| 20801 | O'Neill Properties, LTD. | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 20802 | O'Ryan Oil And Gas | Odessa, TX 79768 | Oil & Gas Operator | Jul 2025 |
| 20803 | O'Sand Production, Inc. | Tomball, TX 77377 | Oil & Gas Operator | Aug 2003 |
| 20804 | O'Sullivan & Scully, Inc. | | Oil & Gas Operator | Oct 1994 |
| 20805 | O'Sullivan Oil & Gas Co., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2000 |
| 20806 | O'Tool Oil & Gas, LLC | Dallas, TX 75219 | Oil & Gas Operator | Jul 2025 |
| 20807 | O. B. And Keith Whatley | | Oil Operator | Jul 1993 |
| 20808 | O. B. Beck | | Oil Operator | Feb 1991 |
| 20809 | O. B. Mobley | | Oil & Gas Operator | Jul 1989 |
| 20810 | O. B. Mobley, Et Al | | Oil Operator | Jul 1989 |
| 20811 | O. B. Whatley | | Oil Operator | Jul 1993 |
| 20812 | O. D. Maybrier | | Oil Operator | Dec 2011 |
| 20813 | O. F. H., Inc. | | Oil Operator | May 1990 |
| 20814 | O. G., Inc. | | Oil & Gas Operator | Nov 1992 |
| 20815 | O. H. B. Inc. | San Angelo, TX 76902 | Oil & Gas Operator | Sep 2019 |
| 20816 | O. H. M. Operating | Pampa, TX 79065 | Oil & Gas Operator | Jul 2025 |
| 20817 | O. O. Cummings | | Gas Operator | Jan 1999 |
| 20818 | O.B. Whatley Oil Company, Inc. | | Oil Operator | Feb 2013 |
| 20819 | O.B., Keith & Owen B. Whatley | | Oil Operator | Jul 1989 |
| 20820 | O.G.O. Refining | Luling, TX 78648 | Oil & Gas Operator | Jun 2013 |
| 20821 | O.G.P. Operating, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Jul 2025 |
| 20822 | O.I.L. Energy, Inc. | | Oil & Gas Operator | Dec 1984 |
| 20823 | O.T. Oil | Kilgore, TX 75663 | Oil Operator | Jul 2025 |
| 20824 | Oahe Oil Company | Texline, TX 79087 | Oil & Gas Operator | May 2004 |
| 20825 | Oak Dale Drilling Co | Logan, OH 43138-1851 | Oil & Gas Operator | Dec 2015 |
| 20826 | Oak Energy, LLC | Houston, TX 77027 | Oil & Gas Operator | Jul 2025 |
| 20827 | Oak Grove Resources, LLC | | Gas Operator | Mar 2025 |
| 20828 | Oak Hill Petroleum Corporation | Oklahoma City, OK 73116-5627 | Oil & Gas Operator | Feb 2025 |
| 20829 | Oak Hills Drilling & Oper., LLC | Holdenville, OK 74848 | Oil & Gas Operator | May 2013 |
| 20830 | Oak Hills Energy Inc | Holdenville, OK 74848-0470 | Oil & Gas Operator | Sep 2014 |
| 20831 | Oak Prairie Operations, LLC | The Woodlands, TX 77381 | Oil & Gas Operator | Jul 2025 |
| 20832 | Oak Resources Inc | Tulsa, OK 74153 | Oil & Gas Operator | Aug 2013 |
| 20833 | Oak Ridge LLC | Wellsville, KS 66092 | Oil Operator | Dec 2019 |
| 20834 | Oak Tree Natural Res LLC | Oklahoma City, OK 73120-5065 | Oil & Gas Operator | Mar 2015 |
| 20835 | Oak Valley Operating, LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2015 |
| 20836 | Oak Valley SWD LLC | Enid, OK 73703-4637 | Oil Operator | Aug 2022 |
| 20837 | Oakes Gas Co Inc | Kane, PA 16735-3905 | Gas Operator | Dec 2023 |
| 20838 | Oakfield Energy LLC | | Oil Operator | Jun 2019 |
| 20839 | Oakland Corporation | | Oil & Gas Operator | Dec 1981 |
| 20840 | Oakland Petroleum Oper Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Jul 2025 |
| 20841 | Oakley Oil & Gas, L.L.C. | | Oil & Gas Operator | Mar 2012 |
| 20842 | Oakmont CC | Oakmont, PA 15139-1135 | Gas Operator | Dec 2024 |
| 20843 | Oakmont Oil And Gas | Graham, TX 76450 | Oil & Gas Operator | Jul 2025 |
| 20844 | Oakridge Energy, Inc. | Wichita Falls, TX 76302 | Oil & Gas Operator | Jul 2025 |
| 20845 | Oakridge Oil And Gas, LP | Jacksboro, TX 76458 | Oil & Gas Operator | Jul 2025 |
| 20846 | Oaks Petroleum I | | Oil Operator | Jul 1987 |
| 20847 | Oaktree Oil Company | Albany, TX 76430 | Oil & Gas Operator | Jul 2025 |
| 20848 | Oakwood Energy, Inc. | Jourdanton, TX 78026 | Oil & Gas Operator | Mar 2023 |
| 20849 | Oakwood Resources, Inc. | Dallas, TX 75374 | Oil & Gas Operator | May 1998 |
| 20850 | Oasis Energy Resources LLC | Norman, OK 73072-9668 | Oil & Gas Operator | Apr 2025 |
| 20851 | Oasis Operating, Inc. | Lubbock, TX 79404 | Oil & Gas Operator | Nov 2020 |
| 20852 | Oasis Petroleum North America LLC | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 20853 | Oasis Petroleum Permian LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 20854 | Oasis Production Co., Inc. | | Oil & Gas Operator | Jun 1988 |
| 20855 | Oast, Thomas H. | Greenville, NC 27835 | Oil Operator | Nov 1985 |
| 20856 | Oates, John Co., Inc. | Stinnett, TX 79083 | Oil & Gas Operator | Jul 2025 |
| 20857 | Obax Oil And Gas LLC | Saint Louis, MO 63131 | Oil Operator | Jul 2025 |
| 20858 | Obele Oil Corporation | Sedona, AZ 86336-5745 | Oil & Gas Operator | May 2017 |
| 20859 | Obele Operating Company LLC | Sedona, AZ 86336-5745 | Oil & Gas Operator | Apr 2025 |
| 20860 | Oberlander Leslie A Jake | Covington, OK 73730 | Oil Operator | Jun 2007 |
| 20861 | Obermiller Clarence Trust | Creston, OH 44217 | Oil & Gas Operator | Dec 1987 |
| 20862 | Obermiller Paul J | Creston, OH 44217 | Oil & Gas Operator | Dec 2014 |
| 20863 | Oblaen Resources LLC | Wallis, TX 77485 | Oil & Gas Operator | Jul 2025 |
| 20864 | Occ Operating Co. | | Oil & Gas Operator | Apr 2019 |
| 20865 | Occam Petroleum E&P, LLC | Meeker, OK 74855 | Oil Operator | Jul 2025 |
| 20866 | Occidental Energy Company, Inc. | Houston, TX 77282 | Oil & Gas Operator | Jul 2021 |
| 20867 | Occidental Energy Marketing, Inc. | Houston, TX 77227 | Gas Operator | Sep 2015 |
| 20868 | Occidental Of Elk Hills Inc. | | Oil & Gas Operator | Dec 2014 |
| 20869 | Occidental Permian LTD. | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 20870 | Occidental Petroleum Corporation | | Oil & Gas Operator | Dec 2021 |
| 20871 | Occidental W TX Overthrust, Inc. | Houston, TX 77210 | Oil & Gas Operator | Dec 2021 |
| 20872 | Ocean Energy Inc Ndba Devon Louisiana Corp | | Oil & Gas Operator | Jul 2001 |
| 20873 | Ocean Energy Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 20874 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 20875 | Ocfiw Oil Company, Inc. | Hartington, NE 68739 | Oil & Gas Operator | Dec 2009 |
| 20876 | Ochiltree Oil Company | Edmond, OK 73034 | Oil & Gas Operator | Apr 2020 |
| 20877 | Oci LLC | Thermopolis, WY 82443 | Oil Operator | Jan 2024 |
| 20878 | Octagon Resources Corporation | | Oil Operator | Apr 2005 |
| 20879 | Octagon Resources LLC | Norman, OK 73071-1295 | Oil & Gas Operator | May 2015 |
| 20880 | Octane Energy Operating, LLC | Midland, TX 79701 | Oil & Gas Operator | Jul 2025 |
| 20881 | Odebralski, Michael & Connie | Fredonia, NY 14063 | Gas Operator | Dec 2024 |
| 20882 | Odegard Energy, Inc. | Houston, TX 77024 | Oil & Gas Operator | Jul 2020 |
| 20883 | Odegard Resources/Omni Exp | Columbus, OH 43207 | Oil & Gas Operator | Sep 1986 |
| 20884 | Odell Larry | Oologah, OK 74053 | Oil Operator | Apr 2011 |
| 20885 | Oden, Robin H., Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 1994 |
| 20886 | Odessa Exploration, Inc. | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 20887 | Odessa Oil Investment Co., Inc. | Odessa, TX 79762 | Oil & Gas Operator | Nov 2016 |
| 20888 | Odom, Claude | | Oil Operator | Jul 1983 |
| 20889 | Odom, R. H. | Snyder, TX 79550 | Oil & Gas Operator | Jun 1996 |
| 20890 | Odom, Ralph R. | | Oil & Gas Operator | Aug 1993 |
| 20891 | Odum Oil & Gas Co. | Harper, TX 78631 | Oil & Gas Operator | Jul 2025 |
| 20892 | Odum Ronald L | Garfield, AR 72732 | Oil Operator | Apr 2025 |
| 20893 | Ody Oil Corp. | | Oil & Gas Operator | Oct 1994 |
| 20894 | Odyssey Operating Company | | Oil & Gas Operator | Sep 2020 |
| 20895 | Odyssey Petroleum Company | Houston, TX 77010 | Oil & Gas Operator | Apr 1995 |
| 20896 | Odyssey Petroleum Corp. | | Oil & Gas Operator | Jun 2011 |
| 20897 | Oedekoven Amerifields Resources LLC | Sugar Land, TX 77478 | Oil Operator | Apr 2025 |
| 20898 | Oedekoven Water & Hot Oil | Recluse, WY 82725 | Oil & Gas Operator | Jun 2025 |
| 20899 | Oeth DRLG Co | | Oil Operator | Dec 2018 |
| 20900 | Oex-1 LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Mar 2024 |