| 1 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 2 | Maddux, Elizabeth H. | San Antonio, TX 78217 | Oil & Gas Operator | Nov 1995 |
| 3 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2024 |
| 4 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 5 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2024 |
| 6 | Manley, John D. III, Oper., Inc | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Feb 2016 |
| 7 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | May 2024 |
| 8 | Mark IV Energy | San Antonio, TX 78213 | Oil & Gas Operator | Apr 1993 |
| 9 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | May 2024 |
| 10 | Marwell Petroleum LTD Partnrship | Houston, TX 77056 | Oil & Gas Operator | May 2024 |
| 11 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 12 | Mass Energy, Inc | Houston, TX 77056 | Oil & Gas Operator | Mar 2008 |
| 13 | Maverick Brothers Operating,Inc. | Enid, OK 73702 | Oil & Gas Operator | May 2024 |
| 14 | McDay Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | May 2024 |
| 15 | McDonald & Johnson Resources,LLC | Cypress, TX 77429 | Oil & Gas Operator | Dec 2010 |
| 16 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 17 | McFarland Energy, Inc. | New Orleans, LA 70160 | Oil & Gas Operator | Dec 2009 |
| 18 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | May 2024 |
| 19 | Messy Oil And Gas, LLC | Garwood, TX 77442 | Oil & Gas Operator | May 2024 |
| 20 | Metano Energy III, LP | Tulsa, OK 74121 | Oil & Gas Operator | May 2024 |
| 21 | Metano Energy, LP | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2008 |
| 22 | MGM Well Service, Inc. | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Oct 2004 |
| 23 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 24 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 25 | Millennium Petro-Physics, Inc. | Corpus Chrsti, TX 78480 | Oil & Gas Operator | May 2024 |
| 26 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | May 2024 |
| 27 | Mina Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Feb 2012 |
| 28 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | May 2024 |
| 29 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 30 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | May 2024 |
| 31 | Mohican Oil & Gas, L.L.C. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Apr 2013 |
| 32 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 33 | Momentum Oil & Gas, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | May 2015 |
| 34 | Momentum Production Corp. | Baytown, TX 77521 | Oil & Gas Operator | May 2024 |
| 35 | Morningstar Gas, Inc. | Las Vegas, NV 89117 | Gas Operator | May 2024 |
| 36 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 37 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | May 2024 |
| 38 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 39 | Mueller Exploration, Inc. | Portland, TX 78374 | Oil & Gas Operator | May 2024 |
| 40 | Mustang Oil & Gas Corporation | Wichita Falls, TX 76308 | Oil & Gas Operator | Jul 2021 |