| 401 | Lime Rock Resources A, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2025 |
| 402 | Linc Gulf Coast Petroleum, Inc. | Katy, TX 77494 | Oil & Gas Operator | Apr 2025 |
| 403 | Live Oak Gas Company | Dallas, TX 75251 | Oil & Gas Operator | Apr 2025 |
| 404 | Lomak Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Aug 1998 |
| 405 | Louisiana Energy Consultant Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2025 |
| 406 | Lovelady, I. W. | Albuquerque, NM 87111 | Oil & Gas Operator | Jan 1996 |
| 407 | Low-End Oil LLC | Austin, TX 78748 | Oil Operator | Apr 2025 |
| 408 | Lundberg Operating Corporation | Dallas, TX 75225 | Oil & Gas Operator | Oct 2002 |
| 409 | Lynd, J. L., Inc. | Austin, TX 78716 | Oil & Gas Operator | Sep 2009 |
| 410 | Lytle Creek Operating, Inc. | Abilene, TX 79606 | Oil & Gas Operator | Apr 2025 |
| 411 | M-V Company | Refugio, TX 78377 | Oil & Gas Operator | Jun 2004 |
| 412 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 413 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2025 |
| 414 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2025 |
| 415 | Maralo, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 1998 |
| 416 | Mariah Energy Corp. | Austin, TX 78716 | Oil & Gas Operator | Apr 1999 |
| 417 | Mark IV Energy | San Antonio, TX 78213 | Oil & Gas Operator | Apr 1993 |
| 418 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Apr 2025 |
| 419 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Apr 2025 |
| 420 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 421 | Masters Resources, L.L.C. | Houston, TX 77079 | Oil & Gas Operator | Dec 2008 |
| 422 | Maverick Drilling Co., Inc. | Austin, TX 78729 | Oil & Gas Operator | Mar 2015 |
| 423 | Maverick Prod. Co., Inc. | Houston, TX 77056 | Oil & Gas Operator | Apr 2025 |
| 424 | Maverick Properties, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Sep 1994 |
| 425 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 426 | Mayfield Engineering Service | Tulsa, OK 74104 | Oil & Gas Operator | Apr 2025 |
| 427 | Mayne & Mertz, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2013 |
| 428 | McDay Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | Apr 2025 |
| 429 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 430 | McGuffin, Joe Jr. | Christoval, TX 76935 | Oil & Gas Operator | Apr 2025 |
| 431 | Mecom Energy Corporation | Houston, TX 77030 | Oil & Gas Operator | Jan 1999 |
| 432 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 433 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 434 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2025 |
| 435 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 436 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2025 |
| 437 | Mina Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Feb 2012 |
| 438 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 439 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Apr 2025 |
| 440 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 441 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 442 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2025 |
| 443 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Apr 2025 |
| 444 | Mogul Energy International, Inc. | Houston, TX 77042 | Oil & Gas Operator | Oct 2017 |
| 445 | Mohican Oil & Gas, L.L.C. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Apr 2013 |
| 446 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 447 | Montgomery Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2007 |
| 448 | Moose Oil & Gas Co. | Houston, TX 77002 | Oil & Gas Operator | Feb 2000 |
| 449 | Moose Operating Co., Inc. | Houston, TX 77006 | Oil & Gas Operator | Apr 2025 |
| 450 | Morris, W. Dale Inc. | Mineral Wells, TX 76068 | Oil & Gas Operator | Apr 2025 |
| 451 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2025 |
| 452 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 453 | Moy, Gary | Falls City, TX 78113 | Oil & Gas Operator | Nov 1998 |
| 454 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 455 | Mueller Exploration, Inc. | Portland, TX 78374 | Oil & Gas Operator | Apr 2025 |
| 456 | Nadsoilco LLC | Chicago, IL 60606 | Oil & Gas Operator | Apr 2025 |
| 457 | Ncey Holdings, LLC | Houston, TX 77056 | Oil & Gas Operator | Jun 2013 |
| 458 | Nelson, James L. | Pettus, TX 78146 | Oil & Gas Operator | Apr 2025 |
| 459 | Neuhaus, V. F. Properties, Inc. | Palmhurst, TX 78573 | Oil & Gas Operator | Dec 2022 |
| 460 | Neumin Production Company | Point Comfort, TX 77978 | Oil & Gas Operator | Apr 2025 |
| 461 | New Source Oil & Gas, LLC | Victoria, TX 77903 | Oil & Gas Operator | Apr 2025 |
| 462 | Newton Corp.,The | Dallas, TX 75251 | Oil & Gas Operator | Apr 2025 |
| 463 | Nitro Oil & Gas, LLC | Midland, TX 79701 | Oil & Gas Operator | Apr 2025 |
| 464 | Noex, L.L.C. | Houston, TX 77057 | Oil & Gas Operator | Apr 1998 |
| 465 | Nog Production & Operating LLC | Goliad, TX 77963 | Oil & Gas Operator | Apr 2025 |
| 466 | Nomeco Oil & Gas Co. | Jackson, MI 49204 | Oil & Gas Operator | Dec 1994 |
| 467 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | Apr 2025 |
| 468 | North Central Oil Corp. | Houston, TX 77252 | Oil & Gas Operator | Dec 2005 |
| 469 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Apr 2025 |
| 470 | North Shore Energy, L.L.C. | Austin, TX 78750 | Oil & Gas Operator | Apr 2025 |
| 471 | NRG Assets Management, LLC | Houston, TX 77057 | Oil & Gas Operator | Nov 2016 |
| 472 | Oak Energy, LLC | Houston, TX 77027 | Oil & Gas Operator | Apr 2025 |
| 473 | Oblaen Resources LLC | Wallis, TX 77485 | Oil & Gas Operator | Apr 2025 |
| 474 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 475 | Okla. Magic Circle Energy Corp. | Shawnee, OK 74801 | Oil & Gas Operator | Jul 2004 |
| 476 | Oklahoma Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2013 |
| 477 | Oldfield Acquisition LP | Austin, TX 78733 | Oil & Gas Operator | Sep 1996 |
| 478 | Olipdp II, LLC | Lafayette, LA 70503 | Oil & Gas Operator | Apr 2025 |
| 479 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | Apr 2025 |
| 480 | Omega Energy, LLC | Corpus Chrsti, TX 78418 | Oil & Gas Operator | Apr 2025 |
| 481 | Opal Energy, Inc. | Katy, TX 77494 | Oil & Gas Operator | Jun 2009 |
| 482 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 483 | Osr Oil & Gas Company | Victoria, TX 77902 | Oil & Gas Operator | Jul 2000 |
| 484 | Osyka Oil & Gas, Inc. | Metairie, LA 70004 | Oil & Gas Operator | Apr 2025 |
| 485 | Outline Oil Company LLC | Beeville, TX 78104 | Oil Operator | Apr 2025 |
| 486 | Outline Oil Corp. | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2025 |
| 487 | Overly Operating Co. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2013 |
| 488 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Apr 2025 |
| 489 | Pace Oil And Gas Company | Austin, TX 78715 | Oil & Gas Operator | Apr 2025 |
| 490 | Pace Production Co. | San Angelo, TX 76902 | Oil & Gas Operator | Apr 2025 |
| 491 | Pace West Production LC | San Angelo, TX 76904 | Oil & Gas Operator | Sep 1995 |
| 492 | Pacific Operators, Inc. | San Antonio, TX 78205 | Oil & Gas Operator | Mar 1999 |
| 493 | Paleo Oil Company LLC | Corpus Chrsti, TX 78411 | Oil & Gas Operator | Apr 2025 |
| 494 | Paloma Operating, LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2025 |
| 495 | Pantano Energy | San Antonio, TX 78258 | Oil & Gas Operator | Jul 1999 |
| 496 | Paradis Investments, L.L.C. | Bellaire, TX 77401 | Oil Operator | Jun 2020 |
| 497 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 498 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 499 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 500 | Patrick Pet. Corp. Of Michigan | Houston, TX 77227 | Oil & Gas Operator | Aug 1995 |