| 1 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 2 | Maclane Gas Company L.P. | Corpus Chrsti, TX 78478 | Oil & Gas Operator | Mar 1994 |
| 3 | Maggert Energy Corp. | Spring, TX 77387 | Gas Operator | Jun 1998 |
| 4 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 5 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 6 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 7 | Marquise Oil Properties Inc | Konawa, OK 74849 | Oil & Gas Operator | Nov 1992 |
| 8 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 9 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 10 | McCoy Petroleum Corporation | Wichita, KS 67207 | Oil & Gas Operator | Aug 2025 |
| 11 | McCulliss Resources Co Inc | Littleton, CO 80161-3248 | Oil & Gas Operator | Jun 2009 |
| 12 | McDaniel Company, Inc., The | Dallas, TX 75230 | Oil & Gas Operator | Oct 2025 |
| 13 | McDonald Production | Lubbock, TX 79408 | Oil & Gas Operator | Mar 2003 |
| 14 | McFarland & Scobey, Inc. | El Paso, TX 79947 | Oil & Gas Operator | Oct 2025 |
| 15 | McRae Exploration & Prod., Inc. | Houston, TX 77064 | Oil & Gas Operator | Feb 2017 |
| 16 | Melton Operating Co. | Friendswood, TX 77546 | Oil & Gas Operator | Jul 2005 |
| 17 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 18 | Merit Energy Company, LLC | Dallas, TX 75009 | Oil & Gas Operator | Jun 2025 |
| 19 | Metano Energy, LP | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2008 |
| 20 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 21 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 22 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 23 | MGM Well Service, Inc. | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Oct 2004 |
| 24 | Michael Petroleum Corporation | Houston, TX 77040 | Oil & Gas Operator | Dec 2001 |
| 25 | Midas Resources, Inc. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2025 |
| 26 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 27 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 28 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 29 | Milo-Austintatious | Houston, TX 77005 | Oil & Gas Operator | Aug 2006 |
| 30 | Miramar Petroleum, Inc. | Corpus Chrsti, TX 78463 | Oil & Gas Operator | Sep 2017 |
| 31 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Oct 2025 |
| 32 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 33 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 34 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 35 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 36 | Modena Operating LLC | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 37 | Momentum Production Corp. | Baytown, TX 77521 | Oil & Gas Operator | Oct 2025 |
| 38 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 39 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 40 | Mueller Exploration, Inc. | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |
| 41 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |