| 201 | Uptex Operating, L.P. | Dallas, TX 75201 | Oil & Gas Operator | May 2010 |
| 202 | Upton Resources U.S.A. Inc. | | Oil & Gas Operator | Oct 2013 |
| 203 | Uranus, Inc. | Kansas City, MO 64112 | Oil Operator | Jan 2000 |
| 204 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Feb 2026 |
| 205 | Urban, C A & Tersell L W | | Gas Operator | Aug 1937 |
| 206 | Urroz Oil & Gas LLC | Evanston, WY 82931 | Oil & Gas Operator | Jun 2020 |
| 207 | Ursa Major (Crow Og), LLC | Billings, MT 59101 | Gas Operator | Aug 2017 |
| 208 | Ursa Operating Company LLC | Denver, CO 80265 | Oil & Gas Operator | Feb 2014 |
| 209 | Ursus Oil And Gas | Tyler, TX 75703 | Oil & Gas Operator | Feb 2026 |
| 210 | Us Ecology Winnie, LLC | Winnie, TX 77665 | Oil Operator | Feb 2026 |
| 211 | Us Energy Corp. | Houston, TX 77057 | Oil & Gas Operator | Dec 2021 |
| 212 | Us Energy Dev Corp | Getzville, NY 14068-1558 | Oil & Gas Operator | Dec 2021 |
| 213 | Us Energy Exploration Corp | Rural Valley, PA 16249 | Oil & Gas Operator | Dec 2025 |
| 214 | Us Energy Holdings, LLC | Richardson, TX 75080 | Oil & Gas Operator | Feb 2026 |
| 215 | Us Energy Oh LLC | Rural Valley, PA 16249 | Oil & Gas Operator | Dec 2024 |
| 216 | Us Gypsum Co | Oakfield, NY 14125-9722 | Gas Operator | Dec 2005 |
| 217 | Us Liquids Of La, LTD | | Oil Operator | Jul 2002 |
| 218 | Us Navy | | Gas Operator | Apr 1950 |
| 219 | Us Oil & Gas Inc | Marietta, OH 45750 | Oil & Gas Operator | Jan 2026 |
| 220 | Us Oil Resources LLC | Lakewood, CO 80123 | Oil Operator | Sep 2025 |
| 221 | Us Ore Corporation | Pacific Beach, CA 92109 | Oil Operator | Feb 2014 |
| 222 | Us Petro LP | Amarillo, TX 79106 | Oil & Gas Operator | Apr 2020 |
| 223 | Us. Fuels, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Feb 2026 |
| 224 | USA Energy LLC | Lance Creek, WY 82222 | Oil & Gas Operator | Nov 2024 |
| 225 | USA Exploration & Production LLC | Mills, WY 82644 | Oil & Gas Operator | Sep 2012 |
| 226 | USA Superior Energy LLC | Houston, TX 77077 | Oil Operator | Mar 2010 |
| 227 | USA Tubulars, Inc. | Valley Spring, TX 76885 | Oil & Gas Operator | Dec 1995 |
| 228 | Uscan Oil Inc | Oil City, PA 16301-1412 | Oil & Gas Operator | Dec 1991 |
| 229 | Usedc Okc LLC | Getzville, NY 14068-1296 | Oil & Gas Operator | May 2018 |
| 230 | Usfg Oil & Gas, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Dec 2005 |
| 231 | Usins Oil Compan | | Oil Operator | Jan 1993 |
| 232 | Usoil Corporation | | Oil & Gas Operator | Nov 1998 |
| 233 | Usx Operating Co., Inc. | Barnstall, OK 74002 | Oil & Gas Operator | Apr 2017 |
| 234 | Utah Gas Op LTD | Rangely, CO 81648 | Oil & Gas Operator | Dec 2025 |
| 235 | Utah Gas Operating Solutions, LLC | Minneapolis, MN 55402 | Gas Operator | Jan 2026 |
| 236 | Utah Oil LLC | Rantoul, KS 66079 | Oil Operator | Sep 2025 |
| 237 | Utah-Westar DRL Ventures | Dallas, TX 75201 | Oil & Gas Operator | Nov 1987 |
| 238 | Ute Energy Upstream Holdings LLC | Denver, CO 80202 | Oil & Gas Operator | Dec 2012 |
| 239 | Utex Oil Company | Elko, NV 89803 | Oil & Gas Operator | Dec 1988 |
| 240 | Utica Resource Operating LLC | Marietta, OH 45750 | Oil & Gas Operator | Sep 2023 |
| 241 | Utility Ventures Company | Pasadena, TX 77504 | Oil & Gas Operator | Feb 2026 |
| 242 | Utoco, LTD. | Midland, TX 79704 | Oil Operator | Feb 2026 |
| 243 | Uvalde Energy Co. | Austin, TX 78747 | Oil & Gas Operator | Nov 1994 |