| 31401 | Underwood Oil And Gas LLC | Chandler, OK 74834-1414 | Oil & Gas Operator | Dec 2025 |
| 31402 | Underwood, D. W. | Eldorado, TX 76936 | Oil & Gas Operator | Nov 1997 |
| 31403 | Underwood, Donald D. Dba Mustang Oil Co | Salem, WV 26426 | Oil & Gas Operator | Dec 2020 |
| 31404 | Underwood, Jim | Graham, TX 76450 | Oil & Gas Operator | Mar 2018 |
| 31405 | Underwood, Rip C | Amarillo, TX 79101 | Gas Operator | Sep 1963 |
| 31406 | Unger Well Drilling Corp | Dennison, OH 44621 | Oil & Gas Operator | Dec 1999 |
| 31407 | Uni Production Company, Inc. | | Oil & Gas Operator | Apr 1988 |
| 31408 | Unicon Producing Company | Houston, TX 75252 | Gas Operator | Mar 1994 |
| 31409 | Unicorn Drilling Inc | Cody, WY 82414 | Oil Operator | Dec 1998 |
| 31410 | Unicorn Energy, Inc. | Elgin, TX 78621 | Oil & Gas Operator | Feb 2026 |
| 31411 | Unicorn Oil & Gas Co Inc | Dorset, OH 44032 | Oil & Gas Operator | Dec 1993 |
| 31412 | Unifid Oil & Gas Corp. | | Oil & Gas Operator | Mar 1994 |
| 31413 | Unified Oil & Gas Corp. | Snyder, TX 79550 | Oil Operator | Feb 2026 |
| 31414 | Unioil | Denver, CO 80203 | Oil & Gas Operator | Dec 2010 |
| 31415 | Union Camp Corp | Dover, OH 44622 | Oil & Gas Operator | Dec 2002 |
| 31416 | Union City Boro Muni Auth Erie Cnty | Union City, PA 16438-1326 | Gas Operator | Dec 2024 |
| 31417 | Union Crude Company | Baytown, TX 77521 | Oil & Gas Operator | Apr 2018 |
| 31418 | Union Crude Operating Co. | Baytown, TX 77521 | Oil Operator | Aug 2003 |
| 31419 | Union Development Company Inc | | Oil & Gas Operator | Dec 1992 |
| 31420 | Union Diversified Investments, Inc. | | Gas Operator | Nov 2024 |
| 31421 | Union Diversified, Inc. | | Gas Operator | Dec 2008 |
| 31422 | Union Drilling &Management Inc | | Gas Operator | Feb 1991 |
| 31423 | Union Expl. Partners, LTD. | | Oil & Gas Operator | Aug 1990 |
| 31424 | Union Gas Corp. (Union Gas Co.) | Charleston, WV 25338-0000 | Oil & Gas Operator | Aug 2021 |
| 31425 | Union Gas Operating Company | Spring, TX 77391 | Oil & Gas Operator | Feb 2026 |
| 31426 | Union Oil Co | Danville, OH 43014 | Oil & Gas Operator | Dec 2014 |
| 31427 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 31428 | Union Operating Corp | Lakewoord, CO 80215 | Oil Operator | Dec 2023 |
| 31429 | Union Pacific Austin Chalk Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 31430 | Union Pacific Re | | Oil & Gas Operator | Dec 1996 |
| 31431 | Union Pacific Resour | | Oil & Gas Operator | Apr 2002 |
| 31432 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 31433 | Union Petro Inc | Uniontown, KY 42461 | Oil Operator | Dec 2023 |
| 31434 | Union Petrochemical | | Oil & Gas Operator | Dec 1982 |
| 31435 | Union Producing Co. | | Gas Operator | Dec 1992 |
| 31436 | Union Royalty, Inc. | Midland, TX 79706 | Oil & Gas Operator | Jul 2014 |
| 31437 | Union Seaboard Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 31438 | Union Springs Central School District | Union Springs, NY 13160 | Gas Operator | Dec 2024 |
| 31439 | Union Texas Petroleum | Houston, TX 77252 | Oil & Gas Operator | Oct 1991 |
| 31440 | Union Texas Petroleum Corp | Houston, TX 77252-2120 | Oil & Gas Operator | Dec 2014 |
| 31441 | Union Valley Petroleum Corp | Enid, OK 73701 | Oil & Gas Operator | Dec 2025 |
| 31442 | Unionville Explo | | Oil Operator | Jul 1984 |
| 31443 | Unit Drilling & Exploration Co | Tulsa, OK 74132-5300 | Oil & Gas Operator | Nov 2025 |
| 31444 | Unit Manager, Citronelle Unit | | Oil & Gas Operator | Sep 2001 |
| 31445 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Feb 2026 |
| 31446 | United Company | Lubbock, TX 79408 | Oil & Gas Operator | Jun 1995 |
| 31447 | United Energy & Expl Inc | Ada, OK 74821-2449 | Oil & Gas Operator | Nov 2025 |
| 31448 | United Energy & Exploration LLC | Ada, OK 74821 | Oil & Gas Operator | Dec 2025 |
| 31449 | United Energy Corporation | San Antonio, TX 78209 | Oil & Gas Operator | Feb 2026 |
| 31450 | United Energy Develop Co LTD | Bartlesville, OK 74003 | Oil Operator | Mar 2004 |
| 31451 | United Energy Operating, LLC | Edmond, OK 73083 | Oil & Gas Operator | Feb 2026 |
| 31452 | United Energy Partners, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2008 |
| 31453 | United Energy, Inc. | Wichita, KS 67230 | Oil & Gas Operator | Dec 2002 |
| 31454 | United Fuel Gas Co | | Oil & Gas Operator | Dec 2022 |
| 31455 | United Gas Pipe Line Co. | | Oil Operator | Aug 1993 |
| 31456 | United Gas Search Inc | Garland, TX 88241 | Oil & Gas Operator | Nov 1993 |
| 31457 | United Investment Group | | Oil Operator | Nov 2004 |
| 31458 | United Meridian | | Oil Operator | Dec 1992 |
| 31459 | United Natural Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2020 |
| 31460 | United Natural Resources Corp | | Oil Operator | Jan 1986 |
| 31461 | United O&G/Atlee Miller | Millersburg, OH 44654 | Oil & Gas Operator | Dec 1985 |
| 31462 | United Oil & Gas | | Oil Operator | Feb 1988 |
| 31463 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 31464 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 31465 | United Oil & Shale LLC | Woodward, OK 73801 | Oil & Gas Operator | Feb 2026 |
| 31466 | United Oil Corporation | Denver, CO 80202-3813 | Oil & Gas Operator | Nov 2025 |
| 31467 | United Operating Company | Olney, TX 76374 | Oil & Gas Operator | Aug 2003 |
| 31468 | United Operating, LLC *** | Midland, TX 79710 | Oil & Gas Operator | Feb 2026 |
| 31469 | United Operators, Inc. | | Oil Operator | Sep 1999 |
| 31470 | United Petro Corp | Columbus, OH 43229-1826 | Gas Operator | Dec 1985 |
| 31471 | United Petro LTD. | | Oil & Gas Operator | Dec 2018 |
| 31472 | United Petroleum | | Oil Operator | Mar 1986 |
| 31473 | United Petroleum & Gas, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Feb 2026 |
| 31474 | United Petroleum Corporation | Edgwater, CO 80214 | Oil & Gas Operator | May 1996 |
| 31475 | United Petroleum Technologies | Hondo, TX 78861 | Oil & Gas Operator | Aug 2001 |
| 31476 | United Primary Resources Inc | Milton, WA 98354-9361 | Oil & Gas Operator | Feb 2016 |
| 31477 | United Producers Inc | Broken Arrow, OK 74012-8247 | Oil & Gas Operator | Mar 2020 |
| 31478 | United Producing Co Inc | | Oil & Gas Operator | May 1961 |
| 31479 | United Production Company LLC | Edmond, OK 73003 | Oil & Gas Operator | Dec 2025 |
| 31480 | United Reserve G | | Oil Operator | Aug 1987 |
| 31481 | United Resources Corp | Olean, NY 14760 | Oil & Gas Operator | Dec 2020 |
| 31482 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 31483 | United Resources LP A Texas LMTD PRNTSHP | Austin, TX 78746 | Oil & Gas Operator | Sep 2003 |
| 31484 | United Security Associates Inc | | Oil Operator | Nov 2016 |
| 31485 | United Southern Resources Inc. | | Gas Operator | Nov 2013 |
| 31486 | United States Exploration, Inc. | Denver, CO 80802 | Oil & Gas Operator | Apr 2007 |
| 31487 | United States Gypsum Company | Oakfield, NY 14125 | Oil & Gas Operator | Dec 2024 |
| 31488 | United Texas Oil LLC | Houston, TX 77027 | Oil & Gas Operator | Feb 2026 |
| 31489 | United Texas Petroleum Inc. | McKinney, TX 75070 | Oil & Gas Operator | Feb 2026 |
| 31490 | United Utilities Corporation | Conroe, TX 77301 | Oil & Gas Operator | Oct 1998 |
| 31491 | United Well Completion, Inc | Corbin, KY 40701 | Oil & Gas Operator | Dec 2023 |
| 31492 | United Western Energy Corp | Oklahoma City, OK 73105 | Oil & Gas Operator | Mar 1994 |
| 31493 | United World Energy Corporation | | Oil & Gas Operator | Dec 2024 |
| 31494 | United World Energy, Inc. | Aurora, CO 80040 | Oil & Gas Operator | Feb 2026 |
| 31495 | Unitex Oil & Gas, L.L.C. | Midland, TX 79701 | Oil & Gas Operator | Feb 2026 |
| 31496 | Unity Petroleum | Howard, OH 43028 | Oil & Gas Operator | Dec 2021 |
| 31497 | Universal Cyclops Specialty Steel Div | Pittsburgh, PA 15228-2702 | Gas Operator | Dec 1985 |
| 31498 | Universal Drilling Company | Denver, CO 80203 | Oil & Gas Operator | Sep 2003 |
| 31499 | Universal Exploration Inc | Wadsworth, OH 44281-9460 | Oil & Gas Operator | Feb 2012 |
| 31500 | Universal Fuels Company | | Oil & Gas Operator | Oct 1993 |