| 1 | Mallard Petroleum, Inc. | | Oil & Gas Operator | Apr 1986 |
| 2 | Mammoth Exploration LLC | Midland, TX 79701 | Oil & Gas Operator | Jul 2023 |
| 3 | Mancal Resources Corporation | | Oil & Gas Operator | Aug 2019 |
| 4 | Mann Oil Company, LLC | | Oil Operator | Jun 2023 |
| 5 | Mar-Win Development Co. | | Oil & Gas Operator | Nov 1988 |
| 6 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Aug 2025 |
| 7 | Marsha Azar | | Oil & Gas Operator | Jan 2017 |
| 8 | Marshall & Winston, Inc. | Midland, TX 79710 | Oil & Gas Operator | Aug 2025 |
| 9 | Mbi Oil & Gas LLC | Dickinson, ND 58601 | Oil & Gas Operator | Aug 2025 |
| 10 | McAlester Fuel Co | Houston, TX 77042 | Oil & Gas Operator | Jan 2010 |
| 11 | McOr Oil & Gas Corp | Houston, TX 77002 | Oil & Gas Operator | Oct 2013 |
| 12 | McRae & Henry LTD | Golden, CO 80401 | Oil & Gas Operator | May 2022 |
| 13 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 14 | Medora Minerals, LLC | | Oil & Gas Operator | Aug 2025 |
| 15 | Mercury Resources LLC | | Oil & Gas Operator | Aug 2025 |
| 16 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 17 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 18 | Mesa Petroleum Co. | | Oil & Gas Operator | Aug 1985 |
| 19 | Mid-Con Energy Operating, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | May 2020 |
| 20 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2025 |
| 21 | Missouri Basin Well Service, Inc. | Belfield, ND 58622 | Oil & Gas Operator | Jan 2018 |
| 22 | Missouri Breaks, LLC | | Oil & Gas Operator | Jun 2011 |
| 23 | Missouri River Resources ND, LLC | | Oil & Gas Operator | Aug 2025 |
| 24 | Missouri River Royalty Corporation | Bismarck, ND 58504 | Oil & Gas Operator | Aug 2025 |
| 25 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 26 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 27 | Moore & Associates | Denver, CO 80202 | Oil & Gas Operator | Dec 1993 |
| 28 | Morgan E&P, LLC | | Oil & Gas Operator | Aug 2025 |
| 29 | Morningstar Operating LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Oct 2025 |
| 30 | Mountain Divide, LLC | | Oil & Gas Operator | Mar 2017 |
| 31 | Murex Petroleum Corporation | Humble, TX 77347 | Oil & Gas Operator | Aug 2025 |
| 32 | Murfin Drilling Company Inc | Wichita, KS 67202 | Oil & Gas Operator | Aug 2025 |