| 601 | Titan Resources LTD | Limaville, OH 44640 | Oil & Gas Operator | Feb 2026 |
| 602 | Toklan Oil And Gas Corporation | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2026 |
| 603 | Toklan Oil Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |
| 604 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 605 | Tower Energy Corporation | Sapulpa, OK 74067-0837 | Oil & Gas Operator | Mar 2015 |
| 606 | Trail Ridge Energy Partners, LLC | Grapevine, TX 76051 | Oil & Gas Operator | Feb 2026 |
| 607 | Transok LLC | Oklahoma City, OK 73124-0300 | Oil & Gas Operator | Jul 2020 |
| 608 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Apr 2026 |
| 609 | Trepco Production Company Inc | Yukon, OK 73099 | Oil & Gas Operator | Feb 2026 |
| 610 | Triumph Resources Inc | Oklahoma City, OK 73114 | Oil & Gas Operator | Nov 2004 |
| 611 | Trivestco Energy Company | Ponca City, OK 74601 | Oil & Gas Operator | Feb 2026 |
| 612 | Tulsa Energy Partners LLC | Tulsa, OK 74103-4461 | Oil & Gas Operator | Feb 2026 |
| 613 | Turner Oil Company | Yale, OK 74085-0234 | Oil & Gas Operator | Nov 2014 |
| 614 | Tuthill S Keith & Bill Barbee | Amarillo, TX 79101-1427 | Oil & Gas Operator | Dec 2004 |
| 615 | Twain Energy LLC | Ridgeland, MS 39157 | Oil & Gas Operator | Feb 2026 |
| 616 | Twisted Resources Inc | Blanchard, OK 73010-8463 | Oil & Gas Operator | Jan 2026 |
| 617 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 618 | Txok Energy Resources Company | Tulsa, OK 74172-0140 | Oil & Gas Operator | Feb 2017 |
| 619 | Tyson Olan | Hobart, OK 73651-6413 | Oil & Gas Operator | Apr 2015 |
| 620 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 621 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 622 | Union Valley Petroleum Corp | Enid, OK 73701 | Oil & Gas Operator | Feb 2026 |
| 623 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2026 |
| 624 | United Energy Operating, LLC | Edmond, OK 73083 | Oil & Gas Operator | Apr 2026 |
| 625 | United Oil Corporation | Denver, CO 80202-3813 | Oil & Gas Operator | Jan 2026 |
| 626 | United Production Company LLC | Edmond, OK 73003 | Oil & Gas Operator | Feb 2026 |
| 627 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Apr 2026 |
| 628 | Vanderbilt Resources Corp. | Midland, TX 79701 | Oil & Gas Operator | Nov 1991 |
| 629 | Vantage Point Operating Co. | Houston, TX 77057 | Oil & Gas Operator | Dec 2014 |
| 630 | Veenker Resources Inc | Oklahoma City, OK 73113 | Oil & Gas Operator | Feb 2026 |
| 631 | Viersen & Cochran Drilling Company | | Oil & Gas Operator | May 2015 |
| 632 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Jan 2026 |
| 633 | Vistatex Energy LLC | Houston, TX 77057 | Oil & Gas Operator | Feb 2026 |
| 634 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2026 |
| 635 | Warren Corporation | Oklahoma City, OK 73118 | Oil & Gas Operator | Jan 2016 |
| 636 | Washita Oil And Gas, L.L.C. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2015 |
| 637 | Washita Production Company | Tulsa, OK 74136 | Oil & Gas Operator | May 2006 |
| 638 | Western Farmers Electric Coop | Anadarko, OK 73005-0429 | Oil & Gas Operator | Apr 2012 |
| 639 | Western Oil And Gas Development Corp | Oklahoma City, OK 73103-3735 | Oil & Gas Operator | Feb 2026 |
| 640 | Wheeler Energy Co. | Tulsa, OK 74101 | Oil & Gas Operator | Feb 2026 |
| 641 | Wheeler Energy, LLC | Tulsa, OK 74101 | Oil & Gas Operator | Apr 2026 |
| 642 | White Goat Resources LLC | Yukon, OK 73099 | Oil & Gas Operator | Feb 2026 |
| 643 | White Stone LLC | Waynoka, OK 73860-4801 | Oil & Gas Operator | Feb 2026 |
| 644 | Whiteman Industries Inc | Oklahoma City, OK 73101 | Oil & Gas Operator | May 2025 |
| 645 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2026 |
| 646 | Will Energy Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jan 2026 |
| 647 | Williford Energy Company | Tulsa, OK 74135 | Oil & Gas Operator | Apr 2026 |
| 648 | Wilson Operating Company LLC | Tulsa, OK 74105 | Oil & Gas Operator | Apr 2026 |
| 649 | Windsor Energy Group LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Aug 2021 |
| 650 | Wolverine Exploration Company | Houston, TX 77002 | Oil & Gas Operator | May 2019 |
| 651 | Woodward Iodine Corporation | Woodward, OK 73801 | Oil & Gas Operator | Feb 2026 |
| 652 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 653 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2026 |
| 654 | Yale Oil Association, Inc. | Oklahoma City, OK 73105 | Oil & Gas Operator | Feb 2026 |
| 655 | Young Tommy Oil Inc | Woodward, OK 73802-0893 | Oil & Gas Operator | Jan 2026 |
| 656 | Z G Operating LLC | Oklahoma City, OK 73134-5038 | Oil & Gas Operator | Nov 2009 |
| 657 | Z G Exploration Inc | Oklahoma City, OK 73112 | Oil & Gas Operator | Feb 2005 |
| 658 | Zenith Oil & Gas, LLC | Kilgore, TX 75663 | Oil & Gas Operator | Jan 2026 |
| 659 | Zephyr Operating Co LLC | Oklahoma City, OK 73118-6035 | Oil & Gas Operator | Feb 2026 |
| 660 | Zilkha Energy Company | Houston, TX 77046 | Oil & Gas Operator | Oct 2002 |
| 661 | Zimtex Energy LLC | Perryton, TX 79070-5818 | Oil & Gas Operator | Nov 2017 |