| 1 | M & S Production, Inc. | | Oil Operator | Jul 1994 |
| 2 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 3 | Mallard Drilling Corp. | | Oil & Gas Operator | Jan 1993 |
| 4 | Maple Gulf Coast Props. Corp. | | Oil & Gas Operator | Jun 1989 |
| 5 | Mark F Preddy & Associates,Inc | | Oil & Gas Operator | Dec 1987 |
| 6 | Mark L Shidler Inc | Houston, TX 77055 | Oil & Gas Operator | Sep 2025 |
| 7 | Mark V Petroleum Company | | Oil & Gas Operator | Feb 2020 |
| 8 | Marlin Exploration, Inc. | | Oil & Gas Operator | Oct 2006 |
| 9 | Marlin Exploration, LLC | | Oil & Gas Operator | Sep 2025 |
| 10 | Marlin Resources, L.L.C. | Midland, TX 79702 | Oil & Gas Operator | Jan 2025 |
| 11 | Martineau Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Jan 2025 |
| 12 | Mass Resources, Inc. | | Oil Operator | Jan 2025 |
| 13 | McGoldrick & Watson | | Oil & Gas Operator | Jul 1987 |
| 14 | McGoldrick & Watson - Alagood | | Oil Operator | Oct 1995 |
| 15 | McGoldrick & Watson DRLG., Co. | | Oil & Gas Operator | Jul 1987 |
| 16 | McGoldrick Oil Company | Shreveport, LA 71129 | Oil & Gas Operator | Jul 2020 |
| 17 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 18 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Dec 2025 |
| 19 | Meason Operating Company | Natchez, MS 39121 | Oil & Gas Operator | Dec 2011 |
| 20 | Meng Oper & Expl Co | | Oil & Gas Operator | Dec 1989 |
| 21 | Menoah Petroleum Inc | | Oil & Gas Operator | Dec 2024 |
| 22 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Dec 2025 |
| 23 | Mid-National Resources Inc. | | Oil Operator | Feb 1999 |
| 24 | Miles Oil & Gas Co. | | Oil & Gas Operator | Feb 1988 |
| 25 | Miller Exploration Company | Tulsa, OK 74136-1020 | Oil & Gas Operator | Mar 2015 |
| 26 | Miocene Oil & Gas, LTD. | Englewood, CO 80110 | Oil & Gas Operator | Dec 2025 |
| 27 | Miss-Lou Oil Producers Inc | | Oil & Gas Operator | Dec 1998 |
| 28 | Mobley & McCain, Et Al | | Oil & Gas Operator | Jul 1986 |
| 29 | Monroe Well Service | | Oil & Gas Operator | Apr 1998 |
| 30 | Monroe Well Service-Ajk | | Oil Operator | Dec 1988 |
| 31 | Monroe Well Service-Ocean | | Oil Operator | Feb 1989 |
| 32 | Monroe Well Service-TBR | | Oil Operator | Aug 1991 |
| 33 | Monsanto Oil Company | | Oil & Gas Operator | Apr 1986 |
| 34 | Munoco Company | El Dorado, AR 71730 | Oil & Gas Operator | Jul 2021 |