| 1 | Aberdeen American Petroleum Co., Inc. | | Oil & Gas Operator | Dec 1989 |
| 2 | Aberdeen Petroleum (USA) Inc. | Abilene, TX 79608 | Oil & Gas Operator | Sep 1994 |
| 3 | Addison Oil, LLC | Addison, TX 75001 | Oil & Gas Operator | Mar 2013 |
| 4 | Adobe Resources Corporation | Midland, TX 79701 | Oil & Gas Operator | Aug 2002 |
| 5 | Aethon Energy Operating LLC | Dallas, TX 75251 | Oil & Gas Operator | Mar 2025 |
| 6 | Alfred Lamson-James A. Crocker | | Oil & Gas Operator | Sep 1986 |
| 7 | All Oil & Gas Inc. | | Oil & Gas Operator | Jul 1989 |
| 8 | Alta Mesa Services, LP | Houston, TX 77084 | Oil & Gas Operator | Mar 2025 |
| 9 | Aminex USA, Inc. | Somerset, TX 78069 | Oil & Gas Operator | May 2018 |
| 10 | Anadarko E&P Company LP | Houston, TX 77251 | Oil & Gas Operator | Aug 2014 |
| 11 | Annco Pet. Co & Equipment, Inc | | Oil & Gas Operator | Sep 1982 |
| 12 | Anr Production Company | Houston, TX 77046 | Oil & Gas Operator | Aug 2017 |
| 13 | Arcadia Operating, LLC | Dallas, TX 75219 | Oil & Gas Operator | Mar 2025 |
| 14 | Arco O & G Co-Div Atl Rich Co | | Oil & Gas Operator | Feb 1994 |
| 15 | Ashland Exploration Inc | Houston, TX 77218 | Oil & Gas Operator | Nov 2000 |
| 16 | Ashland Oil, Inc | | Oil & Gas Operator | Dec 2022 |
| 17 | Austral Oil & Exploration, Inc | | Oil & Gas Operator | Jun 2004 |
| 18 | Avanti Exploration La, LLC | | Oil & Gas Operator | Nov 2024 |