| 1901 | Cardinal Producing Co. | Abilene, TX 79606 | Oil & Gas Operator | Aug 2003 |
| 1902 | Cardinal Shares, Inc. | West Bloomfld, MI 48322 | Oil & Gas Operator | Mar 2004 |
| 1903 | Cardona, LLC | San Angelo, TX 76902 | Oil & Gas Operator | Apr 2025 |
| 1904 | Cardwell Oil Corporation | Midland, TX 79710 | Oil & Gas Operator | Apr 2025 |
| 1905 | Cardwell'S U Bar Oil | Manor, TX 78653 | Oil & Gas Operator | Apr 2025 |
| 1906 | Carey, Shirley L. Trust | Abilene, TX 79608 | Oil & Gas Operator | Apr 2025 |
| 1907 | Caribbean Energy LLC II | Cotulla, TX 78014 | Oil & Gas Operator | Apr 2025 |
| 1908 | Caribbean Energy, L.L.C. | Cotulla, TX 78014 | Oil & Gas Operator | Nov 2019 |
| 1909 | Caribe Production Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Dec 1993 |
| 1910 | Caribou Operating Co. | Granbury, TX 76048 | Oil & Gas Operator | Mar 2010 |
| 1911 | Caribou Operating, Inc. | Granbury, TX 76048 | Oil & Gas Operator | Apr 2025 |
| 1912 | Carken LLC | Andrews, TX 79714 | Oil Operator | Apr 2025 |
| 1913 | Carl Oil & Gas Co. | Bakersfield, CA 93309 | Oil & Gas Operator | Dec 1995 |
| 1914 | Carlon Oil & Gas Co Inc | Derby, KS 67037 | Gas Operator | Dec 2024 |
| 1915 | Carloran Production Corp | Windthorst, TX 76389 | Oil & Gas Operator | Apr 2025 |
| 1916 | Carlow Corp. | Midland, TX 79702 | Oil & Gas Operator | Jan 2025 |
| 1917 | Carlson Petroleum Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 1918 | Carlton, Wayne Inc. | Bronte, TX 76933 | Oil & Gas Operator | Dec 2002 |
| 1919 | Caroil, LLC | Odessa, TX 79761 | Oil Operator | Apr 2025 |
| 1920 | Carol-Holly Oil Corporation | Denver, CO 80237 | Oil & Gas Operator | Mar 2025 |
| 1921 | Carotex Energy, Inc. | Wilson, NC 27893 | Oil & Gas Operator | Aug 2003 |
| 1922 | Carpco Efficient Energy Co., LLC | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2025 |
| 1923 | Carpenter Corporation | Sourlake, TX 77659 | Oil & Gas Operator | Oct 1994 |
| 1924 | Carpenter Services | Colorado City, TX 79512 | Oil & Gas Operator | May 1996 |
| 1925 | Carr Exploration Corp. | Dallas, TX 75225 | Oil & Gas Operator | Aug 2003 |
| 1926 | Carr Resources, Inc. | Tyler, TX 75702 | Oil & Gas Operator | Apr 2025 |
| 1927 | Carr Well Service Inc | Odessa, TX 79769 | Oil & Gas Operator | Nov 1996 |
| 1928 | Carrizo (Eagle Ford) LLC | Houston, TX 77042 | Oil & Gas Operator | Jan 2020 |
| 1929 | Carrizo (Permian) LLC | Houston, TX 77042 | Oil & Gas Operator | Jan 2020 |
| 1930 | Carrizo Exploration, Inc. | Carrizo SPGS, TX 78834 | Oil & Gas Operator | Aug 2016 |
| 1931 | Carrizo Oil & Gas, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 1932 | Carrland Oil & Gas Inc. | Prosper, TX 75078 | Oil & Gas Operator | Apr 2025 |
| 1933 | Carroll Operating, LLC | Abilene, TX 79608 | Oil & Gas Operator | Feb 2022 |
| 1934 | Carroll, Alvis J. | Wichita Falls, TX 76302 | Oil & Gas Operator | Mar 2008 |
| 1935 | Carruth Oil & Gas, LLC | Andrews, TX 79714 | Oil & Gas Operator | Apr 2025 |
| 1936 | Carruth, Chris | Andrews, TX 79714 | Oil & Gas Operator | Nov 2017 |
| 1937 | Carson Buckles Exploration LLC | Midland, TX 79710 | Oil & Gas Operator | Apr 2025 |
| 1938 | Carter Cattle & Crude Company | Luling, TX 78648 | Oil & Gas Operator | Apr 2025 |
| 1939 | Carter E&P, LLC | Johnson City, TX 78636 | Oil & Gas Operator | Dec 2016 |
| 1940 | Carter Energy Corporation | Duncanville, TX 75138 | Oil & Gas Operator | Sep 2010 |
| 1941 | Carter Exploration Company | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Feb 2015 |
| 1942 | Carter Resources | Kilgore, TX 75663 | Oil & Gas Operator | Jan 2005 |
| 1943 | Carter, Gertrude (Trudy) | Rockwall, TX 75032 | Oil & Gas Operator | Apr 2013 |
| 1944 | Carter, Mattye Family Trust | Fort Worth, TX 76109 | Oil & Gas Operator | Oct 2002 |
| 1945 | Carter, Mattye L., Estate Of | Gladewater, TX 75647 | Oil & Gas Operator | Feb 1995 |
| 1946 | Carter, Shirley Oil Co | Round Rock, TX 78665 | Oil & Gas Operator | Jun 2018 |
| 1947 | Carter, Thomas J. | Dallas, TX 75225 | Oil & Gas Operator | Nov 1995 |
| 1948 | Carter-Langham, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Apr 2025 |
| 1949 | Cartex Production | Pampa, TX 79066 | Oil & Gas Operator | Apr 2025 |
| 1950 | Cartex Production Corp. | Pampa, TX 79066 | Oil & Gas Operator | Nov 2000 |
| 1951 | Caruthers Producing Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Feb 2019 |
| 1952 | Cary Oil & Gas, Inc | Decatur, TX 76234 | Oil & Gas Operator | Apr 2025 |
| 1953 | Casa Oil And Gas Company | George West, TX 78022 | Gas Operator | Sep 2005 |
| 1954 | Casa Operations | Borger, TX 79007 | Oil & Gas Operator | Apr 2025 |
| 1955 | Cascade Petroleum Corporation | Quitman, TX 75783 | Oil & Gas Operator | Mar 2002 |
| 1956 | Cascade Resources LLC | Edmond, OK 73083 | Oil & Gas Operator | Dec 2024 |
| 1957 | Casco Energy, Inc. | Denison, TX 75020 | Oil & Gas Operator | May 1996 |
| 1958 | Case Oil | Burkburnett, TX 76354 | Oil & Gas Operator | Apr 2025 |
| 1959 | Case Resources, LLC | Graham, TX 76450 | Oil & Gas Operator | Apr 2025 |
| 1960 | Case, C. W. | Wichita Falls, TX 76308 | Oil & Gas Operator | Apr 2025 |
| 1961 | Casey, W. J. | Fairfield, TX 75840 | Oil & Gas Operator | Apr 2025 |
| 1962 | Cashco Oil Company | Houston, TX 77024 | Oil & Gas Operator | Aug 2003 |
| 1963 | Cashco, L.L.C. | Houston, TX 77024 | Oil & Gas Operator | Jul 1999 |
| 1964 | Cashion, Lyle, Company | Brandon, MS 39047 | Oil & Gas Operator | May 2008 |
| 1965 | Casias Oil Well Service, Inc. | San Antonio, TX 78232 | Oil & Gas Operator | Jul 2020 |
| 1966 | Casillas Petroleum Corp | Satanta, KS 67870 | Oil & Gas Operator | Feb 2025 |
| 1967 | Caskids Operating Company | Houston, TX 77027 | Oil & Gas Operator | Apr 2025 |
| 1968 | Caspen Oil, Inc. | Denver, CO 80226 | Oil & Gas Operator | Jul 1993 |
| 1969 | Caspen Operating Company | Somerset, TX 78069 | Oil & Gas Operator | Mar 2008 |
| 1970 | Casper Oil & Gas | Bandera, TX 78003 | Oil & Gas Operator | Oct 2002 |
| 1971 | Cass Energy Corp | Dallas, TX 75225 | Oil & Gas Operator | Aug 2003 |
| 1972 | Cass Energy LLC | MT Vernon, TX 75457 | Oil Operator | Apr 2025 |
| 1973 | Cassity Company | Wichita Falls, TX 76309 | Oil & Gas Operator | Jul 2013 |
| 1974 | Casteel, Hoyt F. | Graham, TX 76450 | Oil & Gas Operator | Nov 2001 |
| 1975 | Castex Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 1976 | Castillo Oil Company LLC | Luling, TX 78648 | Oil & Gas Operator | Apr 2025 |
| 1977 | Castle Exploration Company Inc | Blue Bell, PA 19422 | Oil & Gas Operator | May 2018 |
| 1978 | Castle Gas Corporation | San Angelo, TX 76902 | Oil & Gas Operator | Oct 2014 |
| 1979 | Castle Operating LLC | Oklahoma City, OK 73114-7444 | Oil & Gas Operator | Jan 2025 |
| 1980 | Castle Production Company | Henderson, TX 75652 | Oil & Gas Operator | May 1997 |
| 1981 | Castlerock Ef Operating LLC | San Antonio, TX 78232 | Oil & Gas Operator | Apr 2025 |
| 1982 | Castlerock Oil Company, Inc. | Addison, TX 75001 | Oil & Gas Operator | Feb 2006 |
| 1983 | Castlerock Operating, LLC | San Antonio, TX 78232 | Oil & Gas Operator | Dec 2020 |
| 1984 | Caswell Bros. Oil Co. | Bowie, TX 76230 | Oil & Gas Operator | Apr 2025 |
| 1985 | Catarina Petroleum L. C. | Dallas, TX 75228 | Oil & Gas Operator | Jun 2008 |
| 1986 | Catfish Minerals LLC | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 1987 | Cathexis Oil & Gas, LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2014 |
| 1988 | Cathey Petroleum Company, Inc. | Big Spring, TX 79720 | Oil & Gas Operator | Apr 2008 |
| 1989 | Caths Oil & Gas | Midland, TX 79706 | Oil & Gas Operator | Apr 2025 |
| 1990 | Catlin Drilling Company | Iowa Park, TX 76367 | Oil & Gas Operator | Aug 2003 |
| 1991 | Catlin, Carl | Jacksboro, TX 76458 | Oil & Gas Operator | Mar 2008 |
| 1992 | Catlin, Cecil | Iowa Park, TX 76367 | Oil & Gas Operator | Dec 1995 |
| 1993 | Catlin, Cecil, Oil Co. | Iowa Park, TX 76367 | Oil & Gas Operator | Jun 2000 |
| 1994 | Catlin, Delbert | Iowa Park, TX 76367 | Oil & Gas Operator | Apr 2025 |
| 1995 | Catlin, Randy | Iowa Park, TX 76367 | Oil Operator | Apr 2025 |
| 1996 | Catoilan Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 1997 | Cavalcade Operating Company LLC | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2017 |
| 1998 | Cavalier Oil & Gas, Inc. | Buchanan Dam, TX 78609 | Oil & Gas Operator | Apr 2025 |
| 1999 | Cavalry Resources LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2010 |
| 2000 | Cavilla Energy, Inc. | Longview, TX 75606 | Oil Operator | Apr 2025 |