| 501 | McShane, J. Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2004 |
| 502 | MDC Operating, Inc. | Midland, TX 79708 | Oil & Gas Operator | Oct 2022 |
| 503 | Me-Tex Oil & Gas, Inc. | Hobbs, NM 88241 | Oil & Gas Operator | Sep 2026 |
| 504 | Me-Tex Supply Company | Hobbs, NM 88240 | Oil & Gas Operator | Jun 1993 |
| 505 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 506 | Melzer Exploration Company | Midland, TX 79702-2083 | Oil & Gas Operator | May 2013 |
| 507 | Memorial Exploration Company | Saint Louis, MO 63105 | Oil & Gas Operator | Aug 1996 |
| 508 | Memorial Production Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 509 | Mercury Operating, LLC | Dallas, TX 75208 | Oil & Gas Operator | Sep 2026 |
| 510 | Meridian Exploration Corp. | Pittsburgh, PA 15222 | Oil & Gas Operator | Dec 2021 |
| 511 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 512 | Meridian Oil Inc.-Midland | Midland, TX 79702 | Oil & Gas Operator | Jul 1996 |
| 513 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Sep 2026 |
| 514 | Merrico Resources, Inc. | Ardmore, OK 73402 | Oil & Gas Operator | Mar 2008 |
| 515 | Merritt Operating, Inc. | Mineola, TX 75773 | Oil & Gas Operator | Sep 2026 |
| 516 | Merritt, William Kevin | Dallas, TX 75225 | Oil & Gas Operator | Dec 1994 |
| 517 | Mesquite SWD Inc | Carlsbad, NM 88221 | Oil & Gas Operator | Sep 2026 |
| 518 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Sep 2026 |
| 519 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 520 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 521 | MGM Oil & Gas Company | Midland, TX 79702 | Oil & Gas Operator | Sep 2026 |
| 522 | Mid-Continent Energy, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2020 |
| 523 | Mid-States Operating Company | Midland, TX 79702 | Oil & Gas Operator | Sep 2026 |
| 524 | Midenergy Operating, LLC | Houston, TX 77024 | Oil & Gas Operator | Sep 2026 |
| 525 | Midland Operating, Inc. | Midland, TX 79710 | Oil & Gas Operator | May 2026 |
| 526 | Midland TMG Inc. | Midland, TX 79705 | Oil & Gas Operator | Apr 2017 |
| 527 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 528 | Mills, Pete | Midland, TX 79707 | Oil & Gas Operator | Sep 2005 |
| 529 | Miltex Oil Company | Boerne, TX 78006 | Oil & Gas Operator | Sep 2026 |
| 530 | Mineral Technologies, Inc. | Midland, TX 79704 | Oil & Gas Operator | Sep 2026 |
| 531 | Minihan Oil & Gas Corporation | Midland, TX 79704 | Oil & Gas Operator | Apr 2004 |
| 532 | Minihan Oil & Gas LTD. | Denver, CO 80202 | Oil & Gas Operator | Jul 2006 |
| 533 | Miocene Oil & Gas, Inc. | Englewood, CO 80155 | Oil & Gas Operator | Jul 1998 |
| 534 | Miocene Oil & Gas, LTD. | Englewood, CO 80110 | Oil & Gas Operator | Sep 2026 |
| 535 | Miranda Energy Corporation | Midland, TX 79705 | Oil & Gas Operator | Jun 2016 |
| 536 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 537 | MJM Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Aug 2003 |
| 538 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 2007 |
| 539 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Feb 2026 |
| 540 | Momentum Energy Corporation | Austin, TX 78746 | Oil & Gas Operator | Sep 2026 |
| 541 | Momentum Operating Co., Inc. | Albany, TX 76430 | Oil & Gas Operator | Sep 2026 |
| 542 | Montare Operating, LTD. | Flower Mound, TX 75022 | Oil & Gas Operator | Sep 2026 |
| 543 | Montgomery Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2007 |
| 544 | Montrose Operating LLC | Broken Arrow, OK 74012 | Oil & Gas Operator | Sep 2026 |
| 545 | Moody Oil Co. | Pearsall, TX 78061 | Oil & Gas Operator | Sep 2026 |
| 546 | Morningstar Operating LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2026 |
| 547 | Morningstar Partners, L.P. | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2022 |
| 548 | Moss Petroleum Company | Dallas, TX 75207 | Oil & Gas Operator | Sep 2026 |
| 549 | Mr Oil Company | Monahans, TX 79756 | Oil & Gas Operator | Nov 2004 |
| 550 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 551 | Mulloy Operating, Inc. | Midland, TX 79707 | Oil & Gas Operator | Sep 2026 |
| 552 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Jun 2026 |
| 553 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 554 | Myco Industries, Inc. | Artesia, NM 88211 | Oil & Gas Operator | Feb 2015 |
| 555 | Nadel And Gussman Permian,L.L.C. | Tulsa, OK 74103 | Oil & Gas Operator | Sep 2026 |
| 556 | Naumann Oil & Gas, Inc. | Austin, TX 78716 | Oil & Gas Operator | Sep 2026 |
| 557 | NBL Permian LLC | Houston, TX 77070 | Oil & Gas Operator | Aug 2018 |
| 558 | Nearburg Producing Company | Dallas, TX 75380 | Oil & Gas Operator | Sep 2026 |
| 559 | Necessity Well Service, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Sep 2006 |
| 560 | Newpark Environmental SVCS LLC | Lafayette, LA 70506 | Oil Operator | Jul 2014 |
| 561 | Newton Corp.,The | Dallas, TX 75251 | Oil & Gas Operator | Sep 2026 |
| 562 | Nitro Oil & Gas, LLC | Cuero, TX 77954 | Oil & Gas Operator | Sep 2026 |
| 563 | Noramco Production, LLC | Midland, TX 79710 | Oil & Gas Operator | Jan 2023 |
| 564 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | Sep 2026 |
| 565 | North American Royalties, Inc. | Chattanooga, TN 37408 | Oil & Gas Operator | Oct 2001 |
| 566 | North Fork Operating LP | Mustang, OK 73064 | Oil & Gas Operator | Sep 2026 |
| 567 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Sep 2026 |
| 568 | O & O Operators, LLC. | Fate, TX 75132 | Oil & Gas Operator | Sep 2026 |
| 569 | O'Brien, George H. Jr. | Midland, TX 79701 | Oil & Gas Operator | Jun 1994 |
| 570 | O'Ryan Oil And Gas | Odessa, TX 79768 | Oil & Gas Operator | Sep 2026 |
| 571 | O.G.P. Operating, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Sep 2026 |
| 572 | Occidental Energy Company, Inc. | Houston, TX 77282 | Oil & Gas Operator | Jul 2021 |
| 573 | Occidental Energy Marketing, Inc. | Houston, TX 77227 | Gas Operator | Sep 2015 |
| 574 | Occidental Permian LTD. | Houston, TX 77046 | Oil & Gas Operator | Sep 2026 |
| 575 | Ocean Energy Inc | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 576 | Octane Energy Operating, LLC | Midland, TX 79701 | Oil & Gas Operator | Sep 2026 |
| 577 | Odessa Exploration, Inc. | Midland, TX 79702 | Oil & Gas Operator | Sep 2026 |
| 578 | Odessa Oil Investment Co., Inc. | Odessa, TX 79762 | Oil & Gas Operator | Nov 2016 |
| 579 | Ogris Operating, LLC | Midland, TX 79710 | Oil & Gas Operator | Sep 2026 |
| 580 | Oilfield Management, Inc. (A) | Midland, TX 79702 | Oil & Gas Operator | Sep 2026 |
| 581 | Oilwell Operators, Inc. | Pampa, TX 79066 | Oil & Gas Operator | Sep 2026 |
| 582 | Ojai Oil Company | Camarillo, CA 93012 | Oil & Gas Operator | Jul 2026 |
| 583 | Ok Arena Operating Company | Oklahoma City, OK 73101 | Oil & Gas Operator | Sep 2026 |
| 584 | Okla. Magic Circle Energy Corp. | Shawnee, OK 74801 | Oil & Gas Operator | Jul 2004 |
| 585 | Oklahoma Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2013 |
| 586 | Olsen Energy Inc. | Boerne, TX 78006 | Oil & Gas Operator | Sep 2026 |
| 587 | Omar Operating Company | Midland, TX 79702 | Oil & Gas Operator | Sep 2013 |
| 588 | Opal Resources Operating Co.,LLC | Cypress, TX 77429 | Oil & Gas Operator | Jan 2019 |
| 589 | Opco Oil & Gas Co. | Dallas, TX 75231 | Oil & Gas Operator | Aug 2003 |
| 590 | Orbitron Operating Corp. | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 1995 |
| 591 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 592 | Oso Exploration & Production, LLC | Houston, TX 77269 | Oil Operator | Sep 2026 |
| 593 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 594 | Ouut Investing LLC | Mineral Wells, TX 76068 | Oil Operator | Mar 2020 |
| 595 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Sep 2026 |
| 596 | Owens Petroleum, Inc. | Midland, TX 79702 | Oil & Gas Operator | Aug 1995 |
| 597 | Oxy USA Eor, LLC | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 598 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Sep 2026 |
| 599 | Oxy USA WTP Eor, LLC | Houston, TX 77002 | Oil Operator | Sep 2026 |
| 600 | Oxy USA WTP LP | Houston, TX 77046 | Oil & Gas Operator | Sep 2026 |