| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | O'Brien Energy Company | Shreveport, LA 71136 | Oil & Gas Operator | Sep 2019 |
| 2 | O'Brien Operating Company | Oil & Gas Operator | Dec 2004 | |
| 3 | O. B. Mobley | Oil & Gas Operator | Jul 1989 | |
| 4 | O. G., Inc. | Oil & Gas Operator | Nov 1992 | |
| 5 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 6 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2024 |
| 7 | Oracle Oil, LLC | Oil & Gas Operator | Jul 2013 | |
| 8 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 9 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | May 2024 |
| 10 | Ozark Production Company, Inc. | Oil & Gas Operator | Jan 2024 |