| 1 | M & M Oil Co., LLC | Oil City, LA 71061 | Oil & Gas Operator | Oct 2025 |
| 2 | Main Energy, Inc. | Houston, TX 77079 | Oil & Gas Operator | May 2009 |
| 3 | Marion Corporation | | Oil & Gas Operator | Jan 2001 |
| 4 | Mark L Shidler Inc | Houston, TX 77055 | Oil & Gas Operator | Jul 2025 |
| 5 | Marquis Resources, LLC | | Oil & Gas Operator | Jul 2021 |
| 6 | Marsh Engineering, Inc. | | Oil & Gas Operator | Dec 1990 |
| 7 | Matador Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Jul 2003 |
| 8 | Maxim Energy Corporation | Baytown, TX 77520 | Oil & Gas Operator | Jul 2025 |
| 9 | McCord Exploration Co. | | Oil & Gas Operator | Dec 1990 |
| 10 | McCord-Dale Exploration | | Oil & Gas Operator | May 1986 |
| 11 | McCord-Goodrich Oil Company | | Oil & Gas Operator | Oct 1991 |
| 12 | McCormick Operating Company | | Oil & Gas Operator | Mar 1984 |
| 13 | McFarland Energy, Inc. | New Orleans, LA 70160 | Oil & Gas Operator | Dec 2009 |
| 14 | McMoran Exploration Company | | Oil & Gas Operator | May 1985 |
| 15 | McMoran Oil & Gas LLC | New Orleans, LA 70160 | Oil & Gas Operator | Oct 2021 |
| 16 | McMoran Production Co. | | Oil & Gas Operator | May 1985 |
| 17 | McOr Oil Development, Inc. | | Oil & Gas Operator | Feb 1990 |
| 18 | McRae Exploration, Inc. | | Oil & Gas Operator | Mar 1984 |
| 19 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 20 | Micron Minerals Company | | Oil & Gas Operator | Sep 1988 |
| 21 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 22 | Minatome Corpora | | Oil & Gas Operator | Sep 1987 |
| 23 | Mobil E&P North America Inc. | | Oil & Gas Operator | Jan 1994 |
| 24 | Mobil Oil E & P Southeast Inc | | Oil & Gas Operator | Sep 2013 |
| 25 | Monsanto Oil Company | | Oil & Gas Operator | Apr 1986 |
| 26 | Monterey Pipeline Co. | | Oil Operator | Aug 1993 |
| 27 | Moore McCormack Energy, Inc. | | Oil & Gas Operator | Jul 1988 |
| 28 | MTBB Acquisition Company, LLC | Houston, TX 77002 | Oil & Gas Operator | Aug 2022 |
| 29 | Mullins & Prichard | | Oil & Gas Operator | May 1992 |
| 30 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |