| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | Ultramar Oil & Gas LTD | Houston, TX 77060 | Oil & Gas Operator | Jul 1995 |
| 2 | Underwood, Rip C | Amarillo, TX 79101 | Gas Operator | Sep 1963 |
| 3 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 4 | Union Texas Petroleum | Houston, TX 77252 | Oil & Gas Operator | Oct 1991 |
| 5 | United Energy Corporation | San Antonio, TX 78209 | Oil & Gas Operator | Mar 2025 |
| 6 | Urban, C A & Tersell L W | Gas Operator | Aug 1937 | |
| 7 | Utah Gas Op LTD | Rangely, CO 81648 | Oil & Gas Operator | Jan 2025 |
| 8 | Utex Oil Company | Elko, NV 89803 | Oil & Gas Operator | Dec 1988 |