| 601 | Kirby Oil Company | | Oil Operator | Dec 2024 |
| 602 | Kiss Productions | | Oil & Gas Operator | Oct 2002 |
| 603 | Knightsbridge Petroleum Corp. | | Oil Operator | Jul 1991 |
| 604 | Koch Gateway Pipeline Company | | Oil & Gas Operator | Feb 2001 |
| 605 | Kyl-Kat Petroleum | | Oil & Gas Operator | Oct 1996 |
| 606 | L & J Oil Co. | Borger, TX 79007 | Oil & Gas Operator | Apr 1999 |
| 607 | L & N Co. | | Oil Operator | Jul 1991 |
| 608 | L & S Service Corp. | | Oil Operator | Jul 1989 |
| 609 | L And L Production Company | Skellytown, TX 79080 | Oil & Gas Operator | Sep 1996 |
| 610 | L'Oil Operating And MGMT. Co. | | Oil & Gas Operator | Dec 2008 |
| 611 | L. R. Fitzgerald | | Oil & Gas Operator | Feb 2015 |
| 612 | La. Land & Expl. Co. | | Oil & Gas Operator | Dec 2010 |
| 613 | La.-TX. Operating, Inc. | | Oil & Gas Operator | May 1998 |
| 614 | Lamar Matlock | | Oil Operator | Jan 2025 |
| 615 | Lance Gas & Oil Productions | | Oil & Gas Operator | Jan 2025 |
| 616 | Landmark Venture Group No. 1, Inc. | | Oil & Gas Operator | Jan 2025 |
| 617 | Landmark Venture Group, Inc. | | Oil Operator | Dec 2008 |
| 618 | Lanford Drilling Co., Inc. | | Oil Operator | Jun 1996 |
| 619 | Lanmarc Resources | | Oil Operator | Dec 2003 |
| 620 | Largo Oil Company | Longview, TX 75606 | Oil & Gas Operator | Jun 2026 |
| 621 | Lark Production, Inc. | | Oil & Gas Operator | Mar 2023 |
| 622 | Las Services, Inc. | | Oil & Gas Operator | Oct 1997 |
| 623 | Latex Petroleum Corp. | Houston, TX 77090 | Oil & Gas Operator | Aug 2012 |
| 624 | Latexo Oil & Gas Co. | | Oil Operator | Sep 1986 |
| 625 | Latham & Bonner | | Oil Operator | Aug 1987 |
| 626 | Latham Exploration Company Inc | | Oil & Gas Operator | Aug 1992 |
| 627 | Latham Production & Service Co | | Oil Operator | Jul 1989 |
| 628 | Lax, Inc. | | Oil & Gas Operator | Nov 1987 |
| 629 | Legacy Resources Co., L.P. | | Oil & Gas Operator | Apr 2019 |
| 630 | Legend Fund, LLC | | Oil & Gas Operator | Jan 2025 |
| 631 | Leshen Energy USA LLC | | Oil Operator | Jan 2025 |
| 632 | Lewis & Manziel | | Oil Operator | Apr 1989 |
| 633 | Li'L Sugar Oil Company | | Oil Operator | Nov 2019 |
| 634 | Liberty Oil & Gas Corp | Olney, IL 62450-2489 | Oil & Gas Operator | Dec 2021 |
| 635 | Limited Resources | Perryton, TX 79070 | Oil & Gas Operator | Aug 2003 |
| 636 | LL&N Oil & Gas Co., Inc. | | Oil Operator | Sep 1982 |
| 637 | Lloyd M McKenzie | | Oil Operator | Mar 2001 |
| 638 | Long Bros. Oil Co. | | Oil Operator | Jul 2015 |
| 639 | Long Oil & Natural Gas Corp. | | Oil & Gas Operator | Feb 1996 |
| 640 | Louis J. Roussel | | Oil & Gas Operator | Sep 1991 |
| 641 | Louisiana Energy Consultants, Inc. | | Oil & Gas Operator | Dec 2024 |
| 642 | Louisiana Energy Investors, L.L.C. | | Oil & Gas Operator | Jun 2016 |
| 643 | Louisiana Operating Co., Inc. | | Oil & Gas Operator | Aug 1994 |
| 644 | Louisiana-Caddo Invest, Inc. | | Oil & Gas Operator | Jun 2008 |
| 645 | Loutex Production Company | Kilgore, TX 75663 | Oil & Gas Operator | Jun 2026 |
| 646 | Lucky Strike Production LLC | | Oil Operator | Dec 2024 |
| 647 | Luray Oil Co., L.L.C. | | Oil Operator | Jan 2025 |
| 648 | Luther W. Davis | | Oil & Gas Operator | Jun 1996 |
| 649 | Lwood Energy, Inc. | | Oil Operator | Dec 2002 |
| 650 | Lyons Petroleum, Inc. | | Oil & Gas Operator | Oct 1988 |
| 651 | Lyons, Hilliard & Watson, Inc. | | Oil & Gas Operator | Jan 1989 |
| 652 | M & M Oil Co., LLC | Oil City, LA 71061 | Oil & Gas Operator | Jun 2026 |
| 653 | M & M Oil Company | Monahans, TX 79756 | Oil & Gas Operator | Feb 2026 |
| 654 | M & M Production | | Oil & Gas Operator | Jun 2010 |
| 655 | M G Gulff | | Oil Operator | May 1988 |
| 656 | M. A. Robison | | Oil & Gas Operator | Oct 1998 |
| 657 | M. E. Fitzgerald | | Oil & Gas Operator | May 1993 |
| 658 | M. F. McCain, Inc. | | Oil & Gas Operator | Jul 1987 |
| 659 | M. P. S. Prod. Co. | Houston, TX 77225 | Oil & Gas Operator | Dec 1996 |
| 660 | M. Parker Production Co. | | Oil Operator | Dec 2024 |
| 661 | M. T. R. Production | | Oil Operator | Mar 2006 |
| 662 | Mako Exploration Management, LLC | Shreveport, LA 71105 | Oil & Gas Operator | Jun 2026 |
| 663 | Mallard Drilling Corp. | | Oil & Gas Operator | Jan 1993 |
| 664 | Malone Oil & Gas Exploration, Inc. | | Oil Operator | Dec 2018 |
| 665 | Mandina & Murphy Oil Company | | Oil Operator | Nov 1990 |
| 666 | Manolo Energy, Inc. | | Oil Operator | Sep 1996 |
| 667 | Manti Exploration Operating LLC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Feb 2015 |
| 668 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | Jun 2026 |
| 669 | Map Associates, L.P. | | Oil & Gas Operator | Mar 1995 |
| 670 | Mar-Bec Energy Company, L.L.C. | Shreveport, LA 71105 | Oil & Gas Operator | May 2001 |
| 671 | Marathon Corporation | | Oil Operator | Dec 1994 |
| 672 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Apr 2026 |
| 673 | Marion Corporation | | Oil & Gas Operator | Jan 2001 |
| 674 | Mark Seifer | | Oil & Gas Operator | Dec 2024 |
| 675 | Maroski, Inc. | | Oil Operator | Jan 1989 |
| 676 | Marquis Resources, LLC | | Oil & Gas Operator | Jul 2021 |
| 677 | Marshall & McCain | | Oil & Gas Operator | Oct 1988 |
| 678 | Marshall Exploration, Inc. | | Oil & Gas Operator | Jun 1992 |
| 679 | Martin Oil & Gas Co. | | Oil Operator | Jul 1981 |
| 680 | Martin Production Company | | Oil & Gas Operator | Dec 2024 |
| 681 | Matador Production Company | Dallas, TX 75240 | Oil & Gas Operator | Jun 2026 |
| 682 | Matrix Production Company | Sugar Land, TX 77478 | Oil & Gas Operator | Apr 2026 |
| 683 | Maurine B. Pyle | | Oil & Gas Operator | Mar 1993 |
| 684 | Maximus Operating, LTD. | Kilgore, TX 75663 | Oil & Gas Operator | Jun 2026 |
| 685 | Maxum Energy Corp | Plano, TX 75025 | Oil & Gas Operator | Jan 2003 |
| 686 | McCormick Production Co, Inc. | Oil City, LA 71061 | Oil & Gas Operator | Jun 2026 |
| 687 | McCurdy Oil Co. | Fort Worth, TX 76116 | Oil & Gas Operator | Jan 2025 |
| 688 | McGoldrick Oil Company | Shreveport, LA 71129 | Oil & Gas Operator | Jul 2020 |
| 689 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 690 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Jun 2026 |
| 691 | McLaurin Oil Co. | | Oil Operator | Jan 2025 |
| 692 | McLeod Gas Gath & Proc Co. L.L.C. | | Oil Operator | Jul 2012 |
| 693 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 694 | Memorial Production Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Jun 2026 |
| 695 | Metro Energy Group, Inc. | Bossier City, LA 71112 | Oil & Gas Operator | May 2013 |
| 696 | Michael D Brown | | Oil Operator | Jul 1993 |
| 697 | Mid Field Oil Co. | | Oil & Gas Operator | Mar 1989 |
| 698 | Midwest Enterprises Inc | Cashion, OK 73016-9626 | Oil & Gas Operator | Apr 2025 |
| 699 | Mike Bonner | | Oil Operator | Aug 1999 |
| 700 | Mobil Oil E & P Southeast Inc | | Oil & Gas Operator | Sep 2013 |