| 1 | Acadian Gas Pipeline System | | Oil Operator | Jan 2025 |
| 2 | Ada Oil Exploration Corp | | Oil & Gas Operator | Jan 1986 |
| 3 | Alamo Petroleum Company | | Oil & Gas Operator | Jun 1985 |
| 4 | Alliance Operating Corporation | | Oil & Gas Operator | Jan 1995 |
| 5 | Allwaste Oilfield Services Inc | | Oil Operator | May 1996 |
| 6 | Alpine Energy, Inc. | | Oil & Gas Operator | Dec 1999 |
| 7 | Alpine Expl. Companies, Inc. | | Oil & Gas Operator | Jan 2024 |
| 8 | Alta Mesa Services, LP | Houston, TX 77084 | Oil & Gas Operator | Oct 2025 |
| 9 | Amax Petroleum Corporation | Houston, TX 77042 | Oil & Gas Operator | Dec 2012 |
| 10 | Amerada Hess Corporation | Houston, TX 77252 | Oil & Gas Operator | Aug 2013 |
| 11 | American Coastal Energy, Inc. | Houston, TX 77225 | Oil & Gas Operator | May 2008 |
| 12 | American Quasar Petroleum Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2014 |
| 13 | Amoco Production Co. | Houston, TX 77253 | Oil & Gas Operator | Jun 2015 |
| 14 | Anderson Exploration Co., Inc. | | Oil & Gas Operator | Sep 2023 |
| 15 | Apache Corporation | Houston, TX 77042 | Oil & Gas Operator | Oct 2025 |
| 16 | Arco O & G Co-Div Atl Rich Co | | Oil & Gas Operator | Feb 1994 |