| 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 | Shreveport, LA 71164 | Oil & Gas Operator | Dec 2004 |
| 3 | O. G., Inc. | Oil & Gas Operator | Nov 1992 | |
| 4 | Occ Operating Co. | Oil & Gas Operator | Apr 2019 | |
| 5 | Onshore Pipeline Const Co Inc | Oil & Gas Operator | Aug 1998 | |
| 6 | Orx Resources, L.L.C. | Houston, TX 77067 | Oil & Gas Operator | Oct 2025 |
| 7 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 8 | Otis C. Coles, Jr. | Oil & Gas Operator | Jan 1998 | |
| 9 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |
| 10 | Ozark Production Company, Inc. | Oil & Gas Operator | Jan 2025 |