operator | Apr 2026 |
| 582 | Miller Production Co. | Tyler, TX 75701 | Oil & Gas Operator | Apr 2026 |
| 583 | Miller, B. H. Oil Co. | Corsicana, TX 75110 | Oil & Gas Operator | Sep 2002 |
| 584 | Miller, Bob I. | Abilene, TX 79604 | Oil & Gas Operator | Mar 2008 |
| 585 | Miller, C. R. Oil Co. | Olney, TX 76374 | Oil & Gas Operator | Apr 2026 |
| 586 | Miller, Cecil G. | Corsicana, TX 75110 | Oil & Gas Operator | Jan 2023 |
| 587 | Miller, Cecil G. Estate Of | Corsicana, TX 75110 | Oil Operator | Apr 2026 |
| 588 | Miller, Donny | Cisco, TX 76437 | Oil & Gas Operator | Apr 2026 |
| 589 | Miller, Dyer & Co LLC | Denver, CO 80202 | Oil & Gas Operator | May 2009 |
| 590 | Miller, Glenn J. | Muenster, TX 76252 | Oil & Gas Operator | Jul 2025 |
| 591 | Miller, L. Joe & Bobby J. Parker | Wichita Falls, TX 76308 | Oil & Gas Operator | Jul 2000 |
| 592 | Miller, M. M. & Sons | Alice, TX 78333 | Oil & Gas Operator | Apr 2007 |
| 593 | Miller, Mike | Corsicana, TX 75110 | Oil & Gas Operator | Apr 2026 |
| 594 | Miller, Mike / Miller Prod. Co. | Corsicana, TX 75110 | Oil & Gas Operator | Apr 2026 |
| 595 | Miller, R. A. Energy, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Aug 2003 |
| 596 | Miller, Rex M. | Putnam, TX 76469 | Oil & Gas Operator | Sep 2022 |
| 597 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2026 |
| 598 | Mills Oil & Gas | Jacksboro, TX 76458 | Oil & Gas Operator | Mar 2008 |
| 599 | Mills, H. E. | Lipan, TX 76462 | Oil & Gas Operator | Sep 2004 |
| 600 | Mills, Pete | Midland, TX 79707 | Oil & Gas Operator | Sep 2005 |