| 501 | Cap Production | | Oil Operator | Dec 2024 |
| 502 | Capataz Operating Inc | Midland, TX 79702 | Oil & Gas Operator | Sep 2020 |
| 503 | Capco Offshore Of Texas, Inc. | Houston, TX 77056 | Oil & Gas Operator | Dec 2025 |
| 504 | Capco Offshore, Inc. | Irving, TX 75063 | Oil & Gas Operator | May 2012 |
| 505 | Capco Resource Corporation | Orange,, CA 92869 | Oil Operator | Sep 2007 |
| 506 | Capco Resources Corporation | Irving, TX 75016 | Oil & Gas Operator | Mar 2004 |
| 507 | Capco Resources Of Texas, Inc | Irving, TX 75063 | Oil & Gas Operator | Jun 2003 |
| 508 | Cape Oil Associates | | Oil & Gas Operator | Sep 1997 |
| 509 | Cape Operating, Inc. | Longview, TX 75608 | Oil & Gas Operator | Nov 2007 |
| 510 | Cape, Randy | Tyler, TX 75703 | Oil & Gas Operator | Mar 2008 |
| 511 | Capio Oil & Gas, Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2015 |
| 512 | Capital A Corp. | San Antonio, TX 78279 | Oil & Gas Operator | Jun 2002 |
| 513 | Capital Energy Group, Inc. | Bardonia, NY 10954 | Oil Operator | Jan 1998 |
| 514 | Capital Energy, LLC | Ripley, WV 25271 | Oil & Gas Operator | Dec 2021 |
| 515 | Capital Gas, Inc. | | Gas Operator | Jan 1998 |
| 516 | Capital Oil & Gas Inc | Austintown, OH 44515-3033 | Oil & Gas Operator | Dec 2024 |
| 517 | Capital Pet & Investments Inc | Oklahoma City, OK 73102-7400 | Oil & Gas Operator | Mar 2015 |
| 518 | Capital Production Company | | Oil Operator | Dec 1997 |
| 519 | Capital Programs Company Inc | Addison, TX 75001-6030 | Oil Operator | Jul 2021 |
| 520 | Capital Resource Management Inc | Austin, TX 78716 | Oil & Gas Operator | May 1999 |
| 521 | Capital Star Oil & Gas, Inc. | Houston, TX 77027 | Oil & Gas Operator | Dec 2025 |
| 522 | Capitan Energy, Incorporated | Carlsbad, NM 88221 | Oil & Gas Operator | Dec 2025 |
| 523 | Capitan Operating LLC | Reno, NV 89502 | Oil & Gas Operator | Jan 2013 |
| 524 | Capitol Oil & Gas Corporation | Centennial, WY 82055 | Oil Operator | Feb 2006 |
| 525 | Capitol Oil Corporation | | Oil & Gas Operator | Sep 2025 |
| 526 | Capitol Operating & Expl., Inc. | Austin, TX 78766 | Oil & Gas Operator | Feb 2001 |
| 527 | Capitol Operating Group, LLC | Lafayette, LA 70503-5334 | Oil & Gas Operator | Oct 2025 |
| 528 | Capitol Well Servicing Co., Inc. | Oklahoma City, OK 73143 | Oil & Gas Operator | May 2023 |
| 529 | Capmac Inc | Tulsa, OK 74105-7119 | Oil & Gas Operator | Jan 2007 |
| 530 | Capp Petroleum, LLC | Ashland, KY 41105 | Oil & Gas Operator | Dec 2020 |
| 531 | Cappellino, Nancy J. & Marina A. | Arcade, NY 14009 | Gas Operator | Dec 2024 |
| 532 | Capps, R. Oil Corp. | Midland, TX 79704 | Oil & Gas Operator | Oct 2002 |
| 533 | Caprock Drilling & Operating Co Inc | Edmonton, KY 42129 | Oil Operator | Dec 2023 |
| 534 | Caprock Energy, Inc. | Denton, TX 76205 | Oil & Gas Operator | Apr 1993 |
| 535 | Caprock Engineering, Inc. | Pampa, TX 79066 | Oil & Gas Operator | Nov 2018 |
| 536 | Caprock Exploration, Inc. | Monahans, TX 79756 | Oil & Gas Operator | Dec 2025 |
| 537 | Caprock Operating, Inc. | Midland, TX 79708 | Oil & Gas Operator | Dec 2007 |
| 538 | Caprock, Inc. | Ralls, TX 79357 | Oil & Gas Operator | Mar 2013 |
| 539 | Capstone Cactus Operating Comp. | Hennessey, OK 73742 | Oil & Gas Operator | Dec 2025 |
| 540 | Capstone Natural Res II, LLC | Tulsa, OK 74170 | Oil & Gas Operator | Feb 2020 |
| 541 | Capstone Natural Resources, LLC | Tulsa, OK 74136 | Oil & Gas Operator | May 2015 |
| 542 | Capstone Oil & Gas LLC | Hennessey, OK 73742 | Oil & Gas Operator | Aug 2025 |
| 543 | Capstone Oil Producing LLC | Millersburg, OH 44654 | Oil & Gas Operator | Dec 2024 |
| 544 | Capstone Oilfield Disposal Service LLC | Hennessey, OK 73742 | Oil Operator | Dec 2019 |
| 545 | Captain'S Oil Inc. | Louisburg, KS 66053 | Oil Operator | Sep 2003 |
| 546 | Capturepoint LLC | Allen, TX 75013 | Oil & Gas Operator | Dec 2025 |
| 547 | Car-Tex Producing Company | | Oil & Gas Operator | Dec 1994 |
| 548 | Cara Ventures In | | Oil Operator | May 1995 |
| 549 | Carageannis, Paul C | Attica, KS 67009 | Oil Operator | Feb 2001 |
| 550 | Caravel Energy O | | Oil & Gas Operator | Feb 1987 |
| 551 | Caraway Operating Co. | San Angelo, TX 76902 | Oil & Gas Operator | Dec 2025 |
| 552 | Caraway, Robert | Cisco, TX 76437 | Oil & Gas Operator | Dec 2025 |
| 553 | Caraway, Robert R. | Cisco, TX 76437 | Oil & Gas Operator | Dec 2025 |
| 554 | Carbon California Operating Company LLC | | Oil & Gas Operator | Oct 2025 |
| 555 | Carbon Creek Energy LLC | Sheridan, WY 82801 | Oil & Gas Operator | Sep 2025 |
| 556 | Carbon Economy LLC | Chickasha, OK 73023 | Oil & Gas Operator | Sep 2025 |
| 557 | Carbon Energy Corporation (USA) | Denver, CO 80290 | Oil & Gas Operator | Jul 2004 |
| 558 | Carbon Field Energy, L.L.C. | Kilgore, TX 75663 | Oil Operator | Apr 2019 |
| 559 | Carbon Oil Inc | Vidor, TX 77670 | Oil & Gas Operator | Dec 2025 |
| 560 | Carbon Ridge Energy LLC | Norman, OK 73069 | Oil & Gas Operator | Sep 2025 |
| 561 | Carburante Exploration Co, LTD. | Granbury, TX 76048 | Oil & Gas Operator | Dec 2025 |
| 562 | Card Operating Company, Inc. | Tyler, TX 75713 | Oil & Gas Operator | Dec 1995 |
| 563 | Carder Oil Company | | Oil & Gas Operator | Dec 2024 |
| 564 | Cardinal & Great Plains & Kaufman | | Oil Operator | Apr 1985 |
| 565 | Cardinal Drilling Co. | | Oil Operator | Jan 2007 |
| 566 | Cardinal Energy | | Oil & Gas Operator | Dec 2008 |
| 567 | Cardinal Energy Company | Rowlett, TX 75088 | Oil & Gas Operator | Dec 2025 |
| 568 | Cardinal Expl And Prod | | Oil & Gas Operator | May 2019 |
| 569 | Cardinal Oil & Gas, Inc. | | Oil & Gas Operator | Jun 1995 |
| 570 | Cardinal Oil Company, Inc. | | Oil Operator | Dec 2024 |
| 571 | Cardinal Oil LLC | Drumright, OK 74030 | Oil & Gas Operator | Sep 2025 |
| 572 | Cardinal Operating Corporation | Waxahachie, TX 75165 | Oil & Gas Operator | Jan 1997 |
| 573 | Cardinal Petroleum Co. | | Oil & Gas Operator | May 2004 |
| 574 | Cardinal Petroleum Corp Of La | | Oil Operator | May 2003 |
| 575 | Cardinal Producing Co. | Abilene, TX 79606 | Oil & Gas Operator | Aug 2003 |
| 576 | Cardinal River Operating LLC | Oklahoma City, OK 73102-7109 | Oil & Gas Operator | Aug 2025 |
| 577 | Cardinal Shares, Inc. | West Bloomfld, MI 48322 | Oil & Gas Operator | Mar 2004 |
| 578 | Cardinal Wyoming LLC | | Oil & Gas Operator | Sep 2025 |
| 579 | Cardneaux Inc | | Oil & Gas Operator | Aug 2009 |
| 580 | Cardwell Oil Corporation | Midland, TX 79710 | Oil & Gas Operator | Dec 2025 |
| 581 | Cardwell'S U Bar Oil | Manor, TX 78653 | Oil & Gas Operator | Dec 2025 |
| 582 | Carey Gas Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Jun 1999 |
| 583 | Carey Resources Inc | Great Neck, NY 11023 | Oil & Gas Operator | Dec 1988 |
| 584 | Carey, Shirley L. Trust | Abilene, TX 79608 | Oil & Gas Operator | Dec 2025 |
| 585 | Cargas Operating Company | | Oil & Gas Operator | Dec 2024 |
| 586 | Caribbean Energy LLC II | Cotulla, TX 78014 | Oil & Gas Operator | Dec 2025 |
| 587 | Caribbean Energy, L.L.C. | Cotulla, TX 78014 | Oil & Gas Operator | Nov 2019 |
| 588 | Caribbean Oil & Gas Corp | | Oil & Gas Operator | Mar 1980 |
| 589 | Caribe Production Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Dec 1993 |
| 590 | Caribe Resources, Inc. | | Oil & Gas Operator | Jan 1985 |
| 591 | Caribou Operating Co. | Granbury, TX 76048 | Oil & Gas Operator | Mar 2010 |
| 592 | Caribou Operating, Inc. | Granbury, TX 76048 | Oil & Gas Operator | Dec 2025 |
| 593 | Carken LLC | Andrews, TX 79714 | Oil Operator | Dec 2025 |
| 594 | Carl E Gungoll Exploration Inc | Oklahoma City, OK 73154-0466 | Oil & Gas Operator | Jan 2016 |
| 595 | Carl E Gungoll Exploration LLC | Oklahoma City, OK 73154 | Oil & Gas Operator | Aug 2025 |
| 596 | Carl E Smith Petroleum Inc | Dallas, TX 75234-6057 | Oil & Gas Operator | Dec 2019 |
| 597 | Carl E. Hansford | | Oil Operator | Oct 1980 |
| 598 | Carl Humphries Inc | Piedmont, OK 73078-0514 | Oil & Gas Operator | Sep 2025 |
| 599 | Carl Oil & Gas Co. | Bakersfield, CA 93309 | Oil & Gas Operator | Dec 1995 |
| 600 | Carl Oil & Gas Co.-CNG | | Oil & Gas Operator | Dec 1995 |