| 1 | O'Donnell Bill C | Tulsa, OK 74135-4241 | Oil & Gas Operator | Oct 2014 |
| 2 | O'Neal Oil & Gas Co | Fort Worth, TX 76107-1479 | Oil & Gas Operator | Feb 2024 |
| 3 | Oak Hill Petroleum Corporation | Oklahoma City, OK 73116-5627 | Oil & Gas Operator | Jan 2024 |
| 4 | Oakland Petroleum Oper Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2024 |
| 5 | Octagon Resources LLC | Norman, OK 73071-1295 | Oil & Gas Operator | May 2015 |
| 6 | Oil & Gas Exploration Inc | Cleveland, OK 74020 | Oil & Gas Operator | Aug 2013 |
| 7 | Oil Center Operating Inc | Fort Worth, TX 76102-5108 | Oil & Gas Operator | Apr 2014 |
| 8 | Oil Pool Inc | Tulsa, OK 74132-2659 | Oil & Gas Operator | Jan 2024 |
| 9 | Oil Recovery Systems Inc | | Oil & Gas Operator | Jan 2024 |
| 10 | Oil State Petroleum Inc | Jennings, OK 74038 | Oil & Gas Operator | Jan 2024 |
| 11 | Oilco Energy Inc | Duncan, OK 73533 | Oil & Gas Operator | Mar 2015 |
| 12 | Oilfield Operating Company | Cushing, OK 74023-1347 | Oil & Gas Operator | Jan 2018 |
| 13 | Oilton Petroleum Inc | Oilton, OK 74052-0459 | Oil & Gas Operator | Oct 2001 |
| 14 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2024 |
| 15 | Okla Petroleum Reclaimers Inc | Kellyville, OK 74039 | Oil Operator | Jul 2020 |
| 16 | Oklahoma Crude Inc | Broken Arrow, OK 74012 | Oil & Gas Operator | Dec 2023 |
| 17 | Oklahoma Energy Development Co | | Oil & Gas Operator | Sep 2008 |
| 18 | Oklahoma Gas & Oil Corporation | Okemah, OK 74859 | Oil Operator | Oct 2018 |
| 19 | Oklahoma Liquid Resources Inc | Owasso, OK 74055-0841 | Oil & Gas Operator | Jan 2024 |
| 20 | Oklahoma Natural Resources Inc | Woodward, OK 73801 | Oil & Gas Operator | Sep 1996 |
| 21 | Oklahoma Oil & Gas MGMT Inc | | Oil & Gas Operator | Jan 2024 |
| 22 | Oklahoma Petroleum Allies LLC | Ardmore, OK 73401 | Oil Operator | Oct 2023 |
| 23 | Oklahoma Petroleum MGMT Corp | Tulsa, OK 74119 | Oil & Gas Operator | Jun 1993 |
| 24 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 25 | Olive Oil & Gas Inc | Oilton, OK 74052-0178 | Oil & Gas Operator | Nov 2023 |
| 26 | Onpoint Oil & Gas LLC | | Oil & Gas Operator | Jan 2024 |
| 27 | Orason Resources Inc | Tulsa, OK 74169-1225 | Oil & Gas Operator | Nov 2006 |
| 28 | Osage Energy Resources LLC | Bartlesville, OK 74005-2527 | Oil & Gas Operator | Jan 2024 |
| 29 | Osage Oil & Transportation Inc | Cleveland, OK 74020 | Oil & Gas Operator | Nov 2000 |
| 30 | Osburn Gerald Dba Ozzy & Son Oil & Gas | Drumright, OK 74030-5467 | Oil Operator | Oct 2020 |
| 31 | Osterhout Phillip L | Drumright, OK 74030-0693 | Oil & Gas Operator | Jan 2014 |
| 32 | Overflow Energy, LLC | Booker, TX 79005 | Oil & Gas Operator | Apr 2024 |
| 33 | Owens James W | Tulsa, OK 74114-1425 | Oil & Gas Operator | Oct 2022 |