| 701 | Juniper Petroleum Corporation | | Oil & Gas Operator | Aug 1983 |
| 702 | Justice Oil & Gas LLC | Gillette, WY 82716 | Oil & Gas Operator | Oct 2025 |
| 703 | Jva Operating Company | Midland, TX 79710 | Oil & Gas Operator | Oct 2021 |
| 704 | K & W Oil Company | MT Carmel, IL 62830 | Oil & Gas Operator | May 2013 |
| 705 | K N Energy Inc | Lakewood, CO 80228 | Oil & Gas Operator | Nov 2000 |
| 706 | Kachina Exploration Inc | Cheyenne, WY 82003 | Oil & Gas Operator | Jul 2000 |
| 707 | Kaiser Energy Inc | Denver, CO 80202 | Oil & Gas Operator | Dec 1990 |
| 708 | Kaiser-Francis Oil Company | Tulsa, OK 74121 | Oil & Gas Operator | Dec 2025 |
| 709 | Kamco Limited | Salt Lake City, UT 84105 | Oil Operator | Sep 2016 |
| 710 | Kaneb Oil & Gas | | Oil & Gas Operator | Oct 1987 |
| 711 | Kant Walter F | Lance Creek, WY 82222 | Oil & Gas Operator | Dec 2002 |
| 712 | Kara Enterprises Inc | Upton, WY 82730 | Oil Operator | Jul 2013 |
| 713 | Karlton Terry Oil Company | | Oil Operator | Jan 1991 |
| 714 | Kase Energy LLC | Roseville, MN 55113 | Oil Operator | Aug 2006 |
| 715 | Katherman Vance E | Casper, WY 82601 | Oil Operator | Dec 2004 |
| 716 | Kauffman K P Company Inc | Denver, CO 80202 | Oil & Gas Operator | Mar 1996 |
| 717 | KC Resources Inc | Snowmass VLG., CO 81615 | Oil & Gas Operator | Aug 2025 |
| 718 | KC Well Service | Big Piney, WY 83113 | Gas Operator | Sep 2025 |
| 719 | KCS Medallion Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Nov 2018 |
| 720 | KCS Mountain Resources Inc | Manderson, WY 82432 | Oil & Gas Operator | Nov 2006 |
| 721 | Keas Production Company LLC | Estes Park, CO 80517 | Oil Operator | Sep 2025 |
| 722 | Keba Energy LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2015 |
| 723 | Kedco Management Corp | | Oil & Gas Operator | Jul 1985 |
| 724 | Keith Walker O & G Co LLC | | Oil Operator | Oct 2025 |
| 725 | Keiths Pumping Service | Douglas, WY 82633 | Oil & Gas Operator | Aug 2003 |
| 726 | Kelly Operating Company | | Oil & Gas Operator | Oct 1991 |
| 727 | Kem Ventures, LP | Katy, TX 77450 | Oil & Gas Operator | Sep 2025 |
| 728 | Kemmerer Coal Co | | Oil & Gas Operator | Dec 1981 |
| 729 | Kenai Oil & Gas Inc | | Oil & Gas Operator | Jun 1987 |
| 730 | Kennedy & Mitchell | Woodward, OK 73802 | Oil & Gas Operator | Dec 1988 |
| 731 | Kennedy George C | Upton, WY 82730 | Oil & Gas Operator | Oct 2018 |
| 732 | Kennedy Oil | Gillette, WY 82716 | Oil & Gas Operator | Sep 2025 |
| 733 | Kentex Worland LLC | Dallas, TX 75225 | Oil & Gas Operator | Oct 2025 |
| 734 | Kentta & Drwenski | Casper, WY 82602 | Oil & Gas Operator | Nov 1995 |
| 735 | Kerr-McGee Corporation | Dallas, TX 75380 | Oil & Gas Operator | Aug 2025 |
| 736 | Kerr-McGee Oil & Gas Onshore LP | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 737 | Kerr-McGee Rocky Mountain Corp | Denver, CO 80202 | Oil & Gas Operator | Jan 2007 |
| 738 | Kerry Petroleum Co Inc | Midland, TX 79708 | Oil & Gas Operator | Jun 2010 |
| 739 | Kestrel Energy Inc | Lakewood, CO 80401 | Oil & Gas Operator | Jan 2008 |
| 740 | Kewanee Oil Company | Houston, TX 77001 | Oil & Gas Operator | Aug 1978 |
| 741 | Key Production Company, Inc. | Longview, TX 75606 | Oil & Gas Operator | Aug 2025 |
| 742 | Kiesling Oil Company | Osage, WY 82723 | Oil & Gas Operator | Oct 2007 |
| 743 | Kinder Morgan Inc | Lakewood, CO 80228 | Oil & Gas Operator | Dec 2011 |
| 744 | Kings Peak Energy LLC | Denver, CO 80264 | Oil & Gas Operator | Feb 2019 |
| 745 | Kings X Oil Company LLC | Gillette, WY 82717 | Oil Operator | Aug 2016 |
| 746 | Kirkwood W C | Casper, WY 82602 | Oil & Gas Operator | May 2005 |
| 747 | Kiska Oil & Gas Inc | Tulsa, OK 74103 | Oil Operator | Oct 2012 |
| 748 | Kissack Resources. LLC | | Oil & Gas Operator | Oct 2025 |
| 749 | Kissack Water & Oil Service Inc | Rozet, WY 82727 | Oil & Gas Operator | Oct 2025 |
| 750 | Kissinger Petroleum Corp | | Oil & Gas Operator | Nov 1983 |
| 751 | Klabzuba Oil & Gas Inc | Denver, CO 80202 | Oil & Gas Operator | Aug 2012 |
| 752 | Kobar Corporation | Riverton, WY 82501 | Gas Operator | Dec 1996 |
| 753 | Koch Exploration Company | Houston, TX 77046 | Oil & Gas Operator | Apr 2003 |
| 754 | Koch Exploration Company, LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2019 |
| 755 | Koch Production Company | Worland, WY 82401 | Oil & Gas Operator | Dec 2002 |
| 756 | Kodiak Oil & Gas (USA) Inc. | Denver, CO 80202 | Oil & Gas Operator | Sep 2020 |
| 757 | Krejci Harry L | | Oil & Gas Operator | Sep 2025 |
| 758 | KWB Oil Property Management Inc | Tulsa, OK 74103 | Oil & Gas Operator | Aug 2025 |
| 759 | L & B Oil Company Inc | Houston, TX 77019-3115 | Oil & Gas Operator | Mar 2025 |
| 760 | L & J Operating Inc | Gillette, WY 82718 | Oil & Gas Operator | Aug 2016 |
| 761 | L & R Drilling Company | Belle Fourche, SD 57717 | Oil & Gas Operator | Dec 1999 |
| 762 | L B Industries Inc | Englewood, CO 80112 | Oil & Gas Operator | Jun 2003 |
| 763 | L R Company | Casper, WY 82602 | Oil & Gas Operator | Sep 2007 |
| 764 | La Prele Exploration | | Oil & Gas Operator | Oct 1979 |
| 765 | Labarge Minerals Inc | Labarge, WY 83123 | Oil & Gas Operator | Jan 2020 |
| 766 | Ladd & Lukowicz | | Oil & Gas Operator | May 1983 |
| 767 | Lagniappe Interest Inc | Evergreen, CO 80439 | Oil & Gas Operator | Jun 2006 |
| 768 | Laguna Petroleum Company | Casper, WY 82601 | Oil & Gas Operator | Dec 1982 |
| 769 | Lakota Partnership | Denver, CO 80202 | Oil Operator | Oct 1990 |
| 770 | Lance Oil & Gas Company Inc | Kirtland, NM 87417 | Oil & Gas Operator | Mar 2013 |
| 771 | Langley Energy | Euless, TX 76040 | Gas Operator | Jan 2016 |
| 772 | Lappin Oil LLC | Douglas, WY 82633 | Oil & Gas Operator | Nov 2025 |
| 773 | Lario Oil & Gas Company | Odessa, TX 79762 | Oil & Gas Operator | Dec 2025 |
| 774 | Lasmo Energy Corporation | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2024 |
| 775 | Lawson Oil Company | Buckeye, AR 85326 | Oil Operator | Mar 1996 |
| 776 | Lear Petroleum Exploration | | Oil & Gas Operator | Jul 2013 |
| 777 | Leclair-Westwood Inc | | Oil & Gas Operator | Mar 1982 |
| 778 | Leeman Don J | Oklahoma City, OK 73112 | Oil & Gas Operator | Sep 1998 |
| 779 | Legacy Energy Inc | Carpinteria, CA 93013 | Oil & Gas Operator | Jun 2012 |
| 780 | Legacy Reserves Operating LP | Denver, CO 80201 | Oil & Gas Operator | Dec 2025 |
| 781 | Levinson Partners Corporation | Denver, CO 80202 | Oil & Gas Operator | Jul 1995 |
| 782 | Lewis & Clark Exploration | | Oil Operator | Feb 1989 |
| 783 | Lewis Yale H | | Oil & Gas Operator | Aug 1986 |
| 784 | Lexicon Resources Corporation | | Oil & Gas Operator | Apr 1986 |
| 785 | Liberty Production Co | Houston, TX 77002 | Oil & Gas Operator | Nov 1994 |
| 786 | Liberty Resources Management Co LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 787 | Lilis Energy Inc | Denver, CO 80203 | Oil & Gas Operator | Aug 2017 |
| 788 | Lincero LLC | Sinclair, WY 82334 | Oil Operator | Nov 2025 |
| 789 | Linn Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Jan 2019 |
| 790 | Lissolo J W | Yuma, AZ 85365 | Oil & Gas Operator | Feb 2017 |
| 791 | Lissolo Timothy C | Newcastle, WY 82701 | Oil Operator | Nov 2025 |
| 792 | Llosu Corporation | Rawlins, WY 82301 | Oil & Gas Operator | Mar 2002 |
| 793 | Loco | Casper, WY 82602 | Oil & Gas Operator | Jul 2022 |
| 794 | Lodestone Operating | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |
| 795 | Loil Oil LLC | Golden, CO 80402 | Oil & Gas Operator | Oct 2025 |
| 796 | Lone Star Land And Energy II LLC | Dallas, TX 75214 | Oil & Gas Operator | Jan 2020 |
| 797 | Long Beach Oil Development Co | Glendale, CA 91203 | Oil & Gas Operator | Jun 2004 |
| 798 | Long Trust The | Kilgore, TX 75663 | Oil & Gas Operator | Aug 2008 |
| 799 | Longs Peak Resources LLC | Houston, TX 77019 | Oil & Gas Operator | Oct 2025 |
| 800 | Loral Operating LLC | Sheridan, WY 82801 | Gas Operator | Apr 2011 |