| 501 | Mack Oil Company | Duncan, OK 73534 | Oil & Gas Operator | Nov 2000 |
| 502 | Mackellar Inc | Oklahoma City, OK 73116-7101 | Oil & Gas Operator | Jan 2026 |
| 503 | Magnum Energy Inc | Norman, OK 73072-2403 | Oil & Gas Operator | Jan 2026 |
| 504 | Maguire Oil Company | Dallas, TX 75270 | Oil & Gas Operator | Mar 2015 |
| 505 | Malson Oil Company | Crawford, OK 73638 | Oil & Gas Operator | Dec 2016 |
| 506 | Manuel Corporation | Wichita, KS 67206 | Oil & Gas Operator | Dec 2025 |
| 507 | Marathon Oil Company LLC | Houston, TX 77079 | Oil & Gas Operator | Jan 2026 |
| 508 | Mark Holloway Inc | Oklahoma City, OK 73107-6526 | Oil & Gas Operator | Dec 2025 |
| 509 | Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2025 |
| 510 | Massad George H Estate | Holdenville, OK 74848 | Oil & Gas Operator | Dec 2014 |
| 511 | Matador E & P Company Inc | | Oil & Gas Operator | May 2020 |
| 512 | Mator LLC | Hennessey, OK 73742-1235 | Oil & Gas Operator | Jan 2026 |
| 513 | Maverick Brothers Resources LLC | Enid, OK 73701 | Oil & Gas Operator | Dec 2025 |
| 514 | McDe Energy Company Inc | Enid, OK 73706 | Oil & Gas Operator | May 2009 |
| 515 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 516 | MCM Energy Inc | Edmond, OK 73013-8035 | Oil & Gas Operator | Nov 2021 |
| 517 | McQueen Ed & Company Inc | Lindsey, OK 73052 | Oil & Gas Operator | Apr 2014 |
| 518 | Meade Energy Corporation | Oklahoma City, OK 73118-4015 | Oil & Gas Operator | Jan 2026 |
| 519 | Meadowbrook Oil Corporation Of Ok Inc | Del City, OK 73115-3608 | Oil & Gas Operator | Jan 2026 |
| 520 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 521 | Mep Operating LLC | Houston, TX 77056-2733 | Oil & Gas Operator | Aug 2025 |
| 522 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 523 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Mar 2026 |
| 524 | Mermac Operating Company Inc | Norman, OK 73072 | Oil & Gas Operator | Mar 2015 |
| 525 | Meroda Resources LLC | Mustang, OK 73064-9408 | Oil & Gas Operator | Apr 2000 |
| 526 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 527 | Metropolitan Resources Corp | Tulsa, OK 74169-1734 | Oil & Gas Operator | Mar 2015 |
| 528 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Mar 2026 |
| 529 | Mid-Con Central Expl Co | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2014 |
| 530 | Mid-Continent Energy Operating Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 531 | Midgard Energy Company | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2014 |
| 532 | Midnight Hour LLC | Enid, OK 73702 | Oil & Gas Operator | Apr 2020 |
| 533 | Midstates Oil Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Nov 2000 |
| 534 | Miller Oil & Gas Co | Okmulgee, OK 74447 | Oil & Gas Operator | Oct 2017 |
| 535 | Miracle Production Inc | Yukon, OK 73085-0680 | Oil & Gas Operator | Jun 2007 |
| 536 | Monroe Natural Gas Inc | Norman, OK 73071 | Oil & Gas Operator | Dec 2025 |
| 537 | Montgomery Exploration Co LTD | Dallas, TX 75204-2634 | Oil & Gas Operator | Jan 2026 |
| 538 | MT Energy LLC | Waskom, TX 75692 | Oil & Gas Operator | Mar 2026 |
| 539 | Mud Operations Inc | Ames, OK 73718-9501 | Oil & Gas Operator | Dec 2025 |
| 540 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Dec 2025 |
| 541 | Murchison Oil & Gas Inc | Plano, TX 75024 | Oil & Gas Operator | Aug 2020 |
| 542 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 543 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Jan 2026 |
| 544 | Mustang Gas Products LLC | Oklahoma City, OK 73114-7406 | Oil & Gas Operator | Sep 2022 |
| 545 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 546 | Nadel And Gussman LLC | Tulsa, OK 74119 | Oil & Gas Operator | Mar 2026 |
| 547 | National Cooperative RFG Assoc | McPherson, KS 67460-1404 | Oil & Gas Operator | Oct 2025 |
| 548 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 549 | National Oil Co Ohio The | Columbus, OH 43215 | Oil & Gas Operator | Sep 1999 |
| 550 | National Oil Company | Garden City, KS 67846 | Oil & Gas Operator | Jun 2024 |
| 551 | Nbi Services, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | Mar 2026 |
| 552 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Aug 2025 |
| 553 | Nicor Supply Company | Golden, CO 80401 | Oil & Gas Operator | Jun 1993 |
| 554 | Nielson & Associates, Inc | Cody, WY 82414 | Oil & Gas Operator | Feb 2016 |
| 555 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Mar 2026 |
| 556 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Mar 2026 |
| 557 | Nomoc Oil Company Inc | Oklahoma City, OK 73112 | Oil & Gas Operator | May 2006 |
| 558 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Mar 2026 |
| 559 | Northern Pump Company | Denver, CO 80202-3130 | Oil & Gas Operator | Feb 2006 |
| 560 | Nova Energy Corporation | Denver, CO 80201 | Oil & Gas Operator | Jun 2003 |
| 561 | NWM Operating Inc | Okeene, OK 73763 | Oil & Gas Operator | Dec 2025 |
| 562 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 563 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Dec 2025 |
| 564 | O'Donnell Bill C | Tulsa, OK 74135-4241 | Oil & Gas Operator | Oct 2014 |
| 565 | O'Neill Properties, LTD. | Midland, TX 79702 | Oil & Gas Operator | Mar 2026 |
| 566 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Mar 2026 |
| 567 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Dec 2025 |
| 568 | Oklahoma Energy Acquisitions LP | Houston, TX 77094-1900 | Oil & Gas Operator | Dec 2025 |
| 569 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 570 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Dec 2025 |
| 571 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 572 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Jan 2026 |
| 573 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 574 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 575 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2022 |
| 576 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 577 | Onshore Royalties LLC | Houston, TX 77269 | Oil & Gas Operator | Dec 2025 |
| 578 | Onyx Properties Corp | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2006 |
| 579 | Opal Operating Company LLC | Edmond, OK 73013 | Oil & Gas Operator | Mar 2026 |
| 580 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Jan 2026 |
| 581 | Oso Resources LLC | Edmond, OK 73003 | Oil & Gas Operator | Dec 2025 |
| 582 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 583 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Dec 2025 |
| 584 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Mar 2026 |
| 585 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Mar 2026 |
| 586 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 587 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 588 | Paleo, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Mar 2026 |
| 589 | Palm Oil & Gas Company | Sedona, AZ 86340 | Oil & Gas Operator | Jan 2026 |
| 590 | Paluca Petroleum Inc | Holdenville, OK 74848 | Oil & Gas Operator | Dec 2025 |
| 591 | Panenergy Services Inc | Houston, TX 77525 | Oil & Gas Operator | May 2001 |
| 592 | Panexco Operating LLC | Oklahoma City, OK 73103-2203 | Oil & Gas Operator | Oct 2014 |
| 593 | Panhandle Oil & Gas Consultants Inc | Woodward, OK 73802-5011 | Oil & Gas Operator | Jul 2015 |
| 594 | Pantera Energy Company | Amarillo, TX 79101 | Oil & Gas Operator | Mar 2026 |
| 595 | Papal Enterprises Inc | Oklahoma City, OK 73154-1555 | Oil & Gas Operator | Apr 2015 |
| 596 | Paragon Production Company | Edmond, OK 73013-5051 | Oil & Gas Operator | Feb 2021 |
| 597 | Pardee Production Co. | Skiatook, OK 74070 | Oil & Gas Operator | Mar 2021 |
| 598 | Park William M | Sperry, OK 74073 | Oil & Gas Operator | Dec 2025 |
| 599 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 600 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |