| 501 | Mendell Petroleum Corporation | Castle Rock, CO 80104-9045 | Oil & Gas Operator | Sep 2004 |
| 502 | Mep Operating LLC | | Oil & Gas Operator | Jan 2024 |
| 503 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Apr 2024 |
| 504 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 505 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Apr 2024 |
| 506 | Mge Resources, Inc. | Perryton, TX 79070 | Oil & Gas Operator | Jan 2024 |
| 507 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 508 | Mid-Con Central Expl Co | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2014 |
| 509 | Mid-Con Energy Operating, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | May 2020 |
| 510 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2024 |
| 511 | Mid-Continent Petroleum Corp | | Oil & Gas Operator | Mar 2017 |
| 512 | Mid-Continent Petroleum Management Inc | Cement, OK 73017-0600 | Oil & Gas Operator | Jan 2024 |
| 513 | Midwest Enterprises, Inc. | Cashion, OK 73016-9626 | Oil & Gas Operator | Jan 2024 |
| 514 | Mija LLC | | Oil & Gas Operator | Feb 2024 |
| 515 | Mild Oil Company | Duncan, OK 73533-9532 | Oil Operator | Mar 2000 |
| 516 | Minerva Oil Company | Tulsa, OK 74152-0858 | Oil & Gas Operator | Mar 2015 |
| 517 | Mink Oil Company | | Oil Operator | Nov 2003 |
| 518 | Mobil Exp & Prod Us Inc | Houston, TX 77060-1991 | Oil & Gas Operator | May 2001 |
| 519 | Monexco Operating Company | Dallas, TX 75204-2634 | Oil & Gas Operator | Jan 2024 |
| 520 | Monroe Natural Gas Inc | Norman, OK 73070-5687 | Oil & Gas Operator | Jan 2024 |
| 521 | Montgomery Exploration Co LTD | Dallas, TX 75204-2634 | Oil & Gas Operator | Feb 2024 |
| 522 | Monty L Hott Production Corporation | Oklahoma City, OK 73142 | Oil & Gas Operator | Jan 2024 |
| 523 | Moore & Moore Energy Inc | Purcell, OK 73080-0674 | Oil & Gas Operator | Dec 2012 |
| 524 | Moore David K | Duncan, OK 73575 | Oil & Gas Operator | Oct 2009 |
| 525 | Moore Richard L | Morris, OK 74445 | Oil Operator | Aug 2013 |
| 526 | Mott Oil & Gas | Sugarland, TX 77478 | Oil & Gas Operator | May 2001 |
| 527 | Mott Petroleum Corporation | Sugar Land, TX 77487-3058 | Oil & Gas Operator | Jan 2024 |
| 528 | Mud Operations Inc | Ames, OK 73718-9501 | Oil & Gas Operator | Feb 2024 |
| 529 | Muirfield Resources Company | Tulsa, OK 74101-3166 | Oil & Gas Operator | Jan 2024 |
| 530 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 531 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Feb 2024 |
| 532 | Mustang Gas Products LLC | Oklahoma City, OK 73114-7406 | Oil & Gas Operator | Sep 2022 |
| 533 | Mustang Transport Company | Oklahoma City, OK 73106 | Oil Operator | Jul 1993 |
| 534 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 535 | National Cooperative RFG Assoc | McPherson, KS 67460-1404 | Oil & Gas Operator | Jun 2006 |
| 536 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 537 | National Oil Company | Garden City, KS 67846 | Oil & Gas Operator | Jan 2024 |
| 538 | Natomas North America Inc | | Oil & Gas Operator | Aug 1993 |
| 539 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 540 | Nbi Services, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | Apr 2024 |
| 541 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Apr 2017 |
| 542 | Nelson Exploration Corporation | | Oil & Gas Operator | Jan 2024 |
| 543 | Nemaha Environmental Services LLC | Enid, OK 73703 | Oil Operator | Feb 2024 |
| 544 | Neok Production Company LLC | Nowata, OK 74048-0428 | Oil & Gas Operator | Jan 2024 |
| 545 | NFC Petroleum Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1996 |
| 546 | Nielson & Associates Inc | Cody, WY 82414 | Oil & Gas Operator | Feb 2016 |
| 547 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Apr 2024 |
| 548 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Apr 2024 |
| 549 | Noble Operating, LLC | Flower Mound, TX 75028 | Oil & Gas Operator | Sep 2013 |
| 550 | Northbrook Oil & Gas Co LLC | Norman, OK 73072 | Oil & Gas Operator | Nov 2014 |
| 551 | Northbrook Oil & Gas Company | Norman, OK 73070-4916 | Oil & Gas Operator | Jun 2016 |
| 552 | Northport Production Company | Oklahoma City, OK 73113 | Oil & Gas Operator | Feb 2024 |
| 553 | Nova Energy Corporation | Denver, CO 80201 | Oil & Gas Operator | Jun 2003 |
| 554 | Nyc Resources LTD | Tulsa, OK 74133-5700 | Oil & Gas Operator | Sep 2014 |
| 555 | O G & E | Oklahoma City, OK 73124-0300 | Oil & Gas Operator | Feb 2014 |
| 556 | O'Neal Oil & Gas Co | Fort Worth, TX 76107-1479 | Oil & Gas Operator | Feb 2024 |
| 557 | Oil Investors Inc | | Oil & Gas Operator | Mar 2024 |
| 558 | Oilco Gas Co LC | Duncan, OK 73534 | Oil & Gas Operator | Dec 2014 |
| 559 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2024 |
| 560 | Oklahoma & Northwestern Co. | Oklahoma City, OK 73102 | Oil & Gas Operator | Jan 1997 |
| 561 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 562 | Oklahoma Liquid Resources Inc | Owasso, OK 74055-0841 | Oil & Gas Operator | Jan 2024 |
| 563 | Oklahoma O & G Royalties Inc | Duncan, OK 73533 | Oil & Gas Operator | Nov 2000 |
| 564 | Oklahoma Oil & Gas MGMT Inc | | Oil & Gas Operator | Jan 2024 |
| 565 | Oklahoma Petroleum Allies LLC | Ardmore, OK 73401 | Oil Operator | Oct 2023 |
| 566 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Feb 2024 |
| 567 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 568 | Oktex Operating LLC | Edmond, OK 73013-1961 | Oil & Gas Operator | May 2020 |
| 569 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 570 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2022 |
| 571 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 572 | Oryx Crude Trading & Transporation LP | Dallas, TX 75221 | Oil & Gas Operator | Jun 1999 |
| 573 | Otc Petroleum Corporation | Oklahoma City, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 574 | Otc/Occ Not Assigned | | Oil & Gas Operator | Nov 2023 |
| 575 | Ouachita Exploration Inc | Chickasha, OK 73023-0926 | Oil & Gas Operator | Jan 2024 |
| 576 | Overflow Energy, LLC | Booker, TX 79005 | Oil & Gas Operator | Apr 2024 |
| 577 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Jan 2024 |
| 578 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Apr 2024 |
| 579 | Oxley John C | Tulsa, OK 74103 | Oil & Gas Operator | Sep 1996 |
| 580 | Oxley Petroleum | Tulsa, OK 74119-3609 | Oil & Gas Operator | Jan 2020 |
| 581 | Oxley Petroleum Co | Oklahoma City, OK 73118-1044 | Oil & Gas Operator | Sep 2017 |
| 582 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Apr 2024 |
| 583 | Ozark Gas Gathering LLC | Fort Smith, AR 72916 | Oil & Gas Operator | Jan 2024 |
| 584 | P O & G Operating LLC | Houston, TX 77057 | Oil & Gas Operator | Apr 2024 |
| 585 | P O & G Panhandle LP | | Oil & Gas Operator | Jan 2024 |
| 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 | Paloma Operating Co Inc | | Oil & Gas Operator | Dec 2023 |
| 589 | Panhandle Trading Company | Houston, TX 77251-1642 | Oil & Gas Operator | Jun 2003 |
| 590 | Pap Oil Company Inc | Cement, OK 73017-0240 | Oil & Gas Operator | Nov 1998 |
| 591 | Paramount Petroleum Corp | Dallas, TX 75374 | Oil Operator | Dec 2000 |
| 592 | Park Avenue Exploration Corp | Oklahoma City, OK 73102-5604 | Oil & Gas Operator | Sep 2011 |
| 593 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 594 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 595 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 596 | Patina Oklahoma Corp | Duncan, OK 73533-9523 | Oil & Gas Operator | Nov 2014 |
| 597 | Payne Exploration Company | Crescent, OK 73028-0502 | Oil & Gas Operator | Jan 2024 |
| 598 | Payne W C Family Trust | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Mar 2015 |
| 599 | PBT Enterprises Inc | Garber, OK 73738-0262 | Oil & Gas Operator | May 2023 |
| 600 | Pedestal Oil Company Inc | Oklahoma City, OK 73101-1522 | Oil & Gas Operator | May 2019 |