| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | U.S. Exploration Company | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 2 | Union Gas Operating Company | Houston, TX 77014 | Oil & Gas Operator | Oct 2025 |
| 3 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 4 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 5 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Oct 2025 |
| 6 | Unknown | Houston, TX 77208 | Oil & Gas Operator | Dec 2023 |