| 2901 | Manorado Oil Company | | Oil Operator | Feb 1999 |
| 2902 | Manti Exploration Operating LLC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Feb 2015 |
| 2903 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | Feb 2026 |
| 2904 | Mantle Oil & Gas, LLC | Friendswood, TX 77546 | Oil & Gas Operator | Feb 2026 |
| 2905 | Manursing Island Prod. Corp. | | Oil & Gas Operator | Sep 2002 |
| 2906 | Map Associates, L.P. | | Oil & Gas Operator | Mar 1995 |
| 2907 | Map Drilling Company | | Oil & Gas Operator | Apr 2012 |
| 2908 | Map Oil Co. | | Oil Operator | Jan 1978 |
| 2909 | Mapco Oil & Gas Company | Tulsa, OK 74101-2115 | Oil & Gas Operator | Jan 1985 |
| 2910 | Mapco Production Co | Billings, MT 59102 | Oil & Gas Operator | Apr 1994 |
| 2911 | Maple Gulf Coast Props. Corp. | | Oil & Gas Operator | Jun 1989 |
| 2912 | Mar-Bec Energy Company, L.L.C. | Shreveport, LA 71105 | Oil & Gas Operator | May 2001 |
| 2913 | Mar-Low Corporation | | Oil & Gas Operator | Mar 1992 |
| 2914 | Maralo, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 1998 |
| 2915 | Marathon Corporation | | Oil Operator | Dec 1994 |
| 2916 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Dec 2025 |
| 2917 | Marathon Oil Company/Fina | | Oil & Gas Operator | Jan 2005 |
| 2918 | Marben Corporation | | Oil Operator | Jul 1995 |
| 2919 | Marine Cont. & Supply Inc. | | Oil & Gas Operator | Nov 1985 |
| 2920 | Marine Properties, Inc. | | Oil & Gas Operator | Feb 1995 |
| 2921 | Mariner Energy, Inc. | Houston, TX 77042 | Oil & Gas Operator | Nov 2010 |
| 2922 | Marion Corporation | | Oil & Gas Operator | Jan 2001 |
| 2923 | Maritech Resources, LLC | | Oil & Gas Operator | May 2011 |
| 2924 | Marjo, Inc. | | Oil & Gas Operator | Sep 1991 |
| 2925 | Mark F Preddy & Associates,Inc | | Oil & Gas Operator | Dec 1987 |
| 2926 | Mark L Shidler Inc | Houston, TX 77055 | Oil & Gas Operator | Dec 2025 |
| 2927 | Mark Producing Inc | Houston, TX 77057 | Oil & Gas Operator | Dec 1987 |
| 2928 | Mark Seifer | | Oil & Gas Operator | Dec 2024 |
| 2929 | Mark V Petroleum Company | | Oil & Gas Operator | Feb 2020 |
| 2930 | Markham Enterprises Inc | | Oil & Gas Operator | May 1981 |
| 2931 | Marks Operating LLC | | Oil & Gas Operator | Jul 2016 |
| 2932 | Marlan Anderson | | Oil Operator | Jan 2025 |
| 2933 | Marlin And Davis | | Oil Operator | Sep 1987 |
| 2934 | Marlin Coastal, L.L.C. | | Oil & Gas Operator | Apr 2008 |
| 2935 | Marlin Energy Offshore, L.L.C. | | Oil & Gas Operator | Jun 2006 |
| 2936 | Marlin Expl.,Inc&Exchg O&G Co | | Oil & Gas Operator | Jun 1987 |
| 2937 | Marlin Exploration, Inc. | | Oil & Gas Operator | Oct 2006 |
| 2938 | Marlin Exploration, LLC | | Oil & Gas Operator | Nov 2025 |
| 2939 | Marlin Resources, L.L.C. | Midland, TX 79702 | Oil & Gas Operator | Jan 2025 |
| 2940 | Marline Oil Corp | Houston, TX 77002 | Oil & Gas Operator | Dec 1989 |
| 2941 | Marline Petroleum Corporation | | Oil & Gas Operator | Dec 1985 |
| 2942 | Marmaton Oil Company | Houston, TX 77002 | Oil & Gas Operator | Jul 1998 |
| 2943 | Maroski, Inc. | | Oil Operator | Jan 1989 |
| 2944 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Feb 2026 |
| 2945 | Marquis Resources, LLC | | Oil & Gas Operator | Jul 2021 |
| 2946 | Marr Company | | Oil & Gas Operator | Mar 1989 |
| 2947 | Marsh Engineering, Inc. | | Oil & Gas Operator | Dec 1990 |
| 2948 | Marshall & McCain | | Oil & Gas Operator | Oct 1988 |
| 2949 | Marshall Exploration, Inc. | | Oil & Gas Operator | Jun 1992 |
| 2950 | Marshall Petroleum, Inc. | Houston, TX 77040 | Oil & Gas Operator | Aug 2003 |
| 2951 | Marshall Prod. & Energy Inc. | | Oil & Gas Operator | Jan 1992 |
| 2952 | Marshland Exploration Company | | Oil & Gas Operator | May 2006 |
| 2953 | Martin Energy LLC | | Oil & Gas Operator | Apr 2023 |
| 2954 | Martin Exploration Co. | | Oil & Gas Operator | Apr 1986 |
| 2955 | Martin Oil & Gas Co. | | Oil Operator | Jul 1981 |
| 2956 | Martin Oil Co. | Aspermont, TX 79502 | Oil & Gas Operator | Jul 2023 |
| 2957 | Martin Production Company | | Oil & Gas Operator | Dec 2024 |
| 2958 | Martin-Marks Operating Co. LLC | | Oil & Gas Operator | Dec 2010 |
| 2959 | Martineau Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Jan 2025 |
| 2960 | Marvin L. Muslow | | Oil Operator | Jun 1995 |
| 2961 | Mass Resources, Inc. | | Oil Operator | Jan 2025 |
| 2962 | Master Well Works, Inc. | | Oil Operator | Dec 2024 |
| 2963 | Masters Resources, L.L.C. | Houston, TX 77079 | Oil & Gas Operator | Dec 2008 |
| 2964 | Matador Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Jul 2003 |
| 2965 | Matador Production Company | Dallas, TX 75240 | Oil & Gas Operator | Feb 2026 |
| 2966 | Matrix Oil & Gas, Inc. | | Oil & Gas Operator | Jul 2001 |
| 2967 | Matrix Production Company | Sugar Land, TX 77478 | Oil & Gas Operator | Dec 2025 |
| 2968 | Matthews Operating Co., Inc. | | Gas Operator | Aug 2001 |
| 2969 | Matthews-Bunn Operating Co. | | Oil & Gas Operator | Apr 1981 |
| 2970 | Matzinger & Bell Inc-Carl O&G | | Oil & Gas Operator | Dec 1981 |
| 2971 | Matzinger & Bell, Inc. | | Oil & Gas Operator | Dec 1982 |
| 2972 | Matzinger Expl Co& Texas Crude | | Oil & Gas Operator | Jun 1980 |
| 2973 | Matzinger Petroleum Co. | | Oil & Gas Operator | Jan 1991 |
| 2974 | Maurine B. Pyle | | Oil & Gas Operator | Mar 1993 |
| 2975 | Maverick Oil Co. | Richland, TX 76681 | Oil Operator | Feb 2026 |
| 2976 | Maverick Oil Corp. | | Oil Operator | May 1997 |
| 2977 | Maverick Producers, Inc. | | Oil Operator | May 2012 |
| 2978 | Maxim Energy Corporation | Baytown, TX 77520 | Oil & Gas Operator | Nov 2025 |
| 2979 | Maximum Energy, Inc. | | Oil & Gas Operator | Aug 2001 |
| 2980 | Maximus Operating, LTD. | Kilgore, TX 75663 | Oil & Gas Operator | Feb 2026 |
| 2981 | Maxum Energy Corp | Plano, TX 75025 | Oil & Gas Operator | Jan 2003 |
| 2982 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 2983 | Maxwell Oil & Gas Corp. | Kilgore, TX 75663 | Oil & Gas Operator | Jan 2001 |
| 2984 | May Oil & Gas, L.L.C. | | Oil & Gas Operator | Dec 2013 |
| 2985 | May Petroleum Inc | Dallas, TX 75231 | Oil & Gas Operator | Nov 1998 |
| 2986 | Maybrier Brothers | | Oil Operator | Apr 2006 |
| 2987 | Maybrier Production, L.L.C. | | Oil Operator | Oct 2022 |
| 2988 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 2989 | Mayne & Mertz, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2013 |
| 2990 | MBM Partnership | | Gas Operator | Nov 1991 |
| 2991 | Mbo, LLC | | Oil Operator | Jan 2025 |
| 2992 | McAlester Fuel Co. | Houston, TX 77042 | Oil & Gas Operator | Jan 2010 |
| 2993 | McBrayer Oil Corporation | Rockport, TX 78381 | Oil & Gas Operator | Nov 1994 |
| 2994 | McCarter | | Gas Operator | Nov 1996 |
| 2995 | McCarter-Greenbrier-Macdonald | | Oil Operator | Sep 1981 |
| 2996 | McClinton & 4-M Invest Inc | | Oil & Gas Operator | Aug 1992 |
| 2997 | McClinton & Mosing | | Oil & Gas Operator | Oct 1977 |
| 2998 | McConathy & Associates | | Oil & Gas Operator | Dec 1983 |
| 2999 | McConathy Production Co.,Inc. | | Oil & Gas Operator | Jun 1990 |
| 3000 | McCord Exploration Co. | | Oil & Gas Operator | Dec 1990 |