| 1 | A N R Pipeline Co | | Oil & Gas Operator | Jan 2025 |
| 2 | A N R Storage Company | | Oil & Gas Operator | Oct 2016 |
| 3 | Ace Energy LLC | Leawood, KS 66211 | Oil & Gas Operator | Sep 2025 |
| 4 | Adler Energy LC | | Oil Operator | May 2017 |
| 5 | Alexander Resources, Inc. | Abilene, TX 79608 | Oil & Gas Operator | Dec 2025 |
| 6 | Alumni Petroleum And Resource Management Corp | | Oil & Gas Operator | Mar 1988 |
| 7 | Amoco Production Co And C M S Oil And Gas | | Oil & Gas Operator | Sep 1996 |
| 8 | Amoco Production Co And Peninsular Oil And Gas Co | | Oil & Gas Operator | Sep 1998 |
| 9 | Annex Oil Corp | | Oil & Gas Operator | Jun 2000 |
| 10 | Anr Production Company | Houston, TX 77046 | Oil & Gas Operator | Aug 2017 |
| 11 | Antrim Development Corp | | Oil & Gas Operator | Oct 2018 |
| 12 | Apache Corporation | Houston, TX 77042 | Oil & Gas Operator | Dec 2025 |
| 13 | Apollo Exploration And Development Inc | | Oil & Gas Operator | Aug 2025 |
| 14 | Arbor Operating LLC | | Oil & Gas Operator | Mar 2024 |
| 15 | Arbor Petroleum Inc | | Oil Operator | Jan 2003 |
| 16 | Arbor Resources LLC | | Oil & Gas Operator | Dec 2007 |
| 17 | Aries Operating, LLC | Houston, TX 77010 | Oil & Gas Operator | Feb 2009 |
| 18 | Atlantic Richfield Company | Plano, TX 75074 | Oil & Gas Operator | Dec 2016 |
| 19 | Austin Energy LLC | | Oil Operator | Oct 2025 |
| 20 | Axia Energy II LLC | HGHLNDS Ranch, CO 80129 | Oil & Gas Operator | Jan 2020 |
| 21 | Aztec Producing Company Inc | | Oil & Gas Operator | May 2022 |