| 1 | Mark F Preddy & Associates,Inc | | Oil & Gas Operator | Dec 1987 |
| 2 | Marlin Expl.,Inc&Exchg O&G Co | | Oil & Gas Operator | Jun 1987 |
| 3 | Marlin Exploration, Inc. | | Oil & Gas Operator | Oct 2006 |
| 4 | Martineau Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Jan 2025 |
| 5 | Mass Resources, Inc. | | Oil Operator | Jan 2025 |
| 6 | McGoldrick & Watson DRLG., Co. | | Oil & Gas Operator | Jul 1987 |
| 7 | McGoldrick Oil Company | Shreveport, LA 71129 | Oil & Gas Operator | Jul 2020 |
| 8 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 9 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Oct 2025 |
| 10 | MCZ Oil Co, Inc. | | Oil Operator | Feb 1994 |
| 11 | Meason Operating Company | Natchez, MS 39121 | Oil & Gas Operator | Dec 2011 |
| 12 | Meng Oper. & Expl. Co. | | Oil & Gas Operator | Dec 1989 |
| 13 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 14 | Merrico Resources, Inc. | Ardmore, OK 73402 | Oil & Gas Operator | Mar 2008 |
| 15 | Mid-National Resources Inc. | | Oil Operator | Feb 1999 |
| 16 | Middle Bay Production Co. Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2014 |
| 17 | Miocene Oil & Gas, LTD. | Englewood, CO 80110 | Oil & Gas Operator | Oct 2025 |
| 18 | Miss Lou Oil Producers, Inc. | | Oil & Gas Operator | Dec 1998 |
| 19 | Miss-Lou Operating LLC | | Oil & Gas Operator | Jul 2025 |
| 20 | MJB Production Company, Inc. | Brownfield, TX 79316 | Oil & Gas Operator | Oct 2025 |
| 21 | Mobil Oil E & P Southeast Inc | | Oil & Gas Operator | Sep 2013 |
| 22 | Monsanto Oil Company | | Oil & Gas Operator | Apr 1986 |
| 23 | Munoco Co. | El Dorado, AR 71730 | Oil & Gas Operator | Jul 2021 |