| 20901 | Oexco, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2015 |
| 20902 | Off Broadway Mineral Rights LLC | | Oil & Gas Operator | Oct 2024 |
| 20903 | Offield Lease Operations LLC | Wilson, OK 73463 | Oil & Gas Operator | May 2023 |
| 20904 | Offset Oil & Gas | Big Spring, TX 79720 | Oil & Gas Operator | Aug 2003 |
| 20905 | Offshore Group, Inc. The | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 20906 | Offshore Oil & Gas Inc | Houston, TX 77063 | Oil & Gas Operator | Sep 1994 |
| 20907 | Offshore Shelf LLC | | Oil & Gas Operator | Dec 2007 |
| 20908 | Ofs-Tulsa Corporation | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1997 |
| 20909 | Oft Inc. | Houston, TX 77079 | Oil & Gas Operator | Jul 2025 |
| 20910 | Og Co., Inc. | Houston, TX 77057 | Oil & Gas Operator | Jul 2025 |
| 20911 | Oga Operating L.L.C. | Midland, TX 79702 | Oil & Gas Operator | Jan 2000 |
| 20912 | Ogden Oil Co., Inc. | | Oil Operator | May 1981 |
| 20913 | Ogden Resources Corporation | Bryan, TX 77802 | Oil & Gas Operator | Jul 2025 |
| 20914 | Ogden Resources, LTD. | Bryan, TX 77802 | Oil & Gas Operator | Feb 2009 |
| 20915 | Ogh Oil Company | | Oil Operator | Sep 1995 |
| 20916 | Ogle Petroleum Inc. | | Oil & Gas Operator | Dec 1989 |
| 20917 | Oglesby Oil Company | | Oil & Gas Operator | Nov 2023 |
| 20918 | Oglesby Prod & Expl Co Inc | | Oil & Gas Operator | Nov 1987 |
| 20919 | Oglesby, Marshall | | Oil Operator | May 1990 |
| 20920 | Ogog Operating, LLC | Dallas, TX 75367 | Oil & Gas Operator | Jul 2025 |
| 20921 | Ogris Operating LLC | | Gas Operator | May 2025 |
| 20922 | Ogs Operating Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | Sep 2008 |
| 20923 | Ogx Operating, LLC | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 20924 | Ogx Resources LLC | Midland, TX 79702 | Oil & Gas Operator | Oct 2011 |
| 20925 | Ohio Energy Assets, Inc. | Laurelville, OH 43135 | Oil & Gas Operator | Dec 2014 |
| 20926 | Ohio Energy Group Inc | Uniontown, OH 44685 | Oil & Gas Operator | Dec 1988 |
| 20927 | Ohio Energy Operators LLC | Colorado Spring, CO 80908 | Oil Operator | Dec 2018 |
| 20928 | Ohio Kentucky Oil Corporation | Lexington, KY 40503 | Oil & Gas Operator | Dec 2023 |
| 20929 | Ohio L & M Company Inc | Marietta, OH 45750 | Oil & Gas Operator | Dec 2008 |
| 20930 | Ohio Natural Fuel Co | Canton, OH 44718 | Oil & Gas Operator | Dec 1985 |
| 20931 | Ohio Oil & Gas | Fowler, OH 44418 | Oil & Gas Operator | Dec 1988 |
| 20932 | Ohio Production Corp | Westerville, OH 43081 | Oil & Gas Operator | Dec 2001 |
| 20933 | Ohio Production* | Newark, OH 43055 | Oil & Gas Operator | Dec 1987 |
| 20934 | Ohio Valley Energy Systems Corp | Austintown, OH 44515 | Oil & Gas Operator | Dec 2024 |
| 20935 | Ohio Valley Energy, Inc | Livermore, KY 42352 | Oil Operator | Dec 2023 |
| 20936 | Ohlhausen Oil Company | Abilene, TX 79608 | Oil & Gas Operator | Jul 2025 |
| 20937 | Oi Auburn, Inc. | Tulsa, OK 74135 | Gas Operator | Dec 2024 |
| 20938 | Oil & Gas Acquisition Group Inc | Austin, TX 78716 | Oil & Gas Operator | May 2003 |
| 20939 | Oil & Gas Development Company | | Oil & Gas Operator | May 1991 |
| 20940 | Oil & Gas Exploration Inc | Cleveland, OK 74020 | Oil & Gas Operator | Aug 2013 |
| 20941 | Oil & Gas MGMT Inc | Mount Pleasant, PA 15666-3304 | Oil & Gas Operator | Dec 2024 |
| 20942 | Oil & Gas Operations | Midland, TX 79706 | Oil & Gas Operator | Jul 2025 |
| 20943 | Oil & Gas Producers, Inc. | Topeka, KS 66604 | Oil Operator | Jun 2004 |
| 20944 | Oil & Gas Properties | Midland, TX 79704 | Oil & Gas Operator | Jul 2025 |
| 20945 | Oil & Gas Property MGMT., Inc. | Dallas, TX 75201 | Oil & Gas Operator | Jul 1996 |
| 20946 | Oil & Gas Servic | | Oil Operator | Jun 1983 |
| 20947 | Oil & Gas Solutions LTD | Wooster, OH 44691 | Oil & Gas Operator | Dec 2007 |
| 20948 | Oil & Gas SVC Inc | Reelsville, IN 46171-9686 | Gas Operator | Dec 1991 |
| 20949 | Oil & Gas Unlimited Inc | | Oil & Gas Operator | May 2013 |
| 20950 | Oil & Realty Devlop Inc | Columbus, OH 43212 | Oil Operator | Dec 1986 |
| 20951 | Oil And Gas Futures, Inc. | | Oil & Gas Operator | May 1977 |
| 20952 | Oil Capital Corporation | Littleton, CO 80122 | Gas Operator | May 2009 |
| 20953 | Oil Center Operating Inc | Fort Worth, TX 76102-5108 | Oil & Gas Operator | Apr 2014 |
| 20954 | Oil Coast Corp. | S Houston, TX 77587 | Oil & Gas Operator | Jul 2025 |
| 20955 | Oil Company Of America, Inc. | Hays, KS 67601 | Oil Operator | Dec 2009 |
| 20956 | Oil Country Management, Inc. | | Oil & Gas Operator | Jan 2005 |
| 20957 | Oil Creek Production Company | Prague, OK 74864-0667 | Oil & Gas Operator | Feb 2025 |
| 20958 | Oil Development Co | | Oil & Gas Operator | Jan 1979 |
| 20959 | Oil Drillers & D | | Oil & Gas Operator | Feb 1992 |
| 20960 | Oil Enterprises | Logan, OH 43138 | Oil & Gas Operator | Dec 2024 |
| 20961 | Oil Equipment As | | Gas Operator | Jun 1989 |
| 20962 | Oil Exploration Of America Inc | Sisseton, SD 57262-9503 | Oil & Gas Operator | Jun 2001 |
| 20963 | Oil Field Manage | | Oil Operator | Jun 1991 |
| 20964 | Oil Gas Management, Inc. | Kansas City, MO 64106 | Oil Operator | Apr 2011 |
| 20965 | Oil Inc | | Oil & Gas Operator | Dec 1971 |
| 20966 | Oil Internationa | | Oil Operator | Jun 1986 |
| 20967 | Oil Investors Inc | Crescent, OK 73028 | Oil & Gas Operator | May 2025 |
| 20968 | Oil Lease Operating Co. | Coldspring, TX 77331 | Oil & Gas Operator | Aug 2003 |
| 20969 | Oil Lift, Incorporated | Metairie, LA 70002 | Oil & Gas Operator | Apr 2020 |
| 20970 | Oil Management Corporation | Dallas, TX 75206 | Oil & Gas Operator | Apr 2022 |
| 20971 | Oil Mountain Energy Inc | Casper, WY 82609 | Oil Operator | Jun 2025 |
| 20972 | Oil Operations Inc | | Oil & Gas Operator | Apr 2011 |
| 20973 | Oil Operators Inc. | | Oil & Gas Operator | Nov 2024 |
| 20974 | Oil Palace, Inc. | | Oil Operator | Jun 2016 |
| 20975 | Oil Partners | Salina, KS 67401 | Oil Operator | Jun 2001 |
| 20976 | Oil Partners, LLC | Salina, KS 67401 | Oil Operator | Mar 2025 |
| 20977 | Oil Patch Energy LLC | Broken Arrow, OK 74014 | Oil & Gas Operator | Jan 2025 |
| 20978 | Oil Patch Operators Co., L.L.C. | Kilgore, TX 75663 | Oil & Gas Operator | Jul 2025 |
| 20979 | Oil Patch Operators, LLC | | Oil & Gas Operator | Jul 2005 |
| 20980 | Oil Pool Inc | Tulsa, OK 74132-2659 | Oil & Gas Operator | Apr 2025 |
| 20981 | Oil Producers In | | Oil & Gas Operator | Dec 1996 |
| 20982 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Jul 2025 |
| 20983 | Oil Production Management Inc | Squaw Valley, CA 93675-9725 | Oil & Gas Operator | Dec 2002 |
| 20984 | Oil Production S | | Oil Operator | Sep 1993 |
| 20985 | Oil Production Systems Inc | Cushing, OK 74023 | Oil & Gas Operator | Jan 2013 |
| 20986 | Oil Projects, LLC | Houston, TX 77027 | Oil & Gas Operator | Jul 2025 |
| 20987 | Oil Prop Company | | Oil & Gas Operator | Sep 1995 |
| 20988 | Oil Prop Investm | | Oil Operator | Dec 1995 |
| 20989 | Oil Properties Co., Inc. | Wichita, KS 67208 | Gas Operator | Dec 2009 |
| 20990 | Oil Property Man | | Oil & Gas Operator | Jun 1995 |
| 20991 | Oil Property Management, Inc. | Attica, KS 67009 | Oil & Gas Operator | Feb 2021 |
| 20992 | Oil Recovery Systems Inc | Tulsa, OK 74145-4619 | Oil & Gas Operator | Apr 2025 |
| 20993 | Oil Recovery, Inc. | | Oil Operator | Sep 1992 |
| 20994 | Oil Reserves Corp Of America | | Oil & Gas Operator | May 2002 |
| 20995 | Oil Rock Energy Inc. / O.R.E. | Dallas, TX 75208 | Oil & Gas Operator | Jul 2025 |
| 20996 | Oil Rock Oil Company, Inc. | Elizabeth, WV 26143 | Oil & Gas Operator | Dec 2021 |
| 20997 | Oil Rock Resources, LLC | Weatherford, TX 76088 | Oil & Gas Operator | Jan 2024 |
| 20998 | Oil Search (Alaska), LLC | | Oil & Gas Operator | Jun 2025 |
| 20999 | Oil Search Inc | Brookfield, OH 44403 | Oil & Gas Operator | Dec 2024 |
| 21000 | Oil Securities Inc. | | Gas Operator | Dec 2003 |