| 401 | Lime Rock Resources A, L.P. | Houston, TX 77002 | Oil & Gas Operator | Sep 2025 |
| 402 | Lime Rock Resources II-A, L.P. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 403 | Lincoln Rock Corporation | Northfield, IL 60093 | Oil & Gas Operator | Jul 2003 |
| 404 | Lindenmuth & Associates Inc | Austin, TX 78703 | Oil & Gas Operator | Jun 2025 |
| 405 | Lobo Exploration Company | Yukon, OK 73099 | Oil & Gas Operator | Oct 2025 |
| 406 | Locators Oil And Gas Inc | Guthrie, OK 73044 | Oil & Gas Operator | Oct 2022 |
| 407 | Locin Oil Corporation | Katy, TX 77494 | Oil & Gas Operator | Dec 2025 |
| 408 | Lorentz Oil & Gas LLC | Edmond, OK 73034-7266 | Oil & Gas Operator | Oct 2025 |
| 409 | LTJ Enterprises LLC | Lone Grove, OK 73443 | Oil & Gas Operator | May 2025 |
| 410 | LVM Oil Production LLC | Yale, OK 74085-6688 | Oil & Gas Operator | Jul 2021 |
| 411 | LX4, LLC | Laverne, OK 73848 | Oil Operator | Oct 2025 |
| 412 | Lyon Energy, Inc. | Plano, TX 75075 | Oil & Gas Operator | Feb 2000 |
| 413 | M & M Resources Inc | Oklahoma City, OK 73156 | Oil & Gas Operator | Sep 2018 |
| 414 | M M Energy Inc | Oklahoma City, OK 73156 | Oil & Gas Operator | Oct 2025 |
| 415 | Mackellar Inc | Oklahoma City, OK 73116-7101 | Oil & Gas Operator | Oct 2025 |
| 416 | Malson Oil Company | Crawford, OK 73638 | Oil & Gas Operator | Dec 2016 |
| 417 | Marathon Oil Company LLC | Houston, TX 77079 | Oil & Gas Operator | Oct 2025 |
| 418 | Marjo Operating Mid-Continent LLC | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2025 |
| 419 | Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Oct 2025 |
| 420 | Marshall Oil Corporation | Oklahoma City, OK 73154 | Oil & Gas Operator | Apr 2017 |
| 421 | Massad George H Estate | Holdenville, OK 74848 | Oil & Gas Operator | Dec 2014 |
| 422 | Maverick Brothers Resources LLC | Enid, OK 73701 | Oil & Gas Operator | Oct 2025 |
| 423 | MBR Resources, Inc. | Tulsa, OK 74119 | Oil & Gas Operator | Dec 2025 |
| 424 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 425 | McNic Oil & Gas Midcontinent | Oklahoma City, OK 73154-0526 | Oil & Gas Operator | May 2024 |
| 426 | McOr Oil & Gas Corp | Houston, TX 77002 | Oil & Gas Operator | Oct 2013 |
| 427 | Meade Energy Corporation | Oklahoma City, OK 73118-4015 | Oil & Gas Operator | Oct 2025 |
| 428 | Meadowbrook Oil Corporation Of Ok Inc | Del City, OK 73115-3608 | Oil & Gas Operator | Oct 2025 |
| 429 | Mep Operating LLC | Houston, TX 77056-2733 | Oil & Gas Operator | Aug 2025 |
| 430 | Mer Resources Inc | Edmond, OK 73013-7662 | Oil & Gas Operator | Mar 2015 |
| 431 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 432 | Metropolitan Resources Corp | Tulsa, OK 74169-1734 | Oil & Gas Operator | Mar 2015 |
| 433 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Dec 2025 |
| 434 | Mge Resources, Inc. | Perryton, TX 79070 | Oil & Gas Operator | Sep 2025 |
| 435 | Mid Center Oil Company | | Oil & Gas Operator | Mar 2014 |
| 436 | Mid-Con Central Expl Co | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2014 |
| 437 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Oct 2025 |
| 438 | Mid-Continent Energy Operating Company | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2025 |
| 439 | Middle Bay Production Co. Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2014 |
| 440 | Midgard Energy Company | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2014 |
| 441 | Midnight Hour LLC | Enid, OK 73702 | Oil & Gas Operator | Apr 2020 |
| 442 | Midwest Energy Corporation | Tulsa, OK 74105-6083 | Oil & Gas Operator | Aug 2016 |
| 443 | Mija LLC | Oklahoma City, OK 73151 | Oil & Gas Operator | Oct 2025 |
| 444 | Milmac Operating Company | Lubbock, TX 79408-2976 | Oil & Gas Operator | Sep 2004 |
| 445 | Miracle Production Inc | Yukon, OK 73085-0680 | Oil & Gas Operator | Jun 2007 |
| 446 | Mito Resources LLC | Edmond, OK 73013 | Oil & Gas Operator | Oct 2025 |
| 447 | Moabb Oil Corp | | Oil & Gas Operator | Apr 1998 |
| 448 | Mobil Exp & Prod Us Inc | Houston, TX 77060-1991 | Oil & Gas Operator | May 2001 |
| 449 | Monarch Energy Company LLC | Eufaula, OK 74432 | Oil & Gas Operator | Oct 2025 |
| 450 | Montgomery Exploration Co LTD | Dallas, TX 75204-2634 | Oil & Gas Operator | Oct 2025 |
| 451 | Monty L Hott Production Corporation | Oklahoma City, OK 73142 | Oil & Gas Operator | Oct 2025 |
| 452 | Morris Ed Dba Morris Operating Company | Mounds, OK 74047-4801 | Oil & Gas Operator | Oct 2025 |
| 453 | Morrison International Energy Inc | Oklahoma City, OK 73189-0537 | Oil & Gas Operator | Feb 2025 |
| 454 | Muirfield Resources Company | Tulsa, OK 74101-3166 | Oil & Gas Operator | Jun 2024 |
| 455 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 456 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Oct 2025 |
| 457 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 458 | National Cooperative RFG Assoc | McPherson, KS 67460-1404 | Oil & Gas Operator | Oct 2025 |
| 459 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 460 | Native Gas Company LLC | Edmond, OK 73083-7435 | Oil & Gas Operator | Mar 2015 |
| 461 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 462 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Aug 2025 |
| 463 | Nelson Exploration Corporation | Cleveland, OK 74020-5725 | Oil & Gas Operator | Oct 2025 |
| 464 | Nerco Oil & Gas Inc | | Oil & Gas Operator | Dec 1996 |
| 465 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Dec 2025 |
| 466 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Dec 2025 |
| 467 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | Dec 2025 |
| 468 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Dec 2025 |
| 469 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 470 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Oct 2025 |
| 471 | Oexco, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2015 |
| 472 | Ofs-Tulsa Corporation | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1997 |
| 473 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Dec 2025 |
| 474 | Oilfield Operating Company | Cushing, OK 74023-1347 | Oil & Gas Operator | Jan 2018 |
| 475 | Oilsearch Corporation | Albuquerque, NM 87109 | Oil & Gas Operator | Feb 1994 |
| 476 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2025 |
| 477 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 478 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Sep 2025 |
| 479 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 480 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Oct 2025 |
| 481 | Okt Petroleum Company Inc | Oklahoma City, OK 73118-7425 | Oil & Gas Operator | Oct 2013 |
| 482 | Omimex International Corp | Fort Worth, TX 76103-2300 | Oil & Gas Operator | Oct 2025 |
| 483 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2022 |
| 484 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 485 | Onyx Energy Corporation | Oklahoma City, OK 73157 | Oil & Gas Operator | May 1994 |
| 486 | Onyx Properties Corp | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2006 |
| 487 | Opal Operating Company LLC | Edmond, OK 73013 | Oil & Gas Operator | Dec 2025 |
| 488 | Opubco Resources Of TX Inc | Dallas, TX 75231 | Oil & Gas Operator | Sep 2005 |
| 489 | Orca Operating Company LLC | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 490 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 491 | Overflow Energy Stack LLC | Booker, TX 79005 | Oil Operator | Sep 2022 |
| 492 | Overflow Energy, LLC | Perryton, TX 79070 | Oil & Gas Operator | Dec 2025 |
| 493 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Oct 2025 |
| 494 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2025 |
| 495 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 496 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Dec 2025 |
| 497 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 498 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 499 | Paloma Operating Co Inc | Houston, TX 77002-5220 | Oil & Gas Operator | Jul 2025 |
| 500 | Paluca Petroleum Inc | Holdenville, OK 74848 | Oil & Gas Operator | Oct 2025 |