| 30101 | Unbridled Resources, LLC | Houston, TX 77002 | Oil & Gas Operator | Nov 2024 |
| 30102 | Unc Texas Incorp | | Gas Operator | May 1987 |
| 30103 | Underground Energy Inc. | | Oil & Gas Operator | Aug 2024 |
| 30104 | Underwood Oil & Gas | Casper, WY 82602 | Oil & Gas Operator | Sep 2024 |
| 30105 | Underwood Oil And Gas LLC | Chandler, OK 74834-1414 | Oil & Gas Operator | Sep 2024 |
| 30106 | Underwood, Donald D. Dba Mustang Oil Co | Salem, WV 26426 | Oil & Gas Operator | Dec 2020 |
| 30107 | Underwood, Jim | Graham, TX 76450 | Oil & Gas Operator | Mar 2018 |
| 30108 | Unger Well Drilling Corp | Dennison, OH 44621 | Oil & Gas Operator | Dec 1999 |
| 30109 | Uni Production Company, Inc. | | Oil & Gas Operator | Apr 1988 |
| 30110 | Unicon Producing Company | Houston, TX 75252 | Gas Operator | Mar 1994 |
| 30111 | Unicorn Drilling Inc | Cody, WY 82414 | Oil Operator | Dec 1998 |
| 30112 | Unicorn Energy, Inc. | Elgin, TX 78621 | Oil & Gas Operator | Nov 2024 |
| 30113 | Unicorn Oil & Gas Co Inc | Dorset, OH 44032 | Oil & Gas Operator | Dec 1993 |
| 30114 | Unifid Oil & Gas Corp. | | Oil & Gas Operator | Mar 1994 |
| 30115 | Unified Oil & Gas Corp. | Snyder, TX 79550 | Oil Operator | Nov 2024 |
| 30116 | Unioil | Denver, CO 80203 | Oil & Gas Operator | Jun 2012 |
| 30117 | Union Camp Corp | Dover, OH 44622 | Oil & Gas Operator | Dec 2002 |
| 30118 | Union City Boro Muni Auth Erie Cnty | Union City, PA 16438-1326 | Gas Operator | Dec 2023 |
| 30119 | Union Crude Company | Baytown, TX 77521 | Oil & Gas Operator | Apr 2018 |
| 30120 | Union Crude Operating Co. | Baytown, TX 77521 | Oil Operator | Aug 2003 |
| 30121 | Union Development Company Inc | | Oil & Gas Operator | Dec 1992 |
| 30122 | Union Diversified Investments, Inc. | | Gas Operator | Jun 2024 |
| 30123 | Union Diversified, Inc. | | Gas Operator | Dec 2008 |
| 30124 | Union Drilling &Management Inc | | Gas Operator | Feb 1991 |
| 30125 | Union Exploration Partners, LTD. | | Oil & Gas Operator | Aug 1990 |
| 30126 | Union Gas Operating Company | Houston, TX 77014 | Oil & Gas Operator | Nov 2024 |
| 30127 | Union Oil Co | Danville, OH 43014 | Oil & Gas Operator | Dec 2014 |
| 30128 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 30129 | Union Operating Corp | Lakewoord, CO 80215 | Oil Operator | Dec 2022 |
| 30130 | Union Pacific Austin Chalk Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 30131 | Union Pacific Re | | Oil & Gas Operator | Dec 1996 |
| 30132 | Union Pacific Resour | | Oil & Gas Operator | Apr 2002 |
| 30133 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 30134 | Union Petro Inc | Uniontown, KY 42461 | Oil Operator | Dec 2022 |
| 30135 | Union Petrochemical | | Oil & Gas Operator | Dec 1982 |
| 30136 | Union Producing Co. | | Gas Operator | Dec 1992 |
| 30137 | Union Resources Inc | | Oil & Gas Operator | Dec 1996 |
| 30138 | Union Royalty, Inc. | Midland, TX 79706 | Oil & Gas Operator | Jul 2014 |
| 30139 | Union Seaboard Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 30140 | Union Springs Central School District | Union Springs, NY 13160 | Gas Operator | Dec 2023 |
| 30141 | Union Texas Petroleum | Houston, TX 77252 | Oil & Gas Operator | Oct 1991 |
| 30142 | Union Texas Petroleum Corp. | Houston, TX 77252-2120 | Oil & Gas Operator | Dec 2014 |
| 30143 | Union Texas Products Corp | Houston, TX 77252 | Oil & Gas Operator | Nov 1994 |
| 30144 | Union Valley Petroleum Corporation | Enid, OK 73701 | Oil & Gas Operator | Sep 2024 |
| 30145 | Unionville Explo | | Oil Operator | Jul 1984 |
| 30146 | Unit Drilling & Exploration Co | Tulsa, OK 74132-5300 | Oil & Gas Operator | Aug 2024 |
| 30147 | Unit Manager, Citronelle Unit | | Oil & Gas Operator | Sep 2001 |
| 30148 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2024 |
| 30149 | United Company | Lubbock, TX 79408 | Oil & Gas Operator | Jun 1995 |
| 30150 | United Energy & Expl Inc | Ada, OK 74821-2449 | Oil & Gas Operator | Sep 2024 |
| 30151 | United Energy & Exploration LLC | Ada, OK 74821 | Oil & Gas Operator | Sep 2024 |
| 30152 | United Energy Corporation | San Antonio, TX 78209 | Oil & Gas Operator | Nov 2024 |
| 30153 | United Energy Develop Co LTD | Bartlesville, OK 74003 | Oil Operator | Mar 2004 |
| 30154 | United Energy Inc. | Wichita, KS 67230 | Oil & Gas Operator | Dec 2002 |
| 30155 | United Energy Operating, LLC | Edmond, OK 73083 | Oil & Gas Operator | Nov 2024 |
| 30156 | United Energy Partners, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2008 |
| 30157 | United Energy Trading LLC | Tulsa, OK 74133 | Gas Operator | Feb 2015 |
| 30158 | United Fuel Gas Co | | Oil & Gas Operator | Dec 2022 |
| 30159 | United Gas Pipe Line Co. | | Oil Operator | Aug 1993 |
| 30160 | United Investment Group | | Oil Operator | Nov 2004 |
| 30161 | United Meridian | | Oil Operator | Dec 1992 |
| 30162 | United Natural Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2020 |
| 30163 | United Natural Resources Corp | | Oil Operator | Jan 1986 |
| 30164 | United O&G/Atlee Miller | Millersburg, OH 44654 | Oil & Gas Operator | Dec 1985 |
| 30165 | United Oil & Gas | | Oil Operator | Feb 1988 |
| 30166 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 30167 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 30168 | United Oil Corporation | Denver, CO 80202-3813 | Oil & Gas Operator | Aug 2024 |
| 30169 | United Operating Co. | Olney, TX 76374 | Oil & Gas Operator | Aug 2003 |
| 30170 | United Operating, LLC *** | Midland, TX 79710 | Oil & Gas Operator | Nov 2024 |
| 30171 | United Operators, Inc. | | Oil Operator | Sep 1999 |
| 30172 | United Petro LTD. | | Oil & Gas Operator | Dec 2018 |
| 30173 | United Petroleum | | Oil Operator | Mar 1986 |
| 30174 | United Petroleum & Gas, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Nov 2024 |
| 30175 | United Petroleum Corporation | Edgwater, CO 80214 | Oil & Gas Operator | May 1996 |
| 30176 | United Petroleum Technologies | Hondo, TX 78861 | Oil & Gas Operator | Aug 2001 |
| 30177 | United Primary Resources Inc | Milton, WA 98354-9361 | Oil & Gas Operator | Feb 2016 |
| 30178 | United Producers Inc | Broken Arrow, OK 74012-8247 | Oil & Gas Operator | Mar 2020 |
| 30179 | United Producing Co Inc | | Oil & Gas Operator | May 1961 |
| 30180 | United Production Company LLC | Edmond, OK 73003 | Oil & Gas Operator | Sep 2024 |
| 30181 | United Reserve G | | Oil Operator | Aug 1987 |
| 30182 | United Resources Corp | Olean, NY 14760 | Oil & Gas Operator | Dec 2020 |
| 30183 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 30184 | United Resources LP A Texas LMTD PRNTSHP | Austin, TX 78746 | Oil & Gas Operator | Sep 2003 |
| 30185 | United Security Associates Inc | | Oil & Gas Operator | Dec 2020 |
| 30186 | United Southern Resources Inc. | | Gas Operator | Nov 2013 |
| 30187 | United States Energy Corp. | Longview, TX 75601 | Oil & Gas Operator | Jun 2024 |
| 30188 | United States Exploration, Inc. | Denver, CO 80802 | Oil & Gas Operator | Jun 2009 |
| 30189 | United States Gypsum Co | Oakfield, NY 14125 | Oil & Gas Operator | Dec 2023 |
| 30190 | United States Trading & Trans | Dallas, TX 75380-3342 | Oil & Gas Operator | Dec 1994 |
| 30191 | United Texas Oil LLC | Houston, TX 77027 | Oil & Gas Operator | Nov 2024 |
| 30192 | United Texas Petroleum Inc. | McKinney, TX 75070 | Oil & Gas Operator | Nov 2024 |
| 30193 | United Utilities Corp | Conroe, TX 77301 | Oil & Gas Operator | Oct 1998 |
| 30194 | United Well Completion, Inc | Corbin, KY 40701 | Oil & Gas Operator | Dec 2022 |
| 30195 | United World Energy Corporation | | Oil & Gas Operator | Jun 2024 |
| 30196 | United World Energy, Inc. | Aurora, CO 80040 | Oil & Gas Operator | Nov 2024 |
| 30197 | Unitex Oil & Gas, L.L.C. | Midland, TX 79701 | Oil & Gas Operator | Nov 2024 |
| 30198 | Unity Petroleum | Howard, OH 43028 | Oil & Gas Operator | Dec 2021 |
| 30199 | Universal Cyclops Specialty Steel Div | Pittsburgh, PA 15228-2702 | Gas Operator | Dec 1985 |
| 30200 | Universal Drilling Co., Inc. | Denver, CO 80203 | Oil & Gas Operator | Sep 2003 |