| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | O'Hare Energy Co | Oil Operator | Dec 1983 | |
| 2 | Oil Internationa | Oil Operator | Jun 1986 | |
| 3 | Oil Producers In | Oil & Gas Operator | Dec 1996 | |
| 4 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Oct 2025 |
| 5 | Oil Property Man | Oil & Gas Operator | Jun 1995 | |
| 6 | Oil-Tech Prod Co | Oil & Gas Operator | Oct 1992 | |
| 7 | Okmar Oil Compan | Oil & Gas Operator | Feb 1995 | |
| 8 | Osborn Heirs Company LTD | San Antonio, TX 78217 | Oil & Gas Operator | Jun 2025 |
| 9 | Osborn Oil & Gas | Oil & Gas Operator | Jun 1991 | |
| 10 | Owen'S Pumping Service | Oil Operator | Jun 2025 | |
| 11 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |