| 401 | Amoco Production Co. | Houston, TX 77253 | Oil & Gas Operator | Jun 2015 |
| 402 | Ampak Oil Company | Plano, TX 75074 | Oil & Gas Operator | Jul 2025 |
| 403 | Amplify Energy Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 404 | Amron Petroleum, Inc. | Midland, TX 79708 | Oil & Gas Operator | Jan 1996 |
| 405 | Amt Resources, Inc. | Cisco, TX 76437 | Oil & Gas Operator | Jul 2025 |
| 406 | Amtex Energy | Midland, TX 79702 | Oil & Gas Operator | Aug 1995 |
| 407 | Amtex Energy, Inc. | Fort Worth, TX 76147 | Oil & Gas Operator | Jul 2025 |
| 408 | Amx Energy, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Jul 2025 |
| 409 | Anadarko Austin Chalk Company | Houston, TX 77251 | Oil & Gas Operator | Feb 2006 |
| 410 | Anadarko E&P Company LP | Houston, TX 77251 | Oil & Gas Operator | Aug 2014 |
| 411 | Anadarko E&P Onshore LLC | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 412 | Anadarko Minerals Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | May 2025 |
| 413 | Anadarko Ogc Company | Houston, TX 77251 | Oil & Gas Operator | Dec 1998 |
| 414 | Anadarko Petroleum Co | Houston, TX 77227 | Oil & Gas Operator | Feb 1998 |
| 415 | Anadarko Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | May 2025 |
| 416 | Ananda Energy Inc. | Pampa, TX 79065 | Oil & Gas Operator | Jan 2021 |
| 417 | Anaqua Oil & Gas, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Mar 2008 |
| 418 | Anatexas Offshore, Inc. | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 419 | Anathema, Inc. | Abilene, TX 79601 | Oil & Gas Operator | Dec 1994 |
| 420 | Ancell Oil Co. | Wichita Falls, TX 76309 | Oil & Gas Operator | Dec 2018 |
| 421 | Anchor B Production, Inc. | Orla, TX 79770 | Oil & Gas Operator | Aug 2003 |
| 422 | Anchor Oil Company | Gruver, TX 79040 | Gas Operator | Jul 2025 |
| 423 | Anchor Operating Co. | Houston, TX 77055 | Oil & Gas Operator | Jul 2025 |
| 424 | Anchor Petroleum, Inc. | Lubbock, TX 79464 | Oil & Gas Operator | Jan 1996 |
| 425 | Anco Account | Wichita Falls, TX 76301 | Oil & Gas Operator | Oct 1995 |
| 426 | Andalucia Oil Company | San Antonio, TX 78258 | Oil Operator | Jul 2025 |
| 427 | Andector Exploration Company | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 428 | Anderman/Smith Operating Company | Tulsa, OK 74136 | Oil & Gas Operator | Sep 1995 |
| 429 | Anderson Energy Corporation | Arvada, CO 80004 | Oil & Gas Operator | Jul 2025 |
| 430 | Anderson Oil & Gas Account | Wichita Falls, TX 76301 | Oil & Gas Operator | Nov 2013 |
| 431 | Anderson Oil Company | Burkburnett, TX 76354 | Oil & Gas Operator | Dec 2015 |
| 432 | Anderson Oil Corporation | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Nov 1999 |
| 433 | Anderson Oil LTD. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2025 |
| 434 | Anderson Petro-Equipment, Inc. | Montgomery, TX 77356 | Oil & Gas Operator | Jul 2025 |
| 435 | Anderson Producing, Inc. | Houston, TX 77057 | Oil & Gas Operator | Sep 2013 |
| 436 | Anderson Production | Cisco, TX 76437 | Oil & Gas Operator | Jul 2025 |
| 437 | Anderson, Carl T. | Wichita Falls, TX 76301 | Oil & Gas Operator | Feb 2014 |
| 438 | Anderson, Dorman | Wichita Falls, TX 76307 | Oil & Gas Operator | Dec 2012 |
| 439 | Anderson, E D | Cisco, TX 76437 | Oil & Gas Operator | Nov 2009 |
| 440 | Anderson, James K. Inc. | Abilene, TX 79608 | Oil & Gas Operator | Jul 2025 |
| 441 | Anderson, Roger W. Corp. | Clyde, TX 79510 | Oil & Gas Operator | Apr 2020 |
| 442 | Anderson, Steven C. | Victoria, TX 77902 | Gas Operator | Jun 2004 |
| 443 | Ando Energy, Inc. | Graham, TX 76450 | Oil & Gas Operator | Feb 1998 |
| 444 | Andrew Alan Exploration, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2017 |
| 445 | Andrew, Robert Oneal | Olney, TX 76374 | Oil & Gas Operator | Sep 1998 |
| 446 | Andrews & Corkran, L.L.C. | Austin, TX 78746 | Oil & Gas Operator | Feb 2000 |
| 447 | Andrews, B. C. | Graham, TX 76450 | Oil & Gas Operator | Jul 2025 |
| 448 | Andrus Resources Corporation | Houston, TX 77046 | Oil & Gas Operator | Oct 2002 |
| 449 | Anegada Resources | Kerrville, TX 78029 | Oil & Gas Operator | Jan 2002 |
| 450 | Anejo Production, LLC | Electra, TX 76360 | Oil & Gas Operator | Jul 2025 |
| 451 | Angel Operating LLC | Metairie, LA 70033 | Oil Operator | Jul 2025 |
| 452 | Angelo, Ernest, Jr. | Midland, TX 79701 | Oil & Gas Operator | Mar 2008 |
| 453 | Angle Oil Company | Hays, KS 67601 | Oil Operator | Sep 2002 |
| 454 | Anloc, LLC | Houston, TX 77024 | Oil & Gas Operator | Apr 2019 |
| 455 | Anr Production Company | Houston, TX 77046 | Oil & Gas Operator | Aug 2017 |
| 456 | Anschutz Exploration Corporation | Denver, CO 80202 | Oil & Gas Operator | Jul 2025 |
| 457 | Anson Company | Oklahoma City, OK 73124 | Oil & Gas Operator | Apr 2018 |
| 458 | Antara Resources Inc | Houston, TX 77002 | Oil & Gas Operator | Apr 2004 |
| 459 | Antares Energy Company | Houston, TX 77010 | Oil & Gas Operator | Jul 2025 |
| 460 | Antares Oil Corp | Denver, CO 80202 | Oil & Gas Operator | Oct 2015 |
| 461 | Antelope Energy Company LLC | Denver, CO 80202 | Oil & Gas Operator | Dec 2024 |
| 462 | Antelope Energy Partners, LLC | Houston, TX 77027 | Oil & Gas Operator | Jul 2025 |
| 463 | Antelope Production Co. | Midland, TX 79701 | Oil & Gas Operator | Oct 1995 |
| 464 | Antelope Resources Inc | Billings, MT 59101 | Oil & Gas Operator | May 2017 |
| 465 | Antero Resources I, LP | Denver, CO 80202 | Oil & Gas Operator | Jun 2005 |
| 466 | Antero Resources II, LP | Denver, CO 80202 | Oil & Gas Operator | May 2006 |
| 467 | Anthony Oil & Gas Co. | Shreveport, LA 71135 | Oil Operator | May 1993 |
| 468 | Anthony, Bob G. Inc. | Brookhaven, MS 39601 | Oil & Gas Operator | Jul 2025 |
| 469 | Antilley, Joe | Abilene, TX 79602 | Oil & Gas Operator | Jan 2024 |
| 470 | Antle Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | Jul 2025 |
| 471 | Antle, E. | Graham, TX 76450 | Oil & Gas Operator | Oct 1994 |
| 472 | Aoco Operating Company, L.L.C. | Houston, TX 77008 | Oil & Gas Operator | Feb 2005 |
| 473 | Aoco Operating, L.P. | Houston, TX 77008 | Oil & Gas Operator | Mar 2008 |
| 474 | Aog, Inc. | Norman, OK 73070 | Oil & Gas Operator | Nov 2014 |
| 475 | Aogp, LLC | Turtle Lake, WI 54889 | Oil & Gas Operator | Sep 2019 |
| 476 | Aop Operating Corporation | Dallas, TX 75313 | Oil & Gas Operator | Aug 2003 |
| 477 | Ap Operating, Inc. | Plano, TX 75074 | Oil & Gas Operator | Jul 2025 |
| 478 | Apache Corporation | Houston, TX 77042 | Oil & Gas Operator | Jul 2025 |
| 479 | Apache Energy Resources Corp | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 480 | Apache Oil Company | San Antonio, TX 78227 | Oil & Gas Operator | Jun 2023 |
| 481 | Apache Production Company | Holliday, TX 76366 | Oil & Gas Operator | Jul 2025 |
| 482 | Apache Shelf, Inc. | Houston, TX 77056 | Oil & Gas Operator | Jan 2014 |
| 483 | Apb Oil Corporation | Houston, TX 77052 | Oil & Gas Operator | Apr 1996 |
| 484 | Apc Operating Partnership | Tulsa, OK 74136 | Oil & Gas Operator | Oct 1996 |
| 485 | Apco Oil Corporation | Oklahoma City, OK 73116 | Oil & Gas Operator | Jun 1993 |
| 486 | Apex Energy, Inc. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Jul 2025 |
| 487 | Apex Oil & Gas, Inc. | Houston, TX 77067 | Oil & Gas Operator | Oct 2009 |
| 488 | Apex Operating & Equip. Co. | Bowie, TX 76230 | Oil & Gas Operator | Nov 2003 |
| 489 | Apex Operating Partners, LLC | San Angelo, TX 76902 | Oil & Gas Operator | Jul 2025 |
| 490 | Apex Production LTD. | Albany, TX 76430 | Oil Operator | Jul 2025 |
| 491 | Apex Resources Inc | Allison Park, PA 15101-3838 | Oil & Gas Operator | Dec 1993 |
| 492 | Apex Resources LLC | Kilgore, TX 75663 | Oil & Gas Operator | Jul 2025 |
| 493 | Apex Royalties, Inc. | Midland, TX 79702 | Oil & Gas Operator | May 1997 |
| 494 | Apexco, Inc. | Sand Springs, OK 74063 | Oil & Gas Operator | Mar 2025 |
| 495 | API Operating Co. | Houston, TX 77036 | Oil & Gas Operator | Jul 2025 |
| 496 | Apollo Energy Operating Co, LP | Lake Charles, LA 70601 | Oil & Gas Operator | Dec 2024 |
| 497 | Appling, J. B. | Midland, TX 79702 | Oil & Gas Operator | Jul 1997 |
| 498 | Approach Operating LLC | Fort Worth, TX 76116 | Oil & Gas Operator | Sep 2020 |
| 499 | Apr Operating LLC | Midland, TX 79701 | Oil & Gas Operator | Jun 2022 |
| 500 | Apv McCamey LLC | MC Camey, TX 79752 | Oil & Gas Operator | Jul 2025 |