| 1 | M-V Company | Refugio, TX 78377 | Oil & Gas Operator | Jun 2004 |
| 2 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 3 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 4 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 5 | Maralo, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 1998 |
| 6 | Mariah Energy Corp. | Austin, TX 78716 | Oil & Gas Operator | Apr 1999 |
| 7 | Mark IV Energy | San Antonio, TX 78213 | Oil & Gas Operator | Apr 1993 |
| 8 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 9 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 10 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 11 | Masters Resources, L.L.C. | Houston, TX 77079 | Oil & Gas Operator | Dec 2008 |
| 12 | Maverick Drilling Co., Inc. | Austin, TX 78729 | Oil & Gas Operator | Mar 2015 |
| 13 | Maverick Prod. Co., Inc. | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 14 | Maverick Properties, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Sep 1994 |
| 15 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 16 | Mayfield Engineering Service | Tulsa, OK 74104 | Oil & Gas Operator | Oct 2025 |
| 17 | Mayne & Mertz, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2013 |
| 18 | McCulliss Resources Co Inc | Littleton, CO 80161-3248 | Oil & Gas Operator | Jun 2009 |
| 19 | McDay Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | Oct 2025 |
| 20 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 21 | McGuffin, Joe Jr. | Christoval, TX 76935 | Oil & Gas Operator | Oct 2025 |
| 22 | Mecom Energy Corporation | Houston, TX 77030 | Oil & Gas Operator | Jan 1999 |
| 23 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 24 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 25 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 26 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 27 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 28 | Mina Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Feb 2012 |
| 29 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 30 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | 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 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 34 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Oct 2025 |
| 35 | Mogul Energy International, Inc. | Houston, TX 77042 | Oil & Gas Operator | Oct 2017 |
| 36 | Mohican Oil & Gas, L.L.C. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Apr 2013 |
| 37 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 38 | Moose Oil & Gas Co. | Houston, TX 77002 | Oil & Gas Operator | Feb 2000 |
| 39 | Moose Operating Co., Inc. | Houston, TX 77006 | Oil & Gas Operator | Oct 2025 |
| 40 | Morris, W. Dale Inc. | Mineral Wells, TX 76068 | Oil & Gas Operator | Oct 2025 |
| 41 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 42 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 43 | Moy, Gary | Falls City, TX 78113 | Oil & Gas Operator | Nov 1998 |
| 44 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 45 | Mueller Exploration, Inc. | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |