| 501 | Merzbacher, George F. Jr. | Robstown, TX 78380 | Oil & Gas Operator | May 1994 |
| 502 | Mesa Chica Corp. | San Antonio, TX 78278 | Oil & Gas Operator | May 2018 |
| 503 | Mesa Energy, Inc. | Austin, TX 78755 | Oil & Gas Operator | Dec 2013 |
| 504 | Mesa Operating Co. | Irving, TX 75039 | Oil & Gas Operator | Aug 1997 |
| 505 | Mesa Operating LTD Partnership | Amarillo, TX 79189 | Oil & Gas Operator | May 1994 |
| 506 | Mesa Operating, LLC | Plano, TX 75093 | Oil & Gas Operator | Feb 2026 |
| 507 | Mesa Ridge Holdings LLC | Abilene, TX 79603 | Oil Operator | Feb 2026 |
| 508 | Mesa VIsta Operating, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2026 |
| 509 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 510 | Mesquite Land & Minerals Co. | Albany, TX 76430 | Oil Operator | Feb 2026 |
| 511 | Mesquite Oil & Gas Production | Breckenridge, TX 76424 | Oil & Gas Operator | Feb 2026 |
| 512 | Mesquite SWD Inc | Carlsbad, NM 88221 | Oil & Gas Operator | Feb 2026 |
| 513 | Messer Helium Cliffside LLC | Bridgewater, NJ 08807 | Gas Operator | Feb 2026 |
| 514 | Messy Oil And Gas, LLC | Garwood, TX 77442 | Oil & Gas Operator | Feb 2026 |
| 515 | Mestena Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Aug 2015 |
| 516 | Mestena Operating, LTD. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jun 2009 |
| 517 | Mestena, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Nov 2001 |
| 518 | Metano Energy III, LP | Tulsa, OK 74121 | Oil & Gas Operator | Feb 2026 |
| 519 | Metano Energy, LP | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2008 |
| 520 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 521 | Metis Energy LLC | Houston, TX 77019 | Oil & Gas Operator | Feb 2026 |
| 522 | Metro Energy Group, Inc. | Bossier City, LA 71112 | Oil & Gas Operator | May 2013 |
| 523 | Metroplex Barnett Shale LLC | Houston, TX 77001 | Gas Operator | Sep 2008 |
| 524 | Metzner, Norma J. Estate | Wichita Falls, TX 76307 | Oil & Gas Operator | Oct 1998 |
| 525 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Feb 2026 |
| 526 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 527 | Mextex Operating Company | Austin, TX 78734 | Oil & Gas Operator | Feb 2026 |
| 528 | Meyer Oil Co., Inc. | Skellytown, TX 79080 | Oil & Gas Operator | Nov 2025 |
| 529 | MFP Petroleum LP | Oklahoma City, OK 73142-3017 | Gas Operator | Nov 2025 |
| 530 | MFP Petroleum LTD. Partnership | Oklahoma City, OK 73142 | Oil & Gas Operator | Nov 2017 |
| 531 | Mge Resources, Inc. | Perryton, TX 79070 | Oil & Gas Operator | Nov 2025 |
| 532 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 533 | MGM Oil & Gas Company | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 534 | MGM Oil & Gas Inc. | Ballinger, TX 76821 | Oil & Gas Operator | Feb 2026 |
| 535 | MGM Well Service, Inc. | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Oct 2004 |
| 536 | MGR Resources | San Antonio, TX 78209 | Oil & Gas Operator | Feb 2026 |
| 537 | MHM Oil Co. | Dallas, TX 75240 | Oil & Gas Operator | Oct 2002 |
| 538 | MHM Pipeline Co., Inc. | Dallas, TX 75252 | Oil & Gas Operator | Feb 2026 |
| 539 | Mi-Co Oil & Gas LLC | Caddo, TX 76429 | Oil Operator | Feb 2026 |
| 540 | Michael Petr. & Hurd Ent., LTD. | Houston, TX 77056 | Oil & Gas Operator | Oct 1993 |
| 541 | Michael Petroleum Corporation | Houston, TX 77040 | Oil & Gas Operator | Dec 2001 |
| 542 | Michaelson Producing Company | MC Camey, TX 79752 | Oil & Gas Operator | Feb 2026 |
| 543 | Micro Operating, Inc. | Tomball, TX 77375 | Oil & Gas Operator | Feb 2026 |
| 544 | Mid Continent Resources, Inc. | Houston, TX 77060 | Oil & Gas Operator | Feb 2026 |
| 545 | Mid Texas Natural Gas | Kyle, TX 78640 | Oil & Gas Operator | May 2019 |
| 546 | Mid-Con Energy Operating, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | May 2020 |
| 547 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Dec 2025 |
| 548 | Mid-Continent Energy Operating Company | Tulsa, OK 74103 | Oil & Gas Operator | Dec 2025 |
| 549 | Mid-Continent Energy, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2020 |
| 550 | Mid-Continental Exploration,Inc. | Sanger, TX 76266 | Oil & Gas Operator | Feb 2026 |
| 551 | Mid-Gulf, Inc. | Brenham, TX 77834 | Oil & Gas Operator | Mar 2008 |
| 552 | Mid-States Operating Company | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 553 | Mid-Tex Energy Inc. | Costa Mesa, CA 92626 | Oil & Gas Operator | Jan 1999 |
| 554 | Mid-Tex Operating, Inc. | Austin, TX 78748 | Oil & Gas Operator | Feb 2026 |
| 555 | Mid-Tex Resources | Merkel, TX 79536 | Oil & Gas Operator | Feb 2001 |
| 556 | Midas Resources, Inc. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Feb 2026 |
| 557 | Midcoast G & P (East Texas) L.P. | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 558 | Midcon Offshore, Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 559 | Middle Bay Oil Company, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 1998 |
| 560 | Middle Bay Production Co. Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2014 |
| 561 | Middleton Oil Company | Houston, TX 77006 | Oil & Gas Operator | Feb 2026 |
| 562 | Mideast Gas Systems, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 2005 |
| 563 | Midenergy Operating, LLC | Houston, TX 77024 | Oil & Gas Operator | Feb 2026 |
| 564 | Midgard Energy Company | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2014 |
| 565 | Midkiff, John | Midland, TX 79705 | Oil & Gas Operator | Mar 2008 |
| 566 | Midland Energy, Inc. | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 567 | Midland Oil And Gas, Inc. | Midland, TX 79705 | Oil & Gas Operator | Feb 2026 |
| 568 | Midland Operating, Inc. | Midland, TX 79710 | Oil & Gas Operator | Oct 2025 |
| 569 | Midland Res. Oper. Co., Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 1998 |
| 570 | Midland Southwest Cold Lake Inc | Midland, TX 79702 | Oil & Gas Operator | Jun 1997 |
| 571 | Midland TMG Inc. | Midland, TX 79705 | Oil & Gas Operator | Apr 2017 |
| 572 | Midnite Oil Co. | Wichita Falls, TX 76310 | Oil & Gas Operator | Feb 2026 |
| 573 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 574 | Midsco | Cross Plains, TX 76443 | Oil & Gas Operator | Feb 2026 |
| 575 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Feb 2026 |
| 576 | Midstates Petroleum Company LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2018 |
| 577 | Midville Energy, LLC. | Midland, TX 79705 | Oil & Gas Operator | Jul 2024 |
| 578 | Midway Drilling Co. | Richmond, TX 77469 | Oil & Gas Operator | Feb 2026 |
| 579 | Midway Energy Partners Operating LLC | Midland, TX 79701 | Oil & Gas Operator | Feb 2026 |
| 580 | Midway Operating Company, L.L.C. | Woodward, OK 73802 | Oil & Gas Operator | Feb 2026 |
| 581 | Midwest Operating, LLC | Tulsa, OK 74133 | Oil & Gas Operator | Feb 2026 |
| 582 | Midwestern Energy | Mankato, MN 56003 | Oil & Gas Operator | Feb 2026 |
| 583 | Midwestern Exploration Company | Edmond, OK 73013 | Oil & Gas Operator | May 2025 |
| 584 | Miesch Exploration Corporation | Dallas, TX 75229 | Oil & Gas Operator | Nov 2002 |
| 585 | Mike Oil LLC | Colorado City, TX 79512 | Oil Operator | Feb 2026 |
| 586 | Miken Oil, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Feb 2026 |
| 587 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 588 | Milam, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Feb 2026 |
| 589 | Miles Production Co. | Argyle, TX 76226 | Oil & Gas Operator | Mar 2008 |
| 590 | Milestone Operating, Inc. | Montgomery, TX 77316 | Oil & Gas Operator | Feb 2026 |
| 591 | Millennium Exploration Co. LLC | San Antonio, TX 78232 | Oil & Gas Operator | Feb 2026 |
| 592 | Millennium Minerals Corporation | Fredericksbrg, TX 78624 | Oil Operator | Feb 2026 |
| 593 | Millennium Offshore Group, Inc. | Houston, TX 77007 | Oil & Gas Operator | Sep 2005 |
| 594 | Millennium Operating Company | Houston, TX 77057 | Oil & Gas Operator | Feb 2026 |
| 595 | Millennium Petro-Physics, Inc. | Corpus Chrsti, TX 78480 | Oil & Gas Operator | Feb 2026 |
| 596 | Millennium Resources, LLC. | Big Lake, TX 76932 | Oil & Gas Operator | Sep 2012 |
| 597 | Millennium Resources, LP | Midland, TX 79708 | Oil Operator | Feb 2026 |
| 598 | Miller Energy Inc | Houston, TX 77024 | Oil & Gas Operator | Oct 2016 |
| 599 | Miller Oil & Gas, LLC | Snyder, TX 79549 | Oil & Gas Operator | Feb 2026 |
| 600 | Miller Oil Company | Corsicana, TX 75110 | Oil & Gas Operator | Dec 2015 |