| 501 | Mackellar Inc | Oklahoma City, OK 73116-7101 | Oil & Gas Operator | Feb 2026 |
| 502 | Magaw & Zimmer | Perry, OK 73077-1055 | Oil & Gas Operator | Aug 2013 |
| 503 | Maggard Oil Co Inc | Manford, OK 74044 | Oil & Gas Operator | Sep 1997 |
| 504 | Malson Oil Company | Crawford, OK 73638 | Oil & Gas Operator | Dec 2016 |
| 505 | Manna Corporation | Oklahoma City, OK 73162 | Oil & Gas Operator | Dec 2014 |
| 506 | Manuel Corporation | Wichita, KS 67206 | Oil & Gas Operator | Feb 2026 |
| 507 | Marathon Oil Company LLC | Houston, TX 77079 | Oil & Gas Operator | Feb 2026 |
| 508 | Marbet LLC | Edmond, OK 73013-6691 | Oil & Gas Operator | Jan 2026 |
| 509 | Marjo Oil Company | Lockhart, TX 78644 | Oil & Gas Operator | Oct 1999 |
| 510 | Marjo Operating Company Inc | Tulsa, OK 741010729 | Oil & Gas Operator | Jan 2026 |
| 511 | Marjo Operating Mid-Continent LLC | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2026 |
| 512 | Mark A Meier Dba MSC Oil And Gas Co | Oklahoma City, OK 73105 | Oil & Gas Operator | Dec 2025 |
| 513 | Mark Holloway Inc | Oklahoma City, OK 73107-6526 | Oil & Gas Operator | Feb 2026 |
| 514 | Mathews Billy J | Morris, OK 74445-4826 | Oil & Gas Operator | Dec 2025 |
| 515 | May Petroleum Inc | Dallas, TX 75231 | Oil & Gas Operator | Nov 1998 |
| 516 | Mayabb Oil Company Inc | Tulsa, OK 74105-5158 | Oil & Gas Operator | Oct 2025 |
| 517 | McCoy Petroleum Corporation | Wichita, KS 67207 | Oil & Gas Operator | Feb 2026 |
| 518 | McGriff Craig Exploration Inc | Oklahoma City, OK 73172-0364 | Oil & Gas Operator | Mar 2023 |
| 519 | McMillin C C & Company Inc | Guthrie, OK 73044 | Oil & Gas Operator | Jan 2026 |
| 520 | McQueen Ed & Company Inc | Lindsey, OK 73052 | Oil & Gas Operator | Apr 2014 |
| 521 | Meadowbrook Oil Corporation Of Ok Inc | Del City, OK 73115-3608 | Oil & Gas Operator | Feb 2026 |
| 522 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 523 | Mercer Oil And Gas Co Inc | Norman, OK 73070 | Oil & Gas Operator | Apr 2015 |
| 524 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 525 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Apr 2026 |
| 526 | Metropolitan Resources Corp | Tulsa, OK 74169-1734 | Oil & Gas Operator | Mar 2015 |
| 527 | Mid-Con Central Expl Co | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2014 |
| 528 | Mid-Con Energy Operating, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | May 2020 |
| 529 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2026 |
| 530 | Mid-Continent Energy Operating Company | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2026 |
| 531 | Middle Bay Production Co. Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2014 |
| 532 | Midnight Hour LLC | Enid, OK 73702 | Oil & Gas Operator | Apr 2020 |
| 533 | Midwest Energy Corporation | Tulsa, OK 74105-6083 | Oil & Gas Operator | Aug 2016 |
| 534 | Midwest Enterprises Inc | Cashion, OK 73016-9626 | Oil & Gas Operator | Apr 2025 |
| 535 | Midwest Pipe & Supply Company | Oklahoma City, OK 73154-0245 | Oil & Gas Operator | Dec 2008 |
| 536 | Midwestern Exploration Company | Edmond, OK 73013 | Oil & Gas Operator | May 2025 |
| 537 | Miller Exploration Company | Tulsa, OK 74136-1020 | Oil & Gas Operator | Mar 2015 |
| 538 | Milmac Operating Company | Lubbock, TX 79408-2976 | Oil & Gas Operator | Sep 2004 |
| 539 | Min-Tex Oil Corporation | Tulsa, OK 74170 | Oil & Gas Operator | Dec 1996 |
| 540 | Miracle Production Inc | Yukon, OK 73085-0680 | Oil & Gas Operator | Jun 2007 |
| 541 | Mogul Energy Corp | Los Angeles, CA 90024 | Oil & Gas Operator | Jan 2001 |
| 542 | Monroe Natural Gas Inc | Norman, OK 73071 | Oil & Gas Operator | Feb 2026 |
| 543 | Moore Clay | Bradenton, FL 34211 | Oil & Gas Operator | Jan 2026 |
| 544 | Moore Investments LC | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Feb 2023 |
| 545 | Moore Petroleum Invest Corp | Norman, OK 73072-4217 | Oil & Gas Operator | Oct 2025 |
| 546 | Mott Petroleum Corporation | Sugar Land, TX 77487 | Oil & Gas Operator | Aug 2024 |
| 547 | MT Energy LLC | Waskom, TX 75692 | Oil & Gas Operator | Apr 2026 |
| 548 | Mud Operations Inc | Ames, OK 73718-9501 | Oil & Gas Operator | Feb 2026 |
| 549 | Mullen William Company | Edmond, OK 73083-1372 | Oil & Gas Operator | May 1999 |
| 550 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Jan 2026 |
| 551 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 552 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Apr 2026 |
| 553 | Mustang Gas Products LLC | Oklahoma City, OK 73114-7406 | Oil & Gas Operator | Sep 2022 |
| 554 | National Cooperative RFG Assoc | McPherson, KS 67460-1404 | Oil & Gas Operator | Oct 2025 |
| 555 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 556 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 557 | Natural Progression Oil & Gas Corp | Stillwater, OK 74075 | Oil & Gas Operator | Jan 2026 |
| 558 | Nbi Services, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | Apr 2026 |
| 559 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Aug 2025 |
| 560 | Nelson Exploration Corporation | Cleveland, OK 74020-5725 | Oil & Gas Operator | Feb 2026 |
| 561 | Nerco Oil & Gas Inc | | Oil & Gas Operator | Dec 1996 |
| 562 | New Century Petroleum Corp | Oklahoma City, OK 73105 | Oil & Gas Operator | May 2013 |
| 563 | New Dominion LLC | Tulsa, OK 74119-3220 | Oil & Gas Operator | Feb 2026 |
| 564 | New Horizon Resources LLC | Houston, TX 77057 | Oil & Gas Operator | Apr 2026 |
| 565 | Newkumet Exploration, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 2020 |
| 566 | Nexus Resources Corporation | Drumright, OK 74030 | Oil & Gas Operator | Jan 2013 |
| 567 | Nielson & Associates, Inc | Cody, WY 82414 | Oil & Gas Operator | Feb 2016 |
| 568 | Nivens Productions LLC | Coyle, OK 73027-9785 | Oil & Gas Operator | Aug 2024 |
| 569 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Apr 2026 |
| 570 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Apr 2026 |
| 571 | Nondorf Oil & Gas Inc | Oklahoma City, OK 73154 | Oil & Gas Operator | Feb 2008 |
| 572 | Norman Production Company | Chandler, OK 74834-8538 | Oil & Gas Operator | May 2015 |
| 573 | North Star Exploration Company | Oklahoma City, OK 73116 | Oil & Gas Operator | Jan 2026 |
| 574 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 575 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Feb 2026 |
| 576 | O'Brien Oil Corporation | Guthrie, OK 73044-3154 | Oil & Gas Operator | Jan 2026 |
| 577 | O'Brien Oil LLC | Guthrie, OK 73044-3154 | Oil & Gas Operator | Apr 2020 |
| 578 | O'Neal Oil & Gas Co | Fort Worth, TX 76107-1479 | Oil & Gas Operator | Feb 2026 |
| 579 | Oakland Petroleum Oper Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2026 |
| 580 | Oex-1 LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Mar 2024 |
| 581 | Ofs-Tulsa Corporation | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1997 |
| 582 | Oil Investors Inc | Crescent, OK 73028 | Oil & Gas Operator | Feb 2026 |
| 583 | Oil Ventures LTD | | Oil & Gas Operator | Jan 2013 |
| 584 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 585 | Oklahoma Energy Acquisitions LP | Houston, TX 77094-1900 | Oil & Gas Operator | Feb 2026 |
| 586 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 587 | Oklahoma Liquid Resources Inc | Collinsville, OK 74021 | Oil & Gas Operator | Dec 2025 |
| 588 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Jan 2026 |
| 589 | Oklahoma Oil And Gas Resources LLC | Guthrie, OK 73044-8095 | Oil & Gas Operator | Jan 2026 |
| 590 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 591 | Omimex International Corp | Fort Worth, TX 76103-2300 | Oil & Gas Operator | Jan 2026 |
| 592 | Oneok Gas Transportation Co | Tulsa, OK 74121-2089 | Oil & Gas Operator | Oct 2014 |
| 593 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 594 | Optima Exploration LLC | Tulsa, OK 74116-5664 | Oil & Gas Operator | Mar 2015 |
| 595 | Opubco Resources Of TX Inc | Dallas, TX 75231 | Oil & Gas Operator | Sep 2005 |
| 596 | Orason Resources Inc | Tulsa, OK 74169-1225 | Oil & Gas Operator | Nov 2006 |
| 597 | Orion Exploration LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Apr 2015 |
| 598 | Orion Exploration Partners LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Nov 2025 |
| 599 | Osage Exploration & Development Inc | San Diego, CA 92131-3807 | Oil & Gas Operator | Oct 2016 |
| 600 | Oso Resources LLC | Edmond, OK 73003 | Oil & Gas Operator | Jan 2026 |