| 31001 | United Production Company LLC | Edmond, OK 73003 | Oil & Gas Operator | Feb 2025 |
| 31002 | United Reserve G | | Oil Operator | Aug 1987 |
| 31003 | United Resources Corp | Olean, NY 14760 | Oil & Gas Operator | Dec 2020 |
| 31004 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 31005 | United Resources LP A Texas LMTD PRNTSHP | Austin, TX 78746 | Oil & Gas Operator | Sep 2003 |
| 31006 | United Security Associates Inc | | Oil & Gas Operator | Dec 2020 |
| 31007 | United Southern Resources Inc. | | Gas Operator | Nov 2013 |
| 31008 | United States Energy Corp. | Longview, TX 75601 | Oil & Gas Operator | Oct 2024 |
| 31009 | United States Exploration, Inc. | Denver, CO 80802 | Oil & Gas Operator | Jun 2009 |
| 31010 | United States Gypsum Company | Oakfield, NY 14125 | Oil & Gas Operator | Dec 2023 |
| 31011 | United States Trading & Trans | Dallas, TX 75380-3342 | Oil & Gas Operator | Dec 1994 |
| 31012 | United Texas Oil LLC | Houston, TX 77027 | Oil & Gas Operator | Apr 2025 |
| 31013 | United Texas Petroleum Inc. | McKinney, TX 75070 | Oil & Gas Operator | Apr 2025 |
| 31014 | United Utilities Corp | Conroe, TX 77301 | Oil & Gas Operator | Oct 1998 |
| 31015 | United Well Completion, Inc | Corbin, KY 40701 | Oil & Gas Operator | Dec 2023 |
| 31016 | United Western Energy Corp | Oklahoma City, OK 73105 | Oil & Gas Operator | Mar 1994 |
| 31017 | United World Energy Corporation | | Oil & Gas Operator | Dec 2024 |
| 31018 | United World Energy, Inc. | Aurora, CO 80040 | Oil & Gas Operator | Apr 2025 |
| 31019 | Unitex Oil & Gas, L.L.C. | Midland, TX 79701 | Oil & Gas Operator | Apr 2025 |
| 31020 | Unity Petroleum | Howard, OH 43028 | Oil & Gas Operator | Dec 2021 |
| 31021 | Universal Cyclops Specialty Steel Div | Pittsburgh, PA 15228-2702 | Gas Operator | Dec 1985 |
| 31022 | Universal Drilling Co., Inc. | Denver, CO 80203 | Oil & Gas Operator | Sep 2003 |
| 31023 | Universal Exploration Inc | Wadsworth, OH 44281-9460-9460 | Oil & Gas Operator | Feb 2012 |
| 31024 | Universal Fuels Company | | Oil & Gas Operator | Oct 1993 |
| 31025 | Universal Geopower LLC | Houston, TX 77057 | Oil & Gas Operator | May 2016 |
| 31026 | Universal Land | | Oil Operator | Dec 2024 |
| 31027 | Universal Oil Co. | | Oil Operator | Jan 2025 |
| 31028 | Universal Operating, Inc | Evansville, IN 47715 | Oil & Gas Operator | Dec 2023 |
| 31029 | Universal Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2002 |
| 31030 | Universal Producers, Inc. | | Oil Operator | Jun 2001 |
| 31031 | Universal Resour | | Oil & Gas Operator | Dec 1996 |
| 31032 | Universal Resources Corp. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jan 2000 |
| 31033 | Universal Resources Holdings Inc | Dunkirk, NY 14048 | Oil & Gas Operator | Dec 2023 |
| 31034 | University Field Management LLC | | Oil Operator | Nov 2024 |
| 31035 | Unknown | Houston, TX 77208 | Oil & Gas Operator | Dec 2023 |
| 31036 | Unknown Owner | Columbus, OH 43229 | Oil & Gas Operator | Dec 2008 |
| 31037 | Unocal Explor. Corp. | | Oil & Gas Operator | Nov 1990 |
| 31038 | Unocal Exploration Corporation | | Oil & Gas Operator | May 1992 |
| 31039 | Unoso Operating Company L.L.C. | Georgetown, TX 78633 | Oil & Gas Operator | Apr 2025 |
| 31040 | Unrein Oil Co | | Oil Operator | Dec 2024 |
| 31041 | Unruh, Elmer | Galva, KS 67443 | Oil & Gas Operator | Aug 1998 |
| 31042 | Unruh, Mark D. | Peru, KS 67360 | Oil Operator | Sep 2011 |
| 31043 | Unswept Oil Company | Corsicana, TX 75151 | Oil & Gas Operator | Jan 2018 |
| 31044 | Untamed Resources, LLC | Spearman, TX 79081 | Gas Operator | Apr 2025 |
| 31045 | Untener Bishop Kenneth (Diocese Of Saginaw) | | Oil Operator | Dec 2024 |
| 31046 | Uosi Operating, Inc. | Lovelady, TX 75851 | Oil & Gas Operator | Apr 2025 |
| 31047 | Upco | Mineral Wells, TX 76068 | Gas Operator | Sep 2001 |
| 31048 | Upcurve Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Apr 2025 |
| 31049 | Upda Operators, Inc. | Jacksboro, TX 76458 | Oil & Gas Operator | Dec 2009 |
| 31050 | Updike Resources Inc | Newcastle, WY 82701 | Oil & Gas Operator | Jun 1998 |
| 31051 | Upham Oil & Gas Company | Mineral Wells, TX 76068 | Oil & Gas Operator | Apr 2025 |
| 31052 | Upham, Chester R., Jr. | Mineral Wells, TX 76067 | Oil & Gas Operator | Aug 2001 |
| 31053 | Uphill Consulting LLC | Pearland, TX 77584 | Oil & Gas Operator | Apr 2025 |
| 31054 | Upland Exploration, LLC | Boerne, TX 78006 | Oil & Gas Operator | Jul 2024 |
| 31055 | Upland Operating, LLC | Dallas, TX 75226 | Oil & Gas Operator | Apr 2025 |
| 31056 | Upland Production Company | Edmond, OK 73083 | Oil & Gas Operator | Apr 2025 |
| 31057 | Upland Resources | | Oil Operator | Jul 1983 |
| 31058 | Upland Resources LLC | Canadian, TX 79014 | Oil & Gas Operator | Apr 2025 |
| 31059 | Upland Resources, Inc. | Canadian, TX 79014 | Oil & Gas Operator | Dec 2009 |
| 31060 | Uplands Resources Inc | Tulsa, OK 74103-4141 | Oil & Gas Operator | Jan 2025 |
| 31061 | Uplift Production Company, Inc. | Shamrock, TX 79079 | Oil & Gas Operator | Feb 1999 |
| 31062 | Upp Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 31063 | Upstream Exploration LLC | Metairie, LA 70002 | Oil & Gas Operator | Jan 2020 |
| 31064 | Upstream Properties, LLC | Southlake, TX 76092 | Oil & Gas Operator | Apr 2025 |
| 31065 | Upstream Resource Partners, LLC | Palestine, TX 75803 | Oil Operator | Apr 2025 |
| 31066 | Uptex Operating Inc. | Dallas, TX 75201 | Oil & Gas Operator | May 2011 |
| 31067 | Uptex Operating, L.P. | Dallas, TX 75201 | Oil & Gas Operator | May 2010 |
| 31068 | Upton Resources U.S.A. Inc. | | Oil & Gas Operator | Oct 2013 |
| 31069 | Uranus, Inc. | Kansas City, MO 64112 | Oil Operator | Jan 2000 |
| 31070 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Apr 2025 |
| 31071 | Urban, C A & Tersell L W | | Gas Operator | Aug 1937 |
| 31072 | Urroz Oil & Gas LLC | Evanston, WY 82931 | Oil & Gas Operator | Jun 2020 |
| 31073 | Ursa Major (Crow Og), LLC | Billings, MT 59101 | Gas Operator | Aug 2017 |
| 31074 | Ursa Operating Company LLC | Denver, CO 80265 | Oil & Gas Operator | Dec 2020 |
| 31075 | Ursus Oil And Gas | Tyler, TX 75703 | Oil & Gas Operator | Apr 2025 |
| 31076 | Us Ecology Winnie, LLC | Winnie, TX 77665 | Oil Operator | Apr 2025 |
| 31077 | Us Energy Dev Corp | Getzville, NY 14068-1558 | Oil & Gas Operator | Dec 2021 |
| 31078 | Us Energy Exploration Corp | Rural Valley, PA 16249 | Oil & Gas Operator | Dec 2024 |
| 31079 | Us Energy Holdings, LLC | Richardson, TX 75080 | Oil & Gas Operator | Apr 2025 |
| 31080 | Us Energy Oh LLC | Rural Valley, PA 16249 | Oil & Gas Operator | Dec 2023 |
| 31081 | Us Gypsum Co | Oakfield, NY 14125-9722 | Gas Operator | Dec 2005 |
| 31082 | Us Liquids Of La, LTD | | Oil Operator | Jul 2002 |
| 31083 | Us Oil & Gas Inc | Marietta, OH 45750 | Oil & Gas Operator | Feb 2025 |
| 31084 | Us Oil Resources LLC | Lakewood, CO 80123 | Oil Operator | Dec 2024 |
| 31085 | Us Ore Corporation | Pacific Beach, CA 92109 | Oil Operator | Feb 2014 |
| 31086 | Us Petro LP | Amarillo, TX 79106 | Oil & Gas Operator | Apr 2020 |
| 31087 | Us. Fuels, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Apr 2025 |
| 31088 | USA Energy LLC | Lance Creek, WY 82222 | Oil & Gas Operator | Nov 2024 |
| 31089 | USA Exploration & Production LLC | Mills, WY 82644 | Oil & Gas Operator | Sep 2012 |
| 31090 | USA Superior Energy LLC | Houston, TX 77077 | Oil Operator | Mar 2010 |
| 31091 | USA Tubulars, Inc. | Valley Spring, TX 76885 | Oil & Gas Operator | Dec 1995 |
| 31092 | Uscan Oil Inc | Oil City, PA 16301-1412 | Oil & Gas Operator | Dec 1991 |
| 31093 | Usedc Okc LLC | Getzville, NY 14068-1296 | Oil & Gas Operator | May 2018 |
| 31094 | Usfg Oil & Gas, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Dec 2005 |
| 31095 | Usins Oil Compan | | Oil Operator | Jan 1993 |
| 31096 | Usoil Corporation | | Oil & Gas Operator | Nov 1998 |
| 31097 | Usx Operating Co., Inc. | Barnstall, OK 74002 | Oil & Gas Operator | Apr 2017 |
| 31098 | Utah Gas Op LTD | Rangely, CO 81648 | Oil & Gas Operator | Feb 2025 |
| 31099 | Utah Oil LLC | Rantoul, KS 66079 | Oil Operator | Dec 2024 |
| 31100 | Utah-Westar DRL Ventures | Dallas, TX 75201 | Oil & Gas Operator | Nov 1987 |