| 1901 | Monroe Res LTD | Fairport, NY 14450-3218 | Gas Operator | Dec 2004 |
| 1902 | Monroe Well Ser-Amsterdam | | Oil Operator | Dec 1988 |
| 1903 | Monroe Well Ser-La Petr Assoc | | Oil Operator | Dec 1988 |
| 1904 | Monroe Well Ser-La Petro II | | Oil Operator | Dec 1988 |
| 1905 | Monroe Well Ser-New American85 | | Oil Operator | Dec 1988 |
| 1906 | Monroe Well Ser-Ocean Petr '84 | | Oil & Gas Operator | Dec 1988 |
| 1907 | Monroe Well Ser-Ocean Yacht II | | Oil Operator | May 1989 |
| 1908 | Monroe Well Ser-Oceanyacht1985 | | Oil Operator | Dec 1988 |
| 1909 | Monroe Well Ser-Riverside 1985 | | Oil Operator | Dec 1988 |
| 1910 | Monroe Well Serv-New American | | Oil Operator | Dec 1988 |
| 1911 | Monroe Well Serv-Northern La | | Oil Operator | Dec 1988 |
| 1912 | Monroe Well Serv-Omega 1985 | | Oil Operator | Dec 1988 |
| 1913 | Monroe Well Service | | Oil & Gas Operator | Apr 1998 |
| 1914 | Monroe Well Service-Ajk | | Oil Operator | Dec 1988 |
| 1915 | Monroe Well Service-Apk | | Oil Operator | Dec 1988 |
| 1916 | Monroe Well Service-Beaver1985 | | Oil Operator | Nov 1991 |
| 1917 | Monroe Well Service-Broadway | | Oil Operator | Dec 1988 |
| 1918 | Monroe Well Service-BWK | | Oil Operator | Dec 1988 |
| 1919 | Monroe Well Service-Columbus | | Oil Operator | Dec 1988 |
| 1920 | Monroe Well Service-Das | | Oil Operator | Mar 1989 |
| 1921 | Monroe Well Service-Derrick | | Oil Operator | Dec 1988 |
| 1922 | Monroe Well Service-East End | | Oil Operator | Dec 1988 |
| 1923 | Monroe Well Service-Empire | | Oil Operator | Dec 1988 |
| 1924 | Monroe Well Service-Energy | | Oil Operator | Dec 1988 |
| 1925 | Monroe Well Service-Energy 84 | | Oil Operator | Aug 1989 |
| 1926 | Monroe Well Service-Ged | | Oil Operator | Dec 1988 |
| 1927 | Monroe Well Service-Gotham | | Oil Operator | Apr 1992 |
| 1928 | Monroe Well Service-Gramercy | | Oil Operator | May 1992 |
| 1929 | Monroe Well Service-HGC | | Oil Operator | Dec 1988 |
| 1930 | Monroe Well Service-Lebo | | Oil Operator | Jun 1989 |
| 1931 | Monroe Well Service-Lexington | | Oil Operator | Feb 1989 |
| 1932 | Monroe Well Service-Newtown | | Oil Operator | Aug 1990 |
| 1933 | Monroe Well Service-Ocean | | Oil Operator | Feb 1989 |
| 1934 | Monroe Well Service-Oceanyacht | | Oil Operator | Jan 1989 |
| 1935 | Monroe Well Service-Oil City | | Oil Operator | Aug 1992 |
| 1936 | Monroe Well Service-Omega | | Oil Operator | Aug 1992 |
| 1937 | Monroe Well Service-Par | | Oil Operator | Jan 1990 |
| 1938 | Monroe Well Service-Petrol | | Oil Operator | Sep 1992 |
| 1939 | Monroe Well Service-Petrovest | | Oil Operator | Dec 1988 |
| 1940 | Monroe Well Service-PRG | | Oil Operator | Nov 1990 |
| 1941 | Monroe Well Service-Redstone | | Oil Operator | Jul 1989 |
| 1942 | Monroe Well Service-RVS | | Oil Operator | Dec 1990 |
| 1943 | Monroe Well Service-Shemen | | Oil Operator | Dec 1988 |
| 1944 | Monroe Well Service-Shemen1984 | | Oil Operator | Jan 1989 |
| 1945 | Monroe Well Service-Shemen1985 | | Oil Operator | Nov 1990 |
| 1946 | Monroe Well Service-Sla | | Oil Operator | Mar 1989 |
| 1947 | Monroe Well Service-SPD | | Oil Operator | Dec 1988 |
| 1948 | Monroe Well Service-SPD 1985 | | Oil Operator | Dec 1988 |
| 1949 | Monroe Well Service-TBR | | Oil Operator | Aug 1991 |
| 1950 | Monroe Well Service-TG I | | Oil Operator | Oct 1990 |
| 1951 | Monroe Well Service-TG II | | Oil Operator | Oct 1990 |
| 1952 | Monroe Well Service-TG III | | Oil Operator | Jul 1992 |
| 1953 | Monroe Well Service-TG VI | | Oil Operator | Aug 1989 |
| 1954 | Monroe Well Service-Tpa 1985 | | Oil Operator | Dec 1990 |
| 1955 | Monroe Well Service-Vista | | Oil Operator | Nov 1990 |
| 1956 | Monroe Well Service-West End | | Oil Operator | Dec 1988 |
| 1957 | Monroe Well Service-York | | Oil Operator | Dec 1988 |
| 1958 | Monroe, Cameron | Westfield, NY 14787 | Gas Operator | Dec 2025 |
| 1959 | Monsanto | Englewood, CO 80111 | Oil & Gas Operator | Apr 1986 |
| 1960 | Monsanto Company | Indianapolis, IN 46280 | Oil & Gas Operator | Jan 2005 |
| 1961 | Monsanto Oil Com | | Oil Operator | Nov 1996 |
| 1962 | Monsanto Oil Company | | Oil & Gas Operator | Apr 1986 |
| 1963 | Montalban Oil & Gas Operations, Inc. | Cut Bank, MT 59427 | Oil & Gas Operator | Jun 2026 |
| 1964 | Montana Energy Company, LLC | McAllen, TX 78504 | Oil & Gas Operator | Jan 2026 |
| 1965 | Montana Heartland LLC | Bismarck, ND 58504 | Oil & Gas Operator | Jun 2026 |
| 1966 | Montana Land & Exploration, Inc. | Calgary, AB T2P 3E7 | Oil & Gas Operator | Apr 2019 |
| 1967 | Montana Land & Mineral Co. | Billings, MT 59105 | Gas Operator | Mar 2026 |
| 1968 | Montana Oil Field Acquisition I, LLC | Rutherford, NJ 07070 | Oil Operator | Jun 2016 |
| 1969 | Montana Power Company | Butte, MT 59701 | Oil & Gas Operator | Apr 2002 |
| 1970 | Montana Power Gas Company | | Oil & Gas Operator | Apr 2002 |
| 1971 | Montare Operating, LTD. | Flower Mound, TX 75022 | Oil & Gas Operator | Sep 2026 |
| 1972 | Montclair Energy LLC | Edmond, OK 73034-7291 | Oil & Gas Operator | Jan 2026 |
| 1973 | Montclair Production Company | Austin, TX 78755 | Oil & Gas Operator | Sep 2026 |
| 1974 | Montco Oil & Gas, Inc. | Pampa, TX 79066 | Oil & Gas Operator | May 1999 |
| 1975 | Monte Grande Exploration, Inc. | Cut Bank, MT 59427 | Oil Operator | Oct 2000 |
| 1976 | Montego Resources Inc | Oklahoma City, OK 73172-0192 | Oil & Gas Operator | Mar 2015 |
| 1977 | Monterey Pipeline Co. | | Oil Operator | Aug 1993 |
| 1978 | Monterey Production Company LLC | Tulsa, OK 74136 | Oil & Gas Operator | May 2026 |
| 1979 | Monterey Resources Inc. | | Oil & Gas Operator | Dec 1997 |
| 1980 | Monterey Resources LLC | Fort Worth, TX 76185 | Oil & Gas Operator | Oct 2019 |
| 1981 | Montex Drilling Company LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2026 |
| 1982 | Montex Exploration | Sugarland, TX 77478 | Oil Operator | Apr 2003 |
| 1983 | Montex Exploration Company | Houston, TX 77057 | Oil & Gas Operator | Mar 2011 |
| 1984 | Montgomery Count | | Oil Operator | Dec 1992 |
| 1985 | Montgomery Exploration Co LTD | Dallas, TX 75204-2634 | Oil & Gas Operator | Jun 2026 |
| 1986 | Montgomery Jake E | Henryetta, OK 74437 | Oil & Gas Operator | May 2026 |
| 1987 | Montgomery Oil & Gas Expl Inc | Tulsa, OK 74170-1884 | Oil & Gas Operator | Mar 2005 |
| 1988 | Montgomery Oil Co | | Oil Operator | Dec 2018 |
| 1989 | Montgomery Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2007 |
| 1990 | Montgomery Production & Operating LLC | Herington, KS 67449 | Oil & Gas Operator | Apr 2026 |
| 1991 | Montgomery Royalty | Moran, TX 76464 | Oil & Gas Operator | Sep 2026 |
| 1992 | Montrose Operating LLC | Broken Arrow, OK 74012 | Oil & Gas Operator | Sep 2026 |
| 1993 | Monty L Hott Production Corporation | Oklahoma City, OK 73142 | Oil & Gas Operator | May 2026 |
| 1994 | Monument Gas Marketing Inc | | Oil & Gas Operator | Oct 2025 |
| 1995 | Monument Global Resources Inc | Dallas, TX 75243 | Oil & Gas Operator | Jan 2025 |
| 1996 | Monument Production Inc. | | Oil & Gas Operator | Dec 2011 |
| 1997 | Monument Resources, Inc. | Castle Rock, CO 80104 | Oil & Gas Operator | Jun 2012 |
| 1998 | Moody Energy Co. | Canadian, TX 79014 | Oil & Gas Operator | Dec 2004 |
| 1999 | Moody Oil & Gas Co. | Bridgeport, WV 263301051 | Oil & Gas Operator | Dec 2004 |
| 2000 | Moody Oil Co. | Pearsall, TX 78061 | Oil & Gas Operator | Sep 2026 |