| 501 | Cimarron Engineering Corp. | Kingsville, TX 78364 | Oil & Gas Operator | May 2015 |
| 502 | Cimarron Engineering, LLC | Kingsville, TX 78364 | Oil & Gas Operator | Nov 2024 |
| 503 | Cimarron Properties, Inc. | San Angelo, TX 76904 | Oil & Gas Operator | Nov 1997 |
| 504 | Cinco Natural Resources Corp | La Grange, TX 78945 | Oil & Gas Operator | Nov 2024 |
| 505 | Cinco Oil & Gas, LLC | Dallas, TX 75204 | Oil & Gas Operator | Nov 2024 |
| 506 | Cinnabar Energy, LTD. | Fort Worth, TX 76107 | Oil & Gas Operator | May 2018 |
| 507 | Cinnabar Operating, LLC | Fort Worth, TX 76121 | Oil & Gas Operator | Nov 2024 |
| 508 | Cinron Energy, LLC | Arp, TX 75750 | Oil & Gas Operator | Nov 2024 |
| 509 | Circle "M" Energy Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Aug 2003 |
| 510 | Circle B Oil & Gas | Bowie, TX 76230 | Oil & Gas Operator | Dec 2021 |
| 511 | Circle C Operations | Winnsboro, TX 75494 | Oil Operator | Nov 2024 |
| 512 | Circle D Oil & Gas, Inc. | Brownwood, TX 76801 | Oil & Gas Operator | Nov 2024 |
| 513 | Circle H Oil Company | Big Spring, TX 79721 | Oil & Gas Operator | Apr 2020 |
| 514 | Circle Ridge Production, Inc. | Graham, TX 76450 | Oil & Gas Operator | Nov 2024 |
| 515 | Circle W Oil & Gas Company | Pampa, TX 79066 | Oil & Gas Operator | Nov 2024 |
| 516 | Circle-S Energy, LLC | McKinney, TX 75071 | Oil & Gas Operator | Nov 2024 |
| 517 | Cirrus Exploration Company | Prosper, TX 75078 | Oil & Gas Operator | Nov 2024 |
| 518 | Cirrus Production Company | Enid, OK 73702 | Oil & Gas Operator | Aug 2024 |
| 519 | Cisco Operating LLC | Plano, TX 75024 | Oil & Gas Operator | Sep 2024 |
| 520 | Cisco Production Company, LLC | Victoria, TX 77902 | Oil & Gas Operator | May 2012 |
| 521 | Citation Oil & Gas Corp. | Houston, TX 77269 | Oil & Gas Operator | Nov 2024 |
| 522 | Citori Oil Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Nov 2004 |
| 523 | Citori Oil Company, LLC | Wichita Falls, TX 76308 | Oil & Gas Operator | May 2014 |
| 524 | Citrus Energy Corporation | Castle Rock, CO 80104 | Oil & Gas Operator | Mar 2020 |
| 525 | City Of Dumas | Dumas, TX 79029 | Gas Operator | Nov 2024 |
| 526 | City Of McLean | McLean, TX 79057 | Gas Operator | Nov 2024 |
| 527 | City Of Sunray Utilities | Sunray, TX 79086 | Oil & Gas Operator | Nov 2024 |
| 528 | City Of White Deer | White Deer, TX 79097 | Gas Operator | May 2017 |
| 529 | Civitas Permian Operating, LLC | Denver, CO 80202 | Oil & Gas Operator | Nov 2024 |
| 530 | Civron Petroleum Res., LLC | San Antonio, TX 78229 | Oil & Gas Operator | Nov 2024 |
| 531 | CJ Tejas Energy, LLC | Pearland, TX 77581 | Oil Operator | Nov 2024 |
| 532 | CJRW Oil & Gas | MC Camey, TX 79752 | Oil Operator | Nov 2024 |
| 533 | CJW Operating Co. | Tucson, AZ 85718 | Oil Operator | Mar 2024 |
| 534 | CK Operating Company, LLC | Wichita Falls, TX 76308 | Oil Operator | Nov 2024 |
| 535 | CK5 Services LLC | Zephyr, TX 76890 | Oil & Gas Operator | Nov 2024 |
| 536 | CKB Corporation | Borger, TX 79008 | Oil & Gas Operator | Aug 1997 |
| 537 | CL&F Operating LLC | Spring, TX 77389 | Oil & Gas Operator | Dec 2022 |
| 538 | Clamp Operating | San Antonio, TX 78264 | Oil & Gas Operator | Apr 2002 |
| 539 | Clamp Operating Incorporated | San Antonio, TX 78264 | Oil & Gas Operator | Mar 2011 |
| 540 | Clark Oil Co. | Dallas, TX 75206 | Oil & Gas Operator | Nov 2024 |
| 541 | Clark Operating | Wichita Falls, TX 76308 | Oil & Gas Operator | Aug 2003 |
| 542 | Clark Operating Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Nov 2024 |
| 543 | Clark, B. C. | Cross Plains, TX 76443 | Oil Operator | Dec 2007 |
| 544 | Clark, G. A., Trustee | San Antonio, TX 78210 | Oil & Gas Operator | Nov 2017 |
| 545 | Clark, John M. | Midland, TX 79701 | Oil & Gas Operator | Dec 1993 |
| 546 | Clark, John M., Inc. | Midland, TX 79704 | Oil & Gas Operator | Nov 2024 |
| 547 | Clark, Richard E., Inc. | Longview, TX 75604 | Oil & Gas Operator | May 2001 |
| 548 | Claron Corporation | Houston, TX 77219 | Oil & Gas Operator | Nov 2024 |
| 549 | Classic Energy Incorporated | Tyler, TX 75701 | Oil & Gas Operator | Jul 2005 |
| 550 | Classic Oil & Gas, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Jan 2004 |
| 551 | Classic Operating Co. LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 552 | Classic Petroleum Partners, Inc. | Whitehouse, TX 75791 | Oil & Gas Operator | Nov 2024 |
| 553 | Claude-Maggie Co. | Midland, TX 79702 | Oil & Gas Operator | Nov 2024 |
| 554 | Clausen, A. G. | Cross Plains, TX 76443 | Oil & Gas Operator | Nov 2024 |
| 555 | Clavo Oil, LLC | Graham, TX 76450 | Oil & Gas Operator | Nov 2024 |
| 556 | Clay Exploration, Inc. | Spring, TX 77387 | Oil & Gas Operator | Jun 2019 |
| 557 | Clay Petroleum | Prosper, TX 75078 | Oil & Gas Operator | Feb 2023 |
| 558 | Clay, Charles E. | Jacksboro, TX 76458 | Oil & Gas Operator | Sep 2010 |
| 559 | Clay, Jerry H. | Tyler, TX 75702 | Oil & Gas Operator | Mar 2006 |
| 560 | Clayton Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | May 2004 |
| 561 | Clayton Williams Energy, Inc. | Houston, TX 77070 | Oil & Gas Operator | Apr 2017 |
| 562 | CLC Operations Inc | Midland, TX 79701 | Oil & Gas Operator | Mar 1997 |
| 563 | Cleantex Oilfield Services, LLC | Tyler, TX 75702 | Oil Operator | Nov 2024 |
| 564 | Clear Brooke Ranches, LLC | Fort Worth, TX 76179 | Oil & Gas Operator | Nov 2024 |
| 565 | Clear Fork Gas Company | Albany, TX 76430 | Oil & Gas Operator | Nov 2024 |
| 566 | Clear Fork, Incorporated | Abilene, TX 79604 | Oil & Gas Operator | Nov 2024 |
| 567 | Clear Water Inc. | Midland, TX 79710 | Oil & Gas Operator | Nov 2024 |
| 568 | Clearfork Operating LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Aug 2011 |
| 569 | Clearfork Petroleum Inc. (A) | Lubbock, TX 79408 | Oil & Gas Operator | Nov 2024 |
| 570 | Clearfork Production, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Nov 2018 |
| 571 | Clearly Petroleum, LLC | Houston, TX 77086 | Oil & Gas Operator | Jun 2020 |
| 572 | Cleary Petroleum Corporation | Edmond, OK 73083 | Oil & Gas Operator | Jul 2019 |
| 573 | Clements Exploration Co | Oklahoma City, OK 73132-5922 | Oil & Gas Operator | Jan 2006 |
| 574 | Clements Operating Company, Inc. | Luling, TX 78648 | Oil & Gas Operator | Aug 2003 |
| 575 | Clemons, Tony W. | Minden, LA 71055 | Oil & Gas Operator | Dec 2016 |
| 576 | Cleo Oil, Inc. | Olney, TX 76374 | Oil & Gas Operator | May 1997 |
| 577 | Cleveland Oil & Gas | Wichita Falls, TX 76308 | Oil Operator | Nov 2024 |
| 578 | Cleveland Oil Company,L.L.C.,The | Midland, TX 79702 | Oil & Gas Operator | Sep 1999 |
| 579 | Cleveland Production Company | Summit, MS 39666 | Oil & Gas Operator | Jul 1999 |
| 580 | Click Corp | Monroe, LA 71207 | Oil & Gas Operator | Jan 2004 |
| 581 | Click Energy Company | Houston, TX 77269 | Oil & Gas Operator | Nov 2024 |
| 582 | Clide Oil Corp. | Iraan, TX 79744 | Oil & Gas Operator | Nov 2015 |
| 583 | Cliffwood Production Co. | Houston, TX 77090 | Oil & Gas Operator | Aug 2013 |
| 584 | Clifton Oil | Muenster, TX 76252 | Oil & Gas Operator | Mar 2006 |
| 585 | Clifton, B.W. | Graham, TX 76450 | Oil & Gas Operator | Mar 2000 |
| 586 | Clifton, Joe B. Exploration, Inc | Pauls Valley, OK 73075 | Oil & Gas Operator | Mar 2008 |
| 587 | Clipper Operating Co., Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Jan 2000 |
| 588 | CLM Operating | Graham, TX 76450 | Oil & Gas Operator | Aug 2017 |
| 589 | Close, Bryan H. | Shamrock, TX 79079 | Gas Operator | Nov 2024 |
| 590 | Clover Production Company | Sourlake, TX 77659 | Oil & Gas Operator | Nov 2024 |
| 591 | CLR Gauging Corp. | Tuleta, TX 78162 | Oil & Gas Operator | Nov 2024 |
| 592 | CLR Secondary Recovery, LLC | Wichita Falls, TX 76306 | Oil & Gas Operator | Nov 2024 |
| 593 | CLS Interests, Incorporated | Austin, TX 78734 | Oil & Gas Operator | Jan 1997 |
| 594 | CLS Petroleum Holdings LLC | Wichita Falls, TX 76308 | Oil Operator | Nov 2024 |
| 595 | Clsog L.C. | Houston, TX 77024 | Gas Operator | Jun 2008 |
| 596 | CM TX Production, LLC | Lakewood, CO 80228 | Oil & Gas Operator | Feb 2023 |
| 597 | CML Exploration, LLC | Austin, TX 78746 | Oil & Gas Operator | Nov 2024 |
| 598 | CMR Energy, L.P. | Houston, TX 77077 | Oil & Gas Operator | Nov 2024 |
| 599 | CMS Nomeco Oil & Gas Co. | Jackson, MI 49201 | Oil & Gas Operator | Jan 2015 |
| 600 | CMS Oil And Gas Company | Jackson, MI 49201 | Oil & Gas Operator | Oct 2002 |