| 1401 | Unioil | Denver, CO 80203 | Oil & Gas Operator | Jun 2012 |
| 1402 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 1403 | Union Texas Petroleum | Houston, TX 77252 | Oil & Gas Operator | Oct 1991 |
| 1404 | Unit Drilling & Exploration Co | Tulsa, OK 74132-5300 | Oil & Gas Operator | Feb 2025 |
| 1405 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | May 2025 |
| 1406 | United Energy Corporation | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 1407 | United Natural Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2020 |
| 1408 | United Natural Resources Corp | | Oil Operator | Jan 1986 |
| 1409 | United Petroleum Corporation | Edgwater, CO 80214 | Oil & Gas Operator | May 1996 |
| 1410 | United Utilities Corporation | Conroe, TX 77301 | Oil & Gas Operator | Oct 1998 |
| 1411 | Universal Fuels Company | | Oil & Gas Operator | Oct 1993 |
| 1412 | Updike Resources Inc | Newcastle, WY 82701 | Oil & Gas Operator | Jun 1998 |
| 1413 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | May 2025 |
| 1414 | Urroz Oil & Gas LLC | Evanston, WY 82931 | Oil & Gas Operator | Jun 2020 |
| 1415 | Us Energy Corp. | Houston, TX 77057 | Oil & Gas Operator | Dec 2021 |
| 1416 | Us Ore Corporation | Pacific Beach, CA 92109 | Oil Operator | Feb 2014 |
| 1417 | USA Energy LLC | Lance Creek, WY 82222 | Oil & Gas Operator | Nov 2024 |
| 1418 | USA Exploration & Production LLC | Mills, WY 82644 | Oil & Gas Operator | Sep 2012 |
| 1419 | V A Resources LLC | Casper, WY 82601 | Oil Operator | Apr 2016 |
| 1420 | Valero Producing Company | | Oil Operator | Sep 1987 |
| 1421 | Valkyrie Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Apr 2025 |
| 1422 | Van Norman Pipe And Supply | | Oil & Gas Operator | Mar 2010 |
| 1423 | Vanmark Jack | Torrington, WY 82240 | Oil Operator | Dec 1997 |
| 1424 | Vaquero Big Horn LLC | Bakersfield, CA 93309 | Oil & Gas Operator | Mar 2025 |
| 1425 | Vaquero Energy Inc | Bakersfield, CA 93309 | Oil & Gas Operator | May 2023 |
| 1426 | Vast Oil Inc | Fullerton, CA 92832 | Oil & Gas Operator | Mar 2024 |
| 1427 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Jan 2025 |
| 1428 | Vecta Oil & Gas LTD | Dallas, TX 75235 | Oil & Gas Operator | Mar 2025 |
| 1429 | Vector Minerals Corporation | Aurora, CO 80015 | Oil & Gas Operator | Mar 2025 |
| 1430 | Vermilion Energy USA LLC | | Oil & Gas Operator | Mar 2025 |
| 1431 | Vessels Oil & Gas Company | Denver, CO 80265 | Oil & Gas Operator | Dec 1998 |
| 1432 | Vesta Inc | Great Falls, MT 59403 | Gas Operator | Mar 1997 |
| 1433 | Viable Resources Inc | Casper, WY 82601 | Oil & Gas Operator | Sep 1989 |
| 1434 | Vicorp Energy Inc | Denver, CO 80202-4927 | Oil & Gas Operator | Mar 2001 |
| 1435 | Viking Resources Corp | Deerfield, OH 44411-0160 | Oil & Gas Operator | Dec 2007 |
| 1436 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Feb 2025 |
| 1437 | Viola Production Inc | Dallas, TX 75251 | Oil & Gas Operator | May 2025 |
| 1438 | Vortex Petroleum Inc | Centennial, CO 80111 | Oil Operator | Feb 2025 |
| 1439 | Voyager Exploration Inc | Denver, CO 80202 | Oil & Gas Operator | May 2006 |
| 1440 | Wacker Oil Inc | Houston, TX 77002 | Oil & Gas Operator | Aug 1996 |
| 1441 | Waggoner-Baldridge Energy | | Oil Operator | Jun 1988 |
| 1442 | Wagner & Brown Limited Partnership | Midland, TX 79701 | Oil & Gas Operator | Feb 2013 |
| 1443 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 1444 | Walker L Willis | | Oil Operator | Dec 1985 |
| 1445 | Wallway M J | Casper, WY 82601 | Oil & Gas Operator | Jan 1993 |
| 1446 | Wapiti Oil & Gas LLC | Houston, TX 77024 | Oil Operator | Dec 2011 |
| 1447 | Wapiti Operating, LLC | Houston, TX 77043 | Oil & Gas Operator | May 2025 |
| 1448 | Ward Petroleum Corporation | Enid, OK 73702 | Oil & Gas Operator | Feb 2025 |
| 1449 | Ware House Industries | Casper, WY 82605 | Oil & Gas Operator | Dec 2013 |
| 1450 | Warrego Oil & Gas LLC | Lander, WY 82520 | Oil Operator | May 2018 |
| 1451 | Warren E & P Inc | Dallas, TX 75240 | Oil & Gas Operator | Mar 2025 |
| 1452 | Warren Enterprises Inc | Gillette, WY 82718 | Oil Operator | Dec 2022 |
| 1453 | Washakie Energies Company | Worland, WY 82401 | Oil & Gas Operator | Dec 2019 |
| 1454 | Washakie Oil Company | | Oil & Gas Operator | Dec 1989 |
| 1455 | Washburn Lee | Newcastle, WY 82701 | Oil Operator | Jan 2025 |
| 1456 | Washington Energy Exploration | | Oil & Gas Operator | Dec 1997 |
| 1457 | Waterford Production Co | | Oil Operator | Oct 1992 |
| 1458 | Wave Petroleum Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Apr 2025 |
| 1459 | Weaver Dale Inc | Powell, WY 82435 | Oil Operator | Apr 2005 |
| 1460 | Weaver Oil Inc | | Oil & Gas Operator | Oct 2011 |
| 1461 | Webb Resources Inc | | Oil & Gas Operator | Dec 1985 |
| 1462 | Webster Joe | | Oil Operator | Apr 1987 |
| 1463 | Wellstar Corporation | Northglenn, CO 80233 | Oil & Gas Operator | Mar 2025 |
| 1464 | Wem Joint Venture | Gillette, WY 82716 | Oil & Gas Operator | Sep 2015 |
| 1465 | Wesco Operating, Inc. | Casper, WY 82602 | Oil & Gas Operator | Mar 2025 |
| 1466 | Wesco Production LLC | | Oil & Gas Operator | Feb 2025 |
| 1467 | Wessely Energy Corporation | | Oil & Gas Operator | Feb 1989 |
| 1468 | West Gas Inc | | Oil & Gas Operator | Dec 2017 |
| 1469 | Westburne Petroleum Inc | | Oil Operator | Jun 1990 |
| 1470 | Westech Energy Corporation | Denver, CO 80237 | Oil & Gas Operator | Mar 2011 |
| 1471 | Western American Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2024 |
| 1472 | Western Gas Resources Inc | Denver, CO 80202 | Oil & Gas Operator | Dec 2004 |
| 1473 | Western Interior Energy Inc. | Denver, CO 80202 | Oil & Gas Operator | Jul 2020 |
| 1474 | Western Interior Oil & Gas Corp | Casper, WY 82602 | Oil & Gas Operator | May 2015 |
| 1475 | Western Oil Refining Company | Kemmerrer, WY 83101 | Oil & Gas Operator | Dec 1994 |
| 1476 | Western Operating Company | Denver, CO 80204 | Oil & Gas Operator | Mar 2025 |
| 1477 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 1478 | Weststar Oil & Gas Inc | Edmond, OK 73013 | Oil & Gas Operator | Mar 2025 |
| 1479 | Wexpro Company | Rock Springs, WY 82902-0458 | Oil & Gas Operator | Mar 2025 |
| 1480 | Wexpro Development Company | Salt Lake City, UT 84111 | Oil & Gas Operator | Mar 2025 |
| 1481 | Wexpro II Company | Salt Lake City, UT 84111 | Oil & Gas Operator | Mar 2025 |
| 1482 | Wheless Drilling Company | | Oil & Gas Operator | Dec 1989 |
| 1483 | Whisler Enterprise Company | Erie, CO 80516 | Oil & Gas Operator | Mar 2025 |
| 1484 | White Rock Oil & Gas, LLC | Plano, TX 75024 | Oil & Gas Operator | May 2025 |
| 1485 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 1486 | Wichita River Oil Corporation | Englewood, CO 80111 | Oil & Gas Operator | Apr 2009 |
| 1487 | Wilbanks Exploration Inc | Denver, CO 80202 | Oil & Gas Operator | May 2002 |
| 1488 | Wildfire Partners Inc | Ardmore, OK 73402 | Oil & Gas Operator | Dec 2009 |
| 1489 | Williams Exploration Company | | Oil & Gas Operator | Dec 1986 |
| 1490 | Williams Ted H | | Oil & Gas Operator | Dec 2008 |
| 1491 | Williston Basin Cosul-Profit SH | | Oil Operator | Dec 1989 |
| 1492 | Wilshire Enterprises Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2015 |
| 1493 | Win Oil Company | Russell, KS 67665 | Oil & Gas Operator | Jul 2021 |
| 1494 | Winco Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Dec 1997 |
| 1495 | Wind River Energy Commission | | Oil Operator | Apr 2025 |
| 1496 | Wind River Exploration | Powell, WY 82435 | Oil & Gas Operator | Apr 2025 |
| 1497 | Windsor Energy Group LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Aug 2021 |
| 1498 | Winkler L W & Son | Denver, CO 80222 | Oil & Gas Operator | Dec 2001 |
| 1499 | Winter Ridge Energy LLC | Denver, CO 80202 | Oil & Gas Operator | Sep 2011 |
| 1500 | WLP Oil Inc | Gillette, WY 82717 | Oil & Gas Operator | Dec 2018 |