| 401 | Koch Oil Company | | Oil & Gas Operator | May 2017 |
| 402 | KRS Oil Company | Frisco, TX 75034 | Oil & Gas Operator | Apr 2020 |
| 403 | KTP Energy, Inc. | Denver, CO 80226 | Oil & Gas Operator | Aug 2019 |
| 404 | Ladd Petroleum Corp. | Denver, CO 80202 | Oil & Gas Operator | Oct 2004 |
| 405 | Lagoon Water Logistics LLC | Oklahoma City, OK 73103 | Oil Operator | Jul 2024 |
| 406 | Laguna Petroleum Corporation | Houston, TX 77046 | Oil & Gas Operator | Apr 2025 |
| 407 | Lancer Petroleum Corporation | Irving, TX 75014 | Oil & Gas Operator | Feb 2014 |
| 408 | Landmark Exploration Co | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2013 |
| 409 | Langham Petroleum Expl. Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 2009 |
| 410 | Laran Operating LLC | Dover, OK 73734-0057 | Oil & Gas Operator | Mar 2015 |
| 411 | Lariat Petroleum Inc | Tulsa, OK 74119 | Oil & Gas Operator | Sep 2024 |
| 412 | Latex Petroleum Corp. | Houston, TX 77090 | Oil & Gas Operator | Aug 2012 |
| 413 | Latigo Oil And Gas Inc | Woodward, OK 73801 | Oil & Gas Operator | Feb 2025 |
| 414 | Latigo Petroleum, LLC | Pampa, TX 79066 | Oil & Gas Operator | Apr 2025 |
| 415 | LCB Resources LLC | Kingfisher, OK 73750-2322 | Oil & Gas Operator | Feb 2025 |
| 416 | Le Norman Energy Corporation | Duncan, OK 73534 | Oil & Gas Operator | Nov 2014 |
| 417 | Legacy Reserves Operating LP | Denver, CO 80201 | Oil & Gas Operator | Apr 2025 |
| 418 | Lime Rock Resources A, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2025 |
| 419 | Lime Rock Resources II-A, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2025 |
| 420 | Lincoln Rock Corporation | Northfield, IL 60093 | Oil & Gas Operator | Jul 2003 |
| 421 | Lindenmuth & Associates Inc | Austin, TX 78703 | Oil & Gas Operator | Aug 2024 |
| 422 | Lobo Exploration Company | Yukon, OK 73099 | Oil & Gas Operator | Jan 2025 |
| 423 | Locators Oil And Gas Inc | Guthrie, OK 73044 | Oil & Gas Operator | Oct 2022 |
| 424 | Locin Oil Corporation | Katy, TX 77494 | Oil & Gas Operator | Apr 2025 |
| 425 | Lorentz Oil & Gas LLC | Edmond, OK 73034-7266 | Oil & Gas Operator | Jan 2025 |
| 426 | Louis Dreyfus Gas Marketing | Oklahoma City, OK 73134 | Oil & Gas Operator | Mar 2018 |
| 427 | LTJ Enterprises LLC | Lone Grove, OK 73443 | Oil & Gas Operator | Dec 2024 |
| 428 | LVM Oil Production LLC | Yale, OK 74085-6688 | Oil & Gas Operator | Jul 2021 |
| 429 | LX4 LLC | Gage, OK 73843 | Oil Operator | Dec 2024 |
| 430 | Lyon Energy, Inc. | Plano, TX 75075 | Oil & Gas Operator | Feb 2000 |
| 431 | M M Energy, Inc. | Oklahoma City, OK 73156 | Oil & Gas Operator | Jan 2025 |
| 432 | M M Resources, Inc. | Oklahoma City, OK 73156 | Oil & Gas Operator | Sep 2018 |
| 433 | M V Purchasing LLC | Wichita, KS 67202 | Oil & Gas Operator | Jan 2025 |
| 434 | Mac Laskey Kelly Oilfield | El Dorado, KS 67042 | Oil & Gas Operator | Feb 2025 |
| 435 | Mackellar Inc | Oklahoma City, OK 73116-7101 | Oil & Gas Operator | Feb 2025 |
| 436 | Malson Oil Company | Crawford, OK 73638 | Oil & Gas Operator | Dec 2016 |
| 437 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Feb 2025 |
| 438 | Marjo Operating Mid-Continent LLC | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2025 |
| 439 | Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Jan 2025 |
| 440 | Marshall Oil Corporation | Oklahoma City, OK 73154 | Oil & Gas Operator | Apr 2017 |
| 441 | Massad George H Estate | Holdenville, OK 74848 | Oil & Gas Operator | Dec 2014 |
| 442 | Maverick Brothers Resources LLC | Enid, OK 73701 | Oil & Gas Operator | Jan 2025 |
| 443 | MBR Resources, Inc. | Tulsa, OK 74119 | Oil & Gas Operator | Apr 2025 |
| 444 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 445 | McNeal & Shahan Oil Co Inc | | Oil & Gas Operator | Apr 2014 |
| 446 | McNic Oil & Gas Midcontinent | Oklahoma City, OK 73154-0526 | Oil & Gas Operator | May 2024 |
| 447 | McOr Oil & Gas Corp | Houston, TX 77002 | Oil & Gas Operator | Oct 2013 |
| 448 | Meade Energy Corporation | Oklahoma City, OK 73118-4015 | Oil & Gas Operator | Feb 2025 |
| 449 | Meadowbrook Oil Corporation Of Ok Inc | Del City, OK 73115-3608 | Oil & Gas Operator | Feb 2025 |
| 450 | Medina-Pierce Oil & Gas Co | | Oil & Gas Operator | Feb 2012 |
| 451 | Mep Operating LLC | Houston, TX 77056-2733 | Oil & Gas Operator | Jan 2025 |
| 452 | Mer Resources Inc | Edmond, OK 73013-7662 | Oil & Gas Operator | Mar 2015 |
| 453 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 454 | Metropolitan Resources Corp | Tulsa, OK 74169-1734 | Oil & Gas Operator | Mar 2015 |
| 455 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Apr 2025 |
| 456 | Mge Resources, Inc. | Perryton, TX 79070 | Oil & Gas Operator | Jan 2025 |
| 457 | Mid Center Oil Company | | Oil & Gas Operator | Mar 2014 |
| 458 | Mid-Con Central Expl Co | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2014 |
| 459 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2025 |
| 460 | Mid-Continent Energy Operating Company | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2025 |
| 461 | Middle Bay Production Co. Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2014 |
| 462 | Midgard Energy Company | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2014 |
| 463 | Midnight Hour LLC | Enid, OK 73702 | Oil & Gas Operator | Apr 2020 |
| 464 | Midwest Energy Corporation | Tulsa, OK 74105-6083 | Oil & Gas Operator | Aug 2016 |
| 465 | Mija LLC | Edmond, OK 73034 | Oil & Gas Operator | Feb 2025 |
| 466 | Milmac Operating Company | Lubbock, TX 79408-2976 | Oil & Gas Operator | Sep 2004 |
| 467 | Miracle Production Inc | Yukon, OK 73085-0680 | Oil & Gas Operator | Jun 2007 |
| 468 | Mito Resources LLC | Edmond, OK 73013 | Oil & Gas Operator | Feb 2025 |
| 469 | Moabb Oil Corp | | Oil & Gas Operator | Apr 1998 |
| 470 | Mobil Exp & Prod Us Inc | Houston, TX 77060-1991 | Oil & Gas Operator | May 2001 |
| 471 | Monarch Energy Company LLC | Eufaula, OK 74432 | Oil & Gas Operator | Feb 2025 |
| 472 | Moncrief W A Jr | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 2025 |
| 473 | Montgomery Exploration Co LTD | Dallas, TX 75204-2634 | Oil & Gas Operator | Jan 2025 |
| 474 | Monty L Hott Production Corporation | Oklahoma City, OK 73142 | Oil & Gas Operator | Jan 2025 |
| 475 | Morris Ed Dba Morris Operating Company | Mounds, OK 74047-4801 | Oil & Gas Operator | Feb 2025 |
| 476 | Morrison International Energy Inc | Oklahoma City, OK 73189-0537 | Oil & Gas Operator | Dec 2024 |
| 477 | Mountain Front Pipeline Co, Inc | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2015 |
| 478 | Muirfield Resources Company | Tulsa, OK 74101-3166 | Oil & Gas Operator | Jun 2024 |
| 479 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 480 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Feb 2025 |
| 481 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 482 | National Cooperative RFG Assoc | McPherson, KS 67460-1404 | Oil & Gas Operator | Jun 2006 |
| 483 | National Energy Group, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 484 | Native Gas Company LLC | Edmond, OK 73083-7435 | Oil & Gas Operator | Mar 2015 |
| 485 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 486 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Nov 2024 |
| 487 | Nelson Exploration Corporation | Cleveland, OK 74020-5725 | Oil & Gas Operator | Jan 2025 |
| 488 | Nerco Oil & Gas, Inc. | | Oil & Gas Operator | Dec 1996 |
| 489 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Apr 2025 |
| 490 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Apr 2025 |
| 491 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | Apr 2025 |
| 492 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Apr 2025 |
| 493 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 494 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Jan 2025 |
| 495 | Oexco, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2015 |
| 496 | Ofs-Tulsa Corporation | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1997 |
| 497 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Apr 2025 |
| 498 | Oilfield Operating Company | Cushing, OK 74023-1347 | Oil & Gas Operator | Jan 2018 |
| 499 | Oilsearch Corporation | Albuquerque, NM 87109 | Oil & Gas Operator | Feb 1994 |
| 500 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2025 |