| 501 | Longfellow Energy, LP | Dallas, TX 75225 | Oil & Gas Operator | Dec 2025 |
| 502 | Lucky Ace Petroleum LLC | Carrollton, TX 75010-4232 | Oil Operator | Oct 2021 |
| 503 | Lucky Oil Company | Comanche, OK 73529-0009 | Oil Operator | Jul 2025 |
| 504 | M-B Operating Co., Inc. | Rowlett, TX 75030 | Oil & Gas Operator | Dec 2025 |
| 505 | Mack Energy Co. | Duncan, OK 73534 | Oil & Gas Operator | Oct 2025 |
| 506 | Mackellar Inc | Oklahoma City, OK 73116-7101 | Oil & Gas Operator | Oct 2025 |
| 507 | Macmart Inc | Wynnewood, OK 73098 | Oil & Gas Operator | Jan 2016 |
| 508 | Magma Resources LLC | Paoli, OK 73074 | Oil & Gas Operator | Apr 2025 |
| 509 | Magnum Energy Inc | Norman, OK 73072-2403 | Oil & Gas Operator | Oct 2025 |
| 510 | Maier Resources Inc | Oklahoma City, OK 73157-2996 | Oil & Gas Operator | Mar 2015 |
| 511 | Maloney Helen V Dba Penn-Ok Corporation | Hockessin, DE 19707-9640 | Oil & Gas Operator | Sep 2025 |
| 512 | Manna Corporation | Oklahoma City, OK 73162 | Oil & Gas Operator | Dec 2014 |
| 513 | Manuel Corporation | Wichita, KS 67206 | Oil & Gas Operator | Sep 2025 |
| 514 | Marathon Oil Company LLC | Houston, TX 77079 | Oil & Gas Operator | Oct 2025 |
| 515 | Mark Holloway Inc | Oklahoma City, OK 73107-6526 | Oil & Gas Operator | Oct 2025 |
| 516 | Mark L Shidler Inc | Houston, TX 77055 | Oil & Gas Operator | Oct 2025 |
| 517 | Marler Philip | Purcell, OK 73080-1522 | Oil & Gas Operator | Nov 2016 |
| 518 | Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Oct 2025 |
| 519 | Marsh Oil & Gas Company | Oklahoma City, OK 73118 | Oil & Gas Operator | Sep 2025 |
| 520 | Marshall Oil Corporation | Oklahoma City, OK 73154 | Oil & Gas Operator | Apr 2017 |
| 521 | Masters Loy C | Davis, OK 73030-0397 | Oil & Gas Operator | Apr 2005 |
| 522 | Mathews Exploration Corporation | Oklahoma City, OK 73155-5328 | Oil & Gas Operator | Mar 2015 |
| 523 | Maverick Brothers Resources LLC | Enid, OK 73701 | Oil & Gas Operator | Oct 2025 |
| 524 | Maxim Energy Corporation | Baytown, TX 77520 | Oil & Gas Operator | Oct 2025 |
| 525 | Maxine Oil Company | Muskogee, OK 74401-0512 | Oil & Gas Operator | Sep 2014 |
| 526 | MBR Resources, Inc. | Tulsa, OK 74119 | Oil & Gas Operator | Dec 2025 |
| 527 | McNutt P L | San Marcos, CA 92069-4817 | Oil & Gas Operator | Jul 1994 |
| 528 | Meade Energy Corporation | Oklahoma City, OK 73118-4015 | Oil & Gas Operator | Oct 2025 |
| 529 | Meadowbrook Oil Corporation Of Ok Inc | Del City, OK 73115-3608 | Oil & Gas Operator | Oct 2025 |
| 530 | Megaenergy Operating, Inc. | Edmond, OK 73034 | Oil & Gas Operator | Jul 2015 |
| 531 | Mep Operating LLC | Houston, TX 77056-2733 | Oil & Gas Operator | Aug 2025 |
| 532 | Mer-Bar Exploration Co Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Oct 1992 |
| 533 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Dec 2025 |
| 534 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 535 | Metropolitan Resources Corp | Tulsa, OK 74169-1734 | Oil & Gas Operator | Mar 2015 |
| 536 | Mija LLC | Oklahoma City, OK 73151 | Oil & Gas Operator | Oct 2025 |
| 537 | Miller Petroleum Company | Yukon, OK 73099-0452 | Oil & Gas Operator | Aug 2009 |
| 538 | Mobil Exp & Prod Us Inc | Houston, TX 77060-1991 | Oil & Gas Operator | May 2001 |
| 539 | Mogo Operating, LLC | Norman, OK 73069 | Oil & Gas Operator | Oct 2025 |
| 540 | Montego Resources Inc | Oklahoma City, OK 73172-0192 | Oil & Gas Operator | Mar 2015 |
| 541 | Moore & Moore Energy Inc | Purcell, OK 73080-0674 | Oil & Gas Operator | Dec 2012 |
| 542 | Moore David K | Duncan, OK 73575 | Oil & Gas Operator | Oct 2009 |
| 543 | Moore Don | Elmore City, OK 73433 | Oil & Gas Operator | Oct 2025 |
| 544 | Moore Petroleum Invest Corp | Norman, OK 73072-4217 | Oil & Gas Operator | Oct 2025 |
| 545 | Moore Richard L | Morris, OK 74445 | Oil Operator | Aug 2013 |
| 546 | Moran Oil Enterprises LLC | Seminole, OK 74818 | Oil & Gas Operator | Dec 2019 |
| 547 | Moran-K Oil LLC | Seminole, OK 74868 | Oil & Gas Operator | Oct 2025 |
| 548 | Mott Oil & Gas | Sugarland, TX 77478 | Oil & Gas Operator | May 2001 |
| 549 | Mott Petroleum Corporation | Sugar Land, TX 77487 | Oil & Gas Operator | Aug 2024 |
| 550 | Mowdy Robert F | Coalgate, OK 74538 | Oil & Gas Operator | May 2001 |
| 551 | MT Energy LLC | Waskom, TX 75692 | Oil & Gas Operator | Dec 2025 |
| 552 | Mullins Jimmy R Dba Southcreek Petroleum Co | Dibble, OK 73031 | Oil & Gas Operator | Jan 2021 |
| 553 | Murchison Oil & Gas Inc | Plano, TX 75024 | Oil & Gas Operator | Aug 2020 |
| 554 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 555 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Oct 2025 |
| 556 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 557 | N & N Oil LLC | Duncan, OK 73533 | Oil & Gas Operator | May 2023 |
| 558 | Nadel And Gussman LLC | Tulsa, OK 74119 | Oil & Gas Operator | Dec 2025 |
| 559 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 560 | Native Exploration Operating LLC | Oklahoma City, OK 73102-5804 | Oil & Gas Operator | Aug 2025 |
| 561 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 562 | Neok Production Company LLC | Nowata, OK 74048 | Oil & Gas Operator | Sep 2025 |
| 563 | Newkumet Exploration, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 2020 |
| 564 | Nexco Inc | Oklahoma City, OK 73102-6801 | Oil & Gas Operator | Nov 2013 |
| 565 | Nitro Petroleum Inc | Phoenix, AZ 85016-4599 | Oil & Gas Operator | May 2020 |
| 566 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Dec 2025 |
| 567 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Dec 2025 |
| 568 | Nooner Cynthia | Ratliff City, OK 73481 | Oil Operator | Aug 2025 |
| 569 | Norman Brothers Tank Truck Inc | Pauls Valley, OK 73075 | Oil & Gas Operator | May 2020 |
| 570 | North American Energy Inc | Duncan, OK 73533-9604 | Oil & Gas Operator | Nov 2000 |
| 571 | North Bound Exploration Co | Pauls Valley, OK 73075-0863 | Oil & Gas Operator | Jan 2018 |
| 572 | Northbrook Oil & Gas Co LLC | Norman, OK 73072 | Oil & Gas Operator | Nov 2014 |
| 573 | Northbrook Oil & Gas Company | Norman, OK 73070-4916 | Oil & Gas Operator | Jun 2016 |
| 574 | Northport Production Company | Oklahoma City, OK 73113 | Oil & Gas Operator | Oct 2025 |
| 575 | NRG Oil LLC | Stratford, OK 74872-9732 | Oil Operator | Feb 2012 |
| 576 | Nub'S Well Servicing Inc | Ratliff City, OK 73481 | Oil & Gas Operator | Oct 2025 |
| 577 | Nutt Jerrie | Duncan, OK 73534-0698 | Oil & Gas Operator | Nov 2016 |
| 578 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Oct 2025 |
| 579 | O'Neal Oil & Gas Co | Fort Worth, TX 76107-1479 | Oil & Gas Operator | Oct 2025 |
| 580 | Oak Hills Drilling & Oper., LLC | Holdenville, OK 74848 | Oil & Gas Operator | May 2013 |
| 581 | Oak Hills Energy Inc | Holdenville, OK 74848-0470 | Oil & Gas Operator | Sep 2014 |
| 582 | Oak Resources Inc | Tulsa, OK 74153 | Oil & Gas Operator | Aug 2013 |
| 583 | Obele Oil Corporation | Sedona, AZ 86336-5745 | Oil & Gas Operator | May 2017 |
| 584 | Obele Operating Company LLC | Sedona, AZ 86336-5745 | Oil & Gas Operator | Oct 2025 |
| 585 | Oil Recovery Systems Inc | Tulsa, OK 74145-4619 | Oil & Gas Operator | Oct 2025 |
| 586 | Oil State Petroleum Inc | Jennings, OK 74038 | Oil & Gas Operator | Oct 2025 |
| 587 | Oilsearch Corporation | Albuquerque, NM 87109 | Oil & Gas Operator | Feb 1994 |
| 588 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2025 |
| 589 | Oklahoma Basic Economy Corp | Houston, TX 77002-6003 | Oil & Gas Operator | Apr 2020 |
| 590 | Oklahoma Energy Exchange LLC | Duncan, OK 73534-1105 | Oil & Gas Operator | Sep 2012 |
| 591 | Oklahoma Liquid Resources Inc | Collinsville, OK 74021 | Oil & Gas Operator | Aug 2025 |
| 592 | Oklahoma O & G Royalties Inc | Duncan, OK 73533 | Oil & Gas Operator | Nov 2000 |
| 593 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Sep 2025 |
| 594 | Oklahoma Prime Energy LLC | Ardmore, OK 73401 | Oil Operator | May 2020 |
| 595 | Oklahoma Tank Service Inc | Oklahoma City, OK 73143 | Oil Operator | Aug 1997 |
| 596 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Oct 2025 |
| 597 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 598 | Oktex Operating LLC | Edmond, OK 73013-1961 | Oil & Gas Operator | May 2020 |
| 599 | Olia Oil & Gas Services LLC | Cedar Park, TX 78630-2049 | Oil & Gas Operator | Aug 2022 |
| 600 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |