| 401 | M-T Petroleum, Inc. | Andrews, TX 79714 | Oil & Gas Operator | Mar 2008 |
| 402 | M2 Squared Operating, LLC | Rockwall, TX 75032 | Oil Operator | May 2025 |
| 403 | Maguire Oil Company | Dallas, TX 75270 | Oil & Gas Operator | Mar 2015 |
| 404 | Mak-J Energy Partners(TX),LTD. | Denver, CO 80206 | Oil & Gas Operator | Sep 2013 |
| 405 | Manhattan Petroleum, Inc. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 406 | Maralo, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 1998 |
| 407 | Maralo, LLC | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 408 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Mar 2025 |
| 409 | Mariner Energy, Inc. | Houston, TX 77042 | Oil & Gas Operator | Nov 2010 |
| 410 | Maroon Energy LLC | Spring, TX 77379 | Oil & Gas Operator | May 2025 |
| 411 | Marshall & Winston, Inc. | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 412 | Marshco Production LLC | Colorado City, TX 79512 | Oil Operator | May 2025 |
| 413 | Mas Operating Co. | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 414 | Matador Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Jul 2003 |
| 415 | Maverick Operating, LLC | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 416 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 417 | Mayo, Eddie | Fredericksbrg, TX 78624 | Oil & Gas Operator | May 2025 |
| 418 | McAlester Fuel Co | Houston, TX 77042 | Oil & Gas Operator | Jan 2010 |
| 419 | McCann Corporation | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 420 | McClure Oil Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 421 | McDonald Production | Lubbock, TX 79408 | Oil & Gas Operator | Mar 2003 |
| 422 | McDonnold Operating, Inc. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 423 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 424 | McFarland & Scobey, Inc. | El Paso, TX 79947 | Oil & Gas Operator | May 2025 |
| 425 | McRae & Henry LTD | Golden, CO 80401 | Oil & Gas Operator | May 2022 |
| 426 | McShane, J. Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2004 |
| 427 | MDC Operating, Inc. | Midland, TX 79708 | Oil & Gas Operator | Oct 2022 |
| 428 | Melton, Joe, DRLG. Co., Inc. | Midland, TX 79704 | Oil & Gas Operator | Dec 2004 |
| 429 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 430 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | May 2025 |
| 431 | Meritage Energy Company LLC | Denver, CO 80202 | Oil & Gas Operator | May 2013 |
| 432 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 433 | MGM Oil & Gas Company | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 434 | Mid-States Operating Company | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 435 | Midland Oil And Gas, Inc. | Midland, TX 79705 | Oil & Gas Operator | May 2025 |
| 436 | Midland Res. Oper. Co., Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 1998 |
| 437 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 438 | Millennium Resources, LLC. | Big Lake, TX 76932 | Oil & Gas Operator | Sep 2012 |
| 439 | Millennium Resources, LP | Midland, TX 79708 | Oil Operator | May 2025 |
| 440 | Millwee Oil, Inc. | Midland, TX 79705 | Oil & Gas Operator | May 2025 |
| 441 | Miltex Oil Company | Boerne, TX 78006 | Oil & Gas Operator | May 2025 |
| 442 | Mineral Technologies, Inc. | Midland, TX 79704 | Oil & Gas Operator | May 2025 |
| 443 | Minuja Oil And Gas LLC | Corpus Christi, TX 78401 | Oil & Gas Operator | Sep 1996 |
| 444 | Miranda Energy Corporation | Midland, TX 79705 | Oil & Gas Operator | Jun 2016 |
| 445 | Mission Exploration, Inc. | Tolar, TX 76476 | Oil & Gas Operator | Dec 1987 |
| 446 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 447 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 448 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | May 2025 |
| 449 | Momentum Energy Corporation | Austin, TX 78746 | Oil & Gas Operator | May 2025 |
| 450 | Momentum Energy, LLC | Midland, TX 79702 | Oil & Gas Operator | Feb 2004 |
| 451 | Momentum Oil Company | Albany, TX 76430 | Oil & Gas Operator | May 2003 |
| 452 | Montgomery Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2007 |
| 453 | Moody Oil & Gas Co. | Bridgeport, WV 26330-1051 | Oil & Gas Operator | Dec 2004 |
| 454 | Moriah Resources, Inc. | Midland, TX 79704 | Oil & Gas Operator | Mar 2008 |
| 455 | Morris Operating Co | Lovington, NM 88260 | Oil & Gas Operator | May 2025 |
| 456 | Moss Petroleum Company | Dallas, TX 75207 | Oil & Gas Operator | May 2025 |
| 457 | MSD Operating, LLC | Big Spring, TX 79721 | Oil & Gas Operator | May 2025 |
| 458 | Mulloy Operating, Inc. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 459 | Munn, W. H. Operating Company | Midland, TX 79702 | Oil & Gas Operator | Sep 2002 |
| 460 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Feb 2025 |
| 461 | Murchison Oil And Gas, LLC | Plano, TX 75024 | Oil & Gas Operator | Feb 2025 |
| 462 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 463 | MWJ Producing Company | Midland, TX 79701 | Oil & Gas Operator | Jul 1998 |
| 464 | MWS Producing, Inc. | Stanton, TX 79782 | Oil & Gas Operator | May 2025 |
| 465 | Nadel And Gussman Permian,L.L.C. | Tulsa, OK 74103 | Oil & Gas Operator | May 2025 |
| 466 | Naumann Oil & Gas, Inc. | Austin, TX 78716 | Oil & Gas Operator | May 2025 |
| 467 | NBL Permian LLC | Houston, TX 77070 | Oil & Gas Operator | Aug 2018 |
| 468 | New Atlantis Oil & Expl., LLC | Big Spring, TX 79721 | Oil & Gas Operator | Feb 2012 |
| 469 | New Height Energy, LLC | Houston, TX 77063 | Oil & Gas Operator | May 2025 |
| 470 | Newfield Exploration Company | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2017 |
| 471 | Newkumet Exploration, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 2020 |
| 472 | Newpark Environmental SVCS LLC | Lafayette, LA 70506 | Oil Operator | Jul 2014 |
| 473 | Nichols,Edwin S Explorations Inc | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 474 | Nimrod Petroleum Inc. | Big Spring, TX 79721 | Oil & Gas Operator | Dec 2002 |
| 475 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | May 2025 |
| 476 | North American Royalties, Inc. | Chattanooga, TN 37408 | Oil & Gas Operator | Oct 2001 |
| 477 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | May 2025 |
| 478 | Northstar Operating Company | Midland, TX 79702 | Oil & Gas Operator | Jun 2024 |
| 479 | Northwest Oil Company | Dallas, TX 75204 | Oil & Gas Operator | Jun 2014 |
| 480 | O'Ryan Oil And Gas | Odessa, TX 79768 | Oil & Gas Operator | May 2025 |
| 481 | Oak Energy, LLC | Houston, TX 77027 | Oil & Gas Operator | May 2025 |
| 482 | Oak Prairie Operations, LLC | The Woodlands, TX 77381 | Oil & Gas Operator | May 2025 |
| 483 | Occidental Energy Marketing, Inc. | Houston, TX 77227 | Gas Operator | Sep 2015 |
| 484 | Occidental Permian LTD. | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 485 | Oga Operating L.L.C. | Midland, TX 79702 | Oil & Gas Operator | Jan 2000 |
| 486 | Ogx Operating, LLC | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 487 | Ogx Resources LLC | Midland, TX 79702 | Oil & Gas Operator | Oct 2011 |
| 488 | Oil Management Corporation | Dallas, TX 75206 | Oil & Gas Operator | Apr 2022 |
| 489 | Okla. Magic Circle Energy Corp. | Shawnee, OK 74801 | Oil & Gas Operator | Jul 2004 |
| 490 | Oklahoma RB Operating Company | Midland, TX 79701 | Oil & Gas Operator | Jan 1998 |
| 491 | Omar Operating Company | Midland, TX 79702 | Oil & Gas Operator | Sep 2013 |
| 492 | Ops Group Limited | Houston, TX 77060 | Oil & Gas Operator | Jun 2014 |
| 493 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 494 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Mar 2025 |
| 495 | Otb Operating, LLC | Stanton, TX 79782 | Oil & Gas Operator | May 2025 |
| 496 | Ouachita Exploration Inc | Chickasha, OK 73018 | Oil & Gas Operator | Feb 2025 |
| 497 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 498 | Owl Operating Ventures L.L.C. | Midland, TX 79708 | Oil & Gas Operator | Dec 2022 |
| 499 | Owl Ops LLC | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 500 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | May 2025 |