| 1 | U S Energy Corp | Houston, TX 77057 | Oil & Gas Operator | Dec 2021 |
| 2 | Ullum Oil And Gas Development Corporation, Inc. | Grantsville, WV 26147-0000 | Oil & Gas Operator | Dec 2021 |
| 3 | Ultra Production Company, LLC | Cedar Bluff, VA 24609 | Gas Operator | Oct 2014 |
| 4 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 5 | Underwood, Donald D. Dba Mustang Oil Co | Salem, WV 26426 | Oil & Gas Operator | Dec 2020 |
| 6 | Union Gas Corp. (Union Gas Co.) | Charleston, WV 25338-0000 | Oil & Gas Operator | Aug 2021 |
| 7 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 8 | United Operating Co. | Olney, TX 76374 | Oil & Gas Operator | Aug 2003 |
| 9 | United Petro LTD. | | Oil & Gas Operator | Dec 2018 |
| 10 | Upland Resources, Inc. | Canadian, TX 79014 | Oil & Gas Operator | Dec 2009 |