| 401 | Metropolitan Resources Corp | Tulsa, OK 74169-1734 | Oil & Gas Operator | Mar 2015 |
| 402 | Mid-Con Central Expl Co | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2014 |
| 403 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Apr 2026 |
| 404 | Midnight Hour LLC | Enid, OK 73702 | Oil & Gas Operator | Apr 2020 |
| 405 | Midwest Energy Corporation | Tulsa, OK 74105-6083 | Oil & Gas Operator | Aug 2016 |
| 406 | Midwest Pipe & Supply Company | Oklahoma City, OK 73154-0245 | Oil & Gas Operator | Dec 2008 |
| 407 | Milmac Operating Company | Lubbock, TX 79408-2976 | Oil & Gas Operator | Sep 2004 |
| 408 | Mito Resources LLC | Edmond, OK 73013 | Oil & Gas Operator | Mar 2026 |
| 409 | Mobil Exp & Prod Us Inc | Houston, TX 77060-1991 | Oil & Gas Operator | May 2001 |
| 410 | Monroe Natural Gas Inc | Norman, OK 73071 | Oil & Gas Operator | Mar 2026 |
| 411 | Monty L Hott Production Corporation | Oklahoma City, OK 73142 | Oil & Gas Operator | Feb 2026 |
| 412 | Moore Petroleum Invest Corp | Norman, OK 73072-4217 | Oil & Gas Operator | Feb 2026 |
| 413 | Mud Operations Inc | Ames, OK 73718-9501 | Oil & Gas Operator | Feb 2026 |
| 414 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Feb 2026 |
| 415 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 416 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Jun 2026 |
| 417 | Mustang Gas Products LLC | Oklahoma City, OK 73114-7406 | Oil & Gas Operator | Sep 2022 |
| 418 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 419 | Nadel And Gussman LLC | Tulsa, OK 74119 | Oil & Gas Operator | Jun 2026 |
| 420 | National Cooperative RFG Assoc | McPherson, KS 67460-1404 | Oil & Gas Operator | Oct 2025 |
| 421 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 422 | Nbi Services, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | Jun 2026 |
| 423 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Aug 2025 |
| 424 | Nelson Exploration Corporation | Cleveland, OK 74020-5725 | Oil & Gas Operator | Feb 2026 |
| 425 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Jun 2026 |
| 426 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Jun 2026 |
| 427 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Mar 2026 |
| 428 | Nova Energy Corporation | Denver, CO 80201 | Oil & Gas Operator | Jun 2003 |
| 429 | NWM Operating Inc | Okeene, OK 73763 | Oil & Gas Operator | Feb 2026 |
| 430 | Nytex, L.L.C. | Edmond, OK 73083 | Oil & Gas Operator | Feb 2006 |
| 431 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 432 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Feb 2026 |
| 433 | Oak Tree Natural Res LLC | Oklahoma City, OK 73120-5065 | Oil & Gas Operator | Mar 2015 |
| 434 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2026 |
| 435 | Oklahoma Energy Acquisitions LP | Houston, TX 77094-1900 | Oil & Gas Operator | Feb 2026 |
| 436 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Feb 2026 |
| 437 | Oklahoma Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2013 |
| 438 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 439 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Mar 2026 |
| 440 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 441 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 442 | Oneok Gas Transportation Co | Tulsa, OK 74121-2089 | Oil & Gas Operator | Oct 2014 |
| 443 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 444 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Mar 2026 |
| 445 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 446 | Overflow Energy Stack LLC | Booker, TX 79005 | Oil Operator | Sep 2022 |
| 447 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Mar 2026 |
| 448 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Jun 2026 |
| 449 | Oxley Petroleum | Tulsa, OK 74119-3609 | Oil & Gas Operator | Jan 2020 |
| 450 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Jun 2026 |
| 451 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 452 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 453 | Paloma Operating Co Inc | Houston, TX 77002-5220 | Oil & Gas Operator | Mar 2026 |
| 454 | Palomino Petroleum Inc | Newton, KS 67114 | Oil & Gas Operator | Feb 2026 |
| 455 | Panhandle Oil & Gas Consultants Inc | Woodward, OK 73802-5011 | Oil & Gas Operator | Jul 2015 |
| 456 | Pantera Energy Company | Amarillo, TX 79101 | Oil & Gas Operator | Jun 2026 |
| 457 | Pardee Production Co. | Skiatook, OK 74070 | Oil & Gas Operator | Mar 2021 |
| 458 | Park Avenue Exploration Corp | Oklahoma City, OK 73102-5604 | Oil & Gas Operator | Sep 2011 |
| 459 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 460 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 461 | Patina Oklahoma Corp | Duncan, OK 73533-9523 | Oil & Gas Operator | Nov 2014 |
| 462 | Pawnee Petroleum Company | Seminole, OK 74868-0951 | Oil & Gas Operator | Feb 2023 |
| 463 | Payne Exploration Company | Crescent, OK 73028 | Oil & Gas Operator | Feb 2026 |
| 464 | Pearl Oil Company | Nichols Hills, OK 73120-1408 | Oil & Gas Operator | Nov 2023 |
| 465 | Pegasus Energy Corporation | Oklahoma City, OK 73162 | Oil & Gas Operator | Mar 2015 |
| 466 | Pengo Petroleum Inc | | Oil & Gas Operator | Dec 2013 |
| 467 | Perkins Energy Company | Duncan, OK 73533-3853 | Oil & Gas Operator | Mar 2026 |
| 468 | Petro Speed Inc | Norman, OK 73069-8116 | Oil & Gas Operator | Mar 2015 |
| 469 | Petro-Management Assoc., Inc. | Edmond, OK 73083-2346 | Oil & Gas Operator | Jun 2007 |
| 470 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 471 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 472 | Petroleum Investment Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 1998 |
| 473 | Petroleum Properties MGMT. Co. | Oklahoma City, OK 73118 | Oil & Gas Operator | Dec 2014 |
| 474 | Petroleum Reserve Corporation | Plymouth MTNG, PA 19462 | Oil & Gas Operator | May 2008 |
| 475 | Piper Operating LLC | Stigler, OK 74462 | Oil & Gas Operator | Feb 2026 |
| 476 | Pitco Production Company | Tulsa, OK 74170-2320 | Oil & Gas Operator | May 2013 |
| 477 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 478 | Plainsmen Energy LLC | Enid, OK 73703-5747 | Oil & Gas Operator | Mar 2026 |
| 479 | Plotner Ralph Oil & Gas Inv Co | Oklahoma City, OK 73112 | Oil & Gas Operator | Nov 2021 |
| 480 | Post Oak Oil Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Jul 2013 |
| 481 | Prentice, Napier & Green, Inc. | Oklahoma City, OK 73142 | Oil & Gas Operator | Mar 2026 |
| 482 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Jun 2026 |
| 483 | Primary Natural Resources Inc. | Tulsa, OK 74136-6351 | Oil & Gas Operator | Mar 2023 |
| 484 | Prime Operating Company | Midland, TX 79705 | Oil & Gas Operator | Jun 2026 |
| 485 | Primexx Operating Corporation | Dallas, TX 75206 | Oil & Gas Operator | Mar 2024 |
| 486 | Prospective Investment & Trading | Scottsdale, AZ 85261-4190 | Oil & Gas Operator | Jun 2016 |
| 487 | Protege Energy LLC | Tulsa, OK 74135 | Oil & Gas Operator | Jan 2018 |
| 488 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Feb 2026 |
| 489 | Questar Explor & Prod Co | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2017 |
| 490 | Quinn Energy Corp | MT Vernon, IN 47620 | Oil & Gas Operator | Oct 1999 |
| 491 | R.E.J.A.S. Energy LLC | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2026 |
| 492 | Ra-Jac LLC | Norman, OK 73069 | Oil & Gas Operator | Mar 2026 |
| 493 | Rachael Exploration Corp | Traverse City, MI 49686 | Oil & Gas Operator | Apr 2001 |
| 494 | Raker Resources LLC | Houston, TX 77042 | Oil & Gas Operator | Jun 2026 |
| 495 | Ram Asset Management Co | Oklahoma City, OK 73114 | Oil & Gas Operator | Mar 2015 |
| 496 | Rambler Oil Co | Oklahoma City, OK 73154 | Oil & Gas Operator | Jan 1999 |
| 497 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 498 | Ramsey Nichols Operating Company LLC | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Feb 2026 |
| 499 | Ramsey Property Management LLC | Oklahoma City, OK 73120 | Oil & Gas Operator | Jan 2026 |
| 500 | Randy Inc | Hennessey, OK 73742 | Oil & Gas Operator | Jan 2026 |