| 1401 | Cig Exploration | Denver, CO 80201 | Oil & Gas Operator | Sep 1999 |
| 1402 | Cig Exploration Inc | Houston, TX 77046 | Oil & Gas Operator | Nov 1999 |
| 1403 | Cig Resources Company | Colorado Spring, CO 80944-1087 | Oil & Gas Operator | Jun 2018 |
| 1404 | Cigna Energy Resources Inc | Englewood, CO 80155-5038 | Oil Operator | Nov 1998 |
| 1405 | Cimarex Energy Co | Midland, TX 79706 | Oil & Gas Operator | Apr 2025 |
| 1406 | Cimarex Energy Co. Of Colorado | Midland, TX 79706 | Oil & Gas Operator | Apr 2025 |
| 1407 | Cimarron Engineering Corp. | Kingsville, TX 78364 | Oil & Gas Operator | May 2015 |
| 1408 | Cimarron Engineering, LLC | Kingsville, TX 78364 | Oil & Gas Operator | Apr 2025 |
| 1409 | Cimarron Management Corp | | Oil & Gas Operator | Jul 2020 |
| 1410 | Cimarron Oil & Gas Inc | Perry, OK 73077-1318 | Oil & Gas Operator | Sep 2000 |
| 1411 | Cimarron Operating Company | Oklahoma City, OK 73112-3967 | Oil & Gas Operator | May 2011 |
| 1412 | Cimarron Petroleum Corporation | Houston, TX 77057-2696 | Oil & Gas Operator | Jan 2025 |
| 1413 | Cimarron Production Co Inc | Oklahoma City, OK 73142-3017 | Oil & Gas Operator | Jan 2025 |
| 1414 | Cimarron Properties, Inc. | San Angelo, TX 76904 | Oil & Gas Operator | Nov 1997 |
| 1415 | Cimarron River Operating Co | Mannford, OK 74044 | Oil & Gas Operator | Jan 2025 |
| 1416 | Cimarron Transmission Co | Ardmore, OK 73401 | Oil Operator | Jan 2025 |
| 1417 | Cimarron Valley Energy Inc | Stillwater, OK 74076 | Oil Operator | Apr 2015 |
| 1418 | Cimic Energy, LLC | | Oil Operator | Jan 2025 |
| 1419 | Ciminello, Angeline | Fredonia, NY 14063 | Gas Operator | Dec 2023 |
| 1420 | Cinab, Inc. | FT. Scott, KS 66701 | Oil Operator | Jan 1998 |
| 1421 | Cinco Exploratio | | Oil & Gas Operator | Jan 1988 |
| 1422 | Cinco General Partnership | Albuquerque, NM 87103 | Oil & Gas Operator | Oct 1999 |
| 1423 | Cinco Natural Resources Corp | La Grange, TX 78945 | Oil & Gas Operator | Apr 2025 |
| 1424 | Cinco Oil & Gas, LLC | Dallas, TX 75204 | Oil & Gas Operator | Apr 2025 |
| 1425 | Cincris Energy C | | Oil & Gas Operator | Jun 1991 |
| 1426 | Cinder Production Company | | Oil & Gas Operator | Apr 2014 |
| 1427 | Cinnabar Energy, LTD. | Fort Worth, TX 76107 | Oil & Gas Operator | May 2018 |
| 1428 | Cinnabar Operating, LLC | Fort Worth, TX 76121 | Oil & Gas Operator | Apr 2025 |
| 1429 | Cinnamon Creek Oil & Gas Inc | | Oil Operator | Feb 2025 |
| 1430 | Cinron Energy, LLC | Arp, TX 75750 | Oil & Gas Operator | Apr 2025 |
| 1431 | Cippele Resources Co. | Longview, TX 75608 | Oil & Gas Operator | May 1994 |
| 1432 | Circle "M" Energy Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Aug 2003 |
| 1433 | Circle 9 Resources LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Jan 2025 |
| 1434 | Circle B Oil & Gas | Bowie, TX 76230 | Oil & Gas Operator | Dec 2021 |
| 1435 | Circle C Oilfield Supply Inc | Wetumka, OK 74883-0068 | Oil & Gas Operator | Apr 2017 |
| 1436 | Circle C Operations | Winnsboro, TX 75494 | Oil Operator | Apr 2025 |
| 1437 | Circle D Oil & Gas, Inc. | Brownwood, TX 76801 | Oil & Gas Operator | Apr 2025 |
| 1438 | Circle E Oil - E | | Oil Operator | May 1990 |
| 1439 | Circle H Oil Company | Big Spring, TX 79721 | Oil & Gas Operator | Apr 2020 |
| 1440 | Circle K Enterprises | | Oil & Gas Operator | Jun 2024 |
| 1441 | Circle K Oil & Gas Inc | Sand Springs, OK 74063 | Oil & Gas Operator | Jan 2025 |
| 1442 | Circle L Exploration | Independence, KS 67301 | Gas Operator | May 2015 |
| 1443 | Circle Ridge Production, Inc. | Graham, TX 76450 | Oil & Gas Operator | Apr 2025 |
| 1444 | Circle T Oil | | Oil Operator | Nov 2024 |
| 1445 | Circle W Oil & Gas Company | Pampa, TX 79066 | Oil & Gas Operator | Apr 2025 |
| 1446 | Circle W Operating, Inc. | Mertzon, TX 76941 | Oil & Gas Operator | Apr 2025 |
| 1447 | Circle-S Energy, LLC | McKinney, TX 75071 | Oil & Gas Operator | Apr 2025 |
| 1448 | Circleville Gas Co | Westerville, OH 43081 | Oil & Gas Operator | Dec 2004 |
| 1449 | Ciri Production Company | | Gas Operator | Mar 1994 |
| 1450 | Ciris Energy Inc | Centennial, CO 80112 | Gas Operator | Dec 2016 |
| 1451 | Cirque Resources LP | Denver, CO 80202 | Oil & Gas Operator | Aug 2016 |
| 1452 | Cirrus Exploration Company | Prosper, TX 75078 | Oil & Gas Operator | Apr 2025 |
| 1453 | Cirrus Production Company | Enid, OK 73702 | Oil & Gas Operator | Jan 2025 |
| 1454 | Cisco Expro LLC | Park City, UT 84098-5178 | Oil & Gas Operator | Nov 2009 |
| 1455 | Cisco Operating LLC | Plano, TX 75024 | Oil & Gas Operator | Feb 2025 |
| 1456 | Cisco Petroleum, Inc. | | Oil & Gas Operator | Oct 2010 |
| 1457 | Cisco Production Company, LLC | Victoria, TX 77902 | Oil & Gas Operator | May 2012 |
| 1458 | Citadel Exploration Inc. | | Oil Operator | Dec 2024 |
| 1459 | Citadel Oil LLC | Edmond, OK 73083 | Oil Operator | Dec 2024 |
| 1460 | Citadel Production Company, Inc. | Denver, CO 80201 | Oil Operator | Sep 1996 |
| 1461 | Citation Energy | | Oil & Gas Operator | Jul 1993 |
| 1462 | Citation Energy Company | Marietta, OH 45750 | Oil & Gas Operator | Dec 2023 |
| 1463 | Citation Oil & G | | Oil & Gas Operator | Dec 1996 |
| 1464 | Citation Oil & Gas Corp. | Houston, TX 77269 | Oil & Gas Operator | Apr 2025 |
| 1465 | Cities Serv Oil & Gas Corp | Oklahoma City, OK 73112 | Oil & Gas Operator | Sep 1964 |
| 1466 | Cities Service Company | | Oil & Gas Operator | Mar 1983 |
| 1467 | Cities Service Oil & Gas Corp | | Oil & Gas Operator | Mar 1988 |
| 1468 | Cities Service Oil Co. | | Oil & Gas Operator | Dec 1986 |
| 1469 | Cities Services Company | | Oil & Gas Operator | Mar 2008 |
| 1470 | Citizen Energy II LLC | Tulsa, OK 74103-3729 | Oil & Gas Operator | Dec 2024 |
| 1471 | Citizen Energy III LLC | Devner, CO 80202 | Oil & Gas Operator | Jan 2025 |
| 1472 | Citmoco Services, Inc. | | Oil Operator | Jan 1971 |
| 1473 | Citori Oil Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Nov 2004 |
| 1474 | Citori Oil Company, LLC | Wichita Falls, TX 76308 | Oil & Gas Operator | May 2014 |
| 1475 | Citronelle Operating Co., LLC | | Oil & Gas Operator | Sep 1997 |
| 1476 | Citrus Energy Corporation | Castle Rock, CO 80104 | Oil & Gas Operator | Mar 2020 |
| 1477 | Cits BK & Trust Of Springhill | | Oil & Gas Operator | Jun 1990 |
| 1478 | City & County Of Denver | | Oil & Gas Operator | Sep 2023 |
| 1479 | City Of Akron | Akron, OH 44308 | Oil & Gas Operator | Dec 2024 |
| 1480 | City Of Baker | Baker, MT 59313 | Gas Operator | Jan 2025 |
| 1481 | City Of Brady | Brady, TX 76825 | Gas Operator | Feb 1998 |
| 1482 | City Of Chanute | Chanute, KS 66720 | Oil Operator | Feb 1994 |
| 1483 | City Of Cuyahoga Falls | Cuyahoga Falls, OH 44221 | Oil & Gas Operator | Dec 2024 |
| 1484 | City Of Dumas | Dumas, TX 79029 | Gas Operator | Apr 2025 |
| 1485 | City Of Garden City, Kansas | Garden City, KS 67846 | Gas Operator | Dec 2024 |
| 1486 | City Of Hermosa Beach | | Oil & Gas Operator | Dec 2005 |
| 1487 | City Of Hugoton, Kansas | Hugoton, KS 67951 | Gas Operator | Dec 2024 |
| 1488 | City Of Huntington Beach (Fire Dept.) | | Oil & Gas Operator | Dec 2024 |
| 1489 | City Of McLean | McLean, TX 79057 | Gas Operator | Apr 2025 |
| 1490 | City Of Newport Beach | | Oil & Gas Operator | Dec 2024 |
| 1491 | City Of Santa Fe Springs | | Oil Operator | Dec 2007 |
| 1492 | City Of Satanta | Satanta, KS 67870 | Gas Operator | Sep 2024 |
| 1493 | City Of Sunray Utilities | Sunray, TX 79086 | Oil & Gas Operator | Apr 2025 |
| 1494 | City Of White Deer | White Deer, TX 79097 | Gas Operator | May 2017 |
| 1495 | City Oil Corp. Oper. For | | Oil & Gas Operator | Dec 1989 |
| 1496 | Civego, Inc. | | Oil & Gas Operator | Jul 1994 |
| 1497 | Civic Energy Corporation | Colony, OK 73021 | Oil & Gas Operator | Jan 2025 |
| 1498 | Civiletto, George & Wendy | Fredonia, NY 14063 | Gas Operator | Dec 2023 |
| 1499 | Civitas North LLC | | Oil & Gas Operator | Feb 2025 |
| 1500 | Civitas Permian Operating, LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 2025 |