| 401 | McMoran Oil & Gas LLC | New Orleans, LA 70160 | Oil & Gas Operator | Oct 2021 |
| 402 | McMullan Oil Company | San Antonio, TX 78212 | Oil & Gas Operator | Jun 2023 |
| 403 | McMurrey, R. J., Production Comp | Tyler, TX 75711 | Oil & Gas Operator | Dec 2025 |
| 404 | McNallen & Griffin | Keller, TX 76244 | Oil & Gas Operator | Dec 2025 |
| 405 | McNallen Oil Co., Inc. | Keller, TX 76244 | Oil & Gas Operator | Dec 2025 |
| 406 | McNic Oil & Gas Midcontinent,Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Jul 1999 |
| 407 | McOsker Bros., Inc. | San Antonio, TX 78264 | Oil & Gas Operator | Aug 2003 |
| 408 | McQueen Ed & Company Inc | Lindsey, OK 73052 | Oil & Gas Operator | Apr 2014 |
| 409 | MCR Operating Group | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2025 |
| 410 | McRae & Henry LTD | Golden, CO 80401 | Oil & Gas Operator | May 2022 |
| 411 | McRae Exploration & Prod., Inc. | Houston, TX 77064 | Oil & Gas Operator | Feb 2017 |
| 412 | McRae, Nathan Rathburn | Hebbronville, TX 78361 | Oil & Gas Operator | Apr 1994 |
| 413 | McShane, J. Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2004 |
| 414 | MCZ, Inc. | Houston, TX 77026 | Oil & Gas Operator | Sep 1990 |
| 415 | MD America Energy, LLC | Houston, TX 77224 | Oil & Gas Operator | Apr 2022 |
| 416 | MDC Operating, Inc. | Midland, TX 79708 | Oil & Gas Operator | Oct 2022 |
| 417 | MDC Texas Operator LLC | Midland, TX 79705 | Oil & Gas Operator | Dec 2025 |
| 418 | MDF Oil Company | Floresville, TX 78114 | Oil Operator | Dec 2025 |
| 419 | MDM Energy, Inc. | The Colony, TX 75056 | Oil & Gas Operator | Dec 2025 |
| 420 | Me-Tex Oil & Gas, Inc. | Hobbs, NM 88241 | Oil & Gas Operator | Dec 2025 |
| 421 | Me-Tex Supply Company | Hobbs, NM 88240 | Oil & Gas Operator | Jun 1993 |
| 422 | Meadco Properties | Midland, TX 79702 | Oil & Gas Operator | Dec 2025 |
| 423 | Meade Energy Corporation | Oklahoma City, OK 73118-4015 | Oil & Gas Operator | Sep 2025 |
| 424 | Meador Enterprises, Inc. | Kilgore, TX 75662 | Oil Operator | Oct 2023 |
| 425 | Meador, John E. | Eldorado, TX 76936 | Oil & Gas Operator | Apr 2014 |
| 426 | Meador, T. C. | San Angelo, TX 76902 | Oil & Gas Operator | Dec 2025 |
| 427 | Meadows Oil Company | Plano, TX 75075 | Oil & Gas Operator | Aug 2004 |
| 428 | Means Oil Co. | Corsicana, TX 75110 | Oil & Gas Operator | Feb 2013 |
| 429 | Means Oil Company, LLC | Corsicana, TX 75110 | Oil & Gas Operator | Dec 2025 |
| 430 | Means, Frank L. | Corsicana, TX 75110 | Oil & Gas Operator | Jan 2001 |
| 431 | Meason Operating Company | Natchez, MS 39121 | Oil & Gas Operator | Dec 2011 |
| 432 | Meb, LLC | Austin, TX 78737 | Oil Operator | Dec 2025 |
| 433 | Meco IV Holdco, LLC | Lakewood, CO 80227 | Oil & Gas Operator | Jul 2022 |
| 434 | Meco IV, LLC | Lakewood, CO 80227 | Oil & Gas Operator | Jul 2021 |
| 435 | Mecom Energy Corporation | Houston, TX 77030 | Oil & Gas Operator | Jan 1999 |
| 436 | Medallion Exploration Corp. | Midvale, UT 84047 | Oil & Gas Operator | Oct 1998 |
| 437 | Medallion Oil Company | Houston, TX 77251 | Oil & Gas Operator | Jan 2012 |
| 438 | Medallion Petroleum, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2015 |
| 439 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 440 | Medders Oil Company | Wichita Falls, TX 76308 | Oil & Gas Operator | Dec 2025 |
| 441 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 442 | Meeker & Company | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2025 |
| 443 | Meeker, Dan Management, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | Aug 2007 |
| 444 | Megaenergy Operating, Inc. | Edmond, OK 73034 | Oil & Gas Operator | Jul 2015 |
| 445 | Megargel Drilling Company | Megargel, TX 76370 | Oil Operator | Nov 1998 |
| 446 | Megg, L.P. | Borger, TX 79008 | Oil & Gas Operator | Dec 2025 |
| 447 | Mego Resources, LLC | Taft, TX 78390 | Oil & Gas Operator | Dec 2025 |
| 448 | Mehaffey Investments, Inc. | Eastland, TX 76448 | Oil & Gas Operator | Dec 2025 |
| 449 | Mei Operating Company | Lafayette, LA 70598 | Oil & Gas Operator | Aug 1997 |
| 450 | Melcar Production | Tuscola, TX 79562 | Oil & Gas Operator | Dec 2025 |
| 451 | Mello-Dy Resources, LLC | Devine, TX 78016 | Oil Operator | Dec 2025 |
| 452 | Mellon Creek Operating Co. | Victoria, TX 77901 | Oil & Gas Operator | Jun 1993 |
| 453 | Mellon Oil Unit | Refugio, TX 78377 | Oil & Gas Operator | Jun 2004 |
| 454 | Melrose Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Sep 2011 |
| 455 | Melton Operating Co. | Friendswood, TX 77546 | Oil & Gas Operator | Jul 2005 |
| 456 | Melton, Joe, DRLG. Co., Inc. | Midland, TX 79704 | Oil & Gas Operator | Dec 2004 |
| 457 | Melzer Exploration Company | Midland, TX 79702-2083 | Oil & Gas Operator | May 2013 |
| 458 | Memorial Exploration Company | Saint Louis, MO 63105 | Oil & Gas Operator | Aug 1996 |
| 459 | Memorial Production Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 460 | Menasco, J. | Wichita Falls, TX 76310 | Oil & Gas Operator | Dec 2019 |
| 461 | Mer Resources | Edmond, OK 73013 | Oil & Gas Operator | Dec 2025 |
| 462 | Mercantile Oil & Gas Prod. Corp. | Galena Park, TX 77547 | Oil & Gas Operator | Jun 2016 |
| 463 | Mercury Exploration Co. | Fort Worth, TX 76104 | Oil & Gas Operator | Dec 2006 |
| 464 | Mercury Operating, LLC | Dallas, TX 75208 | Oil & Gas Operator | Dec 2025 |
| 465 | Mereken Energy Corp. | Fort Worth, TX 76102 | Gas Operator | Feb 2006 |
| 466 | Merenco | Midland, TX 79702 | Oil & Gas Operator | Dec 1996 |
| 467 | Merex Resources, Inc. | Amarillo, TX 79159 | Oil & Gas Operator | Sep 2019 |
| 468 | Meridian Exploration Corp. | Pittsburgh, PA 15222 | Oil & Gas Operator | Dec 2021 |
| 469 | Meridian Interests, Inc. | San Antonio, TX 78239 | Oil & Gas Operator | Aug 2003 |
| 470 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 471 | Meridian Oil Inc.-Midland | Midland, TX 79702 | Oil & Gas Operator | Jul 1996 |
| 472 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 473 | Meridian Resource & Expl Co, The | Houston, TX 77077 | Oil & Gas Operator | Dec 2000 |
| 474 | Meridian Resource & Expl LLC,The | Houston, TX 77094 | Oil & Gas Operator | Nov 2012 |
| 475 | Merimac Investments, Inc. | Fort Worth, TX 76109 | Oil & Gas Operator | Jan 1997 |
| 476 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Dec 2025 |
| 477 | Merit Energy Company, LLC | Dallas, TX 75009 | Oil & Gas Operator | Jun 2025 |
| 478 | Merit Oil Company | San Angelo, TX 76901 | Oil & Gas Operator | May 1994 |
| 479 | Meritage Energy Company LLC | Denver, CO 80202 | Oil & Gas Operator | May 2013 |
| 480 | Merkaz Drilling, LLC | Dallas, TX 75229 | Oil Operator | Dec 2025 |
| 481 | Merkin LLC | Austin, TX 78737 | Oil Operator | Dec 2025 |
| 482 | Merlon Texas, Inc. | Houston, TX 77056 | Oil Operator | Jun 2013 |
| 483 | Merrico Resources, Inc. | Ardmore, OK 73402 | Oil & Gas Operator | Mar 2008 |
| 484 | Merrill Operating, LLC | Snyder, TX 79550 | Oil Operator | Apr 2016 |
| 485 | Merrimac Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | Aug 1999 |
| 486 | Merrion Oil & Gas Corp | Farmington, NM 87401 | Oil & Gas Operator | Oct 2025 |
| 487 | Merritt Operating, Inc. | Mineola, TX 75773 | Oil & Gas Operator | Dec 2025 |
| 488 | Merritt, William Kevin | Dallas, TX 75225 | Oil & Gas Operator | Dec 1994 |
| 489 | Merta, Mike | Alice, TX 78333 | Oil & Gas Operator | Aug 2005 |
| 490 | Mertz Energy LLC | Houston, TX 77098 | Oil & Gas Operator | Jan 2025 |
| 491 | Merzbacher, George F. Jr. | Robstown, TX 78380 | Oil & Gas Operator | May 1994 |
| 492 | Mesa Chica Corp. | San Antonio, TX 78278 | Oil & Gas Operator | May 2018 |
| 493 | Mesa Energy, Inc. | Austin, TX 78755 | Oil & Gas Operator | Dec 2013 |
| 494 | Mesa Operating Co. | Irving, TX 75039 | Oil & Gas Operator | Aug 1997 |
| 495 | Mesa Operating LTD Partnership | Amarillo, TX 79189 | Oil & Gas Operator | May 1994 |
| 496 | Mesa Ridge Holdings LLC | Abilene, TX 79603 | Oil Operator | Dec 2025 |
| 497 | Mesa VIsta Operating, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Dec 2025 |
| 498 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 499 | Mesquite Land & Minerals Co. | Albany, TX 76430 | Oil Operator | Dec 2025 |
| 500 | Mesquite Oil & Gas | Olney, TX 76374 | Oil & Gas Operator | Sep 2025 |