| 1 | Aberdeen Petroleum (USA) Inc. | Abilene, TX 79608 | Oil & Gas Operator | Sep 1994 |
| 2 | Abraxas Petroleum Corporation | San Antonio, TX 78259 | Oil & Gas Operator | May 2024 |
| 3 | Adams H D LLC | Moorcroft, WY 82721 | Oil & Gas Operator | Apr 2024 |
| 4 | Adobe Resources Corporation | Midland, TX 79701 | Oil & Gas Operator | Aug 2002 |
| 5 | Aexco Petroleum Inc | Denver, CO 80202 | Oil & Gas Operator | Mar 2024 |
| 6 | Allen And Schramm Inc | Denver, CO 80202 | Oil & Gas Operator | Aug 1996 |
| 7 | Alpha Coal West Inc | Gillette, WY 82716 | Oil & Gas Operator | Jun 2020 |
| 8 | Altex Oil Company | Breckenridge, CO 80424 | Oil & Gas Operator | Dec 2005 |
| 9 | Am-West Petroleum Inc | Upton, WY 82730 | Oil & Gas Operator | Sep 2015 |
| 10 | Amarex Inc | | Oil & Gas Operator | Dec 1996 |
| 11 | Amax Oil & Gas Inc | Fort Worth, TX 76107 | Oil & Gas Operator | Nov 2014 |
| 12 | Amberex Corporation | Denver, CO 80237 | Oil & Gas Operator | Sep 1984 |
| 13 | Aminoil USA Inc | | Oil & Gas Operator | Jan 1985 |
| 14 | Ampolex Wy Inc | Gillette, WY 82716 | Oil & Gas Operator | Mar 1997 |
| 15 | Anadarko E&P Onshore LLC | Houston, TX 77046 | Oil & Gas Operator | May 2024 |
| 16 | Anadarko Minerals Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2024 |
| 17 | Anadarko Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Mar 2024 |
| 18 | Anchor Bay Corporation | Denver, CO 80202 | Oil & Gas Operator | Jun 2007 |
| 19 | Anderson Management Company | Gillette, WY 82716 | Oil & Gas Operator | May 2016 |
| 20 | Anderson Oil Company | Burkburnett, TX 76354 | Oil & Gas Operator | Dec 2015 |
| 21 | Andrikopoulos A G | Cheyenne, WY 82009 | Oil & Gas Operator | Dec 1994 |
| 22 | Anr Production Company | Houston, TX 77046 | Oil & Gas Operator | Aug 2017 |
| 23 | Anschutz Corporation, The | Denver, CO 80202 | Oil & Gas Operator | Sep 2016 |
| 24 | Anschutz Exploration Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2024 |
| 25 | Anschutz Oil Company LLC | Denver, CO 80202 | Oil & Gas Operator | Sep 2020 |
| 26 | Ant Hills Production | Lusk, WY 82225 | Oil & Gas Operator | Dec 2023 |
| 27 | Antelope Energy Company LLC | Denver, CO 80202 | Oil & Gas Operator | Mar 2024 |
| 28 | Antero Energy LLC | Denver, CO 80202 | Gas Operator | Nov 2003 |
| 29 | Apache Corporation | Houston, TX 77056 | Oil & Gas Operator | May 2024 |
| 30 | Apc Operating Partnership | Tulsa, OK 74136 | Oil & Gas Operator | Oct 1996 |
| 31 | Apx Western Corporation | Denver, CO 80217 | Oil & Gas Operator | Sep 1991 |
| 32 | Aquarius Oil And Gas | Casper, WY 82601 | Oil & Gas Operator | Sep 2017 |
| 33 | Argent Energy (Us) Holdings Inc | Sugar Land, TX 77479 | Oil & Gas Operator | Feb 2023 |
| 34 | Argentia Operating Company | | Oil Operator | Oct 1991 |
| 35 | Atlantic Richfield Company | Plano, TX 75094-1744 | Oil & Gas Operator | Dec 2016 |
| 36 | Atr Energy Corp | Dallas, TX 75313 | Oil Operator | Mar 2024 |
| 37 | Avalon Energy Corporation | | Oil & Gas Operator | Jul 1990 |
| 38 | Axem Resources Inc | Denver, CO 80202-4617 | Oil & Gas Operator | Jul 2013 |
| 39 | Azalea Oil Company LLC | Castle Rock, CO 80108 | Oil Operator | Mar 2024 |
| 40 | Aztec Gas And Oil Corporation | Elephant Butte, NM 87935-0370 | Oil & Gas Operator | Mar 2005 |