| 601 | Silver Mountain Energy LLC | | Oil & Gas Operator | May 2025 |
| 602 | Simcoe LLC | Durango, CO 81301 | Oil & Gas Operator | May 2025 |
| 603 | Simmons, Inc.* D. J. | | Oil & Gas Operator | May 2020 |
| 604 | Singletree Resources Inc | | Oil & Gas Operator | Aug 2014 |
| 605 | Skaer Properties LTD Partnership | | Oil & Gas Operator | Jun 2013 |
| 606 | Slate River Resources LLC | Denver, CO 80293 | Oil & Gas Operator | Apr 2008 |
| 607 | Slawson Exploration Company Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Jul 2025 |
| 608 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Jul 2025 |
| 609 | Smith Energy Corp | | Oil & Gas Operator | Jan 2024 |
| 610 | Smith Energy Limited Partnership 1988 | | Oil & Gas Operator | May 2012 |
| 611 | Smith Energy LLC | | Oil & Gas Operator | Jun 2025 |
| 612 | Smith Oil Properties Inc | | Oil & Gas Operator | Nov 2022 |
| 613 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 614 | Sonat Raton, L.L.C. | | Gas Operator | Sep 2005 |
| 615 | Sonterra Energy LLC | Wichita, KS 67226 | Oil & Gas Operator | Jul 2022 |
| 616 | Soper Production | | Oil & Gas Operator | Dec 2011 |
| 617 | Sourcegas Energy Services Co | Golden, CO 80401 | Gas Operator | Jun 2015 |
| 618 | Southland Royalty Company LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2021 |
| 619 | Southwestern Production Corporation | Lakewood, CO 80228 | Oil & Gas Operator | Jun 2025 |
| 620 | Sovereign Energy LLC | | Oil & Gas Operator | Sep 2011 |
| 621 | Sovereign Operating Company LLC | Denver, CO 80202 | Oil & Gas Operator | Apr 2016 |
| 622 | Spellbound Energy LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2025 |
| 623 | St Croix Operating Inc | | Oil Operator | May 2025 |
| 624 | St James Energy Operating Inc | | Oil & Gas Operator | Aug 2013 |
| 625 | Standley* Robert K Dba Otis Energy | | Oil Operator | Jan 2023 |
| 626 | Starlight Resources LLC | | Oil & Gas Operator | Jun 2006 |
| 627 | Stehle Oil Company | | Oil Operator | Jun 2021 |
| 628 | Stelbar Oil Corporation, Inc. | Wichita, KS 67206 | Oil & Gas Operator | Mar 2025 |
| 629 | Stephens Energy Company LLC | | Oil & Gas Operator | Jun 2012 |
| 630 | Stewart Petroleum Corporation | Greenwood VIllage, CO 80111 | Oil & Gas Operator | Dec 2023 |
| 631 | Stone Energy Corporation | Denver, CO 80202-2828 | Oil & Gas Operator | Oct 2014 |
| 632 | Stoneham Production LLC | | Oil & Gas Operator | May 2025 |
| 633 | Strachan Exploration Inc | Englewood, CO 80112 | Oil & Gas Operator | Apr 2025 |
| 634 | Stroud Oil Properties, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | May 2013 |
| 635 | Summit Oil & Gas LLC | | Oil & Gas Operator | May 2025 |
| 636 | Summit Operating LLC | Boulder, CO 80301 | Oil & Gas Operator | Apr 2025 |
| 637 | Sunburst, Inc. | Wheat Ridge, CO 80033 | Oil & Gas Operator | May 2025 |
| 638 | Sundance Energy Inc | Denver, CO 80202 | Oil & Gas Operator | Jul 2014 |
| 639 | Sundance Resources, Inc. | Rio VIsta, TX 76093 | Oil & Gas Operator | Mar 2012 |
| 640 | Swepi LP | Houston, TX 77079 | Oil & Gas Operator | Jul 2020 |
| 641 | Swevco-Sabw LLC | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 642 | Swift Beef Company | | Oil & Gas Operator | May 2006 |
| 643 | SWN Production Company, LLC | Spring, TX 77391 | Oil & Gas Operator | May 2025 |
| 644 | Synergy Operating LLC | Farmington, NM 87499 | Oil & Gas Operator | Jul 2024 |
| 645 | Synergy Resources Corporation | | Oil & Gas Operator | Oct 2022 |
| 646 | T P Operating LLC | | Oil & Gas Operator | Nov 1999 |
| 647 | Tabula Rasa Energy, LLC | Allen, TX 75013 | Oil & Gas Operator | Dec 2020 |
| 648 | Tamco Drilling Inc | | Oil & Gas Operator | Apr 2003 |
| 649 | Tarpon Oil Company | Fort Worth, TX 76107 | Oil & Gas Operator | Mar 2017 |
| 650 | Tbi Production Company | Lakewood, CO 80228 | Oil & Gas Operator | Oct 2004 |
| 651 | Terra Exploration & Production Co. Inc. | | Oil & Gas Operator | Dec 2009 |
| 652 | Texaco Expl. And Prod. Inc. | Houston, TX 77236 | Oil & Gas Operator | May 2025 |
| 653 | Texakoma Operating, L.P. | Plano, TX 75024 | Oil & Gas Operator | Mar 2025 |
| 654 | Texas American Resources Company | Austin, TX 78701 | Oil & Gas Operator | Jul 2025 |
| 655 | Texas Tea Of Colorado LLC Dba Texas Tea LLC | | Oil & Gas Operator | Jun 2021 |
| 656 | The Termo Company | Long Beach, CA 90801 | Oil & Gas Operator | May 2025 |
| 657 | Thomas L Spring LLC | | Oil & Gas Operator | May 2025 |
| 658 | Thomas Operating Company Inc | Greeley, CO 80634 | Oil & Gas Operator | Aug 2008 |
| 659 | Thompson & James Cleo Thompson, Jr.* & J Cleo | | Oil & Gas Operator | Jan 2010 |
| 660 | Thorofare Resources, Inc | | Oil & Gas Operator | May 2011 |
| 661 | Three Forks Resources LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | Jul 2025 |
| 662 | Tidal Wave Energy, Inc. | New Castle, PA 16105 | Oil & Gas Operator | Jun 2022 |
| 663 | Tigges Oil LLC | | Oil & Gas Operator | Dec 2022 |
| 664 | Timber Creek Operating LLC | Granbury, TX 76049 | Oil & Gas Operator | Jul 2025 |
| 665 | Timberline Energy Inc | Franklin, PA 16323-0269 | Oil & Gas Operator | Dec 2024 |
| 666 | Timka Resources LTD | | Oil & Gas Operator | Jun 2025 |
| 667 | Tindall Operating Company | Englewood, CO 80112 | Oil & Gas Operator | Jan 2025 |
| 668 | Tipperary Oil & Gas Corp | Denver, CO 80202 | Oil & Gas Operator | May 2014 |
| 669 | Tom Brown Inc | Denver, CO 80202 | Oil & Gas Operator | Dec 2004 |
| 670 | Tom Fenno Production LLC | | Oil Operator | Nov 2019 |
| 671 | Top Operating Company | | Oil & Gas Operator | Oct 2022 |
| 672 | Trend Exploration Company | Midland, TX 79701 | Oil & Gas Operator | Mar 2008 |
| 673 | Trinity Bay Oil & Gas, Inc. | Lubbock, TX 79416 | Oil & Gas Operator | Jul 2025 |
| 674 | Trinity Energy Corp | Gibsonia, PA 15044-9106 | Oil & Gas Operator | Dec 2007 |
| 675 | Trinity Energy Resources Inc | Houston, TX 77079 | Oil & Gas Operator | Aug 2005 |
| 676 | Triple R Oil Co | | Oil & Gas Operator | Jun 2002 |
| 677 | Trousil & Associates, Inc. | Steamboat SPG, CO 80477 | Oil & Gas Operator | Dec 2006 |
| 678 | True Oil LLC | Casper, WY 82602 | Oil & Gas Operator | Jun 2025 |
| 679 | Tudex Petroleum Inc | | Oil & Gas Operator | Sep 2019 |
| 680 | Twin Arrow Inc | Rangely, CO 81648 | Oil & Gas Operator | Sep 2009 |
| 681 | Tyler Rockies Exploration LTD | Tyler, TX 75710-0119 | Oil & Gas Operator | May 2025 |
| 682 | U S Department Of Energy | | Oil & Gas Operator | Apr 1999 |
| 683 | Unioil | Denver, CO 80203 | Oil & Gas Operator | Jun 2012 |
| 684 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 685 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 686 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Jul 2025 |
| 687 | United States Exploration, Inc. | Denver, CO 80802 | Oil & Gas Operator | Jun 2009 |
| 688 | Universal Resources Corp. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jan 2000 |
| 689 | Upland Exploration, LLC | Boerne, TX 78006 | Oil & Gas Operator | Jul 2024 |
| 690 | Ursa Operating Company LLC | Denver, CO 80265 | Oil & Gas Operator | Dec 2020 |
| 691 | Valkyrie Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2025 |
| 692 | Valley Operating Inc | Denver, CO 80218-3633 | Oil & Gas Operator | Jan 2004 |
| 693 | Vanguard Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Feb 2021 |
| 694 | Vanguard Permian LLC | Houston, TX 77057 | Oil & Gas Operator | Nov 2018 |
| 695 | Vaquero Energy Inc | Bakersfield, CA 93309 | Oil & Gas Operator | May 2023 |
| 696 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Mar 2025 |
| 697 | Vecta Oil & Gas LTD | Dallas, TX 75235 | Oil & Gas Operator | May 2025 |
| 698 | Venoco, Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 699 | Verdad Oil & Gas Corporation | Dallas, TX 75235 | Oil & Gas Operator | Jul 2025 |
| 700 | Verdad Resources LLC | | Oil & Gas Operator | May 2025 |