| 1 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Feb 2026 |
| 2 | Magnum Operating, LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Feb 2026 |
| 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 | Feb 2026 |
| 5 | Maguire Oil Company | Dallas, TX 75270 | Oil & Gas Operator | Mar 2015 |
| 6 | Main Energy, Inc. | Houston, TX 77079 | Oil & Gas Operator | May 2009 |
| 7 | Mamerow Energy Corp | Ganado, TX 77962 | Oil & Gas Operator | Feb 2026 |
| 8 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Dec 2025 |
| 9 | Marmaton Oil Company | Houston, TX 77002 | Oil & Gas Operator | Jul 1998 |
| 10 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Feb 2026 |
| 11 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 12 | Matagorda Operating Company | Kilgore, TX 75663 | Gas Operator | Nov 2005 |
| 13 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 14 | Mayo, Eddie | Fredericksbrg, TX 78624 | Oil & Gas Operator | Feb 2026 |
| 15 | McCarter, A. Nelson | Houston, TX 77063 | Oil & Gas Operator | Aug 2003 |
| 16 | McCord Production, LTD. | Houston, TX 77002 | Gas Operator | Feb 1997 |
| 17 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Feb 2026 |
| 18 | McLeod, George L. Inc. | Houston, TX 77079 | Oil & Gas Operator | Sep 2002 |
| 19 | McQueen Ed & Company Inc | Lindsey, OK 73052 | Oil & Gas Operator | Apr 2014 |
| 20 | Mellon Creek Operating Co. | Victoria, TX 77901 | Oil & Gas Operator | Jun 1993 |
| 21 | Merenco | Midland, TX 79702 | Oil & Gas Operator | Dec 1996 |
| 22 | Meridian Resource & Expl Co, The | Houston, TX 77077 | Oil & Gas Operator | Dec 2000 |
| 23 | Meridian Resource & Expl LLC,The | Houston, TX 77094 | Oil & Gas Operator | Nov 2012 |
| 24 | Metano Energy, LP | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2008 |
| 25 | MFP Petroleum LTD. Partnership | Oklahoma City, OK 73142 | Oil & Gas Operator | Nov 2017 |
| 26 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 27 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 28 | Millennium Exploration Co. LLC | San Antonio, TX 78232 | Oil & Gas Operator | Feb 2026 |
| 29 | Minyak Producing Company, Inc. | Sabine Pass, TX 77655 | Oil & Gas Operator | Feb 2026 |
| 30 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 31 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 32 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 2007 |
| 33 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Feb 2026 |
| 34 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 35 | Mojac Energy Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 1997 |
| 36 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 37 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Feb 2026 |
| 38 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 39 | Mustang Oil & Gas Corporation | Wichita Falls, TX 76308 | Oil & Gas Operator | Jul 2021 |