| 1 | Callon Offshore Production, Inc. | Natchez, MS 39121 | Oil & Gas Operator | Dec 2005 |
| 2 | Calyx Exploration & Production | | Oil & Gas Operator | Jul 1991 |
| 3 | Carl Oil & Gas Co.-CNG | | Oil & Gas Operator | Dec 1995 |
| 4 | Chevron Pipe Line Company | Houston, TX 77001 | Oil Operator | Feb 2015 |
| 5 | Chevron USA Inc | Midland, TX 79706 | Oil & Gas Operator | Apr 2024 |
| 6 | Clayton Williams Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Apr 2017 |
| 7 | Cliffs Drilling Company | | Oil & Gas Operator | Dec 1984 |
| 8 | Cliffwood Production Co. | Houston, TX 77090 | Oil & Gas Operator | Aug 2013 |
| 9 | Clovelly Oil Co., Inc. | | Oil & Gas Operator | Nov 2008 |
| 10 | Clovelly Oil Co., Inc. - Ripco | | Oil & Gas Operator | Nov 1991 |
| 11 | CMS Nomeco Oil & Gas Co. | Jackson, MI 49201 | Oil & Gas Operator | Jan 2015 |
| 12 | CMS Oil And Gas Company | Jackson, MI 49201 | Oil & Gas Operator | Oct 2002 |
| 13 | Cockrell Oil Corporation | Houston, TX 77002-7348 | Oil & Gas Operator | Feb 2001 |
| 14 | Colorado Oil Co., Inc. | | Oil & Gas Operator | Dec 1977 |
| 15 | Columbia Minerals Corp., Inc. | | Oil & Gas Operator | May 1996 |
| 16 | Costilla Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 17 | Cox Operating, L.L.C. | | Oil & Gas Operator | Jan 2024 |
| 18 | Crescent Energy Company | | Oil Operator | May 1993 |
| 19 | Crosstex Lig, LLC | | Oil Operator | Mar 2014 |
| 20 | Cxy Energy, Inc. | Dallas, TX 75251 | Oil & Gas Operator | Nov 2000 |