| 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 | Jul 2025 |
| 3 | O7 Saltwater Disposal LLC | Marietta, OK 73448 | Oil Operator | Jun 2025 |
| 4 | Oak Hill Petroleum Corporation | Oklahoma City, OK 73116-5627 | Oil & Gas Operator | Jul 2025 |
| 5 | Oakland Petroleum Oper Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Sep 2025 |
| 6 | Octagon Resources LLC | Norman, OK 73071-1295 | Oil & Gas Operator | May 2015 |
| 7 | Oil & Gas Exploration Inc | Cleveland, OK 74020 | Oil & Gas Operator | Aug 2013 |
| 8 | Oil Center Operating Inc | Fort Worth, TX 76102-5108 | Oil & Gas Operator | Apr 2014 |
| 9 | Oil Pool Inc | Tulsa, OK 74132-2659 | Oil & Gas Operator | Jun 2025 |
| 10 | Oil Recovery Systems Inc | Tulsa, OK 74145-4619 | Oil & Gas Operator | Jun 2025 |
| 11 | Oil State Petroleum Inc | Jennings, OK 74038 | Oil & Gas Operator | Jun 2025 |
| 12 | Oilco Energy Inc | Duncan, OK 73533 | Oil & Gas Operator | Mar 2015 |
| 13 | Oilfield Operating Company | Cushing, OK 74023-1347 | Oil & Gas Operator | Jan 2018 |
| 14 | Oilton Petroleum Inc | Oilton, OK 74052-0459 | Oil & Gas Operator | Oct 2001 |
| 15 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2025 |
| 16 | Okie Oil Inc | Sapulpa, OK 74067-0290 | Oil & Gas Operator | Mar 2011 |
| 17 | Oklahoma Crude Inc | Morris, OK 74445 | Oil & Gas Operator | Apr 2024 |
| 18 | Oklahoma Gas & Oil Corp | | Oil Operator | Oct 2018 |
| 19 | Oklahoma Liquid Resources Inc | Collinsville, OK 74021 | Oil & Gas Operator | Jun 2025 |
| 20 | Oklahoma Natural Resources Inc | Woodward, OK 73801 | Oil & Gas Operator | Sep 1996 |
| 21 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Jun 2025 |
| 22 | Oklahoma Petroleum MGMT Corp | Tulsa, OK 74119 | Oil & Gas Operator | Jun 1993 |
| 23 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 24 | Olive Oil & Gas Inc | Jennings, OK 74052 | Oil & Gas Operator | Jun 2025 |
| 25 | Onpoint Oil & Gas LLC | Oklahoma City, OK 73170-4848 | Oil & Gas Operator | Jun 2025 |
| 26 | Orason Resources Inc | Tulsa, OK 74169-1225 | Oil & Gas Operator | Nov 2006 |
| 27 | Osage Energy Resources LLC | Bartlesville, OK 74005-2527 | Oil & Gas Operator | Jun 2025 |
| 28 | Osage Oil & Transportation Inc | Cleveland, OK 74020 | Oil & Gas Operator | Nov 2000 |
| 29 | Osburn Gerald Dba Ozzy & Son Oil & Gas | Drumright, OK 74030-5467 | Oil Operator | Oct 2020 |
| 30 | Osterhout Phillip L | Drumright, OK 74030-0693 | Oil & Gas Operator | Jan 2014 |
| 31 | Overflow Energy, LLC | Perryton, TX 79070 | Oil & Gas Operator | Sep 2025 |
| 32 | Owens James W | Tulsa, OK 74114-1425 | Oil & Gas Operator | Oct 2022 |