| 501 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | May 2025 |
| 502 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 503 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 504 | MGM Oil & Gas Company | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 505 | Mid-Continent Energy, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2020 |
| 506 | Mid-States Operating Company | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 507 | Midenergy Operating, LLC | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 508 | Midland Operating, Inc. | Midland, TX 79710 | Oil & Gas Operator | Feb 2025 |
| 509 | Midland TMG Inc. | Midland, TX 79705 | Oil & Gas Operator | Apr 2017 |
| 510 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 511 | Mills, Pete | Midland, TX 79707 | Oil & Gas Operator | Sep 2005 |
| 512 | Miltex Oil Company | Boerne, TX 78006 | Oil & Gas Operator | May 2025 |
| 513 | Mineral Technologies, Inc. | Midland, TX 79704 | Oil & Gas Operator | May 2025 |
| 514 | Minihan Oil & Gas Corporation | Midland, TX 79704 | Oil & Gas Operator | Apr 2004 |
| 515 | Minihan Oil & Gas LTD. | Denver, CO 80202 | Oil & Gas Operator | Jul 2006 |
| 516 | Miocene Oil & Gas, Inc. | Englewood, CO 80155 | Oil & Gas Operator | Jul 1998 |
| 517 | Miocene Oil & Gas, LTD. | Englewood, CO 80110 | Oil & Gas Operator | May 2025 |
| 518 | Miranda Energy Corporation | Midland, TX 79705 | Oil & Gas Operator | Jun 2016 |
| 519 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 520 | MJM Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Aug 2003 |
| 521 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 522 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 523 | Momentum Energy Corporation | Austin, TX 78746 | Oil & Gas Operator | May 2025 |
| 524 | Momentum Operating Co., Inc. | Albany, TX 76430 | Oil & Gas Operator | May 2025 |
| 525 | Montare Operating, LTD. | Flower Mound, TX 75022 | Oil & Gas Operator | May 2025 |
| 526 | Montgomery Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2007 |
| 527 | Montrose Operating LLC | Broken Arrow, OK 74012 | Oil & Gas Operator | May 2025 |
| 528 | Morningstar Operating LLC | Fort Worth, TX 76102 | Oil & Gas Operator | May 2025 |
| 529 | Morningstar Partners, L.P. | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2022 |
| 530 | Moss Petroleum Company | Dallas, TX 75207 | Oil & Gas Operator | May 2025 |
| 531 | Mr Oil Company | Monahans, TX 79756 | Oil & Gas Operator | Nov 2004 |
| 532 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 533 | Mulloy Operating, Inc. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 534 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Feb 2025 |
| 535 | MV Purchasing LLC | Wichita, KS 67206 | Oil & Gas Operator | Dec 2019 |
| 536 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 537 | Myco Industries, Inc. | Artesia, NM 88211 | Oil & Gas Operator | Feb 2015 |
| 538 | Nadel And Gussman Permian,L.L.C. | Tulsa, OK 74103 | Oil & Gas Operator | May 2025 |
| 539 | Naumann Oil & Gas, Inc. | Austin, TX 78716 | Oil & Gas Operator | May 2025 |
| 540 | NBL Permian LLC | Houston, TX 77070 | Oil & Gas Operator | Aug 2018 |
| 541 | Nearburg Producing Company | Dallas, TX 75380 | Oil & Gas Operator | May 2025 |
| 542 | Necessity Well Service, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Sep 2006 |
| 543 | Newpark Environmental SVCS LLC | Lafayette, LA 70506 | Oil Operator | Jul 2014 |
| 544 | Newton Corp.,The | Dallas, TX 75251 | Oil & Gas Operator | May 2025 |
| 545 | Nitro Oil & Gas, LLC | Cuero, TX 77954 | Oil & Gas Operator | May 2025 |
| 546 | Noramco Production, LLC | Midland, TX 79710 | Oil & Gas Operator | Jan 2023 |
| 547 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | May 2025 |
| 548 | North American Royalties, Inc. | Chattanooga, TN 37408 | Oil & Gas Operator | Oct 2001 |
| 549 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | May 2025 |
| 550 | O & O Operators, LLC. | Fate, TX 75132 | Oil & Gas Operator | May 2025 |
| 551 | O'Brien, George H. Jr. | Midland, TX 79701 | Oil & Gas Operator | Jun 1994 |
| 552 | O'Ryan Oil And Gas | Odessa, TX 79768 | Oil & Gas Operator | May 2025 |
| 553 | O.G.P. Operating, Inc. | Dallas, TX 75231 | Oil & Gas Operator | May 2025 |
| 554 | Occidental Energy Company, Inc. | Houston, TX 77282 | Oil & Gas Operator | Jul 2021 |
| 555 | Occidental Energy Marketing, Inc. | Houston, TX 77227 | Gas Operator | Sep 2015 |
| 556 | Occidental Permian LTD. | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 557 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 558 | Odessa Exploration, Inc. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 559 | Odessa Oil Investment Co., Inc. | Odessa, TX 79762 | Oil & Gas Operator | Nov 2016 |
| 560 | Oilfield Management, Inc. (A) | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 561 | Oilwell Operators, Inc. | Pampa, TX 79066 | Oil & Gas Operator | May 2025 |
| 562 | Ojai Oil Company | Camarillo, CA 93012 | Oil & Gas Operator | Feb 2025 |
| 563 | Ok Arena Operating Company | Oklahoma City, OK 73101 | Oil & Gas Operator | May 2025 |
| 564 | Okla. Magic Circle Energy Corp. | Shawnee, OK 74801 | Oil & Gas Operator | Jul 2004 |
| 565 | Oklahoma Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2013 |
| 566 | Olsen Energy Inc. | Boerne, TX 78006 | Oil & Gas Operator | May 2025 |
| 567 | Omar Operating Company | Midland, TX 79702 | Oil & Gas Operator | Sep 2013 |
| 568 | Opal Resources Operating Co.,LLC | Cypress, TX 77429 | Oil & Gas Operator | Jan 2019 |
| 569 | Opco Oil & Gas Co. | Dallas, TX 75231 | Oil & Gas Operator | Aug 2003 |
| 570 | Orbitron Operating Corp. | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 1995 |
| 571 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 572 | Oso Exploration & Production, LLC | Houston, TX 77269 | Oil Operator | May 2025 |
| 573 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 574 | Ouut Investing LLC | Mineral Wells, TX 76068 | Oil Operator | Mar 2020 |
| 575 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 576 | Owens Petroleum, Inc. | Midland, TX 79702 | Oil & Gas Operator | Aug 1995 |
| 577 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 578 | Oxy USA WTP LP | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 579 | Pacesetter Energy, Inc. | Flower Mound, TX 75028 | Oil & Gas Operator | May 2008 |
| 580 | Pacesetter Energy, LLC | Flower Mound, TX 75028 | Oil & Gas Operator | Jul 2020 |
| 581 | Panhandle Oil & Gas Inc | Oklahoma City, OK 73112-5688 | Oil & Gas Operator | May 2007 |
| 582 | Panther Creek Resources, LLC | Denver, CO 80202 | Oil & Gas Operator | May 2012 |
| 583 | Parallel Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | Jan 2010 |
| 584 | Parallel Petroleum LLC | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 585 | Parish, John R. | Andrews, TX 79714 | Oil & Gas Operator | May 2025 |
| 586 | Parker & Parsley Acq. Group LLC | Midland, TX 79702 | Oil & Gas Operator | Aug 2002 |
| 587 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 588 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 589 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 590 | Parsley Energy Operations, LLC | Irving, TX 75038 | Oil & Gas Operator | Jan 2021 |
| 591 | Patriot Production LLC | Southlake, TX 76092 | Oil & Gas Operator | Apr 2023 |
| 592 | Patriot Resources, Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 2017 |
| 593 | Patterson Petroleum LP | Snyder, TX 79550 | Oil & Gas Operator | Mar 2008 |
| 594 | Patterson Petroleum, Inc. | Snyder, TX 79550 | Oil & Gas Operator | Feb 2000 |
| 595 | PDC Energy | Denver, CO 80203 | Oil & Gas Operator | Nov 2012 |
| 596 | PDC-WV-Co Corporation | Denver, CO 80203 | Oil & Gas Operator | Aug 2010 |
| 597 | Pearce, Roy F., Jr. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 598 | Pearl, Bill H. Productions, Inc. | Corpus Chrsti, TX 78460 | Oil & Gas Operator | May 2025 |
| 599 | Pecos Development Corporation | San Antonio, TX 78209 | Oil Operator | Aug 1988 |
| 600 | Pecos Operating Company, LLC | Midland, TX 79701 | Oil & Gas Operator | Jun 2021 |