| 1 | Abraxas Petroleum Corporation | San Antonio, TX 78259 | Oil & Gas Operator | Oct 2025 |
| 2 | Acadian Gas Pipeline System | | Oil Operator | Jan 2025 |
| 3 | Acadiana Reserves, Inc. | | Oil & Gas Operator | Oct 1984 |
| 4 | Ada Oil Exploration Corp | | Oil & Gas Operator | Jan 1986 |
| 5 | Adobe Energy Company | | Oil & Gas Operator | Aug 2010 |
| 6 | Adobe Resources Corporation | Midland, TX 79701 | Oil & Gas Operator | Aug 2002 |
| 7 | Affiliated Holdings, Inc. | | Oil Operator | Dec 2010 |
| 8 | Alliance Operating Corporation | | Oil & Gas Operator | Jan 1995 |
| 9 | Alpine Expl. Companies, Inc. | | Oil & Gas Operator | Jan 2024 |
| 10 | Alpine Resources, Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 11 | Amarex Inc | | Oil & Gas Operator | Dec 1996 |
| 12 | Amerada Hess Corporation | Houston, TX 77252 | Oil & Gas Operator | Aug 2013 |
| 13 | Amerada Hess-Ethyl Corporation | | Oil & Gas Operator | Sep 1990 |
| 14 | American Exploration Company | Houston, TX 77010 | Oil & Gas Operator | Jan 2000 |
| 15 | American Exploration Oper. Co. | | Oil & Gas Operator | May 1990 |
| 16 | American National Petroleum Co. | Houston, TX 77057 | Oil & Gas Operator | Aug 1995 |
| 17 | American Quasar Petroleum Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2014 |
| 18 | American Trading & Prod Corp | Houston, TX 77040-6471 | Oil & Gas Operator | Nov 2014 |
| 19 | Aminoil Of Louisiana, Inc. | | Oil & Gas Operator | Dec 1981 |
| 20 | Aminoil USA Inc | | Oil & Gas Operator | Jan 1985 |
| 21 | Amoco Production Co. | Houston, TX 77253 | Oil & Gas Operator | Jun 2015 |
| 22 | Ampolex (Texas), Inc. | | Oil & Gas Operator | May 1993 |
| 23 | An-Son Corporation | Oklahoma City, OK 73124 | Oil & Gas Operator | Jan 2006 |
| 24 | Anadarko Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Jul 2025 |
| 25 | Anderson Exploration Co., Inc. | | Oil & Gas Operator | Sep 2023 |
| 26 | Apache Corporation | Houston, TX 77042 | Oil & Gas Operator | Oct 2025 |
| 27 | Apache Shelf, Inc. | Houston, TX 77056 | Oil & Gas Operator | Jan 2014 |
| 28 | Aquila Energy Resources Corp. | Houston, TX 77042 | Oil & Gas Operator | Nov 2013 |
| 29 | Araxas Exploration, Inc. | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 1998 |
| 30 | Arco O & G Co-Div Atl Rich Co | | Oil & Gas Operator | Feb 1994 |
| 31 | Aries Operating LP | Houston, TX 77042 | Oil & Gas Operator | Oct 2025 |
| 32 | Aries Operating, LLC | Houston, TX 77010 | Oil & Gas Operator | Feb 2010 |
| 33 | Arkla Exploration Co. | Shreveport, LA 71151 | Oil & Gas Operator | Jan 1993 |
| 34 | Ashland Exploration Inc | Houston, TX 77218 | Oil & Gas Operator | Nov 2000 |
| 35 | Ashland Oil, Inc | | Oil & Gas Operator | Dec 2023 |
| 36 | Aspect Energy, LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 37 | Atc Realty Eight, Inc. | | Oil & Gas Operator | Nov 1988 |
| 38 | Austral Oil & Exploration, Inc | | Oil & Gas Operator | Jun 2004 |
| 39 | Austral Oil Company Incorporated | Sulphur, LA 70663 | Oil & Gas Operator | Mar 2008 |
| 40 | Aviara Energy Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2002 |
| 41 | Azimuth Energy, LLC | Denver, CO 80203 | Oil & Gas Operator | Sep 2006 |