| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | Oasis Production Co., Inc. | Oil & Gas Operator | Jun 1988 | |
| 2 | Oil & Gas Development Company | Oil & Gas Operator | May 1991 | |
| 3 | Oil & Gas Property MGMT., Inc. | Dallas, TX 75201 | Oil & Gas Operator | Jul 1996 |
| 4 | Oil Recovery, Inc. | Oil Operator | Sep 1992 | |
| 5 | Oldfield Operating Corporation | Oil Operator | Dec 2013 | |
| 6 | Oleum Incorporated | Oil & Gas Operator | Mar 1996 | |
| 7 | Oleum Operating La LLC | Oil & Gas Operator | Nov 2022 | |
| 8 | Olipdp II, LLC | Lafayette, LA 70503 | Oil & Gas Operator | Oct 2025 |
| 9 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | Oct 2025 |
| 10 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |