| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | O'Brien Operating Company | Oil & Gas Operator | Dec 2004 | |
| 2 | O'Malley Production Co. Inc. | Oil & Gas Operator | Apr 1988 | |
| 3 | Oakland Corporation | Shreveport, LA 71135 | Oil & Gas Operator | Dec 1981 |
| 4 | Offshore Shelf LLC | Oil & Gas Operator | Dec 2007 | |
| 5 | Oil Palace, Inc. | Oil Operator | May 2016 | |
| 6 | Oilwell Acquisition Co. | Oil & Gas Operator | Jun 1999 | |
| 7 | Omeara Bros. | Oil & Gas Operator | Oct 1982 | |
| 8 | Osr Oil & Gas Corp | Midland, TX 79710 | Oil & Gas Operator | Dec 2023 |
| 9 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Apr 2024 |