| 1 | M & S Oil Company | Lawrenceburg, IN 47025-8675 | Oil & Gas Operator | Aug 2000 |
| 2 | M E Klein & Associates LLC | Washington, OK 73093-4663 | Oil & Gas Operator | Jul 2025 |
| 3 | Manuel Corporation | Wichita, KS 67206 | Oil & Gas Operator | Jul 2025 |
| 4 | Marathon Oil Company LLC | Houston, TX 77079 | Oil & Gas Operator | Jul 2025 |
| 5 | Marjo Operating Company Inc | Tulsa, OK 741010729 | Oil & Gas Operator | Jun 2025 |
| 6 | Marjo Operating Mid-Continent LLC | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2025 |
| 7 | Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Jun 2025 |
| 8 | Marsh Operating Company | Dallas, TX 75221 | Oil & Gas Operator | Jun 2025 |
| 9 | McKinney Operating Company | Canadian, TX 79014 | Gas Operator | May 2002 |
| 10 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 11 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 12 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 13 | Mge Resources, Inc. | Perryton, TX 79070 | Oil & Gas Operator | Jun 2025 |
| 14 | Mid-Con Energy Operating, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | May 2020 |
| 15 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2025 |
| 16 | Mija LLC | Oklahoma City, OK 73151 | Oil & Gas Operator | Jul 2025 |
| 17 | Miller Petroleum Company | Yukon, OK 73099-0452 | Oil & Gas Operator | Aug 2009 |
| 18 | Monexco | Edmond, OK 73034-3776 | Oil & Gas Operator | Mar 2008 |
| 19 | Monexco LLC | Dallas, TX 75204-2634 | Oil & Gas Operator | Jun 2025 |
| 20 | Muegge, Clay A. | Lamont, OK 74643 | Oil & Gas Operator | Jul 2025 |
| 21 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |