| 1 | M E III Corporation | | Oil & Gas Operator | Apr 2022 |
| 2 | Machii-Ross Petroleum Co | | Oil & Gas Operator | Apr 2014 |
| 3 | Magpie Operating, Inc | | Oil & Gas Operator | Jul 2025 |
| 4 | Mallon Oil Company | Denver, CO 80202 | Oil & Gas Operator | Jun 2005 |
| 5 | Manzano LLC | Roswell, NM 88202 | Oil & Gas Operator | Oct 2025 |
| 6 | Maralex Resources Inc | Ignacio, CO 81137 | Oil & Gas Operator | Aug 2025 |
| 7 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Aug 2025 |
| 8 | Markus Production, Inc | | Oil & Gas Operator | Mar 2021 |
| 9 | Markwest Resources Inc | Englewood, CO 801125004 | Oil & Gas Operator | Jun 2003 |
| 10 | Matrix Energy LLC | | Oil & Gas Operator | Apr 2013 |
| 11 | Matrix Oil Corporation | | Oil & Gas Operator | Aug 2025 |
| 12 | Matrix Production Company | Sugar Land, TX 77478 | Oil & Gas Operator | Aug 2025 |
| 13 | Maverick Oil Co. | Richland, TX 76681 | Oil Operator | Oct 2025 |
| 14 | McCartney Engineering LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | Aug 2025 |
| 15 | McCoy Petroleum Corporation | Wichita, KS 67207 | Oil & Gas Operator | Aug 2025 |
| 16 | McElvain Energy Inc | Denver, CO 80265 | Oil & Gas Operator | Nov 2019 |
| 17 | McLane Trust* Dixie | | Gas Operator | Jul 2025 |
| 18 | McRae & Henry LTD | Golden, CO 80401 | Oil & Gas Operator | May 2022 |
| 19 | McWhinney Holding Company LLLP | | Oil & Gas Operator | Mar 2021 |
| 20 | MDS Energy Development LLC | | Oil & Gas Operator | Aug 2025 |
| 21 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 22 | Mendell Finisterre II LLC | | Oil & Gas Operator | Jun 2017 |
| 23 | Mendell Niobrara LLC | | Oil & Gas Operator | Apr 2017 |
| 24 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 25 | Merrion Oil & Gas Corp | Farmington, NM 87401 | Oil & Gas Operator | Aug 2025 |
| 26 | Mesa Energy Partners LLC | | Oil & Gas Operator | Sep 2015 |
| 27 | Mesa Hydrocarbons LLC | | Oil & Gas Operator | Sep 2003 |
| 28 | Messer LLC | | Gas Operator | Aug 2025 |
| 29 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2025 |
| 30 | Mineral Resources, Incorporated | Lewisville, TX 75029 | Oil & Gas Operator | Oct 2025 |
| 31 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 32 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 33 | Monago Operating Inc | | Oil & Gas Operator | Mar 2017 |
| 34 | Monahan* Rex Family Trust | | Oil & Gas Operator | Sep 2010 |
| 35 | Monument Gas Marketing Inc | | Oil & Gas Operator | Aug 2025 |
| 36 | Monument Global Resources Inc | Dallas, TX 75243 | Oil & Gas Operator | Jan 2025 |
| 37 | Morning Gun Exploration LLC | | Oil Operator | Oct 2021 |
| 38 | Morningstar Operating LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Oct 2025 |
| 39 | Mountain Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Jan 2016 |
| 40 | MRD Operating LLC | | Oil & Gas Operator | Dec 2016 |
| 41 | Mull Drilling Company | Wichita, KS 67206 | Oil & Gas Operator | Aug 2025 |
| 42 | Murchison Oil & Gas Inc | Plano, TX 75024 | Oil & Gas Operator | May 2024 |
| 43 | Murchison Trusts | | Gas Operator | Sep 2003 |
| 44 | Murfin Drilling Company Inc | Wichita, KS 67202 | Oil & Gas Operator | Aug 2025 |
| 45 | Mustang Resources LLC | Houston, TX 77256 | Oil & Gas Operator | Aug 2025 |
| 46 | Mystique Resources Company | Aurora, CO 80016 | Oil & Gas Operator | Feb 2023 |