| 501 | Milmac Operating Company | Lubbock, TX 79408-2976 | Oil & Gas Operator | Sep 2004 |
| 502 | Mito Resources LLC | Edmond, OK 73013 | Oil & Gas Operator | Sep 2025 |
| 503 | Miura Petroleum Inc | Topeka, KS 66603 | Oil & Gas Operator | May 2006 |
| 504 | MJM Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Aug 2003 |
| 505 | MJM Resources Inc | Norman, OK 73072 | Oil & Gas Operator | Sep 2025 |
| 506 | Mobil Exp & Prod Us Inc | Houston, TX 77060-1991 | Oil & Gas Operator | May 2001 |
| 507 | Mohawk Operating LLC | Oklahoma City, OK 73173-8907 | Gas Operator | Feb 2004 |
| 508 | Monarch Petroleum Corporation | FT Worth, TX 76102 | Oil & Gas Operator | Dec 2019 |
| 509 | Monroe Natural Gas Inc | Norman, OK 73071 | Oil & Gas Operator | Aug 2025 |
| 510 | Monty L Hott Production Corporation | Oklahoma City, OK 73142 | Oil & Gas Operator | Aug 2025 |
| 511 | Moore & Moore Energy Inc | Purcell, OK 73080-0674 | Oil & Gas Operator | Dec 2012 |
| 512 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 513 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Sep 2025 |
| 514 | Mustang Gas Products LLC | Oklahoma City, OK 73114-7406 | Oil & Gas Operator | Sep 2022 |
| 515 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 516 | Nadel And Gussman LLC | Tulsa, OK 74119 | Oil & Gas Operator | Dec 2025 |
| 517 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 518 | Native Exploration Operating LLC | Oklahoma City, OK 73102-5804 | Oil & Gas Operator | Aug 2025 |
| 519 | Nbi Services, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | Dec 2025 |
| 520 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Aug 2025 |
| 521 | New Dominion LLC | Tulsa, OK 74119-3220 | Oil & Gas Operator | Sep 2025 |
| 522 | NFC Petroleum Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1996 |
| 523 | Nielson & Associates, Inc | Cody, WY 82414 | Oil & Gas Operator | Feb 2016 |
| 524 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | Dec 2025 |
| 525 | North American Royalties, Inc. | Chattanooga, TN 37408 | Oil & Gas Operator | Oct 2001 |
| 526 | Nova Energy Corporation | Denver, CO 80201 | Oil & Gas Operator | Jun 2003 |
| 527 | Nytex, L.L.C. | Edmond, OK 73083 | Oil & Gas Operator | Feb 2006 |
| 528 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 529 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Aug 2025 |
| 530 | Oak Tree Natural Res LLC | Oklahoma City, OK 73120-5065 | Oil & Gas Operator | Mar 2015 |
| 531 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 532 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Aug 2025 |
| 533 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 534 | Oklahoma Rig & Salvage Inc | Oklahoma City, OK 73114 | Oil & Gas Operator | Mar 2015 |
| 535 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Sep 2025 |
| 536 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 537 | Omni Oil & Gas, Inc. | San Antonio, TX 78229 | Oil & Gas Operator | Oct 2017 |
| 538 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 539 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2022 |
| 540 | Oneok Gas Transportation Co | Tulsa, OK 74121-2089 | Oil & Gas Operator | Oct 2014 |
| 541 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 542 | Onyx Energy Corporation | Oklahoma City, OK 73157 | Oil & Gas Operator | May 1994 |
| 543 | Onyx Properties Corp | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2006 |
| 544 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 545 | Outback Petroleum Inc | Moore, OK 73160-9998 | Oil & Gas Operator | Mar 2015 |
| 546 | Ovation Energy II, LP | Houston, TX 77279 | Oil & Gas Operator | Jun 2011 |
| 547 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Aug 2025 |
| 548 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2025 |
| 549 | Oxley Petroleum | Tulsa, OK 74119-3609 | Oil & Gas Operator | Jan 2020 |
| 550 | Oxley Petroleum Company | Oklahoma City, OK 73118-1044 | Oil & Gas Operator | Sep 2017 |
| 551 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 552 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 553 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Dec 2025 |
| 554 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 555 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 556 | Pal Kids Inc | Coronado, CA 92118 | Oil & Gas Operator | Nov 2000 |
| 557 | Paleo, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Dec 2025 |
| 558 | Paloma Operating Co Inc | Houston, TX 77002-5220 | Oil & Gas Operator | Jul 2025 |
| 559 | Pan Western Energy Corporation | Tulsa, OK 74114 | Oil & Gas Operator | Dec 2025 |
| 560 | Panenergy Services Inc | Houston, TX 77525 | Oil & Gas Operator | May 2001 |
| 561 | Panhandle Oil & Gas Consultants Inc | Woodward, OK 73802-5011 | Oil & Gas Operator | Jul 2015 |
| 562 | Pardee Production Co. | Skiatook, OK 74070 | Oil & Gas Operator | Mar 2021 |
| 563 | Park Avenue Exploration Corp | Oklahoma City, OK 73102-5604 | Oil & Gas Operator | Sep 2011 |
| 564 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 565 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 566 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 567 | Payrock Energy LLC | Oklahoma City, OK 73134-2612 | Oil & Gas Operator | Feb 2023 |
| 568 | Pedestal Oil Company Inc | Oklahoma City, OK 73101-1522 | Oil & Gas Operator | May 2019 |
| 569 | Pegasus Energy Corporation | Oklahoma City, OK 73162 | Oil & Gas Operator | Mar 2015 |
| 570 | Penn VIrginia MC Operating Co LLC | Houston, TX 77084-7213 | Oil & Gas Operator | Sep 2025 |
| 571 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 572 | Petro-Lewis Corp. | | Oil & Gas Operator | Feb 1994 |
| 573 | Petro-Management Assoc., Inc. | Edmond, OK 73083-2346 | Oil & Gas Operator | Jun 2007 |
| 574 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 575 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 576 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 577 | Petroleum Investment Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 1998 |
| 578 | Petroleum Properties MGMT. Co. | Oklahoma City, OK 73118 | Oil & Gas Operator | Dec 2014 |
| 579 | Petroquest Energy, L.L.C. | Lafayette, LA 70505 | Oil & Gas Operator | Dec 2025 |
| 580 | Phase III Drilling Inc | Wetumka, OK 74883-0333 | Oil & Gas Operator | Aug 2025 |
| 581 | Phoenix Hydrocarbons Operating Co | Midland, TX 79702-3638 | Oil & Gas Operator | Jul 2018 |
| 582 | Pioneer Exploration Company | Houston, TX 77090 | Oil & Gas Operator | Sep 2025 |
| 583 | Pioneer Natural Res. USA, Inc. | Spring, TX 77389 | Oil & Gas Operator | Dec 2025 |
| 584 | Pioneer Resources Prod LP | Irving, TX 75039-3745 | Oil & Gas Operator | Feb 2005 |
| 585 | Piper Operating LLC | Stigler, OK 74462 | Oil & Gas Operator | Sep 2025 |
| 586 | Pitco Production Company | Tulsa, OK 74170-2320 | Oil & Gas Operator | May 2013 |
| 587 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 588 | Plainsmen Energy LLC | Enid, OK 73703-5747 | Oil & Gas Operator | Sep 2025 |
| 589 | Pletcher Oil Limited Liability Company | Ardmore, OK 73401 | Oil & Gas Operator | Sep 2025 |
| 590 | Plotner Oil Company | Oklahoma City, OK 73122 | Oil & Gas Operator | Sep 2025 |
| 591 | Plotner Ralph Oil & Gas Inv Co | Oklahoma City, OK 73112 | Oil & Gas Operator | Nov 2021 |
| 592 | Portal Energy Corporation | Dallas, TX 75201 | Oil & Gas Operator | Mar 1993 |
| 593 | Post Oak Oil Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Jul 2013 |
| 594 | Post Petroleum Company | Oklahoma City, OK 73116 | Oil & Gas Operator | Aug 2013 |
| 595 | Potter J And D Oil LLC | Kingfisher, OK 73750-3832 | Oil & Gas Operator | Mar 2015 |
| 596 | Powerline Energy Corporation | Arlington, TX 76015 | Oil & Gas Operator | Dec 2025 |
| 597 | Prentice, Napier & Green, Inc. | Oklahoma City, OK 73142 | Oil & Gas Operator | Sep 2025 |
| 598 | Presidio Energy Inc | | Oil & Gas Operator | Jan 1992 |
| 599 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Dec 2025 |
| 600 | Primary Natural Resources Inc. | Tulsa, OK 74136-6351 | Oil & Gas Operator | Mar 2023 |