| 601 | Hay Leonard | Rock Springs, WY 82901 | Oil & Gas Operator | Sep 1994 |
| 602 | Headington Oil Company, L.P. | Dallas, TX 75231 | Oil & Gas Operator | Mar 2008 |
| 603 | Heartland Energy Company | Big Horn, WY 82833 | Gas Operator | Jun 2012 |
| 604 | Hedges Spencer | Casper, WY 82604 | Oil Operator | Mar 2024 |
| 605 | Helena Resources Inc | Lakewood, CO 80215 | Oil & Gas Operator | Jan 2026 |
| 606 | Helis Oil & Gas Company LLC Estate | New Orleans, LA 70130 | Oil & Gas Operator | Jul 2022 |
| 607 | Henderson Petroleum Corp | San Angelo, TX 76906 | Oil & Gas Operator | Jul 2013 |
| 608 | Herbaly Petroleum Corp | FT Worth, TX 76102 | Oil & Gas Operator | Feb 2002 |
| 609 | Hershey Oil Corporation | | Oil & Gas Operator | Jul 1992 |
| 610 | Hesperus Energy II LLC | | Oil Operator | Nov 2025 |
| 611 | Hi-Pro Production | Gillette, WY 82717 | Gas Operator | Nov 2003 |
| 612 | High Plains Gas LLC | Gillette, WY 82717 | Gas Operator | Aug 2014 |
| 613 | High Summit Oil & Gas Inc | | Oil & Gas Operator | Sep 1987 |
| 614 | Highland Exploration | | Oil Operator | Sep 1979 |
| 615 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Apr 2026 |
| 616 | Hilliard Oil & Gas, Inc. | New Orleans, LA 70112 | Oil & Gas Operator | May 2001 |
| 617 | HMX Investments, Inc. | Katy, TX 77494 | Oil & Gas Operator | Jan 2026 |
| 618 | HNG Oil Company | | Oil & Gas Operator | Jun 1987 |
| 619 | Hodge T F | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2007 |
| 620 | Hoff Elmer & Mildred | | Oil & Gas Operator | Jan 1991 |
| 621 | Holden Harold B | Billings, MT 59103 | Oil Operator | Jun 1996 |
| 622 | Holly Energy Inc | | Oil Operator | Apr 1983 |
| 623 | Holwell Drilling Company | | Oil Operator | Sep 1992 |
| 624 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Apr 2026 |
| 625 | Hondo Oil & Gas | Houston, TX 77042 | Oil & Gas Operator | Oct 1995 |
| 626 | Hot Springs Resources LTD | Casper, WY 82601 | Oil Operator | Dec 2014 |
| 627 | Houston Oil And Minerals | | Oil & Gas Operator | Oct 1993 |
| 628 | Howell Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 2015 |
| 629 | HR Energy LLC | Shelby, MT 59474 | Oil & Gas Operator | Feb 2026 |
| 630 | HRM Resources II, LLC | Denver, CO 80202 | Oil & Gas Operator | Jan 2022 |
| 631 | HRM Resources III LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2022 |
| 632 | HRM Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Aug 2015 |
| 633 | Hrubetz Oil Co. | Dallas, TX 75225 | Oil Operator | Sep 1986 |
| 634 | HS Resources, Inc. | Denver, CO 80202 | Oil & Gas Operator | Sep 2002 |
| 635 | Huber J M Corp | Edison, NJ 08837 | Oil & Gas Operator | Apr 2026 |
| 636 | Hudson Group LLC | Casper, WY 82601 | Oil & Gas Operator | Jul 2025 |
| 637 | Hughes Oil Company Inc | Odessa, TX 79765 | Oil & Gas Operator | Feb 2004 |
| 638 | Hugoton Energy Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2019 |
| 639 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Apr 2026 |
| 640 | Hunt Petroleum (Aec), Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 641 | Huntington Energy LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Apr 2026 |
| 642 | Hurley Oil Company | | Oil Operator | Dec 1988 |
| 643 | Husky Oil Company | Cody, WY 82414 | Oil & Gas Operator | Dec 1984 |
| 644 | Hyco Oil Inc | Newcastle, WY 82701 | Oil & Gas Operator | Dec 2006 |
| 645 | Hydrocarbon Management, Inc. | San Antonio, TX 78216 | Oil & Gas Operator | Dec 1996 |
| 646 | Hyland Oil Corporation | | Oil & Gas Operator | Apr 1990 |
| 647 | Hyperion Oil & Gas LLC | Dallas, TX 75251 | Oil & Gas Operator | Apr 2026 |
| 648 | I C Gas Amcana Inc | Tulsa, OK 74103-3713 | Oil & Gas Operator | Apr 1996 |
| 649 | Ibex Resources Operating LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2007 |
| 650 | Iks Operating | Upton, WY 82703 | Oil & Gas Operator | Jul 2013 |
| 651 | Impact Energy Operating LLC | Oklahoma City, OK 73172 | Oil & Gas Operator | Feb 2026 |
| 652 | Impact Exploration & Production LLC | Greenwood VIllage, CO 80111 | Oil & Gas Operator | Dec 2025 |
| 653 | Incline Reserves Inc | Topeka, KS BAD ADDR | Oil & Gas Operator | Mar 1994 |
| 654 | Incremental Oil & Gas USA Holdings Inc | Denver, CO 80202 | Oil & Gas Operator | Apr 2021 |
| 655 | Independent Production Company | Greenwood VIllage, CO 80121 | Oil & Gas Operator | May 2003 |
| 656 | Indian Creek Resources Inc | Loveland, CO 80538 | Oil & Gas Operator | Dec 2024 |
| 657 | Industrial Gas Services Inc | Wheat Ridge, CO 80033 | Oil & Gas Operator | Feb 2023 |
| 658 | Inexco Oil Company | Houston, TX 77210 | Oil & Gas Operator | Mar 2013 |
| 659 | Infield Discovery LLC | Madison, MS 39110 | Oil & Gas Operator | Sep 2025 |
| 660 | Infinity Oil & Gas Of Wyoming | Rock Springs, WY 82902 | Oil & Gas Operator | Feb 2009 |
| 661 | Inland Production Company | Vernal, UT 84079 | Oil & Gas Operator | Dec 2004 |
| 662 | Integrated Energy Inc | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 663 | Integrated Petroleum Corporation | Denver, CO 80202 | Oil Operator | Jan 2010 |
| 664 | Integrity Oil & Gas | Golden, CO 80401 | Oil & Gas Operator | May 2011 |
| 665 | Intercoast Oil And Gas Company | Tulsa, OK 74136 | Oil & Gas Operator | Jun 1997 |
| 666 | Intercontinental Petroleum | | Oil Operator | Oct 2012 |
| 667 | Interline Resources Corp | Casper, WY 82601 | Oil & Gas Operator | Oct 2009 |
| 668 | Internorth Inc | Tulsa, OK 74136 | Oil & Gas Operator | Apr 2014 |
| 669 | Intoil, Inc. | Englewood, CO 80155 | Oil & Gas Operator | Dec 2002 |
| 670 | Intrepid Oil & Gas LLC | Denver, CO 80202 | Oil & Gas Operator | Apr 2021 |
| 671 | Intrepid Production Corporation | Denver, CO 80202 | Oil & Gas Operator | Jan 2026 |
| 672 | Investment Equipment LLC | FT Morgan, CO 80701 | Oil & Gas Operator | Jan 2026 |
| 673 | Ip Petroleum Company, Inc. | Houston, TX 77210 | Oil & Gas Operator | Mar 2008 |
| 674 | Iron Creek Properties Inc | Casper, WY 82604 | Oil & Gas Operator | Sep 2025 |
| 675 | Itr Petroleum Inc | Houston, TX 77002 | Oil & Gas Operator | Apr 1998 |
| 676 | K & W Oil Company | MT Carmel, IL 62830 | Oil & Gas Operator | May 2013 |
| 677 | K N Energy Inc | Lakewood, CO 80228 | Oil & Gas Operator | Nov 2000 |
| 678 | Kachina Exploration Inc | Cheyenne, WY 82003 | Oil & Gas Operator | Jul 2000 |
| 679 | Kaiser Energy Inc | Denver, CO 80202 | Oil & Gas Operator | Dec 1990 |
| 680 | Kaiser-Francis Oil Company | Tulsa, OK 74121 | Oil & Gas Operator | Apr 2026 |
| 681 | Kamco Limited | Salt Lake City, UT 84105 | Oil Operator | Sep 2016 |
| 682 | Kaneb Oil & Gas | | Oil & Gas Operator | Oct 1987 |
| 683 | Kant Walter F | Lance Creek, WY 82222 | Oil & Gas Operator | Dec 2002 |
| 684 | Kara Enterprises Inc | Upton, WY 82730 | Oil Operator | Jul 2013 |
| 685 | Karlton Terry Oil Company | | Oil Operator | Jan 1991 |
| 686 | Kase Energy LLC | Roseville, MN 55113 | Oil Operator | Aug 2006 |
| 687 | Katherman Vance E | Casper, WY 82601 | Oil Operator | Dec 2004 |
| 688 | Kauffman K P Company Inc | Denver, CO 80202 | Oil & Gas Operator | Mar 1996 |
| 689 | KC Resources Inc | Snowmass VLG., CO 81615 | Oil & Gas Operator | Jan 2026 |
| 690 | KC Well Service | Big Piney, WY 83113 | Gas Operator | Jan 2026 |
| 691 | KCS Medallion Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Nov 2018 |
| 692 | KCS Mountain Resources Inc | Manderson, WY 82432 | Oil & Gas Operator | Nov 2006 |
| 693 | Keas Production Company LLC | Estes Park, CO 80517 | Oil Operator | Jan 2026 |
| 694 | Keba Energy LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2015 |
| 695 | Kedco Management Corp | | Oil & Gas Operator | Jul 1985 |
| 696 | Keith Walker O & G Co LLC | | Oil Operator | Jan 2026 |
| 697 | Keiths Pumping Service | Douglas, WY 82633 | Oil & Gas Operator | Aug 2003 |
| 698 | Kelly Operating Company | | Oil & Gas Operator | Oct 1991 |
| 699 | Kem Ventures, LP | Katy, TX 77450 | Oil & Gas Operator | Jan 2026 |
| 700 | Kemmerer Coal Co | | Oil & Gas Operator | Dec 1981 |