| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | M. L. Mayfield | Oil & Gas Operator | Oct 1990 | |
| 2 | M. L. Mayfield Co. | Oil & Gas Operator | Aug 1991 | |
| 3 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 4 | Mantle Oil & Gas, LLC | Friendswood, TX 77546 | Oil & Gas Operator | Oct 2025 |
| 5 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Aug 2025 |
| 6 | Martin Exploration Co. | Oil & Gas Operator | Apr 1986 | |
| 7 | Meridian Resources (USA) Inc. | Oil & Gas Operator | Aug 2024 | |
| 8 | Mid-America Resources, Inc. | Oil & Gas Operator | Feb 2008 | |
| 9 | Miss-Lou Operating LLC | Oil & Gas Operator | Jul 2025 | |
| 10 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Oct 2025 |
| 11 | Mobil Oil E & P Southeast Inc | Oil & Gas Operator | Sep 2013 | |
| 12 | Mongrue Oil Company, Inc. | Oil & Gas Operator | Oct 1999 | |
| 13 | Monterey Pipeline Co. | Oil Operator | Aug 1993 |