| 30601 | Umberham Oil Company Inc | Oklahoma City, OK 73151-4000 | Oil & Gas Operator | Oct 2025 |
| 30602 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 30603 | Umma Resources, LLC | Portland, TX 78374 | Gas Operator | Dec 2025 |
| 30604 | Ummel'S Tank Ser | | Oil Operator | Sep 1994 |
| 30605 | Unbridled Resources, LLC | Oklahoma City, OK 73102 | Oil & Gas Operator | Dec 2025 |
| 30606 | Unc Texas Incorp | | Gas Operator | May 1987 |
| 30607 | Underground Energy Inc. | | Oil & Gas Operator | Oct 2025 |
| 30608 | Underwood Oil & Gas | Casper, WY 82602 | Oil & Gas Operator | Nov 2025 |
| 30609 | Underwood Oil And Gas LLC | Chandler, OK 74834-1414 | Oil & Gas Operator | Oct 2025 |
| 30610 | Underwood, Donald D. Dba Mustang Oil Co | Salem, WV 26426 | Oil & Gas Operator | Dec 2020 |
| 30611 | Underwood, Jim | Graham, TX 76450 | Oil & Gas Operator | Mar 2018 |
| 30612 | Underwood, Rip C | Amarillo, TX 79101 | Gas Operator | Sep 1963 |
| 30613 | Unger Well Drilling Corp | Dennison, OH 44621 | Oil & Gas Operator | Dec 1999 |
| 30614 | Uni Production Company, Inc. | | Oil & Gas Operator | Apr 1988 |
| 30615 | Unicon Producing Company | Houston, TX 75252 | Gas Operator | Mar 1994 |
| 30616 | Unicorn Drilling Inc | Cody, WY 82414 | Oil Operator | Dec 1998 |
| 30617 | Unicorn Energy, Inc. | Elgin, TX 78621 | Oil & Gas Operator | Dec 2025 |
| 30618 | Unicorn Oil & Gas Co Inc | Dorset, OH 44032 | Oil & Gas Operator | Dec 1993 |
| 30619 | Unifid Oil & Gas Corp. | | Oil & Gas Operator | Mar 1994 |
| 30620 | Unified Oil & Gas Corp. | Snyder, TX 79550 | Oil Operator | Dec 2025 |
| 30621 | Unioil | Denver, CO 80203 | Oil & Gas Operator | Dec 2010 |
| 30622 | Union Camp Corp | Dover, OH 44622 | Oil & Gas Operator | Dec 2002 |
| 30623 | Union City Boro Muni Auth Erie Cnty | Union City, PA 16438-1326 | Gas Operator | Dec 2024 |
| 30624 | Union Crude Company | Baytown, TX 77521 | Oil & Gas Operator | Apr 2018 |
| 30625 | Union Crude Operating Co. | Baytown, TX 77521 | Oil Operator | Aug 2003 |
| 30626 | Union Development Company Inc | | Oil & Gas Operator | Dec 1992 |
| 30627 | Union Diversified, Inc. | | Gas Operator | Dec 2008 |
| 30628 | Union Drilling &Management Inc | | Gas Operator | Feb 1991 |
| 30629 | Union Expl. Partners, LTD. | | Oil & Gas Operator | Aug 1990 |
| 30630 | Union Gas Corp. (Union Gas Co.) | Charleston, WV 25338-0000 | Oil & Gas Operator | Aug 2021 |
| 30631 | Union Gas Operating Company | Spring, TX 77391 | Oil & Gas Operator | Dec 2025 |
| 30632 | Union Oil Co | Danville, OH 43014 | Oil & Gas Operator | Dec 2014 |
| 30633 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 30634 | Union Operating Corp | Lakewoord, CO 80215 | Oil Operator | Dec 2023 |
| 30635 | Union Pacific Austin Chalk Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 30636 | Union Pacific Re | | Oil & Gas Operator | Dec 1996 |
| 30637 | Union Pacific Resour | | Oil & Gas Operator | Apr 2002 |
| 30638 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 30639 | Union Petro Inc | Uniontown, KY 42461 | Oil Operator | Dec 2023 |
| 30640 | Union Petrochemical | | Oil & Gas Operator | Dec 1982 |
| 30641 | Union Producing Co. | | Gas Operator | Dec 1992 |
| 30642 | Union Royalty, Inc. | Midland, TX 79706 | Oil & Gas Operator | Jul 2014 |
| 30643 | Union Seaboard Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 30644 | Union Springs Central School District | Union Springs, NY 13160 | Gas Operator | Dec 2024 |
| 30645 | Union Texas Petroleum | Houston, TX 77252 | Oil & Gas Operator | Oct 1991 |
| 30646 | Union Texas Petroleum Corp | Houston, TX 77252-2120 | Oil & Gas Operator | Dec 2014 |
| 30647 | Union Valley Petroleum Corp | Enid, OK 73701 | Oil & Gas Operator | Oct 2025 |
| 30648 | Unionville Explo | | Oil Operator | Jul 1984 |
| 30649 | Unit Drilling & Exploration Co | Tulsa, OK 74132-5300 | Oil & Gas Operator | Oct 2025 |
| 30650 | Unit Manager, Citronelle Unit | | Oil & Gas Operator | Sep 2001 |
| 30651 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Dec 2025 |
| 30652 | United Company | Lubbock, TX 79408 | Oil & Gas Operator | Jun 1995 |
| 30653 | United Energy & Expl Inc | Ada, OK 74821-2449 | Oil & Gas Operator | Aug 2025 |
| 30654 | United Energy & Exploration LLC | Ada, OK 74821 | Oil & Gas Operator | Oct 2025 |
| 30655 | United Energy Corporation | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2025 |
| 30656 | United Energy Develop Co LTD | Bartlesville, OK 74003 | Oil Operator | Mar 2004 |
| 30657 | United Energy Operating, LLC | Edmond, OK 73083 | Oil & Gas Operator | Dec 2025 |
| 30658 | United Energy Partners, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2008 |
| 30659 | United Energy, Inc. | Wichita, KS 67230 | Oil & Gas Operator | Dec 2002 |
| 30660 | United Fuel Gas Co | | Oil & Gas Operator | Dec 2022 |
| 30661 | United Gas Pipe Line Co. | | Oil Operator | Aug 1993 |
| 30662 | United Investment Group | | Oil Operator | Nov 2004 |
| 30663 | United Meridian | | Oil Operator | Dec 1992 |
| 30664 | United Natural Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2020 |
| 30665 | United Natural Resources Corp | | Oil Operator | Jan 1986 |
| 30666 | United O&G/Atlee Miller | Millersburg, OH 44654 | Oil & Gas Operator | Dec 1985 |
| 30667 | United Oil & Gas | | Oil Operator | Feb 1988 |
| 30668 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 30669 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 30670 | United Oil Corporation | Denver, CO 80202-3813 | Oil & Gas Operator | Oct 2025 |
| 30671 | United Operating Company | Olney, TX 76374 | Oil & Gas Operator | Aug 2003 |
| 30672 | United Operating, LLC *** | Midland, TX 79710 | Oil & Gas Operator | Dec 2025 |
| 30673 | United Operators, Inc. | | Oil Operator | Sep 1999 |
| 30674 | United Petro Corp | Columbus, OH 43229-1826 | Gas Operator | Dec 1985 |
| 30675 | United Petro LTD. | | Oil & Gas Operator | Dec 2018 |
| 30676 | United Petroleum | | Oil Operator | Mar 1986 |
| 30677 | United Petroleum & Gas, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 30678 | United Petroleum Corporation | Edgwater, CO 80214 | Oil & Gas Operator | May 1996 |
| 30679 | United Petroleum Technologies | Hondo, TX 78861 | Oil & Gas Operator | Aug 2001 |
| 30680 | United Primary Resources Inc | Milton, WA 98354-9361 | Oil & Gas Operator | Feb 2016 |
| 30681 | United Producers Inc | Broken Arrow, OK 74012-8247 | Oil & Gas Operator | Mar 2020 |
| 30682 | United Producing Co Inc | | Oil & Gas Operator | May 1961 |
| 30683 | United Production Company LLC | Edmond, OK 73003 | Oil & Gas Operator | Oct 2025 |
| 30684 | United Reserve G | | Oil Operator | Aug 1987 |
| 30685 | United Resources Corp | Olean, NY 14760 | Oil & Gas Operator | Dec 2020 |
| 30686 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 30687 | United Resources LP A Texas LMTD PRNTSHP | Austin, TX 78746 | Oil & Gas Operator | Sep 2003 |
| 30688 | United Security Associates Inc | | Oil & Gas Operator | Dec 2020 |
| 30689 | United Southern Resources Inc. | | Gas Operator | Nov 2013 |
| 30690 | United States Energy Corp. | Longview, TX 75601 | Oil & Gas Operator | Mar 2025 |
| 30691 | United States Exploration, Inc. | Denver, CO 80802 | Oil & Gas Operator | Apr 2007 |
| 30692 | United States Gypsum Company | Oakfield, NY 14125 | Oil & Gas Operator | Dec 2024 |
| 30693 | United Texas Oil LLC | Houston, TX 77027 | Oil & Gas Operator | Dec 2025 |
| 30694 | United Texas Petroleum Inc. | McKinney, TX 75070 | Oil & Gas Operator | Dec 2025 |
| 30695 | United Utilities Corporation | Conroe, TX 77301 | Oil & Gas Operator | Oct 1998 |
| 30696 | United Well Completion, Inc | Corbin, KY 40701 | Oil & Gas Operator | Dec 2023 |
| 30697 | United Western Energy Corp | Oklahoma City, OK 73105 | Oil & Gas Operator | Mar 1994 |
| 30698 | United World Energy Corporation | | Oil & Gas Operator | Dec 2024 |
| 30699 | United World Energy, Inc. | Aurora, CO 80040 | Oil & Gas Operator | Dec 2025 |
| 30700 | Unitex Oil & Gas, L.L.C. | Midland, TX 79701 | Oil & Gas Operator | Dec 2025 |