| 1 | Acock Engineering & Assoc., Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2002 |
| 2 | Acock/Anaqua Operating Co., LC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2004 |
| 3 | Activa Resources, LLC | San Antonio, TX 78205 | Oil & Gas Operator | Apr 2024 |
| 4 | Activa Resources, LTD. | San Antonio, TX 78205 | Oil & Gas Operator | Mar 2008 |
| 5 | Alamo Operating Company, L. C. | San Antonio, TX 78278 | Oil & Gas Operator | Aug 2023 |
| 6 | Alegre Energy Operating, LP | San Antonio, TX 78216 | Oil & Gas Operator | Sep 2005 |
| 7 | Alegre Energy, Inc. | San Antonio, TX 78216 | Oil & Gas Operator | Apr 2024 |
| 8 | Alexander Energy Corporation | Dallas, TX 75206 | Oil & Gas Operator | Apr 2015 |
| 9 | Allegiant Resources, LLC | Lafayette, LA 70503 | Oil & Gas Operator | Apr 2024 |
| 10 | American Delta Corporation | Portland, TX 78374 | Oil & Gas Operator | Jun 2013 |
| 11 | Amoco Production Co. | Houston, TX 77253 | Oil & Gas Operator | Jun 2015 |
| 12 | Anadarko Austin Chalk Company | Houston, TX 77251 | Oil & Gas Operator | Feb 2006 |
| 13 | Anadarko E&P Company LP | Houston, TX 77251 | Oil & Gas Operator | Aug 2014 |
| 14 | Anadarko E&P Onshore LLC | Houston, TX 77046 | Oil & Gas Operator | Apr 2024 |
| 15 | Anchor Oil Company | Gruver, TX 79040 | Gas Operator | Apr 2024 |
| 16 | Anchor Operating Co. | Houston, TX 77055 | Oil & Gas Operator | Apr 2024 |
| 17 | Aop Operating Corporation | Dallas, TX 75313 | Oil & Gas Operator | Aug 2003 |
| 18 | Apache Corporation | Houston, TX 77056 | Oil & Gas Operator | Apr 2024 |
| 19 | Arcturus Operating Company | Addison, TX 75001 | Oil & Gas Operator | Apr 2024 |
| 20 | Argent Energy (Us) Holdings Inc | Sugar Land, TX 77479 | Oil & Gas Operator | Feb 2023 |
| 21 | Arkoma Prod Co Of Texas, Inc. | Dallas, TX 75225 | Oil Operator | May 2004 |
| 22 | Arpel, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Apr 2014 |
| 23 | Arrow Exploration Company | Plano, TX 75075 | Oil & Gas Operator | Dec 2004 |
| 24 | Arrowhead Operating Inc. | Argyle, TX 76226 | Oil & Gas Operator | Apr 2024 |
| 25 | Asm Oil & Gas Company, Inc. | Dallas, TX 75367 | Oil & Gas Operator | May 2020 |
| 26 | Atasca Resources Inc | Houston, TX 77219 | Oil & Gas Operator | Apr 2024 |
| 27 | Atkinson Energy Corporation | Giddings, TX 78942 | Oil & Gas Operator | Jan 2010 |