| 1 | Aberdeen American Petroleum Co., Inc. | | Oil & Gas Operator | Dec 1989 |
| 2 | Al Merit Energy Co., Inc. | | Oil & Gas Operator | Jun 2015 |
| 3 | Alabama Energy Group, Inc. | | Oil & Gas Operator | Aug 1986 |
| 4 | Alog, LLC | Brewton, AL 36427 | Oil & Gas Operator | Jul 2025 |
| 5 | Amax Oil & Gas Inc | Fort Worth, TX 76107 | Oil & Gas Operator | Nov 2014 |
| 6 | Amerada Hess Corporation | Houston, TX 77252 | Oil & Gas Operator | Aug 2013 |
| 7 | American Quasar Petroleum Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2014 |
| 8 | Amoco Production Co. | Houston, TX 77253 | Oil & Gas Operator | Jun 2015 |
| 9 | Anderman/Smith Operating Company | Tulsa, OK 74136 | Oil & Gas Operator | Sep 1995 |
| 10 | Anderson, Arden A. | | Oil & Gas Operator | Jun 1970 |
| 11 | Ankor E&P Holdings Corporation | | Oil & Gas Operator | Jan 2021 |
| 12 | Araxas Exploration, Inc. | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 1998 |
| 13 | Arco Oil & Gas Co., Div. Of Atlantic Richfield | | Oil & Gas Operator | Jul 1992 |
| 14 | Aroc (Texas) Inc | Houston, TX 77090 | Oil & Gas Operator | Dec 2014 |
| 15 | Arp Production Company, LLC | Fort Worth, TX 76102 | Gas Operator | Jul 2025 |