| 1 | U. S. Operating, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Dec 2024 |
| 2 | Union Gas Operating Company | Houston, TX 77014 | Oil & Gas Operator | Dec 2024 |
| 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 | United Energy Partners, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2008 |
| 6 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 7 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 8 | United Operating, LLC *** | Midland, TX 79710 | Oil & Gas Operator | Dec 2024 |
| 9 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 10 | United Texas Petroleum Inc. | McKinney, TX 75070 | Oil & Gas Operator | Dec 2024 |
| 11 | Universal Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2002 |
| 12 | Unoso Operating Company L.L.C. | Georgetown, TX 78633 | Oil & Gas Operator | Dec 2024 |