| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | O'Brien Operating Company | Shreveport, LA 71164 | Oil & Gas Operator | Dec 2004 |
| 2 | O. B. Mobley | Oil & Gas Operator | Jul 1989 | |
| 3 | Oakfield Energy LLC | Oil Operator | Jun 2019 | |
| 4 | Occidental Energy Company, Inc. | Houston, TX 77282 | Oil & Gas Operator | Jul 2021 |
| 5 | Ocean Energy Inc | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 6 | Onshore Pipeline Const Co Inc | Oil & Gas Operator | Aug 1998 | |
| 7 | Osr Oil & Gas Corp | Midland, TX 79710 | Oil & Gas Operator | Dec 2024 |
| 8 | Ouida Oil Co. | Oil & Gas Operator | Apr 1999 | |
| 9 | Owl Creek Production Co., Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2006 |
| 10 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 11 | Ozark Production Company, Inc. | Oil & Gas Operator | Jan 2025 |