| 901 | Coastal Plains Exploration, LLC | Port Lavaca, TX 77979 | Oil & Gas Operator | May 2025 |
| 902 | Coastal Production Inc. | | Oil & Gas Operator | Aug 2000 |
| 903 | Coastal States & Emerald Oil | | Oil & Gas Operator | Dec 1979 |
| 904 | Coastal States Gas Prod. Co. | | Oil & Gas Operator | Jun 1996 |
| 905 | Cobra Oil & Gas Corporation | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2025 |
| 906 | Cobra-Lyons-Hilliard-Watson | | Oil & Gas Operator | Jun 1992 |
| 907 | Cochon Properties, LLC | | Oil & Gas Operator | Aug 2016 |
| 908 | Cockrell Oil Corporation | Houston, TX 77002-7348 | Oil & Gas Operator | Feb 2001 |
| 909 | Coda Energy, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Aug 1998 |
| 910 | Cody C. Beasley | | Oil & Gas Operator | Apr 1987 |
| 911 | Cody Energy LLC | Houston, TX 77024 | Oil & Gas Operator | Jun 2020 |
| 912 | Cody Energy, Inc. | Houston, TX 77077 | Oil & Gas Operator | Mar 2025 |
| 913 | Cohen & Kosovitz | | Oil & Gas Operator | May 1998 |
| 914 | Coho Louisiana Production Co | | Gas Operator | Dec 1998 |
| 915 | Coho Resources Inc. | Dallas, TX 75240 | Oil & Gas Operator | Jul 2002 |
| 916 | Colgrade Investment Corp. | | Oil Operator | Apr 2004 |
| 917 | Collet Oil Ventures, Inc. | Denver, CO 80217 | Oil & Gas Operator | Jun 2004 |
| 918 | Colorado Oil Co., Inc. | | Oil & Gas Operator | Dec 1977 |
| 919 | Colt Energy Inc | Iola, KS 66749 | Oil & Gas Operator | Jan 2025 |
| 920 | Colt Production Corp. Inc. | | Oil & Gas Operator | Jul 1996 |
| 921 | Columbia Gas Dev. Corp. | | Oil & Gas Operator | Apr 1996 |
| 922 | Columbia Gulf Transmission Co. | | Oil Operator | Dec 2014 |
| 923 | Columbia Gulf Transmission Company, LLC | | Oil Operator | Jan 2025 |
| 924 | Columbia Minerals Corp., Inc. | | Oil & Gas Operator | May 1996 |
| 925 | Columbia Petroleum Corp. | | Oil & Gas Operator | Jun 1982 |
| 926 | Comco Of Louisiana, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jun 2000 |
| 927 | Commerce Energy, Inc. | | Oil & Gas Operator | Dec 1999 |
| 928 | Commonwealth Energy, Inc. | Weston, WV 26452-0000 | Oil & Gas Operator | Dec 2021 |
| 929 | Compadres, Inc. | | Oil & Gas Operator | Dec 1988 |
| 930 | Compass Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | May 2025 |
| 931 | Comstock Offshore, LLC | | Oil & Gas Operator | Nov 2004 |
| 932 | Comstock Oil & Gas -- La, Inc. | | Oil & Gas Operator | Mar 2005 |
| 933 | Comstock Oil & Gas--La, LLC | | Oil & Gas Operator | Dec 2024 |
| 934 | Concor Petroleum, Inc. | | Oil & Gas Operator | Feb 1983 |
| 935 | Concord Operating Incorporated | Horseshoe Bay, TX 78657 | Oil & Gas Operator | Dec 2008 |
| 936 | Concord Resources, LLC | | Oil & Gas Operator | Nov 2000 |
| 937 | Condor Energy Inc | Great Bend, KS 67530 | Oil & Gas Operator | Oct 2021 |
| 938 | Condor Petroleum Corporation | | Oil & Gas Operator | Aug 2020 |
| 939 | Confed Oil Incorporated | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2008 |
| 940 | Conley P Smith Operating Co. | | Oil & Gas Operator | Jun 1995 |
| 941 | Conn Energy Group, LLC | | Oil & Gas Operator | Apr 2024 |
| 942 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 943 | ConocoPhillips Company | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 944 | Conquest Exploration Co. | | Oil & Gas Operator | Mar 1992 |
| 945 | Conquest Petroleum Inc | | Oil & Gas Operator | Nov 2014 |
| 946 | Consolidated Energy Inv., Inc. | | Oil & Gas Operator | Oct 2013 |
| 947 | Consolidated Energy Res., Inc. | | Oil Operator | Jun 1992 |
| 948 | Consolidated Resources Inc | | Oil & Gas Operator | May 2004 |
| 949 | Contango Operators, Inc. | Houston, TX 77098 | Oil & Gas Operator | Dec 2022 |
| 950 | Contango Operators, LLC | | Oil & Gas Operator | Nov 2024 |
| 951 | Contango Resources Company | | Oil & Gas Operator | Mar 2009 |
| 952 | Contango Resources, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 953 | Continental Oil & Gas Co. Inc. | | Oil & Gas Operator | Jul 1997 |
| 954 | Continental Operating Co. | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 955 | Continental Resources, Inc. | Oklahoma City, OK 73126 | Oil & Gas Operator | May 2025 |
| 956 | Continental U.S. Management Corp | Dallas, TX 75240 | Oil & Gas Operator | Oct 2016 |
| 957 | Contour Energy E & P, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 958 | Contour Energy E & P, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Aug 2003 |
| 959 | Converse Oil Corp. | | Oil Operator | Dec 2010 |
| 960 | Cook Production LLC | | Oil Operator | Jan 2025 |
| 961 | Coquina Oil Corporation | Houston, TX 77227 | Oil & Gas Operator | Mar 2015 |
| 962 | Cordex Petroleums, Inc. | | Oil & Gas Operator | Jun 1996 |
| 963 | Corenergy Operating Group, LLC | Houston, TX 77074 | Oil & Gas Operator | May 2025 |
| 964 | Cornell Oil Company | | Oil & Gas Operator | May 1985 |
| 965 | Cornerstone Gas Processing Inc | | Oil Operator | Jan 1999 |
| 966 | Cornerstone Natural Gas Co. | | Oil Operator | Oct 1999 |
| 967 | Coronado Energy E&P Company, LLC | Houston, TX 77252 | Oil & Gas Operator | Dec 2010 |
| 968 | Coronado Oil & Minerals Co. | | Oil & Gas Operator | Sep 1980 |
| 969 | Corpus Christi Oil & Gas Co. | | Oil & Gas Operator | Dec 1991 |
| 970 | Cortex Energy, Inc. | Wichita, KS 67217 | Oil & Gas Operator | Dec 2024 |
| 971 | Corum Production Co.-Tepco | | Oil & Gas Operator | Dec 1989 |
| 972 | Corum Production Company | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 973 | Costa Energy, LLC | Irving, TX 75063 | Oil & Gas Operator | May 2025 |
| 974 | Costilla Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 975 | Coteau Energy LLC | | Oil & Gas Operator | Dec 2024 |
| 976 | Cotton Petroleum Corporation | Tulsa, OK 74102 | Oil & Gas Operator | Jan 2005 |
| 977 | Cougar Exploration, Inc. | | Oil & Gas Operator | Jun 1988 |
| 978 | Courtney Oil Co. | | Oil Operator | Dec 1998 |
| 979 | Coushatta Oil & Gas Inc. | | Oil & Gas Operator | Jan 2007 |
| 980 | Covey Energy, Inc. | | Oil & Gas Operator | Jun 1998 |
| 981 | Covey Park Gas LLC | | Oil & Gas Operator | Aug 2019 |
| 982 | Cox & Perkins Exploration, Inc. | Houston, TX 77057 | Oil & Gas Operator | May 2025 |
| 983 | Cox Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2014 |
| 984 | Cox Operating, L.L.C. | | Oil & Gas Operator | Jan 2024 |
| 985 | Cox Resources Corporation | Dallas, TX 75244 | Oil & Gas Operator | Mar 2015 |
| 986 | Coy W. Hale | | Oil Operator | Nov 2024 |
| 987 | CPBG, LLC | | Oil Operator | Oct 2019 |
| 988 | Cpi 5, L.L.C | | Oil Operator | Dec 2023 |
| 989 | Cpi Operating Co. | | Oil & Gas Operator | Mar 2003 |
| 990 | Cpi Operating Company, LLC | | Oil Operator | Jan 2025 |
| 991 | Cra International, LTD | | Oil & Gas Operator | Mar 1983 |
| 992 | Crab Run Gas Company | | Oil & Gas Operator | Feb 1982 |
| 993 | Crain & Dore Production Co Inc | | Oil & Gas Operator | Oct 1990 |
| 994 | Cranford Exploration, Inc. | | Oil & Gas Operator | Jul 2002 |
| 995 | Crawford Energy Operating Co | Houston, TX 77056 | Oil & Gas Operator | Aug 2008 |
| 996 | Crawford Hughes Operating Co. | The Woodlands, TX 77380 | Oil & Gas Operator | May 2025 |
| 997 | Crebbs Oil Company | Batson, TX 77519 | Oil & Gas Operator | Jun 2024 |
| 998 | Credo Petroleum Corporation | Denver, CO 80202 | Oil & Gas Operator | Jan 2013 |
| 999 | Creek Operating Company, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Sep 1998 |
| 1000 | Creole Operating, LLC | | Oil & Gas Operator | Dec 2024 |