| 1 | M-B Operating Co., Inc. | Rowlett, TX 75030 | Oil & Gas Operator | Dec 2024 |
| 2 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 3 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Dec 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 | Dec 2024 |
| 6 | Mamerow Energy Corp | Ganado, TX 77962 | Oil & Gas Operator | Dec 2024 |
| 7 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | Dec 2024 |
| 8 | Maralo, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 1998 |
| 9 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Dec 2024 |
| 10 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 11 | Mass Energy, Inc | Houston, TX 77056 | Oil & Gas Operator | Mar 2008 |
| 12 | Mayne & Mertz, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2013 |
| 13 | McGhee Exploration And Prod. Co. | Houston, TX 77019 | Oil & Gas Operator | Feb 2003 |
| 14 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 15 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Dec 2024 |
| 16 | McLeod, George L. Inc. | Houston, TX 77079 | Oil & Gas Operator | Sep 2002 |
| 17 | Medallion Oil Company | Houston, TX 77251 | Oil & Gas Operator | Jan 2012 |
| 18 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 19 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 20 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 21 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Dec 2024 |
| 22 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 23 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2024 |
| 24 | Miner, R. C. Inc. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Apr 2002 |
| 25 | Miner, R. C. Oil, Inc. | MC Queeney, TX 78123 | Oil & Gas Operator | Dec 2024 |
| 26 | Miramar Petroleum, Inc. | Corpus Chrsti, TX 78463 | Oil & Gas Operator | Sep 2017 |
| 27 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Dec 2024 |
| 28 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 29 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 30 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Dec 2024 |
| 31 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Dec 2024 |
| 32 | Mogul Energy International, Inc. | Houston, TX 77042 | Oil & Gas Operator | Oct 2017 |
| 33 | Moose Oil & Gas Co. | Houston, TX 77002 | Oil & Gas Operator | Feb 2000 |
| 34 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 35 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2024 |
| 36 | Mowata Oil Company | Victoria, TX 77903 | Oil & Gas Operator | Oct 1996 |