| 501 | Hyland Oil Corporation | | Oil & Gas Operator | Apr 1990 |
| 502 | Hyperion Oil & Gas LLC | Dallas, TX 75251 | Oil & Gas Operator | Jul 2026 |
| 503 | J & J Production LLC | Worland, WY 82401 | Oil Operator | Dec 2025 |
| 504 | J-Bird Well Service Incorporated | Gillette, WY 82717 | Oil Operator | May 2026 |
| 505 | J-W Operating Company | Christoval, TX 76935 | Oil & Gas Operator | Jul 2026 |
| 506 | Jade Resources Inc | Englewood, CO 80112 | Oil Operator | Jul 1998 |
| 507 | Jay Management Company LLC | Houston, TX 77057 | Oil & Gas Operator | Jul 2026 |
| 508 | Jayne Morton Living Trust | Troup, TX 75789 | Oil Operator | Jul 2023 |
| 509 | Jed Oil USA Inc | | Oil & Gas Operator | Dec 2008 |
| 510 | Jellco LLC | Thermopolis, WY 82443 | Oil Operator | May 2026 |
| 511 | Jenex Petroleum Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Jul 2026 |
| 512 | Jetta Operating Company, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2026 |
| 513 | Jims Water Service Inc | Gillette, WY 82717 | Oil & Gas Operator | Oct 2016 |
| 514 | JM Cox Resources LP | Midland, TX 79702 | Oil & Gas Operator | Apr 2019 |
| 515 | JN Exploration & Production | Billings, MT 59103-0159 | Oil & Gas Operator | Apr 2001 |
| 516 | Joemar Wyoming Operating LLC | | Oil & Gas Operator | May 2026 |
| 517 | Jogruss Oil Corporation | | Oil & Gas Operator | Jul 1991 |
| 518 | Jonah Energy LLC | Denver, CO 80202 | Oil & Gas Operator | Jul 2026 |
| 519 | JP Oil Wyoming LLC | Lafayette, LA 70505 | Oil & Gas Operator | Jun 2026 |
| 520 | JT Operating LLC | Douglas, WY 82633 | Oil & Gas Operator | May 2026 |
| 521 | Julander Energy Company | Denver, CO 80614 | Oil Operator | Apr 2016 |
| 522 | Julius Roy G | Wichita, KS 67206 | Oil & Gas Operator | Apr 2026 |
| 523 | Juniper Petroleum Corporation | | Oil & Gas Operator | Aug 1983 |
| 524 | Justice Oil & Gas LLC | Gillette, WY 82716 | Oil & Gas Operator | May 2026 |
| 525 | Jva Operating Company | Midland, TX 79710 | Oil & Gas Operator | Oct 2021 |
| 526 | K & W Oil Company | MT Carmel, IL 62830 | Oil & Gas Operator | May 2013 |
| 527 | K N Energy Inc | Lakewood, CO 80228 | Oil & Gas Operator | Nov 2000 |
| 528 | Kachina Exploration Inc | Cheyenne, WY 82003 | Oil & Gas Operator | Jul 2000 |
| 529 | Kaiser Energy Inc | Denver, CO 80202 | Oil & Gas Operator | Dec 1990 |
| 530 | Kaiser-Francis Oil Company | Tulsa, OK 74121 | Oil & Gas Operator | Jul 2026 |
| 531 | Kamco Limited | Salt Lake City, UT 84105 | Oil Operator | Sep 2016 |
| 532 | Kaneb Oil & Gas | | Oil & Gas Operator | Oct 1987 |
| 533 | Kant Walter F | Lance Creek, WY 82222 | Oil & Gas Operator | Dec 2002 |
| 534 | Kara Enterprises Inc | Upton, WY 82730 | Oil Operator | Jul 2013 |
| 535 | Karlton Terry Oil Company | | Oil Operator | Jan 1991 |
| 536 | Kase Energy LLC | Roseville, MN 55113 | Oil Operator | Aug 2006 |
| 537 | Katherman Vance E | Casper, WY 82601 | Oil Operator | Dec 2004 |
| 538 | Kauffman K P Company Inc | Denver, CO 80202 | Oil & Gas Operator | Mar 1996 |
| 539 | KC Resources Inc | Snowmass VLG., CO 81615 | Oil & Gas Operator | Apr 2026 |
| 540 | KCS Medallion Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Nov 2018 |
| 541 | KCS Mountain Resources Inc | Manderson, WY 82432 | Oil & Gas Operator | Nov 2006 |
| 542 | Keas Production Company LLC | Estes Park, CO 80517 | Oil Operator | Apr 2026 |
| 543 | Keba Energy LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2015 |
| 544 | Kedco Management Corp | | Oil & Gas Operator | Jul 1985 |
| 545 | Keith Walker O & G Co LLC | | Oil Operator | Jun 2026 |
| 546 | Keiths Pumping Service | Douglas, WY 82633 | Oil & Gas Operator | Aug 2003 |
| 547 | Kelly Operating Company | | Oil & Gas Operator | Oct 1991 |
| 548 | Kem Ventures, LP | Katy, TX 77450 | Oil & Gas Operator | May 2026 |
| 549 | Kemmerer Coal Co | | Oil & Gas Operator | Dec 1981 |
| 550 | Kenai Oil & Gas Inc | | Oil & Gas Operator | Jun 1987 |
| 551 | Kennedy & Mitchell | Woodward, OK 73802 | Oil & Gas Operator | Dec 1988 |
| 552 | Kennedy George C | Upton, WY 82730 | Oil & Gas Operator | Oct 2018 |
| 553 | Kennedy Oil | Gillette, WY 82716 | Oil & Gas Operator | May 2026 |
| 554 | Kentex Worland LLC | Dallas, TX 75225 | Oil & Gas Operator | Sep 2025 |
| 555 | Kentex Worland Operating Co LLC | | Oil & Gas Operator | Jun 2026 |
| 556 | Kentta & Drwenski | Casper, WY 82602 | Oil & Gas Operator | Nov 1995 |
| 557 | Kerr-McGee Corporation | Dallas, TX 75380 | Oil & Gas Operator | Feb 2026 |
| 558 | Kerr-McGee Oil & Gas Onshore LP | Houston, TX 77046 | Oil & Gas Operator | Jul 2026 |
| 559 | Kerr-McGee Rocky Mountain Corp | Denver, CO 80202 | Oil & Gas Operator | Jan 2007 |
| 560 | Kerry Petroleum Co Inc | Midland, TX 79708 | Oil & Gas Operator | Jun 2010 |
| 561 | Kestrel Energy Inc | Lakewood, CO 80401 | Oil & Gas Operator | Jan 2008 |
| 562 | Kewanee Oil Company | Houston, TX 77001 | Oil & Gas Operator | Aug 1978 |
| 563 | Key Production Company, Inc. | Longview, TX 75606 | Oil & Gas Operator | Apr 2026 |
| 564 | Kiesling Oil Company | Osage, WY 82723 | Oil & Gas Operator | Oct 2007 |
| 565 | Kinder Morgan Inc | Lakewood, CO 80228 | Oil & Gas Operator | Dec 2011 |
| 566 | Kings Peak Energy LLC | Denver, CO 80264 | Oil & Gas Operator | Feb 2019 |
| 567 | Kings X Oil Company LLC | Gillette, WY 82717 | Oil Operator | Aug 2016 |
| 568 | Kirkwood W C | Casper, WY 82602 | Oil & Gas Operator | May 2005 |
| 569 | Kiska Oil & Gas Inc | Tulsa, OK 74103 | Oil Operator | Oct 2012 |
| 570 | Kissack Resources. LLC | | Oil & Gas Operator | Jun 2026 |
| 571 | Kissack Water & Oil Service Inc | Rozet, WY 82727 | Oil & Gas Operator | Jun 2026 |
| 572 | Kissinger Petroleum Corp | | Oil & Gas Operator | Nov 1983 |
| 573 | Klabzuba Oil & Gas Inc | Denver, CO 80202 | Oil & Gas Operator | Aug 2012 |
| 574 | Kobar Corporation | Riverton, WY 82501 | Gas Operator | Dec 1996 |
| 575 | Koch Exploration Company | Houston, TX 77046 | Oil & Gas Operator | Apr 2003 |
| 576 | Koch Exploration Company, LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2019 |
| 577 | Koch Production Company | Worland, WY 82401 | Oil & Gas Operator | Dec 2002 |
| 578 | Kodiak Oil & Gas (USA) Inc. | Denver, CO 80202 | Oil & Gas Operator | Sep 2020 |
| 579 | Krejci Harry L | | Oil & Gas Operator | Apr 2026 |
| 580 | KWB Oil Property Management Inc | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2026 |
| 581 | L & B Oil Company Inc | Houston, TX 77079 | Oil & Gas Operator | Mar 2025 |
| 582 | L & J Operating Inc | Gillette, WY 82718 | Oil & Gas Operator | Aug 2016 |
| 583 | L & R Drilling Company | Belle Fourche, SD 57717 | Oil & Gas Operator | Dec 1999 |
| 584 | L B Industries Inc | Englewood, CO 80112 | Oil & Gas Operator | Jun 2003 |
| 585 | L R Company | Casper, WY 82602 | Oil & Gas Operator | Sep 2007 |
| 586 | La Prele Exploration | | Oil & Gas Operator | Oct 1979 |
| 587 | Labarge Minerals Inc | Labarge, WY 83123 | Oil & Gas Operator | Jan 2020 |
| 588 | Ladd & Lukowicz | | Oil & Gas Operator | May 1983 |
| 589 | Lagniappe Interest Inc | Evergreen, CO 80439 | Oil & Gas Operator | Jun 2006 |
| 590 | Laguna Petroleum Company | Casper, WY 82601 | Oil & Gas Operator | Dec 1982 |
| 591 | Lakota Partnership | Denver, CO 80202 | Oil Operator | Oct 1990 |
| 592 | Lance Oil & Gas Company Inc | Kirtland, NM 87417 | Oil & Gas Operator | Mar 2013 |
| 593 | Langley Energy | Euless, TX 76040 | Gas Operator | Jan 2016 |
| 594 | Lappin Oil LLC | Douglas, WY 82633 | Oil & Gas Operator | Jun 2026 |
| 595 | Lario Oil & Gas Company | Odessa, TX 79762 | Oil & Gas Operator | Jul 2026 |
| 596 | Lasmo Energy Corporation | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2024 |
| 597 | Lawson Oil Company | Buckeye, AR 85326 | Oil Operator | Mar 1996 |
| 598 | Lear Petroleum Exploration | | Oil & Gas Operator | Jul 2013 |
| 599 | Leclair-Westwood Inc | | Oil & Gas Operator | Mar 1982 |
| 600 | Leeman Don J | Oklahoma City, OK 73112 | Oil & Gas Operator | Sep 1998 |