| 1001 | Credo Petroleum Corporation | Denver, CO 80202 | Oil & Gas Operator | Jan 2013 |
| 1002 | Creek Operating Company, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Sep 1998 |
| 1003 | Creole Operating, LLC | | Oil & Gas Operator | Dec 2024 |
| 1004 | Crescent Drilling Company, Inc. | | Gas Operator | Dec 2024 |
| 1005 | Crescent DRLG & DVLPMNT, Inc. | | Oil & Gas Operator | Oct 1992 |
| 1006 | Crescent Energy Company | | Oil Operator | May 1993 |
| 1007 | Crescent Pass Energy, LLC | Houston, TX 77070 | Oil & Gas Operator | Mar 2025 |
| 1008 | Creslenn Oil Company | | Oil & Gas Operator | Nov 1998 |
| 1009 | Crest Resources & Expl. Corp. | Houston, TX 77079 | Oil & Gas Operator | Dec 1998 |
| 1010 | Crestmont Operating LLC | New York, NY 10151 | Oil Operator | Mar 2025 |
| 1011 | Crimson Explor Operating, Inc. | | Oil & Gas Operator | Dec 2009 |
| 1012 | Criswell E. White | | Gas Operator | Jun 2015 |
| 1013 | Cross Development Co. | | Oil Operator | Dec 1989 |
| 1014 | Cross Development-MMHS PRTSHP. | | Oil Operator | May 1987 |
| 1015 | Cross Development1984-1 PRTSHP | | Oil & Gas Operator | Sep 1990 |
| 1016 | Cross Timbers Operating Co | Fort Worth, TX 76102 | Oil & Gas Operator | Nov 2024 |
| 1017 | Crossroads Energy Development, LLC | | Oil Operator | Mar 2018 |
| 1018 | Crosstex Lig, LLC | | Oil Operator | Mar 2014 |
| 1019 | Crosstex Processing SVCS, LLC | | Oil Operator | Mar 2014 |
| 1020 | Crosstex Treating Services, L.P. | | Oil Operator | Sep 2009 |
| 1021 | Crow-Eason | | Oil & Gas Operator | Feb 1984 |
| 1022 | Crow-Gulf Coast Venture | | Oil & Gas Operator | Aug 1985 |
| 1023 | Crow-Pittman | | Oil Operator | Aug 1993 |
| 1024 | Crowder Oil Co. | | Oil Operator | Sep 2008 |
| 1025 | Crowder Oil L.L.C. | | Oil Operator | Apr 2015 |
| 1026 | Crown Central Petroleum Corp | Richmond, TX 77469 | Oil & Gas Operator | Dec 1999 |
| 1027 | Crown Zellerbach | | Oil & Gas Operator | May 1986 |
| 1028 | Crown Zellerbach & Newton | | Oil Operator | May 1986 |
| 1029 | Crumpler Oil | | Oil & Gas Operator | Nov 2024 |
| 1030 | Crystal Gas, L.L.C. | | Oil & Gas Operator | Apr 2000 |
| 1031 | Crystal Oil And Land Company | | Oil & Gas Operator | May 1992 |
| 1032 | Crystal Oil Company | Shreveport, LA 71120 | Oil & Gas Operator | Jul 1995 |
| 1033 | CSC Energy Corp. | | Oil & Gas Operator | Dec 2009 |
| 1034 | CSC, Inc. | | Oil Operator | Jan 2000 |
| 1035 | CSL Exploration, LP | Houston, TX 77002 | Oil & Gas Operator | Apr 2018 |
| 1036 | CSM, Inc. | | Gas Operator | Oct 1990 |
| 1037 | CSV Holdings, Inc. | | Oil & Gas Operator | Dec 2014 |
| 1038 | CSX Oil & Gas Corporation | Houston, TX 77210-4326 | Oil & Gas Operator | Mar 1993 |
| 1039 | Cti Associates | | Gas Operator | Jan 1990 |
| 1040 | Cuatro Petro Corp. | Richardson, TX 75080 | Oil & Gas Operator | Mar 2025 |
| 1041 | Culoco, Inc. | Dallas, TX 75374 | Oil & Gas Operator | Nov 2024 |
| 1042 | Cummins & Walker Oil Co., Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2021 |
| 1043 | Curt Weaver Et Al | | Oil Operator | Apr 1982 |
| 1044 | Curtis Beard & Huston P. Ganey | | Oil Operator | Mar 1987 |
| 1045 | Curtis F. Adams | | Oil & Gas Operator | Oct 2024 |
| 1046 | Custer K. Primos | | Oil & Gas Operator | Oct 2002 |
| 1047 | CWJ Operating Co., Inc. | | Oil & Gas Operator | Sep 2001 |
| 1048 | CX Operating, Inc. | | Oil & Gas Operator | Oct 2023 |
| 1049 | Cxy Energy, Inc. | Dallas, TX 75251 | Oil & Gas Operator | Nov 2000 |
| 1050 | Cygnus Producing Corporation | | Oil & Gas Operator | Feb 1990 |
| 1051 | Cymri Corporation, The | Houston, TX 77057 | Oil & Gas Operator | Mar 2008 |
| 1052 | Cypress E & P Corporation | Leander, TX 78646 | Oil & Gas Operator | Sep 2016 |
| 1053 | Cypress Gas Pipeline Company | | Oil Operator | Dec 1998 |
| 1054 | Cypress Gas Pipeline, LLC | | Oil Operator | Sep 2019 |
| 1055 | Cypress Oil Company, Inc. | | Oil & Gas Operator | Aug 2003 |
| 1056 | Cypress Operating, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Mar 2025 |
| 1057 | Cypress Partners, Inc. | Houston, TX 77068 | Oil & Gas Operator | May 1999 |
| 1058 | Cypress Production, Inc. | Azle, TX 76020 | Oil & Gas Operator | Mar 2025 |
| 1059 | Cypress Resources | | Oil & Gas Operator | Jul 2004 |
| 1060 | Czar Resources Inc | Houston, TX 77060 | Oil & Gas Operator | Oct 1992 |
| 1061 | D & C Operating, Inc. | | Oil & Gas Operator | Apr 1999 |
| 1062 | D & D DRLG Co & Saye Oil Co | | Oil Operator | Apr 1982 |
| 1063 | D & D Expl Co-Mba Energy | | Oil Operator | Nov 1985 |
| 1064 | D & D Exploration Co. | | Oil & Gas Operator | Nov 1986 |
| 1065 | D & D Oil Company | Dayton, TX 77535 | Oil & Gas Operator | Mar 2025 |
| 1066 | D & G Energy Corporation | Houston, TX 77056 | Oil & Gas Operator | Dec 1995 |
| 1067 | D & J Producing Company | | Oil Operator | Sep 2006 |
| 1068 | D & L Partnership | Rhome, TX 76078 | Oil Operator | May 1987 |
| 1069 | D & T Company | Denver, CO 80210 | Oil & Gas Operator | Jun 1983 |
| 1070 | D & V Petroleum Corporation | | Oil & Gas Operator | May 1992 |
| 1071 | D & W Oil & Gas Co. | | Gas Operator | Jan 1990 |
| 1072 | D C Bintliff & W W F Oil Corp. | | Oil & Gas Operator | Dec 1989 |
| 1073 | D H & L Operating, Inc. | | Oil & Gas Operator | Sep 1983 |
| 1074 | D J Production | Pasadena, TX 77502 | Oil & Gas Operator | Mar 2025 |
| 1075 | D&S Oil & Gas Operators, Inc. | | Oil & Gas Operator | Dec 2020 |
| 1076 | D-O-R Lease Service, Inc. | | Oil & Gas Operator | Mar 2009 |
| 1077 | D-Ram Construction Co., Inc. | | Gas Operator | Dec 1990 |
| 1078 | D-S-B Properties, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Sep 2014 |
| 1079 | D-Tec Well Production LLC | | Oil Operator | Dec 2024 |
| 1080 | D. A. Biglane | | Oil & Gas Operator | Feb 1990 |
| 1081 | D. A. Milton | | Oil & Gas Operator | Dec 2016 |
| 1082 | D. B. Braddock | | Oil & Gas Operator | Jan 1986 |
| 1083 | D. B. Braddock-Kisatchie Res. | | Oil & Gas Operator | Jan 1985 |
| 1084 | D. B. McClinton | | Oil & Gas Operator | Jun 1992 |
| 1085 | D. B. McConnell | | Oil & Gas Operator | Oct 1991 |
| 1086 | D. B. McConnell Et Al | | Oil & Gas Operator | Nov 1993 |
| 1087 | D. C. Bintliff | | Oil & Gas Operator | Mar 1987 |
| 1088 | D. C. Bintliff Et Al | | Oil & Gas Operator | Feb 1987 |
| 1089 | D. C. Bintliff-McCormick O&G | | Oil & Gas Operator | Oct 1983 |
| 1090 | D. G. Oil Co. | Dennis, TX 76439 | Oil & Gas Operator | Mar 2025 |
| 1091 | D. I. Dupree | | Oil & Gas Operator | Sep 2015 |
| 1092 | D. J. Fritz | | Oil & Gas Operator | Feb 1982 |
| 1093 | D. J. Simmons & Co. Of La. | | Gas Operator | Nov 1996 |
| 1094 | D. L. & Barbara W. Chiles | | Oil Operator | Jan 2025 |
| 1095 | D. L. Gish | | Oil Operator | Mar 1992 |
| 1096 | D. L. Gish Oil Partnership | | Oil Operator | Feb 1989 |
| 1097 | D. L. Gish Oil, Inc. | | Oil Operator | Jul 1998 |
| 1098 | D. L. Gish, Inc. | | Oil Operator | Jun 1990 |
| 1099 | D. L. Trainer | | Oil Operator | Mar 1991 |
| 1100 | D. S. Owens | | Oil & Gas Operator | Dec 1991 |