| 401 | Duncan Energy Company | Denver, CO 80202 | Oil & Gas Operator | Mar 2008 |
| 402 | Duncan Oil Inc | Denver, CO 80210 | Oil & Gas Operator | Jun 2016 |
| 403 | Dyco Petroleum Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |
| 404 | Dyer J G | | Oil & Gas Operator | May 1985 |
| 405 | E & B Natural Resources Management | Guilderland Centek, NY 12085 | Oil & Gas Operator | Oct 2025 |
| 406 | Eagle Oil & Gas Co. | Dallas, TX 75225 | Oil & Gas Operator | Dec 2025 |
| 407 | Earthstone Energy, Inc. | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2017 |
| 408 | Earthstone Operating, LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Sep 2025 |
| 409 | Eason Oil Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Mar 2012 |
| 410 | Eastern American Energy Corp | | Oil & Gas Operator | Dec 2008 |
| 411 | Eberspecher Drilling Inc | Casper, WY 82601 | Oil & Gas Operator | Dec 2000 |
| 412 | Eblen Frank Syndicate Inc | Atlantic, IA 50022 | Oil & Gas Operator | Jul 2014 |
| 413 | Edge Energy II LLC | Golden, CO 80401 | Oil & Gas Operator | Nov 2025 |
| 414 | Eex Corporation | Houston, TX 77060 | Oil & Gas Operator | Feb 2000 |
| 415 | El Paso Natural Gas Company | El Paso, TX 79978 | Oil & Gas Operator | Apr 2013 |
| 416 | El Paso Production Oil & Gas Co. | Houston, TX 77252 | Oil & Gas Operator | Dec 2025 |
| 417 | Eland Energy Inc | Dallas, TX 75248 | Oil & Gas Operator | Sep 2025 |
| 418 | Elephant Operating LLC | Dallas, TX 75204 | Oil & Gas Operator | Oct 2025 |
| 419 | Elf Aquitaine Inc | Houston, TX 77002 | Oil & Gas Operator | May 1991 |
| 420 | Elk Energy Corporation | Denver, CO 80218 | Oil & Gas Operator | Mar 2008 |
| 421 | Elk Petroleum Inc | Casper, WY 82601 | Oil & Gas Operator | Aug 2014 |
| 422 | Ellbogen John P LTD | Casper, WY 82602 | Oil & Gas Operator | Oct 2025 |
| 423 | Ellwood Exploration LLC | San Antonio, TX 78217 | Oil Operator | Oct 2025 |
| 424 | Elm Ridge Exploration Company LLC | Bloomfield, NM 87413 | Oil & Gas Operator | Nov 2017 |
| 425 | Emc Energies Inc | Casper, WY 82604 | Oil Operator | May 1989 |
| 426 | Emc Energy | | Oil & Gas Operator | Jun 1985 |
| 427 | Eme Wyoming LLC | Lakewood, CO 80401 | Oil & Gas Operator | Oct 2025 |
| 428 | Emep II Operating LLC | | Oil & Gas Operator | Oct 2025 |
| 429 | Emerald Operating Company | Plano, TX 75075 | Oil & Gas Operator | Oct 2025 |
| 430 | Emerald Restoration & Prod | Gillette, WY 82718 | Oil & Gas Operator | Jul 2000 |
| 431 | Empire Petroleum Corporation | Tulsa, OK 74137 | Oil & Gas Operator | Dec 2005 |
| 432 | Emre Oil LLC | Moorcroft, WY 82721 | Oil Operator | Oct 2025 |
| 433 | Encana Energy Resources Inc | Denver, CO 80202-2828 | Oil & Gas Operator | Feb 2024 |
| 434 | Encore Operating LP | Plano, TX 75024 | Oil & Gas Operator | Sep 2025 |
| 435 | Endeavor Energy LLC | | Oil Operator | Sep 2023 |
| 436 | Endeavor Energy Resources, LP | Midland, TX 79701 | Oil & Gas Operator | Mar 2025 |
| 437 | Enduro Operating LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2018 |
| 438 | Enerex Limited Liability Co | Craig, CO 81625 | Oil & Gas Operator | Sep 2025 |
| 439 | Energas Corporation | Oklahoma City, OK 73105 | Oil & Gas Operator | Jul 2025 |
| 440 | Energen Resources Maq Inc | Birmingham, AL 35203 | Oil & Gas Operator | Sep 2000 |
| 441 | Energetics Inc | Englewood, CO 80155 | Oil & Gas Operator | Aug 1985 |
| 442 | Energy Equity Company | Columbus, MT 59019 | Oil & Gas Operator | Oct 2025 |
| 443 | Energy Operating Company Inc | Lakewood, CO 80235 | Oil & Gas Operator | Dec 2012 |
| 444 | Energy Production Co | Pittsburgh, PA 15241-3949 | Oil & Gas Operator | Dec 1994 |
| 445 | Energy Reserves Group | Houston, TX 770563020 | Oil & Gas Operator | Apr 1996 |
| 446 | Energy Search Company Inc | Aurora, CO 80011 | Oil & Gas Operator | Jun 2021 |
| 447 | Enervest Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 448 | Enpro LLC | Cottonwood, UT 84047 | Oil & Gas Operator | Nov 2017 |
| 449 | Enre LP | Kingwood, TX 77339 | Oil & Gas Operator | Feb 2004 |
| 450 | Ensource Inc | Midland, TX 79705 | Oil & Gas Operator | Aug 1998 |
| 451 | Enstar Petroleum Inc | | Oil & Gas Operator | Apr 1985 |
| 452 | Entek GRB LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2021 |
| 453 | Envirosearch Corporation | | Oil Operator | Dec 1992 |
| 454 | EOG Resources Inc | Midland, TX 79702 | Oil & Gas Operator | Dec 2025 |
| 455 | EOG Y Resources Inc | Artesia, NM 88210 | Oil & Gas Operator | Feb 2019 |
| 456 | EP Energy E&P Company, LP | Houston, TX 77210 | Oil & Gas Operator | Jan 2023 |
| 457 | Equitable Resources Energy Company | Big Stone Gap, VA 24219 | Oil & Gas Operator | Dec 1997 |
| 458 | Equity Oil Company | Salt Lake City, UT 84110-095 | Oil & Gas Operator | Aug 2004 |
| 459 | Erg Resources LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2015 |
| 460 | Escalera Resources Co | Casper, WY 82602 | Oil & Gas Operator | May 2018 |
| 461 | Essex Energy Inc | Yukon, OK 73099-5126 | Oil & Gas Operator | Apr 2014 |
| 462 | Euroamerican Energy Group Inc | | Oil & Gas Operator | Oct 1993 |
| 463 | Everest Oil & Gas LLC | Santa Barbara, CA 93101 | Oil Operator | Oct 2025 |
| 464 | Evergreen Operating Company | Denver, CO 80202 | Oil & Gas Operator | Apr 1996 |
| 465 | Evertson Operating Company Inc | Kimball, NE 69145 | Oil & Gas Operator | Nov 2022 |
| 466 | Exco Resources Inc | Dallas, TX 75251 | Oil & Gas Operator | Aug 2025 |
| 467 | Exeter Drilling Company | Denver, CO 80217 | Oil & Gas Operator | Sep 1997 |
| 468 | Extraction Oil & Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Sep 2025 |
| 469 | Exxon Mobil Corporation | Spring, TX 77389 | Oil & Gas Operator | Dec 2025 |
| 470 | Exxonmobil Oil Corp | Houston, TX 77210 | Oil & Gas Operator | Aug 2025 |
| 471 | F & J Oil LLC | Newcastle, WY 82701 | Oil & Gas Operator | Oct 2015 |
| 472 | Fairways Offshore Expl Inc | Houston, TX 77040 | Oil & Gas Operator | Mar 2016 |
| 473 | Falcon Creek Resources, Inc. | Tulsa, OK 74137 | Oil & Gas Operator | Apr 2001 |
| 474 | Family Tree Corporation | Lakewood, CO 80228 | Oil & Gas Operator | Feb 2013 |
| 475 | Fancher Oil LLC | Greenwood, CO 80111 | Oil & Gas Operator | Nov 2006 |
| 476 | Farnsworth & Kaiser Oil Company | Newcastle, WY 82701 | Oil & Gas Operator | Sep 2012 |
| 477 | Faulconer, Vernon E., Inc. | Tyler, TX 75711 | Oil & Gas Operator | Sep 2025 |
| 478 | FDF Resources | Newcastle, WY 82701 | Oil & Gas Operator | Oct 2025 |
| 479 | FDL Operating, LLC | Judson, TX 75660 | Oil & Gas Operator | Dec 2025 |
| 480 | Federated Oil & Gas Properties | Traverse City, MI 49685 | Gas Operator | Mar 2014 |
| 481 | Felmont Oil Corporation | Walnut Creek, CA 94596-3568 | Oil & Gas Operator | Feb 1990 |
| 482 | Ferguson & Bosworth | | Oil & Gas Operator | May 2007 |
| 483 | Ferguson Bob | Casper, WY 82605 | Oil Operator | May 2004 |
| 484 | Ferguson Energy Inc | Evanston, WY 82930 | Oil & Gas Operator | Jul 2025 |
| 485 | Ferguson Oil Company Inc | | Oil & Gas Operator | Apr 1994 |
| 486 | Ferreira Oil Properties LLC | Carefree, AZ 85377 | Oil Operator | Apr 2014 |
| 487 | Fidelity Exploration & Production Company | Denver, CO 80203 | Oil & Gas Operator | Nov 2025 |
| 488 | Fina Oil And Chemical Company | Dallas, TX 75221 | Oil & Gas Operator | May 2019 |
| 489 | Finaly Resources LLC | Sunset Beach, CA 90742 | Oil & Gas Operator | Dec 2025 |
| 490 | Finley Resources Inc | Fort Worth, TX 76113 | Oil & Gas Operator | Dec 2025 |
| 491 | First Energy Corporation | | Oil & Gas Operator | Jun 1993 |
| 492 | First Energy Properties | Houston, TX 77060 | Oil & Gas Operator | Dec 1986 |
| 493 | First Sourcenergy Wyoming Inc | Gillette, WY 82718 | Gas Operator | Jul 2003 |
| 494 | Five States Operating Company LLC | Dallas, TX 75206 | Oil & Gas Operator | Oct 2025 |
| 495 | Flag-Redfern Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Jul 2002 |
| 496 | Flahive Oil & Gas LLC | Golden, CO 80401 | Oil Operator | Oct 1995 |
| 497 | Florida Gas Exploration Co | | Oil & Gas Operator | Feb 1985 |
| 498 | Flow Production Company | Midland, TX 79708 | Oil & Gas Operator | Mar 2005 |
| 499 | Flying J Oil & Gas Inc | North Salt Lake, UT 84054 | Oil & Gas Operator | Dec 2009 |
| 500 | FMC Corporation | Green River, WY 82935 | Oil & Gas Operator | Dec 2008 |