| 1 | Acadiana Reserves, Inc. | | Oil & Gas Operator | Oct 1984 |
| 2 | Ada Oil Exploration Corp | | Oil & Gas Operator | Jan 1986 |
| 3 | Adobe Resources Corporation | Midland, TX 79701 | Oil & Gas Operator | Aug 2002 |
| 4 | Aegis Energy, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Sep 1998 |
| 5 | Affiliated Holdings, Inc. | | Oil Operator | Dec 2010 |
| 6 | Alinet Corporation | | Oil & Gas Operator | Aug 2013 |
| 7 | Alta Mesa Services, LP | Houston, TX 77084 | Oil & Gas Operator | Dec 2025 |
| 8 | Amarillo Oil Company | | Oil & Gas Operator | Aug 1980 |
| 9 | Amax Oil & Gas Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | Nov 2014 |
| 10 | Amax Petroleum Corporation | Houston, TX 77042 | Oil & Gas Operator | Dec 2012 |
| 11 | Amerada Hess Corporation | Houston, TX 77252 | Oil & Gas Operator | Aug 2013 |
| 12 | Aminoil USA Inc | | Oil & Gas Operator | Jan 1985 |
| 13 | Amoco Production Company | Houston, TX 77253 | Oil & Gas Operator | Jun 2015 |
| 14 | Anadarko Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Sep 2025 |
| 15 | Anderson Exploration Co., Inc. | | Oil & Gas Operator | Sep 2023 |
| 16 | Anderson Producing, Inc. | Houston, TX 77057 | Oil & Gas Operator | Sep 2013 |
| 17 | Anglo-Dutch Energy, LLC | | Oil & Gas Operator | Sep 2022 |
| 18 | Annco Pet. Co & Equipment, Inc | | Oil & Gas Operator | Sep 1982 |
| 19 | Anr Production Company | Houston, TX 77046 | Oil & Gas Operator | Aug 2017 |
| 20 | Anschutz Corporation | Denver, CO 80202 | Oil & Gas Operator | Sep 2016 |
| 21 | Apache Corporation | Houston, TX 77042 | Oil & Gas Operator | Dec 2025 |
| 22 | Apexco, Inc. | Sand Springs, OK 74063 | Oil & Gas Operator | Jul 2025 |
| 23 | Arco O & G Co-Div Atl Rich Co | | Oil & Gas Operator | Feb 1994 |
| 24 | Arnaudville Company Inc. | | Oil & Gas Operator | Apr 1995 |
| 25 | Aspect Energy, LLC | Denver, CO 80202 | Oil & Gas Operator | Dec 2025 |
| 26 | Austral Oil Company Incorporated | Sulphur, LA 70663 | Oil & Gas Operator | Mar 2008 |