| 901 | Andrikopoulos Resources* A G | | Oil & Gas Operator | Jul 2015 |
| 902 | Andrus Resources Corporation | | Oil & Gas Operator | Oct 2002 |
| 903 | Anegada Resources | | Oil & Gas Operator | Jan 2002 |
| 904 | Angel Exploration Company | Oklahoma City, OK 73102-8868 | Gas Operator | Apr 2018 |
| 905 | Angel Exploration LLC | Oklahoma City, OK 73116-3603 | Oil & Gas Operator | Nov 2018 |
| 906 | Angel Rose Energy, LLC | | Oil Operator | Dec 2011 |
| 907 | Angelo, Ernest, Jr. | Midland, TX 79701 | Oil & Gas Operator | Mar 2008 |
| 908 | Angerman Assoc Inc | Pittsburgh, PA 15238-1359 | Oil & Gas Operator | Dec 1998 |
| 909 | Angerman Associates Inc | | Oil & Gas Operator | Mar 1998 |
| 910 | Angle Exploratio | | Oil Operator | Jan 1987 |
| 911 | Angle George A | | Gas Operator | Dec 1986 |
| 912 | Angle Oil Compan | | Oil Operator | Jun 1994 |
| 913 | Angle Oil Company | Hays, KS 67601 | Oil Operator | Sep 2002 |
| 914 | Anglo Production Company | | Oil & Gas Operator | Nov 1983 |
| 915 | Anglo-Dutch Energy, LLC | | Oil & Gas Operator | Aug 2018 |
| 916 | Angus Petroleum Corporation | Bakersfield, CA 93308 | Oil & Gas Operator | Dec 2017 |
| 917 | Anja Resources | Bridgeport, WV 26330-0020 | Oil & Gas Operator | Dec 2017 |
| 918 | Ankor E&P Holdings Corporation | New Orleans, LA 70112 | Oil & Gas Operator | Jul 2018 |
| 919 | Anloc, LLC | Houston, TX 77024 | Oil & Gas Operator | Jan 2019 |
| 920 | Ann Marie Tiers | | Oil Operator | Dec 1996 |
| 921 | Annarock Petroleum LLC | Cortland, OH 44410 | Oil & Gas Operator | Dec 2017 |
| 922 | Annco Pet. Co & Equipment, Inc | | Oil & Gas Operator | Oct 1982 |
| 923 | Anndell Energy Corporation | Mustang, OK 73064-9338 | Oil & Gas Operator | Jul 2006 |
| 924 | Annex Oil Corp | | Oil & Gas Operator | Jun 2000 |
| 925 | Annie Vavra 1, LLC | Palm Desert, CA 92211 | Oil & Gas Operator | Jan 2019 |
| 926 | Annona Productions, Inc. | | Gas Operator | Nov 2017 |
| 927 | Annulus Energy LLC | | Gas Operator | Dec 2017 |
| 928 | Anr Limited Inc/Coastal | Houston, TX 770460995 | Oil & Gas Operator | Dec 1987 |
| 929 | Anr Production C | | Gas Operator | Apr 1994 |
| 930 | Anr Production Company | Houston, TX 77046 | Oil & Gas Operator | Sep 2017 |
| 931 | Ansbro Petroleum Company, LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2008 |
| 932 | Anschutz Corporation | Denver, CO 80202 | Oil & Gas Operator | Sep 2016 |
| 933 | Anschutz Drilling Co. | | Oil Operator | Jul 1961 |
| 934 | Anschutz Exploration Corporation | Denver, CO 80202 | Oil & Gas Operator | Jan 2019 |
| 935 | Anschutz Oil Co. | | Oil & Gas Operator | Jul 1984 |
| 936 | Anschutz Oil Company LLC | | Oil & Gas Operator | Dec 2018 |
| 937 | Anschutz Pinedale Corporation | | Oil & Gas Operator | Dec 2014 |
| 938 | Anshutz Oil | | Oil Operator | Dec 2009 |
| 939 | Anson Company | Oklahoma City, OK 73116-1679 | Oil & Gas Operator | Oct 1997 |
| 940 | Anson Gas Corporation | Oklahoma City, OK 73116 | Oil & Gas Operator | May 1997 |
| 941 | Anson J W | Seminole, OK 74818-1280 | Oil & Gas Operator | Jun 2017 |
| 942 | Anson Oil | Seminole, OK 74868-9405 | Oil & Gas Operator | Nov 2015 |
| 943 | Anson Robert L & Teresa M | Seminole, OK 74818-0972 | Oil & Gas Operator | Sep 2015 |
| 944 | Anstine & Musgrove Inc. | Ponca City, OK 74602 | Oil Operator | Sep 2018 |
| 945 | Anstine Oil Company | | Oil Operator | Sep 2018 |
| 946 | Anstine-Musgrove | Ponca City, OK 74602 | Oil & Gas Operator | Feb 2017 |
| 947 | Ansythe Exploration Co., Inc. | | Oil & Gas Operator | Oct 1982 |
| 948 | Ant Hills Production | | Oil & Gas Operator | Dec 2018 |
| 949 | Antara Resources, Inc. | | Oil & Gas Operator | Oct 2000 |
| 950 | Antares Energy Company | Houston, TX 77002-7700 | Oil & Gas Operator | Jan 2019 |
| 951 | Antares Oil Corp | Denver, CO 80202 | Oil & Gas Operator | Oct 2015 |
| 952 | Antares Ventures, L.L.C. | | Oil Operator | Aug 2018 |
| 953 | Antelope Energy Company LLC | Midland, TX 79701 | Oil & Gas Operator | Jan 2019 |
| 954 | Antelope Production Co. | Kimball, NE 69145 | Oil & Gas Operator | Oct 1995 |
| 955 | Antelope Resources Inc | Billings, MT 59101 | Oil Operator | May 2017 |
| 956 | Antero Resources Bluestone LLC | Denver, CO 80202 | Gas Operator | Dec 2015 |
| 957 | Antero Resources Corporation | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 958 | Antero Resources I, LP | Denver, CO 80202 | Gas Operator | Jun 2005 |
| 959 | Antero Resources II, LP | | Gas Operator | May 2006 |
| 960 | Anterra Energy Services, Inc. | Santa Paula, CA 93060-9134 | Oil & Gas Operator | Feb 2018 |
| 961 | Anterra Services Inc. | Santa Paula, CA 93060-9134 | Oil & Gas Operator | Feb 2018 |
| 962 | Anthony, Bob G. Inc. | Brookhaven, MS 39601 | Oil & Gas Operator | Jan 2019 |
| 963 | Anticline Energy, LLC | Three Rivers, MI 49093 | Oil & Gas Operator | Jan 2019 |
| 964 | Antilley, Joe | Abilene, TX 79602 | Oil & Gas Operator | Jan 2019 |
| 965 | Antioch Operating LLC | | Oil & Gas Operator | Oct 2018 |
| 966 | Antle Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | Jan 2019 |
| 967 | Antle, E. | Graham, TX 76450 | Oil & Gas Operator | Oct 1994 |
| 968 | Antler Energy LLC | | Oil & Gas Operator | Dec 2018 |
| 969 | Antrim Development Corp | Traverse City, MI 49685-1148 | Oil & Gas Operator | May 2018 |
| 970 | Anvil Oil Co., Inc. | Fairmont, WV 26554-1230 | Oil & Gas Operator | Dec 2011 |
| 971 | Aoco Operating Company, L.L.C. | | Oil & Gas Operator | Feb 2005 |
| 972 | Aoco Operating, L.P. | Houston, TX 77008 | Oil & Gas Operator | Mar 2008 |
| 973 | Aog, Inc. | | Oil & Gas Operator | Nov 2014 |
| 974 | Aogp, LLC | Turtle Lake, WI 54889 | Oil & Gas Operator | Jan 2019 |
| 975 | Aop Operating Corporation | | Oil & Gas Operator | Aug 2003 |
| 976 | Ap Operating LLC | Claflin, KS 67525 | Oil Operator | May 2018 |
| 977 | Ap Production LLC | Utica, OH 43080 | Oil & Gas Operator | Dec 2017 |
| 978 | Apache Corporation | Houston, TX 77056 | Oil & Gas Operator | Jan 2019 |
| 979 | Apache Drilling | | Oil Operator | Sep 1994 |
| 980 | Apache Drilling Co, Inc | Kingman, KS 67068 | Oil Operator | Feb 2006 |
| 981 | Apache Energy Resources Corp. | Houston, TX 77056 | Oil & Gas Operator | Mar 2008 |
| 982 | Apache Oil Company | San Antonio, TX 78211 | Oil & Gas Operator | Jan 2019 |
| 983 | Apache Production Company | Holliday, TX 76366 | Oil & Gas Operator | Jan 2019 |
| 984 | Apache Shelf, Inc. | Houston, TX 77056-4400 | Oil & Gas Operator | Jan 2014 |
| 985 | Apb Oil Corporation | | Oil & Gas Operator | Apr 1996 |
| 986 | Apc Operating Partnership | Denver, CO 802034520 | Oil & Gas Operator | Oct 1996 |
| 987 | Apc Operating Partnership LP | Tulsa, OK 74136-4224 | Gas Operator | Sep 2015 |
| 988 | Apco Oil Corporation | | Oil & Gas Operator | Oct 1977 |
| 989 | Apd Company | | Oil & Gas Operator | Apr 1987 |
| 990 | Apex Crude Oil Co | Logan, OH 43138 | Oil & Gas Operator | Dec 1996 |
| 991 | Apex Energy (Pa) LLC | Wexford, PA 15090-7383 | Gas Operator | Oct 2018 |
| 992 | Apex Energy, Inc. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Jan 2019 |
| 993 | Apex Energy, L.L.C. | Tulsa, OK 74114 | Oil & Gas Operator | Oct 2018 |
| 994 | Apex Oil & Gas, Inc. | | Oil & Gas Operator | Oct 2009 |
| 995 | Apex Operating & Equip. Co. | | Oil & Gas Operator | Nov 2003 |
| 996 | Apex Operating Company, Inc. | Denver, CO 80202 | Gas Operator | Mar 2003 |
| 997 | Apex Production LTD. | Albany, TX 76430 | Oil Operator | Jan 2019 |
| 998 | Apex Resources Inc | Allison Park, PA 15101-3838 | Oil & Gas Operator | Dec 1993 |
| 999 | Apex Royalties, Inc. | Midland, TX 79702 | Oil & Gas Operator | May 1997 |
| 1000 | Apexco, Inc. | Tulsa, OK 74101 | Oil & Gas Operator | Jan 2019 |