| 401 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 402 | Mer-Bar Exploration Co Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Oct 1992 |
| 403 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 404 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Dec 2025 |
| 405 | Meroda Resources LLC | Mustang, OK 73064-9408 | Oil & Gas Operator | Apr 2000 |
| 406 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 407 | MFP Petroleum LP | Oklahoma City, OK 73142-3017 | Gas Operator | Jul 2025 |
| 408 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 409 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Oct 2025 |
| 410 | Mid-Continent Energy Operating Company | Tulsa, OK 74103 | Oil & Gas Operator | Sep 2025 |
| 411 | Mid-Continent Petroleum Management Inc | Cement, OK 73017 | Oil & Gas Operator | Aug 2025 |
| 412 | Midnight Hour LLC | Enid, OK 73702 | Oil & Gas Operator | Apr 2020 |
| 413 | Mild Oil Company | Duncan, OK 73533-9532 | Oil Operator | Mar 2000 |
| 414 | Minerva Oil Company | Tulsa, OK 74152-0858 | Oil & Gas Operator | Mar 2015 |
| 415 | Mink Oil Company | | Oil Operator | Nov 2003 |
| 416 | Mito Resources LLC | Edmond, OK 73013 | Oil & Gas Operator | Sep 2025 |
| 417 | MJM Resources Inc | Norman, OK 73072 | Oil & Gas Operator | Sep 2025 |
| 418 | Moncrief R W Inc | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 1994 |
| 419 | Monty L Hott Production Corporation | Oklahoma City, OK 73142 | Oil & Gas Operator | Aug 2025 |
| 420 | Moore & Moore Energy Inc | Purcell, OK 73080-0674 | Oil & Gas Operator | Dec 2012 |
| 421 | Moore David K | Duncan, OK 73575 | Oil & Gas Operator | Oct 2009 |
| 422 | Mott Energy LLC | Riverview, FL 33569-6702 | Oil & Gas Operator | Sep 2024 |
| 423 | Mott Petroleum Corporation | Sugar Land, TX 77487 | Oil & Gas Operator | Aug 2024 |
| 424 | MT Energy LLC | Waskom, TX 75692 | Oil & Gas Operator | Dec 2025 |
| 425 | Munson Dave Company | Dallas, TX 75201-3591 | Oil Operator | Aug 1996 |
| 426 | Munson, David M. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2015 |
| 427 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 428 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Sep 2025 |
| 429 | Mustang Gas Products LLC | Oklahoma City, OK 73114-7406 | Oil & Gas Operator | Sep 2022 |
| 430 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 431 | Nadel And Gussman LLC | Tulsa, OK 74119 | Oil & Gas Operator | Dec 2025 |
| 432 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 433 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 434 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Aug 2025 |
| 435 | New Horizon Resources LLC | Houston, TX 77057 | Oil & Gas Operator | Dec 2025 |
| 436 | Nexstreem Corporation | | Oil & Gas Operator | Dec 2020 |
| 437 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Dec 2025 |
| 438 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Dec 2025 |
| 439 | Northport Production Company | Oklahoma City, OK 73113 | Oil & Gas Operator | Aug 2025 |
| 440 | Nova Energy Corporation | Denver, CO 80201 | Oil & Gas Operator | Jun 2003 |
| 441 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 442 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Aug 2025 |
| 443 | Oil Recovery Systems Inc | Tulsa, OK 74145-4619 | Oil & Gas Operator | Aug 2025 |
| 444 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Aug 2025 |
| 445 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Aug 2025 |
| 446 | Oklahoma Oil And Gas Resources LLC | Guthrie, OK 73044-8095 | Oil & Gas Operator | Sep 2025 |
| 447 | Oklahoma Tank Service Inc | Oklahoma City, OK 73143 | Oil Operator | Aug 1997 |
| 448 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Sep 2025 |
| 449 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 450 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 451 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2022 |
| 452 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 453 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 454 | Ouachita Exploration Inc | Chickasha, OK 73018 | Oil & Gas Operator | Aug 2025 |
| 455 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Aug 2025 |
| 456 | Oxley Petroleum | Tulsa, OK 74119-3609 | Oil & Gas Operator | Jan 2020 |
| 457 | Oxley Petroleum Company | Oklahoma City, OK 73118-1044 | Oil & Gas Operator | Sep 2017 |
| 458 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 459 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 460 | P O & G Panhandle LP | Houston, TX 77057 | Oil & Gas Operator | Aug 2025 |
| 461 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Dec 2025 |
| 462 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 463 | Paleo, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Dec 2025 |
| 464 | Palisades Asset Holding Co LLC | Dallas, TX 75201 | Oil & Gas Operator | Aug 2017 |
| 465 | Panhandle Eastern Pipeline Company LP | Houston, TX 77002-6803 | Oil & Gas Operator | Oct 1999 |
| 466 | Pap Oil Company Inc | Cement, OK 73017-0240 | Oil & Gas Operator | Nov 1998 |
| 467 | Park Avenue Exploration Corp | Oklahoma City, OK 73102-5604 | Oil & Gas Operator | Sep 2011 |
| 468 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 469 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 470 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 471 | Payne Charlie D | Lawton, OK 73505 | Oil & Gas Operator | May 2001 |
| 472 | Peachridge Energy Operating LLC | Houston, TX 77024-2246 | Oil & Gas Operator | Sep 2025 |
| 473 | Pegasus Energy Corporation | Oklahoma City, OK 73162 | Oil & Gas Operator | Mar 2015 |
| 474 | Penn VIrginia MC Operating Co LLC | Houston, TX 77084-7213 | Oil & Gas Operator | Sep 2025 |
| 475 | Perkins, Earl | | Oil & Gas Operator | Aug 2013 |
| 476 | Pet-Ex Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Jun 2025 |
| 477 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 478 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 479 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 480 | Petroleum Investment Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 1998 |
| 481 | Petroleum Properties MGMT. Co. | Oklahoma City, OK 73118 | Oil & Gas Operator | Dec 2014 |
| 482 | Petroquest Energy, L.L.C. | Lafayette, LA 70505 | Oil & Gas Operator | Dec 2025 |
| 483 | Phoenix Petrocorp, Inc. | McKinney, TX 75070 | Oil & Gas Operator | Sep 2025 |
| 484 | Pierce O M Operations | Duncan, OK 73533 | Oil & Gas Operator | Nov 1998 |
| 485 | Pioneer Exploration Company | Houston, TX 77090 | Oil & Gas Operator | Sep 2025 |
| 486 | Pioneer Natural Res. USA, Inc. | Spring, TX 77389 | Oil & Gas Operator | Dec 2025 |
| 487 | Pioneer Resources Prod LP | Irving, TX 75039-3745 | Oil & Gas Operator | Feb 2005 |
| 488 | Pioneer Trucking, LLC | | Oil Operator | Sep 2025 |
| 489 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 490 | Plainsmen Energy LLC | Enid, OK 73703-5747 | Oil & Gas Operator | Sep 2025 |
| 491 | Poblano Energy LLC | Houston, TX 77024-2217 | Oil & Gas Operator | Aug 2025 |
| 492 | Post Oak Oil Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Jul 2013 |
| 493 | Potter Tom Estate | | Oil Operator | Dec 2014 |
| 494 | Prentice, Napier & Green, Inc. | Oklahoma City, OK 73142 | Oil & Gas Operator | Sep 2025 |
| 495 | Presidio Petroleum LLC | Canadian, TX 79014 | Oil & Gas Operator | Dec 2025 |
| 496 | Pri Producing Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2006 |
| 497 | Price J R Inc | Addington, OK 73520-0099 | Oil & Gas Operator | Apr 2015 |
| 498 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Dec 2025 |
| 499 | Primary Natural Resources Inc. | Tulsa, OK 74136-6351 | Oil & Gas Operator | Mar 2023 |
| 500 | Prime Operating Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2025 |