| Christensen, Jan | 100416 | — | 1 | 1 |
| Christmann, John J | 100417 | Pinedale | 2 | 1 |
| Chritton, George A Jr | 100418 | Moab | 0 | 0 |
| CIG Exploration Inc | 100419 | Denver | 17 | 2 |
| Cimarex Energy Co | 100420 | Tulsa | 7 | 2 |
| Cimarron Chemical Inc | 100421 | Houston | 0 | 0 |
| Cimarron Energy Corp | 100422 | Centennial | 0 | 0 |
| Cimarron Operating Co LC | 100423 | Littleton | 1 | 1 |
| Cimarron Petroleum Corp | 100424 | Calgary, Alberta | 3 | 1 |
| Cisco Drilling & Devel | 100425 | — | 22 | 1 |
| Cisco Expro LLC | 100426 | Park City | 1 | 1 |
| Cisco Pit | 100427 | — | 0 | 0 |
| Citation Oil & Gas CorpActive | 100430 | Houston | 99 | 4 |
| Cities Serv Oil & Gas Corp | 100433 | Oklahoma City | 34 | 8 |
| CKM Drilling Co | 100436 | — | 1 | 1 |
| Clark Energy Corp | 100437 | Denver | 0 | 0 |
| Clarus Energy Advisors LLP | 100438 | Evergreen | 0 | 0 |
| Clayton Investment | 100439 | Farmington | 8 | 1 |
| Clear Creek CBM, Inc.Active | 100440 | Orem | 3 | 1 |
| Clear Energy LLC | 100441 | Price | 0 | 0 |
| Cleary Funds Inc | 100442 | — | 2 | 2 |
| Cleary Petroleum Corporation | 100443 | Oklahoma City | 1 | 1 |
| Cline Oil and Gas Company | 100444 | Santa Fe | 0 | 0 |
| Cline, C E | 100445 | — | 1 | 1 |
| Clinton Oil Co | 100446 | — | 0 | 0 |
| Clyde Kissinger & Co | 100447 | — | 1 | 1 |
| CNG Producing | 100448 | New Orleans | 10 | 1 |
| CNG Producing | 100449 | Dallas | 0 | 0 |
| Coastal Corporation | 100450 | — | 0 | 0 |
| Coastal Oil & Gas Corp | 100451 | Houston | 116 | 4 |
| Coastal Oil & Gas Corp | 100452 | Houston | 0 | 0 |
| Coastal Oil & Gas Corp | 100453 | Houston | 0 | 0 |
| Coastal Oil & Gas Corp | 100454 | Houston | 0 | 0 |
| Coastal Oil & Gas Corp | 100455 | Houston | 0 | 0 |
| Coastal Oil & Gas Corp | 100456 | Houston | 0 | 0 |
| Coastal Oil & Gas Corp | 100457 | Vernal | 0 | 0 |
| Coastal Plains Energy IncActive | 100458 | Oklahoma City | 50 | 2 |
| Coastal States Trading Inc | 100459 | Houston | 0 | 0 |
| Cobra Oil & Gas CorporationActive | 100461 | Wichita Falls | 45 | 1 |
| Cochrane Resources, Inc.Active | 100462 | Roosevelt | 16 | 4 |
| Cockburn, Barney | 100463 | — | 5 | 1 |
| Cockrell Oil Corporation | 100464 | Houston | 5 | 1 |
| Cockrell Reverse Osmosis | 100465 | — | 0 | 0 |
| Collins Brothers Oil Co | 100466 | Mt Vernon | 1 | 1 |
| Colonial Oil Co | 100467 | — | 1 | 1 |
| Colorado Drilling Company | 100468 | Grand Junction | 1 | 1 |
| Colorado Energetics | 100469 | Englewood | 3 | 2 |
| Colorado Interstate Gas | 100470 | Colorado Springs | 1 | 1 |
| Colorado Interstate Gas | 100471 | Colorado Springs | 0 | 0 |
| Colorado Oil & Gas Corp | 100473 | — | 1 | 1 |
| Colorado Petroleum Co | 100474 | Rangely | 1 | 1 |
| Colorado Pica Petro Corp | 100475 | Cortez | 1 | 1 |
| Colorado-Pacific Petroleum | 100476 | — | 1 | 1 |
| Colorado-Utah Natural Gas Inc | 100477 | Reno | 2 | 1 |
| Colt Oil Inc | 100478 | — | 3 | 2 |
| Colt Resources Corporation | 100479 | Billings | 6 | 1 |
| Coltharp, Edward H | 100480 | — | 1 | 1 |
| Columbia Crude Corp | 100481 | — | 1 | 1 |
| Columbia Gas Develop Corp | 100482 | — | 3 | 2 |
| Columbia Gas Development | 100483 | Houston | 6 | 3 |
| Columbine Exploration Corp | 100484 | Denver | 2 | 1 |
| Columbus Energy Corp | 100485 | Denver | 5 | 1 |
| Colvin & Petersen | 100486 | — | 1 | 1 |
| Comanche Oil & Gas Corp | 100487 | Salt Lake City | 0 | 0 |
| Combined Oil & Gas Inc | 100488 | — | 1 | 1 |
| Comdisco Exploration Inc | 100489 | — | 0 | 0 |
| Cominco American Inc | 100490 | Spokane | 1 | 1 |
| Commodore Resources Corp | 100494 | — | 2 | 2 |
| Compass Exploration | 100497 | — | 3 | 1 |
| Concord Royalty Co | 100498 | Casper | 1 | 1 |
| Conley P Smith Operating | 100499 | Denver | 1 | 1 |
| Conoco Inc | 100500 | Ponca City | 38 | 7 |
| ConocoPhillips CompanyActive | 100502 | Houston | 146 | 4 |
| Consolidated Oil & Gas Inc | 100503 | Denver | 5 | 3 |
| Consolidated Oil & Gas Inc | 100504 | Denver | 3 | 1 |
| Conterra Natural Gas LLC | 100505 | Denver | 0 | 0 |
| Continental Oil Company | 100508 | Durango | 65 | 6 |
| Contract Environmental Services Inc | 100509 | Cortez | 0 | 0 |
| Conway, Connie | 100511 | — | 1 | 1 |
| Cook & Wagner Drilling Co | 100512 | — | 1 | 1 |
| Cook, Delila | 100513 | — | 4 | 1 |
| Cook, Roy W | 100514 | — | 1 | 1 |
| Coors Energy | 100515 | Golden | 26 | 6 |
| Copaquen Associated Inc | 100516 | New York | 1 | 1 |
| Coquina Oil Company | 100518 | Midland | 3 | 1 |
| Cordillera Corporation | 100519 | Denver | 9 | 3 |
| Cosco Oil Inc | 100520 | — | 1 | 1 |
| Coseka Resources USA Ltd | 100521 | Denver | 42 | 3 |
| Costilla Energy Inc | 100522 | Midland | 0 | 0 |
| Costilla Petroleum Corp | 100523 | Gillette | 0 | 0 |
| Cotton Petroleum Corp/APC | 100524 | Denver | 20 | 3 |
| Cougar Exploration | 100525 | — | 3 | 1 |
| Cowboy Resources Inc | 100526 | Casper | 0 | 0 |
| Cox, Edwin Oil & Gas | 100527 | Denver | 2 | 1 |
| Cox, John L | 100528 | Midland | 1 | 1 |
| Coyote Oil | 100529 | Jensen | 0 | 0 |
| Crain & Griffith Drl Co | 100530 | — | 3 | 1 |
| Crammer, W H H | 100531 | — | 1 | 1 |
| Credo Petroleum Corp | 100532 | Denver | 2 | 1 |
| Crescendo Energy LLC | 100533 | Denver | 0 | 0 |
| Crescent Drilling Co | 100534 | — | 3 | 1 |
| Crescent Eagle Oil Co | 100535 | — | 1 | 1 |
| Crescent Energy Operating, LLCActive | 105765 | Houston | 806 | 2 |
| Crescent Junction Oil Co | 100536 | — | 1 | 1 |
| Crescent Point Energy US Corp | 100537 | Denver | 610 | 3 |
| Crescent Uinta LLC | 105860 | — | 0 | 0 |
| Cresent Disposal | 100538 | — | 0 | 0 |
| Crest Oil Corp | 100539 | — | 1 | 1 |
| Crestone Energy Corp | 100540 | Denver | 1 | 1 |
| Crews Oil & Gas | 100541 | Fruita | 0 | 0 |
| Cristion & Davis | 100542 | — | 3 | 1 |
| Cross Creek Corporation | 100543 | Duncan | 0 | 0 |
| Cross Creek Corporation | 100544 | Gallup | 0 | 0 |
| Cross Timbers Energy LLC | 100545 | Ft Worth | 0 | 0 |
| Crownquest Operating LLC | 100546 | Farmington | 22 | 1 |
| Crystal Carbon Company | 100547 | — | 6 | 1 |
| Crystal Oil Co | 100548 | — | 2 | 1 |
| CSX Oil & Gas Corp | 100550 | Houston | 1 | 1 |
| CTD Inc | 100551 | Boise | 0 | 0 |
| Cullum Oil and Gas Inc | 100552 | Cortez | 0 | 0 |
| Cullum, Max | 100553 | Cortez | 0 | 0 |
| Curtis & Dixon | 100554 | — | 1 | 1 |
| Cutler, Dal H | 100555 | — | 1 | 1 |
| Cypher, Harry T | 100556 | — | 1 | 1 |
| D & D Oil Co | 100557 | — | 4 | 1 |
| D & J Crude Gathering LLC | 105600 | West Jordan | 0 | 0 |
| D & J Oil Co | 100558 | Park City | 1 | 1 |
| D J Simmons Company | 100559 | Farmington | 0 | 0 |
| D J Simmons, Inc | 100560 | Farmington | 2 | 1 |
| D J Simmons, Inc | 100561 | Farmington | 0 | 0 |
| Dab Oil Co | 100562 | Moab | 1 | 1 |
| Dab Resources | 100563 | Denver | 0 | 0 |
| Dabrous Properties Inc | 100564 | Billings | 0 | 0 |
| Dalbo, Inc | 100565 | Vernal | 0 | 0 |
| Dalbosco, Donald | 100566 | Houston | 1 | 1 |
| Dalen Resources Oil & Gas | 100567 | Dallas | 10 | 2 |
| Damson Oil Corporation | 100568 | Houston | 5 | 2 |
| Daniels Petroleum Co | 100569 | Denver | 0 | 0 |
| Danish Flats Environmental Services Inc | 100570 | Windsor | 0 | 0 |
| Danish Flats Waste Disposal, LLC | 105394 | South Jordan | 0 | 0 |
| Darenco, Inc | 100571 | Denver | 0 | 0 |
| Darenco, Inc | 100572 | Casper | 0 | 0 |
| Dark Horse Exploration Inc | 100573 | Evanston | 0 | 0 |
| Davis Oil Company | 100574 | Denver | 66 | 6 |
| Dawn Petroleum Inc | 100575 | — | 1 | 1 |
| De Kalb Agric Assn Inc | 100576 | Vernal | 10 | 1 |
| Dead Horse Oil Company, LLC | 105106 | Green River | 0 | 0 |
| Defense Plant Corp | 100577 | — | 1 | 1 |
| Del-Rio Resources Inc | 100578 | Vernal | 30 | 1 |
| Delaney Petroleum Corp | 100579 | — | 1 | 1 |
| Delhi-Taylor Oil Corp | 100580 | — | 13 | 5 |
| Delhi-Trading LLCActive | 100581 | Durango | 6 | 2 |
| Delta Company Et Al | 100582 | Mexican Hat | 1 | 1 |
| Delta Petroleum & Energy | 100583 | — | 2 | 1 |
| Delta Petroleum Corp | 100584 | Denver | 31 | 5 |
| Denbe | 100585 | — | 0 | 0 |
| Denbury Onshore LLC | 100586 | Plano | 0 | 0 |
| Denison Mines LTD | 100587 | — | 1 | 1 |
| Denver, Chris/Chasel, John | 100588 | Park City | 0 | 0 |
| Denveramerican Petroleum | 100589 | Billings | 0 | 0 |
| Depco | 100590 | — | 0 | 0 |
| Des Moines Oil Co | 100591 | — | 2 | 1 |
| Deseret Petroleum | 100592 | — | 1 | 1 |
| Desert Eagle Energy LLC | 100593 | Sandy | 1 | 1 |
| Desert Eagle Operating, LLC | 105176 | Dallas | 0 | 0 |
| Deuel, Arch W | 100594 | Casper | 0 | 0 |
| Devereux Corp, The | 100596 | — | 1 | 1 |
| Devon Energy Oper Corp | 100597 | Oklahoma City | 0 | 0 |
| Devon Energy Prod Co LP | 100598 | Oklahoma City | 21 | 2 |
| Devon Energy Prod Co LP | 100599 | Oklahoma City | 0 | 0 |
| Devon SFS Operating Inc | 100600 | Oklahoma City | 0 | 0 |
| Diamond Oil Company | 100601 | — | 21 | 2 |
| Diamond Shamrock Corp | 100602 | Amarillo | 19 | 2 |
| Diamond Shamrock Expl | 100603 | Dallas | 69 | 7 |
| Dickinson & Wing Oil Co | 100604 | — | 0 | 0 |
| Dickinson, G R | 100605 | — | 2 | 1 |
| Dimension Oil & Gas Inc | 100606 | Salt Lake City | 1 | 1 |
| Dirty Devil LP | 100607 | Eenglewood | 5 | 1 |
| Discovery Natural Resources LLC | 100608 | Denver | 7 | 1 |
| Dishman, Lloyd N | 100609 | Fruita | 0 | 0 |
| Diversified Energy LLCActive | 100610 | Parker | 4 | 1 |
| Diversified Operating Corp | 100611 | Denver | 1 | 1 |
| Dixel Resources Inc | 100612 | — | 1 | 1 |
| DKM Resources Inc | 100613 | Houston | 0 | 0 |
| Dobson Exploration LLC | 100614 | Tooele | 2 | 1 |
| Dolar Energy LLC | 100615 | Fountain Hills | 0 | 0 |
| Dolar Oil Properties LC | 100616 | Midvale | 0 | 0 |
| Dolar Oil Properties LC | 100617 | Roosevelt | 1 | 1 |
| Dolton, Lex L | 100618 | Parker | 0 | 0 |
| Domestic Oil & Gas LLC | 100619 | San Francisco | 0 | 0 |
| Dominion Energy Questar Pipeline, LLC | 104370 | Salt Lake City | 0 | 0 |
| Dominion Expl & Prod Inc | 100620 | Oklahoma City | 106 | 2 |
| Dominion Expl & Prod Inc | 100621 | Houston | 0 | 0 |
| Dominion OK TX E & P Inc | 100622 | Oklahoma City | 1 | 1 |
| Dominion Reserves Utah Inc | 100623 | New Orleans | 0 | 0 |
| Don Danvers Co | 100624 | — | 3 | 1 |
| Don E Woodward | 100625 | Whittier | 1 | 1 |
| Dosecc Exploration Services, LLC | 100626 | Salt Lake City | 4 | 2 |
| Dosecc Inc | 100627 | Salt Lake City | 6 | 4 |
| Double Eagle Petroleum & Mining | 100628 | Casper | 1 | 1 |