| 1 | Uhc Petroleum Corporation | Rocksprings, TX 78880 | Oil & Gas Operator | Dec 2024 |
| 2 | Ultra Petroleum (U.S.A.), Inc. | Granbury, TX 76048 | Oil & Gas Operator | Sep 2003 |
| 3 | Ultra Resources Inc | Houston, TX 77060 | Oil & Gas Operator | Sep 2018 |
| 4 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 5 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 6 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 7 | Union Seaboard Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 8 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Dec 2024 |
| 9 | United Company | Lubbock, TX 79408 | Oil & Gas Operator | Jun 1995 |
| 10 | United Energy Trading LLC | Tulsa, OK 74133 | Gas Operator | Feb 2015 |
| 11 | United Operating, LLC *** | Midland, TX 79710 | Oil & Gas Operator | Dec 2024 |
| 12 | Unitex Oil & Gas, L.L.C. | Midland, TX 79701 | Oil & Gas Operator | Dec 2024 |
| 13 | Uptex Operating Inc. | Dallas, TX 75201 | Oil & Gas Operator | May 2011 |
| 14 | Uptex Operating, L.P. | Dallas, TX 75201 | Oil & Gas Operator | May 2010 |
| 15 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Dec 2024 |