| 1 | Mammoth Service Group, LLC | | Oil & Gas Operator | Jul 2025 |
| 2 | Manchester Oil Co | | Oil Operator | Jan 2000 |
| 3 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Sep 2025 |
| 4 | Marion Corporation | | Oil & Gas Operator | Jan 2001 |
| 5 | Marlin Exploration, LLC | | Oil & Gas Operator | Aug 2025 |
| 6 | Marshall Production Co Inc | | Oil & Gas Operator | Jun 1989 |
| 7 | Marshall Young Oil Co | | Oil & Gas Operator | Jan 2007 |
| 8 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 9 | McGoldrick Oil Company | Shreveport, LA 71129 | Oil & Gas Operator | Jul 2020 |
| 10 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Nov 2025 |
| 11 | Meason Oper. Co. For Cinco Energy Corp. | | Oil & Gas Operator | Sep 2000 |
| 12 | Meason Operating Company | Natchez, MS 39121 | Oil & Gas Operator | Dec 2011 |
| 13 | Meng Oper & Expl Co | | Oil & Gas Operator | Dec 1989 |
| 14 | Merit Field LLC | | Oil & Gas Operator | Dec 2001 |
| 15 | Meyer, Ruskin H. Et Al | | Oil Operator | Oct 1980 |
| 16 | Midco Energy, Inc. | | Oil & Gas Operator | Dec 1992 |
| 17 | Midroc Oil Company Et Al | | Oil Operator | Nov 1984 |
| 18 | Midroc Operating Company | | Oil & Gas Operator | Apr 2013 |
| 19 | Midstate Energy Inc | | Oil & Gas Operator | Aug 2017 |
| 20 | Miller Exploration Company | Tulsa, OK 74136-1020 | Oil & Gas Operator | Mar 2015 |
| 21 | Miss Basin Oil & Gas Company | | Oil Operator | Jan 1985 |
| 22 | Miss-Lou Oil Producers Inc | | Oil & Gas Operator | Dec 1998 |
| 23 | Miss-Lou Operating LLC | | Oil & Gas Operator | Sep 2025 |
| 24 | Missala Inc | | Oil & Gas Operator | Dec 1995 |
| 25 | Mississippi Valley Gas Co | | Oil & Gas Operator | Aug 1984 |
| 26 | Mitchell And R. E. Mitchel | | Oil Operator | Feb 2000 |
| 27 | Mitchell Resources, Inc. | Addison, TX 75001 | Oil & Gas Operator | Aug 2003 |
| 28 | Mize Energy Producers, LLC | | Oil & Gas Operator | Sep 2025 |
| 29 | Mize Operations, LLC. | | Oil & Gas Operator | Dec 2018 |
| 30 | Mobil Oil Expl & Prod S E | | Oil & Gas Operator | Dec 1979 |
| 31 | Moon-Hines-Tigrett Operating Co., Inc. | | Oil & Gas Operator | Sep 2025 |
| 32 | Morris Operating Co | Lovington, NM 88260 | Oil & Gas Operator | Nov 2025 |
| 33 | Morrow Oil & Gas Co. | Terry, MS 39170 | Oil & Gas Operator | Sep 2025 |
| 34 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Nov 2025 |
| 35 | MS United, LLC | | Oil & Gas Operator | Sep 2025 |
| 36 | MT. Crescent Operating Company, LLC | | Oil & Gas Operator | Sep 2025 |
| 37 | Mullen Exploration Inc | | Oil & Gas Operator | Dec 2002 |
| 38 | Mullen-Hathorn-Bass | | Oil & Gas Operator | Mar 1985 |
| 39 | Murphy Oil USA, Inc. | New Orleans, LA 70161 | Oil & Gas Operator | Jan 1993 |