| 1901 | Columbian Services Corporation | Topeka, KS 66603 | Gas Operator | Dec 2009 |
| 1902 | Columbine Associates | | Oil & Gas Operator | May 2026 |
| 1903 | Columbine Exploration Corp | Englewood, CO 80111 | Oil & Gas Operator | Aug 1998 |
| 1904 | Columbus Energy Corp. | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2008 |
| 1905 | Columbus Energy, LLC | Houston, TX 77046 | Oil & Gas Operator | Jul 2026 |
| 1906 | Columbus III Production LC | | Oil Operator | Oct 2003 |
| 1907 | Columbus Oil And Gas LLC | | Oil Operator | Oct 2020 |
| 1908 | Columbus Oil Company | Seminole, OK 74868 | Oil & Gas Operator | May 2026 |
| 1909 | Columbus Oilfield Explor Co | Powell, OH 43065-9315 | Gas Operator | Dec 2004 |
| 1910 | Columbus Oilfield Exploration Company | Columbus, OH 43220 | Oil & Gas Operator | Dec 2013 |
| 1911 | Columbus Production Inc | | Oil & Gas Operator | Mar 2005 |
| 1912 | Comac Well Service, Inc. | Borger, TX 79008 | Oil & Gas Operator | Mar 2008 |
| 1913 | Comal Operating LLC | Fredericksbrg, TX 78624 | Oil & Gas Operator | Jul 2026 |
| 1914 | Comanche Drilling Company | Cut Bank, MT 59427 | Oil & Gas Operator | May 2026 |
| 1915 | Comanche Exploration Co LLC | Oklahoma City, OK 73116-7334 | Oil & Gas Operator | May 2026 |
| 1916 | Comanche Exploration Company | Oklahoma City, OK 73120-2797 | Oil & Gas Operator | Feb 2007 |
| 1917 | Comanche Oil & Gas Corp | Salt Lake City, UT 84107-3075 | Oil & Gas Operator | May 2005 |
| 1918 | Comanche Oil And Service, LLC | | Oil Operator | Apr 2026 |
| 1919 | Comanche Operating Co. | Oklahoma City, OK 73120 | Oil & Gas Operator | Aug 2002 |
| 1920 | Comanche Petroleum Corporation | Oklahoma City, OK 73179 | Oil & Gas Operator | Apr 2024 |
| 1921 | Comanche Product | | Oil & Gas Operator | Jan 1992 |
| 1922 | Comanche Production Co | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 1998 |
| 1923 | Comanche Production, Inc. | Longview, TX 75606 | Oil & Gas Operator | Jan 2006 |
| 1924 | Comanche Resources Company | Oklahoma City, OK 73116 | Oil & Gas Operator | May 2026 |
| 1925 | Comanche Well Service Corp. | Plano, TX 75093 | Oil & Gas Operator | Jul 2026 |
| 1926 | Combest A L | Purcell, OK 73080-6829 | Oil & Gas Operator | Aug 2021 |
| 1927 | Combined Oil & Gas | Denver, CO 80202 | Oil & Gas Operator | Feb 1990 |
| 1928 | Combined Resources Corporation | Edmond, OK 73083 | Oil & Gas Operator | Jul 2026 |
| 1929 | Combs Production LLC | Depew, OK 74028 | Oil & Gas Operator | Apr 2026 |
| 1930 | Combs, Steven H | Corydon, KY 42406 | Oil Operator | Dec 2023 |
| 1931 | Comco Of Louisiana, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jun 2000 |
| 1932 | Comdisco Exploration Inc | | Oil Operator | Dec 1990 |
| 1933 | Comdisco Resources Inc | | Oil Operator | Aug 2004 |
| 1934 | Comerica Properties Corp | | Oil Operator | May 1985 |
| 1935 | Comet Energy Services LLC | Traverse City, MI 49686 | Oil & Gas Operator | Oct 2011 |
| 1936 | Comet Oil & Gas, Inc. | Conroe, TX 77305 | Oil & Gas Operator | Jul 2026 |
| 1937 | Comet Oil Company | Velma, OK 73091 | Oil & Gas Operator | May 2005 |
| 1938 | Comet Production | Conroe, TX 77305 | Oil Operator | Jul 2026 |
| 1939 | Comet-Haines Oil Company | Sulphur, OK 73086-0546 | Oil & Gas Operator | Mar 2013 |
| 1940 | Cometra Oil And Gas, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1997 |
| 1941 | Comgas Inc | Hebron, OH 43025-9716 | Oil & Gas Operator | Dec 1988 |
| 1942 | Command Energy Operating LLC | Tulsa, OK 74119 | Oil & Gas Operator | May 2026 |
| 1943 | Commander Oil Company LTD. | | Oil & Gas Operator | Dec 2021 |
| 1944 | Commerce Energy Co | Cleveland, OH 44115 | Oil & Gas Operator | Dec 1987 |
| 1945 | Commerce Energy, Inc. | | Oil & Gas Operator | Dec 1999 |
| 1946 | Commerce Oil & Gas Co | Rocky River, OH 44116 | Oil & Gas Operator | Dec 1996 |
| 1947 | Commercial Energ | | Gas Operator | Oct 1996 |
| 1948 | Commercial Oil - | | Oil Operator | Apr 1994 |
| 1949 | Commercial Oil Company, Inc. | Wichita, KS 67204 | Oil Operator | Jun 2001 |
| 1950 | Commodore Energy Co | Rolling Hills, CA 90274-5265 | Oil & Gas Operator | Dec 2007 |
| 1951 | Common Energy Inc | Douglas, WY 82633 | Oil & Gas Operator | Aug 1995 |
| 1952 | Common Resources L.L.C. | The Woodlands, TX 77380 | Oil & Gas Operator | May 2010 |
| 1953 | Commonwealth Energy, Inc. | Weston, WV 26452-0000 | Oil & Gas Operator | Dec 2021 |
| 1954 | Commonwealth Pet | | Oil & Gas Operator | Nov 1995 |
| 1955 | Commonwealth Resources, LLC | Fort Collins, CO 80524 | Oil Operator | Dec 2008 |
| 1956 | Commonwealth Royalty, LLC | Balmorhea, TX 79718 | Oil Operator | Jul 2026 |
| 1957 | Compadre Drilling & Expl Corp | Ardmore, OK 73402 | Oil & Gas Operator | Mar 2015 |
| 1958 | Compadres, Inc. | | Oil & Gas Operator | Dec 1988 |
| 1959 | Compass Drilling Inc | Enid, OK 73702-5467 | Oil & Gas Operator | Sep 2014 |
| 1960 | Compass Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Jul 2026 |
| 1961 | Compass Exploration LLC | Hill City, KS 67642 | Oil Operator | Mar 2026 |
| 1962 | Compass Global Resources LLC | | Oil & Gas Operator | Dec 2015 |
| 1963 | Compass Operating, L.L.C. | Midland, TX 79702 | Oil & Gas Operator | Jul 2026 |
| 1964 | Compass Resources | Enid, OK 73702 | Oil & Gas Operator | Dec 2007 |
| 1965 | Complete Energy Services LLC | Gainesville, TX 76240 | Oil Operator | Aug 2022 |
| 1966 | Complete Oil & Gas Services, LLC | Perkins, OK 74059 | Oil & Gas Operator | Jul 2026 |
| 1967 | Compostella Oil Company | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 1968 | Compressor Syste | | Oil Operator | May 1991 |
| 1969 | Compro Services Inc | Williamstown, WV 26187 | Oil & Gas Operator | Dec 1985 |
| 1970 | Comstock Energy, LLC | Wichita Falls, TX 76301 | Oil & Gas Operator | Jul 2026 |
| 1971 | Comstock Offshore, LLC | | Oil & Gas Operator | Nov 2004 |
| 1972 | Comstock Oil & Gas -- La, Inc. | | Oil & Gas Operator | Mar 2005 |
| 1973 | Comstock Oil & Gas, Inc. | Frisco, TX 75034 | Oil & Gas Operator | Dec 2012 |
| 1974 | Comstock Oil & Gas, LLC | Frisco, TX 75034 | Oil & Gas Operator | Jul 2026 |
| 1975 | Comstock Oil & Gas, LP | Frisco, TX 75034 | Oil & Gas Operator | Aug 2019 |
| 1976 | Comstock Oil & Gas--La, LLC | | Oil & Gas Operator | Dec 2024 |
| 1977 | Comyn Natural Gas, Inc. | Fort Worth, TX 76163 | Oil & Gas Operator | Jul 2026 |
| 1978 | Con-Lin Oil Co. | Graham, TX 76450 | Oil & Gas Operator | Nov 2017 |
| 1979 | Conch Oil, Inc. | Wichita, KS 67202 | Oil Operator | Jun 2002 |
| 1980 | Concharty Oil, Inc. | Bixby, OK 74008 | Oil Operator | Apr 2026 |
| 1981 | Concho Exploration | Midland, TX 79701 | Oil & Gas Operator | Feb 2004 |
| 1982 | Concho Exploration Inc | Oklahoma City, OK 73154 | Oil & Gas Operator | Mar 2015 |
| 1983 | Concho Oil & Gas Corp. | Midland, TX 79701 | Oil & Gas Operator | May 2003 |
| 1984 | Concho Oilfield Serv & Oper Co. | Eden, TX 76837 | Oil & Gas Operator | Jul 2026 |
| 1985 | Concho Oilfield Service, Inc. | Albany, TX 76430 | Oil & Gas Operator | Apr 2013 |
| 1986 | Concho Petroleum | | Oil & Gas Operator | Dec 1994 |
| 1987 | Concho Resources Inc. | Oklahoma City, OK 73154 | Oil & Gas Operator | Mar 2004 |
| 1988 | Concor Petroleum, Inc. | | Oil & Gas Operator | Feb 1983 |
| 1989 | Concord Energy, Inc. | Glen Rose, TX 76043 | Oil & Gas Operator | Jul 2026 |
| 1990 | Concord Operating Incorporated | Horseshoe Bay, TX 78657 | Oil & Gas Operator | Dec 2008 |
| 1991 | Concord Resources, LLC | | Oil & Gas Operator | Nov 2000 |
| 1992 | Concorde Exploration, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Oct 1994 |
| 1993 | Concorde Resources Corporation | Eufaula, OK 74432 | Oil & Gas Operator | Jan 2026 |
| 1994 | Concordia Resources Inc. | | Oil & Gas Operator | Dec 2025 |
| 1995 | Condor Energy | | Oil Operator | Aug 1995 |
| 1996 | Condor Energy, Inc. | Great Bend, KS 67530 | Oil & Gas Operator | Nov 2019 |
| 1997 | Condor Exploration LLC | Greenwood VIllage, CO 80111 | Oil & Gas Operator | Sep 2009 |
| 1998 | Condor Oil Company Inc. | | Oil & Gas Operator | Dec 2000 |
| 1999 | Condor Oil Corp | Boulder, CO 80303 | Oil & Gas Operator | Dec 1994 |
| 2000 | Condor Operating Co. | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |