| 1301 | Tesoro Petroleum Corporation | | Oil & Gas Operator | May 1982 |
| 1302 | Tex/Con Oil & Gas Company | Houston, TX 77074 | Oil & Gas Operator | Feb 2001 |
| 1303 | Texaco Exploration & Prod | Midland, TX 79702 | Oil & Gas Operator | Aug 2002 |
| 1304 | Texakota | | Oil & Gas Operator | Mar 1995 |
| 1305 | Texas American Oil Corporation | Midland, TX 79701 | Oil & Gas Operator | Jan 2001 |
| 1306 | Texas American Resources Company | Austin, TX 78701 | Oil & Gas Operator | Apr 2024 |
| 1307 | Texas Gas Exploration Corp. | | Oil & Gas Operator | Nov 1986 |
| 1308 | Texas General Petroleum Corp | | Oil & Gas Operator | Sep 1984 |
| 1309 | Texas Oil & Gas Corporation | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 1310 | Texas Vanguard Oil Company | Austin, TX 78720 | Oil & Gas Operator | Jan 2014 |
| 1311 | TGX Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2004 |
| 1312 | The Brinkerhoff Company | Denver, CO 80202 | Oil & Gas Operator | Dec 2017 |
| 1313 | The Termo Company | Long Beach, CA 90801 | Oil & Gas Operator | Feb 2024 |
| 1314 | Thomas Operating Company Inc | Greeley, CO 80634 | Oil & Gas Operator | Aug 2008 |
| 1315 | Three Forks Resources LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | Apr 2024 |
| 1316 | Three G Inc | Cody, WY 82414 | Oil & Gas Operator | Dec 1999 |
| 1317 | Three Sisters LLC | Cheyenne, WY 82001 | Oil Operator | Feb 2024 |
| 1318 | Thunder Basin Resources LLC | Denver, CO 80203 | Oil & Gas Operator | Jul 2023 |
| 1319 | Ticony Inc | | Oil & Gas Operator | Dec 1989 |
| 1320 | Tidemark Exploration | Tulsa, OK 74170 | Oil & Gas Operator | May 2005 |
| 1321 | Tiger Oil Company | Dallas, TX 75221 | Oil & Gas Operator | May 2007 |
| 1322 | Timberline Energy Inc | Franklin, PA 16323-0269 | Oil & Gas Operator | Jun 2018 |
| 1323 | Timberline Production Company LLC | Casper, WY 82601 | Oil & Gas Operator | Oct 2020 |
| 1324 | Tindall Operating Company | Englewood, CO 80112 | Oil & Gas Operator | Feb 2024 |
| 1325 | Tipperary Oil & Gas Corp | Denver, CO 80202 | Oil & Gas Operator | May 2014 |
| 1326 | Tipps Kenneth L | | Oil & Gas Operator | Jun 2000 |
| 1327 | Titan Exploration LLC | Luling, TX 78648 | Oil & Gas Operator | Feb 2024 |
| 1328 | Tobinsnet Oil & Gas LTD | | Oil Operator | Feb 2024 |
| 1329 | Toc Oil Inc | Denver, CO 80202 | Oil & Gas Operator | Feb 2024 |
| 1330 | Toc-Rocky Mountain Inc | | Oil & Gas Operator | Oct 2013 |
| 1331 | Toco Corporation | | Oil & Gas Operator | Oct 1991 |
| 1332 | Tonka Oil & Gas Production Inc | Buffalo, WY 82834 | Oil & Gas Operator | Sep 1999 |
| 1333 | Torch E & P Company | Houston, TX 77010 | Oil & Gas Operator | Jan 2015 |
| 1334 | Torch Oil & Gas Company | Houston, TX 77010 | Oil & Gas Operator | Aug 1997 |
| 1335 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 1336 | Total Petroleum Inc | Denver, CO 80201-0500 | Oil & Gas Operator | Nov 2006 |
| 1337 | Townsend Company | Abilene, TX 79608 | Oil & Gas Operator | Dec 2021 |
| 1338 | TR Operating LLC | Graham, TX 76450 | Oil Operator | Feb 2024 |
| 1339 | Transco Exploration Company | | Oil & Gas Operator | Jul 1989 |
| 1340 | Transcontinental Oil Corp. | | Oil & Gas Operator | Sep 1985 |
| 1341 | Transglobe Oil & Gas Corporation | Littleton, CO 801222710 | Oil & Gas Operator | Dec 1999 |
| 1342 | Transhorizon Energy Inc | Cheyenne, WY 82003 | Oil & Gas Operator | Jul 2023 |
| 1343 | Transworld Systems Petroleum Inc | Denver, CO 80202 | Oil & Gas Operator | Mar 2024 |
| 1344 | Trend Exploration I LLC | Midland, TX 79701 | Oil & Gas Operator | May 2011 |
| 1345 | Tresor Petroleum | | Oil & Gas Operator | Sep 1987 |
| 1346 | Tressler John R & IVa M | | Oil Operator | Apr 1989 |
| 1347 | Tri-Ex Corporation | | Oil & Gas Operator | Jan 1985 |
| 1348 | Triangle J Oil Company | | Oil & Gas Operator | Mar 2007 |
| 1349 | Tribar Resources LLC | | Oil Operator | Feb 2024 |
| 1350 | Trigg Drilling Company Inc | Oklahoma City, OK 73105 | Oil & Gas Operator | Jan 2013 |
| 1351 | Trigg Oil Mining Corporation | | Oil & Gas Operator | Dec 2007 |
| 1352 | Trinity Energy Resources Inc | Houston, TX 77079 | Oil & Gas Operator | Aug 2005 |
| 1353 | Trinity Resources, Inc. | Houston, TX 77277 | Oil & Gas Operator | May 2020 |
| 1354 | Triple B Energy Inc | Gillette, WY 82716 | Oil Operator | Dec 1999 |
| 1355 | Tripower Resources LLC | Ardmore, OK 73402 | Oil & Gas Operator | Apr 2024 |
| 1356 | Tripp Oil Company Inc | Houston, TX 77023 | Oil & Gas Operator | Jan 1992 |
| 1357 | Tristar Energy Corporation | Casper, WY 82602 | Oil & Gas Operator | Dec 2007 |
| 1358 | Triton Oil & Gas Corp. | Houston, TX 77002 | Oil & Gas Operator | Nov 2014 |
| 1359 | Trout Kye Jr | | Oil & Gas Operator | Dec 2010 |
| 1360 | True Oil LLC | Casper, WY 82602 | Oil & Gas Operator | Feb 2024 |
| 1361 | Turner Smith & Associates | Englewood, CO 80111 | Oil & Gas Operator | May 1994 |
| 1362 | Twin Arrow Inc | Rangely, CO 81648 | Oil & Gas Operator | Sep 2009 |
| 1363 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 1364 | Tyl Oil | Canon City, CO 81212 | Gas Operator | May 1994 |
| 1365 | Tyler Rockies Exploration LTD | Tyler, TX 75710-0119 | Oil & Gas Operator | Feb 2024 |
| 1366 | Tyrex Oil Company | Casper, WY 82602 | Oil & Gas Operator | May 1997 |
| 1367 | U V Industries | | Oil & Gas Operator | Jan 1993 |
| 1368 | Ultra Resources Inc | Houston, TX 77060 | Oil & Gas Operator | Jan 2024 |
| 1369 | Ultramar Oil & Gas LTD | Houston, TX 77060 | Oil & Gas Operator | Jul 1995 |
| 1370 | Underwood Oil & Gas | Casper, WY 82602 | Oil & Gas Operator | Jan 2024 |
| 1371 | Unicorn Drilling Inc | Cody, WY 82414 | Oil Operator | Dec 1998 |
| 1372 | Unioil | Denver, CO 80203 | Oil & Gas Operator | Jun 2012 |
| 1373 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 1374 | Union Texas Petroleum | Houston, TX 77252 | Oil & Gas Operator | Oct 1991 |
| 1375 | Unit Drilling & Exploration Co | Tulsa, OK 74132-5300 | Oil & Gas Operator | Dec 2023 |
| 1376 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2024 |
| 1377 | United Energy Corporation | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2024 |
| 1378 | United Natural Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2020 |
| 1379 | United Natural Resources Corp | | Oil Operator | Jan 1986 |
| 1380 | United Petroleum Corporation | Edgwater, CO 80214 | Oil & Gas Operator | May 1996 |
| 1381 | United Utilities Corporation | Conroe, TX 77301 | Oil & Gas Operator | Oct 1998 |
| 1382 | Universal Fuels Company | | Oil & Gas Operator | Oct 1993 |
| 1383 | Updike Resources Inc | Newcastle, WY 82701 | Oil & Gas Operator | Jun 1998 |
| 1384 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Apr 2024 |
| 1385 | Urroz Oil & Gas LLC | Evanston, WY 82931 | Oil & Gas Operator | Jun 2020 |
| 1386 | Us Energy Corp. | Houston, TX 77057 | Oil & Gas Operator | Dec 2021 |
| 1387 | Us Ore Corporation | Pacific Beach, CA 92109 | Oil Operator | Feb 2014 |
| 1388 | USA Energy LLC | Lance Creek, WY 82222 | Oil & Gas Operator | Nov 2023 |
| 1389 | USA Exploration & Production LLC | Mills, WY 82644 | Oil & Gas Operator | Sep 2012 |
| 1390 | V A Resources LLC | Casper, WY 82601 | Oil Operator | Apr 2016 |
| 1391 | Valero Producing Company | | Oil Operator | Sep 1987 |
| 1392 | Valkyrie Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2024 |
| 1393 | Van Norman Pipe And Supply | | Oil & Gas Operator | Mar 2010 |
| 1394 | Vanmark Jack | Torrington, WY 82240 | Oil Operator | Dec 1997 |
| 1395 | Vaquero Big Horn LLC | Bakersfield, CA 93309 | Oil & Gas Operator | Feb 2024 |
| 1396 | Vaquero Energy Inc | Bakersfield, CA 93309 | Oil & Gas Operator | May 2023 |
| 1397 | Vast Oil Inc | Fullerton, CA 92832 | Oil & Gas Operator | May 2023 |
| 1398 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Dec 2023 |
| 1399 | Vecta Oil & Gas LTD | Dallas, TX 75235 | Oil & Gas Operator | Jan 2024 |
| 1400 | Vector Minerals Corporation | Aurora, CO 80015 | Oil & Gas Operator | Jan 2024 |