| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | Oil Producers In | Oil & Gas Operator | Dec 1996 | |
| 2 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Mar 2025 |
| 3 | Oil Property Man | Oil & Gas Operator | Jun 1995 | |
| 4 | Oneok Energy Service | Gas Operator | Dec 2008 | |
| 5 | Oneok Exploratio | Oil & Gas Operator | Mar 1995 | |
| 6 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 7 | Osborn Heirs Company LTD | San Antonio, TX 78217 | Oil & Gas Operator | Nov 2024 |
| 8 | Outback Oil, Inc. | Pratt, KS 67124 | Gas Operator | Sep 2019 |
| 9 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Mar 2025 |