| 1 | C & K Petroleum Inc | Denver, CO 80202 | Oil & Gas Operator | Apr 1984 |
| 2 | Cajun Minerals, Inc. | | Oil & Gas Operator | Mar 1997 |
| 3 | Cajun Operating, Inc. | | Oil & Gas Operator | Jun 2011 |
| 4 | Callon Offshore Production, Inc. | Natchez, MS 39121 | Oil & Gas Operator | Dec 2005 |
| 5 | Calyx Exploration & Production | | Oil & Gas Operator | Jul 1991 |
| 6 | Camex, Inc. | | Oil & Gas Operator | Jun 1992 |
| 7 | Carrollton Resources Corp. | | Oil & Gas Operator | Sep 2000 |
| 8 | Cashco Oil Company | Houston, TX 77024 | Oil & Gas Operator | Aug 2003 |
| 9 | Caskids Operating Company | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 10 | Castex Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 11 | Century Exploration Houston, Inc | The Woodlands, TX 77380 | Oil & Gas Operator | Oct 2011 |
| 12 | Century Exploration Houston, LLC | Austin, TX 78702 | Oil & Gas Operator | Jan 2016 |
| 13 | Century Exploration N.O., Inc. | | Oil & Gas Operator | Sep 2011 |
| 14 | Chesapeake Operating, Inc. | Oklahoma City, OK 73154 | Oil & Gas Operator | Jun 2025 |
| 15 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Oct 2025 |
| 16 | Cities Service Company | | Oil & Gas Operator | Mar 1983 |
| 17 | Cities Service Oil & Gas Corp | | Oil & Gas Operator | Mar 1988 |
| 18 | Cities Service Oil Co. | | Oil & Gas Operator | Dec 1986 |
| 19 | Clovelly DRLG & Dev Co Inc | | Oil & Gas Operator | Oct 1983 |
| 20 | Clovelly Oil Co., Inc. | | Oil & Gas Operator | Nov 2008 |
| 21 | Cockrell Oil Corporation | Houston, TX 77002-7348 | Oil & Gas Operator | Feb 2001 |
| 22 | Cody Energy LLC | Houston, TX 77024 | Oil & Gas Operator | Jun 2020 |
| 23 | Cody Energy, Inc. | Houston, TX 77077 | Oil & Gas Operator | Aug 2025 |
| 24 | Columbia Gas Dev. Corp. | | Oil & Gas Operator | Apr 1996 |
| 25 | Comstock Oil & Gas -- La, Inc. | | Oil & Gas Operator | Mar 2005 |
| 26 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 27 | Consolidated Resources Inc | | Oil & Gas Operator | May 2004 |
| 28 | Contango Operators, Inc. | Houston, TX 77098 | Oil & Gas Operator | Dec 2022 |
| 29 | Contango Operators, LLC | | Oil & Gas Operator | Nov 2024 |
| 30 | Contango Resources Company | | Oil & Gas Operator | Mar 2009 |
| 31 | Continental Resources, Inc. | Oklahoma City, OK 73126 | Oil & Gas Operator | Oct 2025 |
| 32 | Cotton Petroleum Corporation | Tulsa, OK 74102 | Oil & Gas Operator | Jan 2005 |
| 33 | Cox Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2014 |
| 34 | Cox Operating, L.L.C. | | Oil & Gas Operator | Jan 2024 |
| 35 | Cra International, LTD | | Oil & Gas Operator | Mar 1983 |
| 36 | Crescent DRLG & DVLPMNT, Inc. | | Oil & Gas Operator | Oct 1992 |
| 37 | Crosstex Lig, LLC | | Oil Operator | Mar 2014 |
| 38 | Cuatro Petro Corp. | Richardson, TX 75080 | Oil & Gas Operator | Oct 2025 |
| 39 | Cypress Production, Inc. | Azle, TX 76020 | Oil & Gas Operator | Oct 2025 |