| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | Ultramar Oil & Gas LTD | Houston, TX 77060 | Oil & Gas Operator | Jul 1995 |
| 2 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 3 | Union Producing Co. | Gas Operator | Dec 1992 | |
| 4 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2025 |
| 5 | Unocal Explor. Corp. | Oil & Gas Operator | Nov 1990 |