| 3001 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | May 2026 |
| 3002 | Mississippi River Transm. Corp | | Oil & Gas Operator | Sep 2002 |
| 3003 | Mississippi Ventures | | Gas Operator | Feb 1992 |
| 3004 | Mitchell Energy & Goodrich Oil | | Oil & Gas Operator | Feb 1985 |
| 3005 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 3006 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 3007 | MJ Energy LLC | Denver, CO 80206 | Oil Operator | Jan 2025 |
| 3008 | MJ Energy, LLC Of Arkansas | | Oil Operator | Jan 2025 |
| 3009 | MJB Production Company, Inc. | Brownfield, TX 79316 | Oil & Gas Operator | May 2026 |
| 3010 | ML Resources, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Mar 2008 |
| 3011 | MLGW | | Gas Operator | Sep 1984 |
| 3012 | Mobil E&P N.A.-Pel-Tex | | Oil & Gas Operator | Dec 1993 |
| 3013 | Mobil E&P N.A.-WM Scully Et Al | | Oil & Gas Operator | Dec 1993 |
| 3014 | Mobil E&P North America Inc. | | Oil & Gas Operator | Jan 1994 |
| 3015 | Mobil Oil E & P Southeast Inc | | Oil & Gas Operator | Sep 2013 |
| 3016 | Mobil Oil E&P Se Inc - Pel-Tex | | Oil & Gas Operator | Dec 2005 |
| 3017 | Mobley & Davis | | Oil & Gas Operator | Oct 1986 |
| 3018 | Mobley & McCain | | Oil & Gas Operator | Nov 1979 |
| 3019 | Mobley & McCain, Et Al | | Oil & Gas Operator | Jul 1986 |
| 3020 | Mobley Oil Company, Inc. | | Oil & Gas Operator | Feb 1990 |
| 3021 | Mobley Valve Service, Inc. | | Oil & Gas Operator | Nov 2006 |
| 3022 | Moco Operating Company | | Oil & Gas Operator | Mar 2002 |
| 3023 | Mole Operating Co., Inc. | | Oil & Gas Operator | Oct 1983 |
| 3024 | Monarch Petroleum Corporation | FT Worth, TX 76102 | Oil & Gas Operator | Dec 2019 |
| 3025 | Monex | | Oil Operator | Apr 1988 |
| 3026 | Monexco, Inc. | | Oil Operator | Dec 2003 |
| 3027 | Mongrue Oil Company, Inc. | | Oil & Gas Operator | Oct 1999 |
| 3028 | Mongrue, Roland, Inc | | Oil & Gas Operator | Mar 1979 |
| 3029 | Monroe Gas Associates-1 | | Gas Operator | Mar 2000 |
| 3030 | Monroe Gas Joint Venture | | Gas Operator | Sep 2011 |
| 3031 | Monroe Well Ser-Amsterdam | | Oil Operator | Dec 1988 |
| 3032 | Monroe Well Ser-La Petr Assoc | | Oil Operator | Dec 1988 |
| 3033 | Monroe Well Ser-La Petro II | | Oil Operator | Dec 1988 |
| 3034 | Monroe Well Ser-New American85 | | Oil Operator | Dec 1988 |
| 3035 | Monroe Well Ser-Ocean Petr '84 | | Oil & Gas Operator | Dec 1988 |
| 3036 | Monroe Well Ser-Ocean Yacht II | | Oil Operator | May 1989 |
| 3037 | Monroe Well Ser-Oceanyacht1985 | | Oil Operator | Dec 1988 |
| 3038 | Monroe Well Ser-Riverside 1985 | | Oil Operator | Dec 1988 |
| 3039 | Monroe Well Serv-New American | | Oil Operator | Dec 1988 |
| 3040 | Monroe Well Serv-Northern La | | Oil Operator | Dec 1988 |
| 3041 | Monroe Well Serv-Omega 1985 | | Oil Operator | Dec 1988 |
| 3042 | Monroe Well Service | | Oil & Gas Operator | Apr 1998 |
| 3043 | Monroe Well Service-Ajk | | Oil Operator | Dec 1988 |
| 3044 | Monroe Well Service-Apk | | Oil Operator | Dec 1988 |
| 3045 | Monroe Well Service-Beaver1985 | | Oil Operator | Nov 1991 |
| 3046 | Monroe Well Service-Broadway | | Oil Operator | Dec 1988 |
| 3047 | Monroe Well Service-BWK | | Oil Operator | Dec 1988 |
| 3048 | Monroe Well Service-Columbus | | Oil Operator | Dec 1988 |
| 3049 | Monroe Well Service-Das | | Oil Operator | Mar 1989 |
| 3050 | Monroe Well Service-Derrick | | Oil Operator | Dec 1988 |
| 3051 | Monroe Well Service-East End | | Oil Operator | Dec 1988 |
| 3052 | Monroe Well Service-Empire | | Oil Operator | Dec 1988 |
| 3053 | Monroe Well Service-Energy | | Oil Operator | Dec 1988 |
| 3054 | Monroe Well Service-Energy 84 | | Oil Operator | Aug 1989 |
| 3055 | Monroe Well Service-Ged | | Oil Operator | Dec 1988 |
| 3056 | Monroe Well Service-Gotham | | Oil Operator | Apr 1992 |
| 3057 | Monroe Well Service-Gramercy | | Oil Operator | May 1992 |
| 3058 | Monroe Well Service-HGC | | Oil Operator | Dec 1988 |
| 3059 | Monroe Well Service-Lebo | | Oil Operator | Jun 1989 |
| 3060 | Monroe Well Service-Lexington | | Oil Operator | Feb 1989 |
| 3061 | Monroe Well Service-Newtown | | Oil Operator | Aug 1990 |
| 3062 | Monroe Well Service-Ocean | | Oil Operator | Feb 1989 |
| 3063 | Monroe Well Service-Oceanyacht | | Oil Operator | Jan 1989 |
| 3064 | Monroe Well Service-Oil City | | Oil Operator | Aug 1992 |
| 3065 | Monroe Well Service-Omega | | Oil Operator | Aug 1992 |
| 3066 | Monroe Well Service-Par | | Oil Operator | Jan 1990 |
| 3067 | Monroe Well Service-Petrol | | Oil Operator | Sep 1992 |
| 3068 | Monroe Well Service-Petrovest | | Oil Operator | Dec 1988 |
| 3069 | Monroe Well Service-PRG | | Oil Operator | Nov 1990 |
| 3070 | Monroe Well Service-Redstone | | Oil Operator | Jul 1989 |
| 3071 | Monroe Well Service-RVS | | Oil Operator | Dec 1990 |
| 3072 | Monroe Well Service-Shemen | | Oil Operator | Dec 1988 |
| 3073 | Monroe Well Service-Shemen1984 | | Oil Operator | Jan 1989 |
| 3074 | Monroe Well Service-Shemen1985 | | Oil Operator | Nov 1990 |
| 3075 | Monroe Well Service-Sla | | Oil Operator | Mar 1989 |
| 3076 | Monroe Well Service-SPD | | Oil Operator | Dec 1988 |
| 3077 | Monroe Well Service-SPD 1985 | | Oil Operator | Dec 1988 |
| 3078 | Monroe Well Service-TBR | | Oil Operator | Aug 1991 |
| 3079 | Monroe Well Service-TG I | | Oil Operator | Oct 1990 |
| 3080 | Monroe Well Service-TG II | | Oil Operator | Oct 1990 |
| 3081 | Monroe Well Service-TG III | | Oil Operator | Jul 1992 |
| 3082 | Monroe Well Service-TG VI | | Oil Operator | Aug 1989 |
| 3083 | Monroe Well Service-Tpa 1985 | | Oil Operator | Dec 1990 |
| 3084 | Monroe Well Service-Vista | | Oil Operator | Nov 1990 |
| 3085 | Monroe Well Service-West End | | Oil Operator | Dec 1988 |
| 3086 | Monroe Well Service-York | | Oil Operator | Dec 1988 |
| 3087 | Monsanto Company | Indianapolis, IN 46280 | Oil & Gas Operator | Jan 2005 |
| 3088 | Monsanto Oil Company | | Oil & Gas Operator | Apr 1986 |
| 3089 | Monterey Pipeline Co. | | Oil Operator | Aug 1993 |
| 3090 | Monterey Resources LLC | Dallas, TX 75230 | Oil & Gas Operator | Oct 2019 |
| 3091 | Moon Operating, Inc. | Longview, TX 75601 | Oil & Gas Operator | Mar 2003 |
| 3092 | Moon-Hines-Tigrett Opr Co Inc | | Oil & Gas Operator | Oct 1995 |
| 3093 | Moore McCormack Energy, Inc. | | Oil & Gas Operator | Jul 1988 |
| 3094 | Moore Oil & Gas-Marion Corp. | | Oil & Gas Operator | Nov 1986 |
| 3095 | Moore&Munger Hydrocarbons Inc | | Oil Operator | May 1987 |
| 3096 | Mooringsport Energy Prod Corp | | Oil & Gas Operator | Oct 1994 |
| 3097 | Mooringsport Energy Trans Corp | | Oil Operator | Apr 1990 |
| 3098 | Moran Exploration, Inc. | | Oil & Gas Operator | Jan 1985 |
| 3099 | Moran Oil Co., Inc. | | Oil & Gas Operator | Aug 2009 |
| 3100 | Moransco Energy Corporation | Kilgore, TX 75663 | Oil & Gas Operator | May 2026 |