| 1 | M. B. And D. I. Dupree | | Oil Operator | Nov 1992 |
| 2 | Machin & Associates, Inc. | Longview, TX 75606 | Oil & Gas Operator | Apr 2026 |
| 3 | Mallard Drilling Corp. | | Oil & Gas Operator | Jan 1993 |
| 4 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Feb 2026 |
| 5 | Mark F Preddy & Associates,Inc | | Oil & Gas Operator | Dec 1987 |
| 6 | Marlan Anderson | | Oil Operator | Jan 2025 |
| 7 | Marshall Exploration, Inc. | | Oil & Gas Operator | Jun 1992 |
| 8 | Matador Production Company | Dallas, TX 75240 | Oil & Gas Operator | Apr 2026 |
| 9 | Matrix Production Company | Sugar Land, TX 77478 | Oil & Gas Operator | Feb 2026 |
| 10 | Matthews Operating Co., Inc. | | Gas Operator | Aug 2001 |
| 11 | Maxwell Oil & Gas Corp. | Kilgore, TX 75663 | Oil & Gas Operator | Jan 2001 |
| 12 | Mesa Operating LTD Partnership | Amarillo, TX 79189 | Oil & Gas Operator | May 1994 |
| 13 | Midla, LTD. | | Oil & Gas Operator | Jun 1990 |
| 14 | Moon-Hines-Tigrett Opr Co Inc | | Oil & Gas Operator | Oct 1995 |
| 15 | Morgan Enterprises | | Oil & Gas Operator | Aug 1997 |