| 1 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 2 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 3 | Mark IV Energy | San Antonio, TX 78213 | Oil & Gas Operator | Apr 1993 |
| 4 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 5 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 6 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 7 | Mayfield Engineering Service | Tulsa, OK 74104 | Oil & Gas Operator | Oct 2025 |
| 8 | McGuffin, Joe Jr. | Christoval, TX 76935 | Oil & Gas Operator | Oct 2025 |
| 9 | McGuffin, Joe S. Inc. | Mathis, TX 78368 | Gas Operator | Oct 2025 |
| 10 | Mertz Energy LLC | Houston, TX 77098 | Oil & Gas Operator | Jan 2025 |
| 11 | MGM Well Service, Inc. | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Oct 2004 |
| 12 | Michael Petroleum Corporation | Houston, TX 77040 | Oil & Gas Operator | Dec 2001 |
| 13 | Midas Resources, Inc. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2025 |
| 14 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 15 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 16 | Miller, M. M. & Sons | Alice, TX 78333 | Oil & Gas Operator | Apr 2007 |
| 17 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 18 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Oct 2025 |
| 19 | MJM Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Aug 2003 |
| 20 | ML Resources, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Mar 2008 |
| 21 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 22 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 23 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Oct 2025 |
| 24 | Mogul Energy International, Inc. | Houston, TX 77042 | Oil & Gas Operator | Oct 2017 |
| 25 | Moose Oil & Gas Co. | Houston, TX 77002 | Oil & Gas Operator | Feb 2000 |
| 26 | Moose Operating Co., Inc. | Houston, TX 77006 | Oil & Gas Operator | Oct 2025 |
| 27 | MPG Petroleum, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 28 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 29 | Munson Operating, Inc. | Dallas, TX 75251 | Oil & Gas Operator | Oct 2025 |
| 30 | Munson, Charles C. | Dallas, TX 75201 | Oil & Gas Operator | Apr 2002 |