| 1 | Acadian Gas Pipeline System | | Oil Operator | Jan 2025 |
| 2 | Acadiana Gas Systems, Inc. | | Oil & Gas Operator | Jan 1999 |
| 3 | Alamo Petroleum Company | | Oil & Gas Operator | Jun 1985 |
| 4 | Alpine Expl. Companies, Inc. | | Oil & Gas Operator | Jan 2024 |
| 5 | Amax Petroleum Corporation | Houston, TX 77042 | Oil & Gas Operator | Dec 2012 |
| 6 | American Exploration Company | Houston, TX 77010 | Oil & Gas Operator | Jan 2000 |
| 7 | American Exploration Oper. Co. | | Oil & Gas Operator | May 1990 |
| 8 | Anderson Exploration Co., Inc. | | Oil & Gas Operator | Sep 2023 |
| 9 | Annco Pet. Co & Equipment, Inc | | Oil & Gas Operator | Sep 1982 |
| 10 | Apache Corporation | Houston, TX 77042 | Oil & Gas Operator | Oct 2025 |
| 11 | Apb Oil Corporation | Houston, TX 77052 | Oil & Gas Operator | Apr 1996 |
| 12 | Apd Company | | Oil & Gas Operator | Apr 1987 |
| 13 | Arbol Resources, Inc. | Houston, TX 77079 | Oil & Gas Operator | Oct 2025 |
| 14 | Arco O & G Co-Div Atl Rich Co | | Oil & Gas Operator | Feb 1994 |
| 15 | Ash Exploration, Inc. | | Oil & Gas Operator | Apr 2010 |
| 16 | Ashuca | | Oil Operator | Feb 1998 |
| 17 | Atinum Operating, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 18 | Austral Oil & Exploration, Inc | | Oil & Gas Operator | Jun 2004 |