| 1 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 2 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jun 2025 |
| 3 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 4 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jun 2025 |
| 5 | Mandarin Oil & Gas Company | Austin, TX 78714 | Oil & Gas Operator | Jun 2025 |
| 6 | Marathon Oil Ef LLC | Houston, TX 77252 | Oil & Gas Operator | Jun 2025 |
| 7 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Jun 2025 |
| 8 | Marrow, N. S. | Austin, TX 78703 | Oil & Gas Operator | Aug 2012 |
| 9 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Jun 2025 |
| 10 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 11 | Matrix Production Company | Sugar Land, TX 77478 | Oil & Gas Operator | Mar 2025 |
| 12 | Maverick Drilling Co., Inc. | Austin, TX 78729 | Oil & Gas Operator | Mar 2015 |
| 13 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 14 | McCullis Resources Co., Inc. | Littleton, CO 80161 | Oil & Gas Operator | Mar 2025 |
| 15 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 16 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Jun 2025 |
| 17 | McGuffin, Joe Jr. | Christoval, TX 76935 | Oil & Gas Operator | Jun 2025 |
| 18 | McGuffin, Joe S. Inc. | Mathis, TX 78368 | Gas Operator | Jun 2025 |
| 19 | McLelland Engineering & MGMT. | Houston, TX 77042 | Oil & Gas Operator | Mar 1999 |
| 20 | McMahon Operating Co., L.C. | Pampa, TX 79066 | Oil & Gas Operator | Dec 2004 |
| 21 | Meeker & Company | Fort Worth, TX 76102 | Oil & Gas Operator | Jun 2025 |
| 22 | Mego Resources, LLC | Taft, TX 78390 | Oil & Gas Operator | Jun 2025 |
| 23 | Meridian Resource & Expl LLC,The | Houston, TX 77094 | Oil & Gas Operator | Nov 2012 |
| 24 | Merrimac Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | Aug 1999 |
| 25 | Mesa Chica Corp. | San Antonio, TX 78278 | Oil & Gas Operator | May 2018 |
| 26 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 27 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 28 | MGM Well Service, Inc. | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Oct 2004 |
| 29 | Mid-Continent Energy, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2020 |
| 30 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 31 | Millennium Exploration Co. LLC | San Antonio, TX 78232 | Oil & Gas Operator | Jun 2025 |
| 32 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Jun 2025 |
| 33 | Miner, R. C. Inc. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Apr 2002 |
| 34 | Miner, R. C. Oil, Inc. | MC Queeney, TX 78123 | Oil & Gas Operator | Jun 2025 |
| 35 | Miramar Petroleum, Inc. | Corpus Chrsti, TX 78463 | Oil & Gas Operator | Sep 2017 |
| 36 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Jun 2025 |
| 37 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 38 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Jun 2025 |
| 39 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Jun 2025 |
| 40 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 41 | Morris, W. Dale Inc. | Mineral Wells, TX 76068 | Oil & Gas Operator | Jun 2025 |
| 42 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 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 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Mar 2025 |
| 46 | Murphy Production Corp. | Austin, TX 78731 | Oil & Gas Operator | Sep 2013 |