| 501 | Tex/Con Oil & Gas Company | Houston, TX 77074 | Oil & Gas Operator | Feb 2001 |
| 502 | Texaco Expl. And Prod. Inc. | Houston, TX 77236 | Oil & Gas Operator | May 2025 |
| 503 | Texaco Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2017 |
| 504 | Texaco Oils, Inc. | Tulsa, OK 74102-2420 | Oil & Gas Operator | Jan 2003 |
| 505 | Texas Oil & Gas Corporation | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 506 | TGX Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2004 |
| 507 | The Warren Corporation | Oklahoma City, OK 73118 | Oil & Gas Operator | Jan 2016 |
| 508 | Tide West Oil Company | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2021 |
| 509 | TLS Oil & Gas Inc | Kingfisher, OK 73750-0901 | Oil & Gas Operator | May 2025 |
| 510 | Toklan Oil And Gas Corporation | Tulsa, OK 74136 | Oil & Gas Operator | May 2025 |
| 511 | Toklan Oil Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |
| 512 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 513 | Total Minatome Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 1998 |
| 514 | Totalfinaelf E&P USA Inc | Houston, TX 77024 | Oil & Gas Operator | Jul 2007 |
| 515 | Trans-Western Expl. Inc. | Dallas, TX 75240 | Oil & Gas Operator | Mar 1993 |
| 516 | Transok LLC | Oklahoma City, OK 73124-0300 | Oil & Gas Operator | Jul 2020 |
| 517 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Jul 2025 |
| 518 | Trigg Drilling Company Inc | Oklahoma City, OK 73105 | Oil & Gas Operator | Jan 2013 |
| 519 | Troy Energy Operating LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Apr 2025 |
| 520 | Tulsa Energy Partners LLC | Tulsa, OK 74103-4461 | Oil & Gas Operator | May 2025 |
| 521 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 522 | Txok Energy Resources Company | Tulsa, OK 74172-0140 | Oil & Gas Operator | Feb 2017 |
| 523 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 524 | Unbridled Resources, LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 525 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 526 | Union Texas Petroleum Corp. | Houston, TX 77252-2120 | Oil & Gas Operator | Dec 2014 |
| 527 | Unit Drilling & Exploration Co | Tulsa, OK 74132-5300 | Oil & Gas Operator | Apr 2025 |
| 528 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Jul 2025 |
| 529 | United Energy Operating, LLC | Edmond, OK 73083 | Oil & Gas Operator | Jul 2025 |
| 530 | United Oil Corporation | Denver, CO 80202-3813 | Oil & Gas Operator | Apr 2025 |
| 531 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Jul 2025 |
| 532 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Jul 2025 |
| 533 | Validus Energy II Midcon LLC | Denver, CO 80202 | Oil & Gas Operator | Jul 2025 |
| 534 | Valjohn Energy Corporation | Dover, OK 73734 | Oil & Gas Operator | Apr 2025 |
| 535 | Vantage Point Operating Co | Houston, TX 77057 | Oil & Gas Operator | Dec 2014 |
| 536 | Vaquero Resources, LLC | Oklahoma City, OK 73102 | Oil & Gas Operator | Apr 2025 |
| 537 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Mar 2025 |
| 538 | Viersen & Cochran Drilling Company | | Oil & Gas Operator | May 2015 |
| 539 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Apr 2025 |
| 540 | Wagner & Brown LP | Midland, TX 79702-1714 | Oil & Gas Operator | Aug 2022 |
| 541 | Wallace Oil & Gas Inc | Oklahoma City, OK 73156 | Oil & Gas Operator | Jul 2025 |
| 542 | Walsh Jr F Howard | Fort Worth, TX 76102-4773 | Oil & Gas Operator | Apr 2025 |
| 543 | Ward Petroleum Corporation | Enid, OK 73702 | Oil & Gas Operator | Apr 2025 |
| 544 | Warren American Oil Company LLC | Tulsa, OK 74147 | Oil & Gas Operator | Jul 2025 |
| 545 | Weatherly Oil & Gas, LLC | Dallas, TX 75206 | Oil & Gas Operator | Jul 2025 |
| 546 | Western Mountain Resources LLC | Cogan Station, PA 17728 | Oil & Gas Operator | Apr 2025 |
| 547 | Western Oil And Gas Development Corp | Oklahoma City, OK 73103-3735 | Oil & Gas Operator | Apr 2025 |
| 548 | Weststar Oil & Gas Inc | Edmond, OK 73013 | Oil & Gas Operator | May 2025 |
| 549 | Wheeler Energy Co. | Tulsa, OK 74101 | Oil & Gas Operator | Apr 2025 |
| 550 | Whitaker Raymond | Paul Valley, OK 73075-1041 | Oil & Gas Operator | May 2007 |
| 551 | White Goat Resources LLC | Yukon, OK 73099 | Oil & Gas Operator | May 2025 |
| 552 | White Star Petroleum II LLC | Oklahoma City, OK 73113-1360 | Oil & Gas Operator | Apr 2025 |
| 553 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 554 | Whitmar Exploration Company | Denver, CO 80202 | Oil & Gas Operator | Apr 2025 |
| 555 | Whitmar Operating Company | Tulsa, OK 74103-3515 | Oil & Gas Operator | Apr 2009 |
| 556 | Will Energy Corporation | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 557 | Williford Energy Company | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2025 |
| 558 | Wilshire Enterprises Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2015 |
| 559 | Windsor Energy Group LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Aug 2021 |
| 560 | Wiser Oil Co | Denver, CO 80202 | Oil & Gas Operator | Dec 2023 |
| 561 | WLW Oil & Gas LLC | Kingfisher, OK 73750 | Oil & Gas Operator | May 2025 |
| 562 | WM KS Energy Resources LLC | Shreveport, LA 71101 | Oil & Gas Operator | Nov 2019 |
| 563 | Woods Petroleum Corporation | Oklahoma City, OK 73112 | Oil & Gas Operator | Mar 2015 |
| 564 | Wynn-Crosby Operating LP | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 565 | Xanadu Exploration Company | Broken Arrow, OK 74014 | Oil & Gas Operator | May 2025 |
| 566 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |
| 567 | Yale Oil Association, Inc. | Oklahoma City, OK 73105 | Oil & Gas Operator | May 2025 |
| 568 | Yarhola Production Company | Drumright, OK 74030 | Oil & Gas Operator | May 2025 |
| 569 | Z G Exploration Inc | Oklahoma City, OK 73112 | Oil & Gas Operator | Feb 2005 |
| 570 | Zenergy Inc | Tulsa, OK 74136 | Oil & Gas Operator | May 2025 |
| 571 | Zephyr Operating Co LLC | Oklahoma City, OK 73118-6035 | Oil & Gas Operator | Apr 2025 |
| 572 | Zephyr SWD LLC | Oklahoma City, OK 73118-6035 | Oil Operator | Apr 2025 |
| 573 | Zilkha Energy Company | Houston, TX 77046 | Oil & Gas Operator | Oct 2002 |
| 574 | Zinke & Trumbo LTD | Tulsa, OK 74105 | Oil & Gas Operator | Sep 2017 |
| 575 | ZP Disposal Systems LLC | Kingfisher, OK 73750 | Oil Operator | May 2025 |