| 2901 | Maverick Oil Co. | Richland, TX 76681 | Oil Operator | Mar 2025 |
| 2902 | Maverick Oil Corp. | | Oil Operator | May 1997 |
| 2903 | Maverick Producers, Inc. | | Oil Operator | May 2012 |
| 2904 | Maxim Energy Corporation | Baytown, TX 77520 | Oil & Gas Operator | Dec 2024 |
| 2905 | Maximus Operating, LTD. | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2025 |
| 2906 | Maxum Energy Corp | Plano, TX 75025 | Oil & Gas Operator | Jan 2003 |
| 2907 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 2908 | Maxwell Oil & Gas Corp. | Kilgore, TX 75663 | Oil & Gas Operator | Jan 2001 |
| 2909 | May Oil & Gas, L.L.C. | | Oil & Gas Operator | Dec 2013 |
| 2910 | May Petroleum, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Nov 1998 |
| 2911 | Maybrier Brothers | | Oil Operator | Apr 2006 |
| 2912 | Maybrier Production, L.L.C. | | Oil Operator | Oct 2022 |
| 2913 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 2914 | Mayne & Mertz, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2013 |
| 2915 | MBM Partnership | | Gas Operator | Nov 1991 |
| 2916 | Mbo, LLC | | Oil Operator | Jan 2025 |
| 2917 | McAlester Fuel Co | Houston, TX 77042 | Oil & Gas Operator | Jan 2010 |
| 2918 | McBrayer Oil Corporation | Rockport, TX 78381 | Oil & Gas Operator | Nov 1994 |
| 2919 | McCarter-Greenbrier-Macdonald | | Oil Operator | Sep 1981 |
| 2920 | McClinton & 4-M Invest Inc | | Oil & Gas Operator | Aug 1992 |
| 2921 | McClinton & Mosing | | Oil & Gas Operator | Oct 1977 |
| 2922 | McConathy & Associates | | Oil & Gas Operator | Dec 1983 |
| 2923 | McConathy Production Co.,Inc. | | Oil & Gas Operator | Jun 1990 |
| 2924 | McCord Exploration Co. | | Oil & Gas Operator | Dec 1990 |
| 2925 | McCord Oil Co. And T. Walker | | Oil & Gas Operator | Dec 1985 |
| 2926 | McCord-Dale Exploration | | Oil & Gas Operator | May 1986 |
| 2927 | McCord-Goodrich Oil Company | | Oil & Gas Operator | Oct 1991 |
| 2928 | McCormick Operating Company | | Oil & Gas Operator | Mar 1984 |
| 2929 | McCormick Operating PRTNSHP | | Oil & Gas Operator | Sep 1985 |
| 2930 | McCormick Production Co, Inc. | Oil City, LA 71061 | Oil & Gas Operator | Mar 2025 |
| 2931 | McCormick-Bintliff | | Oil & Gas Operator | Feb 1984 |
| 2932 | McCormick-Bintliff-Pettit | | Oil & Gas Operator | Feb 1984 |
| 2933 | McCormick-Ciroco, Inc. | | Oil & Gas Operator | Jan 1984 |
| 2934 | McCormick-Terra-Bintliff | | Oil & Gas Operator | Dec 1979 |
| 2935 | McCormick-WHB | | Gas Operator | Jan 1984 |
| 2936 | McCulloch Oil Corp.-Ids | | Oil & Gas Operator | Dec 1981 |
| 2937 | McCurdy Oil Co. | Fort Worth, TX 76116 | Oil & Gas Operator | Jan 2025 |
| 2938 | McDaniel Petroleum Company, Inc. | | Oil Operator | Jun 2020 |
| 2939 | McDowell And Cook, Inc. | | Oil Operator | Jan 1987 |
| 2940 | McElroy Drilling Co., Inc. | | Gas Operator | Dec 1987 |
| 2941 | McEn 1996 Partnership | | Oil & Gas Operator | Sep 1999 |
| 2942 | McFarland Energy, Inc. | New Orleans, LA 70160 | Oil & Gas Operator | Dec 2009 |
| 2943 | McGoldrick & Watson | | Oil & Gas Operator | Jul 1987 |
| 2944 | McGoldrick & Watson - Alagood | | Oil Operator | Oct 1995 |
| 2945 | McGoldrick & Watson DRLG., Co. | | Oil & Gas Operator | Jul 1987 |
| 2946 | McGoldrick & Watson, Et Al | | Oil Operator | Jul 1987 |
| 2947 | McGoldrick & Watson-Walker | | Oil Operator | Jul 1987 |
| 2948 | McGoldrick Oil Company | Shreveport, LA 71129 | Oil & Gas Operator | Jul 2020 |
| 2949 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 2950 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Mar 2025 |
| 2951 | McGowen Resources Co., Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2003 |
| 2952 | McIlhenny-Powell Operating Co | | Gas Operator | Aug 1983 |
| 2953 | McIntyre Oil Company | | Oil & Gas Operator | Jan 1992 |
| 2954 | McKenzie Management Inc. | | Oil & Gas Operator | Aug 1989 |
| 2955 | McKenzie Petroleum Company | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 2956 | McKenzie Production Company | Houston, TX 77063 | Oil & Gas Operator | May 1995 |
| 2957 | McLain J. Forman | | Oil & Gas Operator | Mar 1988 |
| 2958 | McLaurin Oil Co. | | Oil Operator | Jan 2025 |
| 2959 | McLeod Gas Gath & Proc Co. L.L.C. | | Oil Operator | Jul 2012 |
| 2960 | McMoran Exploration Company | | Oil & Gas Operator | May 1985 |
| 2961 | McMoran Oil & Gas LLC | New Orleans, LA 70160 | Oil & Gas Operator | Oct 2021 |
| 2962 | McMoran Production Co. | | Oil & Gas Operator | May 1985 |
| 2963 | McMoran-Transco | | Oil & Gas Operator | Aug 1979 |
| 2964 | McMullan Oil Company | San Antonio, TX 78212 | Oil & Gas Operator | Jun 2023 |
| 2965 | McOr Oil & Gas Corp | Houston, TX 77002 | Oil & Gas Operator | Oct 2013 |
| 2966 | McOr Oil Development, Inc. | | Oil & Gas Operator | Feb 1990 |
| 2967 | McRae Exploration & Prod., Inc. | Houston, TX 77064 | Oil & Gas Operator | Feb 2017 |
| 2968 | McRae Exploration, Inc. | | Oil & Gas Operator | Mar 1984 |
| 2969 | McRae Exploration, Inc. & Epm | | Oil & Gas Operator | Mar 1978 |
| 2970 | McRae Exploration, Inc. & Herd | | Oil & Gas Operator | Mar 1984 |
| 2971 | McRae Exploration,Inc & Bec | | Oil & Gas Operator | Feb 1984 |
| 2972 | McRae Oil Corporation | | Oil & Gas Operator | Mar 1984 |
| 2973 | MCZ Oil Co, Inc. | | Oil Operator | Feb 1994 |
| 2974 | MCZ, Inc. | Houston, TX 77026 | Oil & Gas Operator | Sep 1990 |
| 2975 | Meason Operating Company | Natchez, MS 39121 | Oil & Gas Operator | Dec 2011 |
| 2976 | Mec-Goodrich Oil Co. | | Oil & Gas Operator | Feb 1985 |
| 2977 | Medallion Petroleum, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2015 |
| 2978 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 2979 | Medders Oil Company | Wichita Falls, TX 76308 | Oil & Gas Operator | Mar 2025 |
| 2980 | Mega Drilling Company | | Oil Operator | Feb 1984 |
| 2981 | Melren Oil & Gas Expl., Inc. | | Gas Operator | Nov 1989 |
| 2982 | Memaca Petroleum Corporation | | Oil & Gas Operator | Jan 1990 |
| 2983 | Memorial Exploration Company | Saint Louis, MO 63105 | Oil & Gas Operator | Aug 1996 |
| 2984 | Memorial Production Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 2985 | Meng Oper. & Expl. Co. | | Oil & Gas Operator | Dec 1989 |
| 2986 | Menoah Petroleum Inc | | Oil & Gas Operator | Dec 2024 |
| 2987 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 2988 | Meridian Oil Offshore Inc. | | Oil & Gas Operator | Aug 1996 |
| 2989 | Meridian Resources USA Inc | | Oil & Gas Operator | Aug 2024 |
| 2990 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Mar 2025 |
| 2991 | Merl Wiggins Et Al | | Oil & Gas Operator | Sep 1996 |
| 2992 | Merlin J Verret | | Gas Operator | Jun 1986 |
| 2993 | Merrico Resources, Inc. | Ardmore, OK 73402 | Oil & Gas Operator | Mar 2008 |
| 2994 | Merritt Operating, Inc. | Mineola, TX 75773 | Oil & Gas Operator | Mar 2025 |
| 2995 | Mertz Energy LLC | Houston, TX 77098 | Oil & Gas Operator | Jan 2025 |
| 2996 | Mesa Gulf Coast LLC | | Oil & Gas Operator | Dec 2020 |
| 2997 | Mesa Operating LTD Partnership | Amarillo, TX 79189 | Oil & Gas Operator | May 1994 |
| 2998 | Mesa Petroleum Co. | | Oil & Gas Operator | Aug 1985 |
| 2999 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 3000 | Metairie Energy Company, Inc. | | Oil & Gas Operator | Nov 2019 |