| 1 | M & B Operating, LLC | Gonzales, TX 78629 | Oil Operator | Jun 2025 |
| 2 | M W Production Co. | New Braunfels, TX 78130 | Oil & Gas Operator | Aug 2003 |
| 3 | Magic Circle Energy | Oklahoma City, OK 73185 | Oil & Gas Operator | Dec 1983 |
| 4 | Magnolia Oil & Gas Operating LLC | Houston, TX 77046 | Oil & Gas Operator | Jun 2025 |
| 5 | Magnum Petroleum, Inc. | Palm Desert, CA 92260 | Oil & Gas Operator | Nov 2013 |
| 6 | Maranatha Oil Company | Gonzales, TX 78629 | Oil & Gas Operator | Jun 2025 |
| 7 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Apr 2025 |
| 8 | Marathon Oil Ef LLC | Houston, TX 77252 | Oil & Gas Operator | Jun 2025 |
| 9 | Mariah Energy Corp. | Austin, TX 78716 | Oil & Gas Operator | Apr 1999 |
| 10 | Mark IV Energy | San Antonio, TX 78213 | Oil & Gas Operator | Apr 1993 |
| 11 | Market Street Energy, Inc. | Flatonia, TX 78941 | Oil & Gas Operator | Jun 2025 |
| 12 | Marshall & Winston, Inc. | Midland, TX 79710 | Oil & Gas Operator | Jun 2025 |
| 13 | Matador Production Company | Dallas, TX 75240 | Oil & Gas Operator | Jun 2025 |
| 14 | McA Petroleum Corporation | Flatonia, TX 78941 | Oil & Gas Operator | Jun 2025 |
| 15 | McCarter, A. Nelson | Houston, TX 77063 | Oil & Gas Operator | Aug 2003 |
| 16 | McCutchin Petroleum Corporation | Dallas, TX 75225 | Oil & Gas Operator | Jun 2025 |
| 17 | McGehee, George T. Operating Co. | Houston, TX 77024 | Oil & Gas Operator | Oct 1997 |
| 18 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 19 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 20 | Meridian Resource & Expl LLC,The | Houston, TX 77094 | Oil & Gas Operator | Nov 2012 |
| 21 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Jun 2025 |
| 22 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 23 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 24 | Millennium Exploration Co. LLC | San Antonio, TX 78232 | Oil & Gas Operator | Jun 2025 |
| 25 | Mina Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Feb 2012 |
| 26 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Jun 2025 |
| 27 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Jun 2025 |
| 28 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Jun 2025 |
| 29 | MV Purchasing LLC | Wichita, KS 67206 | Oil & Gas Operator | Dec 2019 |
| 30 | MWJ Producing Company | Midland, TX 79701 | Oil & Gas Operator | Jul 1998 |