| 1501 | City Of Chanute | Chanute, KS 66720 | Oil Operator | Feb 1994 |
| 1502 | City Of Cuyahoga Falls | Cuyahoga Falls, OH 44221 | Oil & Gas Operator | Dec 2024 |
| 1503 | City Of Dumas | Dumas, TX 79029 | Gas Operator | Feb 2026 |
| 1504 | City Of Dunkirk Waste Water Treatment Plant | Dunkirk, NY 14048 | Gas Operator | Dec 2024 |
| 1505 | City Of Garden City, Kansas | Garden City, KS 67846 | Gas Operator | Sep 2025 |
| 1506 | City Of Hermosa Beach | | Oil & Gas Operator | Dec 2005 |
| 1507 | City Of Hugoton, Kansas | Hugoton, KS 67951 | Gas Operator | Aug 2025 |
| 1508 | City Of Huntington Beach (Fire Dept.) | | Oil & Gas Operator | Dec 2025 |
| 1509 | City Of McLean | McLean, TX 79057 | Gas Operator | Aug 2025 |
| 1510 | City Of Newport Beach | | Oil & Gas Operator | Dec 2025 |
| 1511 | City Of Santa Fe Springs | | Oil Operator | Dec 2007 |
| 1512 | City Of Satanta | Satanta, KS 67870 | Gas Operator | Sep 2025 |
| 1513 | City Of Sunray Utilities | Sunray, TX 79086 | Oil & Gas Operator | Feb 2026 |
| 1514 | City Of White Deer | White Deer, TX 79097 | Gas Operator | May 2017 |
| 1515 | City Oil Corp. Oper. For | | Oil & Gas Operator | Dec 1989 |
| 1516 | Civego, Inc. | | Oil & Gas Operator | Jul 1994 |
| 1517 | Civic Energy Corporation | Colony, OK 73021 | Oil & Gas Operator | Dec 2025 |
| 1518 | Civiletto, George & Wendy | Fredonia, NY 14063 | Gas Operator | Dec 2024 |
| 1519 | Civitas North LLC | | Oil & Gas Operator | Dec 2025 |
| 1520 | Civitas Permian Operating, LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2026 |
| 1521 | Civron Petroleum Res., LLC | San Antonio, TX 78229 | Oil & Gas Operator | Feb 2026 |
| 1522 | CJ Oil Inc | Madison, KS 66860 | Oil Operator | Sep 2025 |
| 1523 | CJR Operating LLC | Wister, OK 74966 | Gas Operator | Nov 2025 |
| 1524 | CJRW Oil & Gas | MC Camey, TX 79752 | Oil Operator | Feb 2026 |
| 1525 | CK Oil | | Oil Operator | Aug 2025 |
| 1526 | CK Oil & Gas LLC | Herington, KS 67449 | Oil & Gas Operator | Mar 2025 |
| 1527 | CK Operating Company, LLC | Wichita Falls, TX 76308 | Oil Operator | Feb 2026 |
| 1528 | CK Resources | Cleveland, OK 74020-0772 | Oil Operator | Aug 2013 |
| 1529 | CK5 Services LLC | Zephyr, TX 76890 | Oil & Gas Operator | Sep 2025 |
| 1530 | CKB Corporation | Borger, TX 79008 | Oil & Gas Operator | Aug 1997 |
| 1531 | CKT Energy LLC | Dallas, TX 75379 | Oil & Gas Operator | Sep 2020 |
| 1532 | CL&F Operating LLC | Spring, TX 77389 | Oil & Gas Operator | Dec 2022 |
| 1533 | Cla-Mar Oil Company, LLC | Hays, KS 67601 | Oil Operator | Dec 2019 |
| 1534 | Claassen Oil And Gas Inc | Estes Park, CO 80517 | Oil & Gas Operator | Sep 2025 |
| 1535 | Claborn Julia | Okmulgee, OK 74447-9781 | Oil & Gas Operator | Mar 2022 |
| 1536 | Claco Oil Co | Artesia, NM 88210 | Oil & Gas Operator | Dec 2014 |
| 1537 | Claiborne-McDonald Inc | Chickasha, OK 73018 | Oil Operator | Jul 2007 |
| 1538 | Claibourn, Darrel R. | Neodesha, KS 66757 | Oil Operator | Oct 2011 |
| 1539 | Clair Oil, Inc. | Russell, KS 67665 | Oil Operator | Nov 2019 |
| 1540 | Clamp Operating | San Antonio, TX 78264 | Oil & Gas Operator | Apr 2002 |
| 1541 | Clamp Operating Incorporated | San Antonio, TX 78264 | Oil & Gas Operator | Mar 2011 |
| 1542 | Clapp Carl O | Cedar Vale, KS 67024 | Oil Operator | Aug 2013 |
| 1543 | Clapp Oil LLC | | Oil Operator | Sep 2025 |
| 1544 | Clarco Gas Co., Inc. | Westmont, IL 60559 | Oil Operator | Dec 2011 |
| 1545 | Claremont Corporation | Tulsa, OK 74114 | Oil & Gas Operator | Nov 2025 |
| 1546 | Claremont Energy | | Gas Operator | Dec 1993 |
| 1547 | Claremont Exploration Inc | Tulsa, OK 74103-4107 | Oil & Gas Operator | Jun 1997 |
| 1548 | Clarence F. Routon, Jr. | | Oil Operator | Apr 1990 |
| 1549 | Clarence K Tussel Jr LTD | Jefferson, OH 44047 | Oil & Gas Operator | Dec 2024 |
| 1550 | Clarence Kenyon | | Gas Operator | Jul 1977 |
| 1551 | Clarence R. Barnett Inc. | | Oil & Gas Operator | Jul 2025 |
| 1552 | Clarita Operating LLC | Ada, OK 74821 | Oil Operator | Jun 2022 |
| 1553 | Clark And Clark | Princeton, NJ 08540-1930 | Oil & Gas Operator | Jul 2013 |
| 1554 | Clark B & Cahoj | | Oil Operator | Apr 1995 |
| 1555 | Clark Blake | | Gas Operator | Sep 2023 |
| 1556 | Clark Energy Company | Edmond, OK 73003-6706 | Oil & Gas Operator | Aug 2013 |
| 1557 | Clark Energy, LLC | Chanute, KS 66720 | Oil & Gas Operator | Jun 2022 |
| 1558 | Clark Exploratio | | Oil & Gas Operator | Jun 1991 |
| 1559 | Clark Exploration Company | Highlands Ranch, CO 80126-7645 | Oil & Gas Operator | Nov 2024 |
| 1560 | Clark Krista | Ada, OK 74820-8595 | Oil Operator | Sep 2001 |
| 1561 | Clark Moran Resources LLC | Tulsa, OK 74135-2282 | Oil & Gas Operator | Oct 2022 |
| 1562 | Clark Oil & Gas Inc | | Oil & Gas Operator | Dec 1990 |
| 1563 | Clark Oil Co. | Dallas, TX 75360 | Oil & Gas Operator | Feb 2026 |
| 1564 | Clark Oil Producing Company | | Oil & Gas Operator | Oct 1979 |
| 1565 | Clark Oil, LLC | Wellsville, KS 66092 | Oil Operator | Apr 2022 |
| 1566 | Clark Operating | Wichita Falls, TX 76308 | Oil & Gas Operator | Aug 2003 |
| 1567 | Clark Operating Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2026 |
| 1568 | Clark Operating Services Inc | Okmulgee, OK 74447 | Oil & Gas Operator | May 2013 |
| 1569 | Clark Well Service | Depew, OK 74028-0296 | Oil & Gas Operator | Aug 2013 |
| 1570 | Clark, B. C. | Cross Plains, TX 76443 | Oil Operator | Dec 2007 |
| 1571 | Clark, Daniel J. | Auburn, NY 13021 | Gas Operator | Dec 2024 |
| 1572 | Clark, Daryl | Phillipsburg, KS 67661 | Oil Operator | Aug 2025 |
| 1573 | Clark, Donald E. | | Gas Operator | Dec 2003 |
| 1574 | Clark, Donald-Roger Young | | Oil & Gas Operator | Jan 1988 |
| 1575 | Clark, G. A., Trustee | San Antonio, TX 78210 | Oil & Gas Operator | Nov 2017 |
| 1576 | Clark, John M. | Midland, TX 79701 | Oil & Gas Operator | Dec 1993 |
| 1577 | Clark, John M., Inc. | Midland, TX 79704 | Oil & Gas Operator | Feb 2026 |
| 1578 | Clark, N.G. Dba Glenn, Inc | | Oil & Gas Operator | Dec 2021 |
| 1579 | Clark, Noel D. Et Al | | Oil & Gas Operator | Mar 1994 |
| 1580 | Clark, Richard E., Inc. | Longview, TX 75604 | Oil & Gas Operator | May 2001 |
| 1581 | Clark, Robert A. | Wichita, KS 67202 | Gas Operator | Jul 1990 |
| 1582 | Clarkco Services, Inc. | | Oil & Gas Operator | Oct 2025 |
| 1583 | Clarke Corporati | Medicine Lodge, KS 67104 | Oil & Gas Operator | Sep 2025 |
| 1584 | Clarkston Oil Co | | Oil Operator | Dec 2025 |
| 1585 | Clarkston Oil Corp | | Oil Operator | Dec 2025 |
| 1586 | Claron Corporation | Houston, TX 77219 | Oil & Gas Operator | Feb 2026 |
| 1587 | Class Oil | Hays, KS 67601 | Oil Operator | Jun 1991 |
| 1588 | Class Petroleum Corporation | Barnsdall, OK 74002 | Oil Operator | Aug 2013 |
| 1589 | Classic Energy Incorporated | Tyler, TX 75701 | Oil & Gas Operator | Jul 2005 |
| 1590 | Classic Hydrocarbons, Inc. | | Gas Operator | Dec 2007 |
| 1591 | Classic Oil & Gas Resources Inc | | Gas Operator | Dec 2008 |
| 1592 | Classic Oil & Gas, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Jan 2004 |
| 1593 | Classic Operating Co. LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 1594 | Classic Petroleum Partners, Inc. | Whitehouse, TX 75791 | Oil & Gas Operator | Feb 2026 |
| 1595 | Classic Well Service, Inc. | Claflin, KS 67525 | Oil Operator | Dec 2019 |
| 1596 | Claude Debeaux, Jr. Et Al | | Oil Operator | Dec 1999 |
| 1597 | Claude S. Hinds | | Oil Operator | Aug 1985 |
| 1598 | Claude-Maggie Co. | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 1599 | Clausen, A. G. | Cross Plains, TX 76443 | Oil & Gas Operator | Feb 2026 |
| 1600 | Clausing, Garry | Coffeyville, KS 67337 | Oil Operator | Apr 2024 |