| 501 | Texas Oil & Gas Corporation | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 502 | Texas Southwest Gas LLC | Tulsa, OK 74121 | Oil & Gas Operator | Oct 2022 |
| 503 | Thomas J L Engineering Inc | Edmond, OK 73003-0026 | Oil & Gas Operator | Jul 2016 |
| 504 | Tidemark Exploration | Tulsa, OK 74170 | Oil & Gas Operator | May 2005 |
| 505 | Titan Resources LTD | Limaville, OH 44640 | Oil & Gas Operator | Feb 2025 |
| 506 | Transcontinental Company | Haltom City, TX 76148-4122 | Oil & Gas Operator | Feb 2025 |
| 507 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Apr 2025 |
| 508 | Trey Resources Inc. | Midland, TX 79710 | Oil & Gas Operator | Jan 2025 |
| 509 | Trueblood Resources, Inc. | Denver, CO 80222 | Oil & Gas Operator | Apr 2025 |
| 510 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 511 | Txok Energy Resources Company | Tulsa, OK 74172-0140 | Oil & Gas Operator | Feb 2017 |
| 512 | Umc Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 513 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 514 | Unit Drilling & Exploration Co | Tulsa, OK 74132-5300 | Oil & Gas Operator | Jan 2025 |
| 515 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2025 |
| 516 | United States Trading & Trans | Dallas, TX 75380-3342 | Oil & Gas Operator | Dec 1994 |
| 517 | Upland Resources, Inc. | Canadian, TX 79014 | Oil & Gas Operator | Dec 2009 |
| 518 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Apr 2025 |
| 519 | Valero Marketing & Supply Co | San Antonio, TX 78269-6000 | Oil & Gas Operator | Sep 2023 |
| 520 | Vantage Point Operating Co | Houston, TX 77057 | Oil & Gas Operator | Dec 2014 |
| 521 | Veenker Resources, Inc. | Oklahoma City, OK 73113 | Oil & Gas Operator | Feb 2025 |
| 522 | Vega Energy Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Sep 2015 |
| 523 | Vintage Marketing Inc | Tulsa, OK 74172 | Oil & Gas Operator | Apr 2003 |
| 524 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Jan 2025 |
| 525 | VRC Oil & Gas Operating Co | Oklahoma City, OK 73116-1431 | Oil & Gas Operator | Jun 2019 |
| 526 | VRK Oil And Gas, Inc. | Arlington, TX 76016 | Oil & Gas Operator | Mar 2014 |
| 527 | W M A Corporation | Wichita, KS 67278-1713 | Oil & Gas Operator | Jan 1998 |
| 528 | Wagner & Brown LP | Midland, TX 79702-1714 | Oil & Gas Operator | Aug 2022 |
| 529 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2025 |
| 530 | Walker Keith F | Ardmore, OK 73401 | Oil & Gas Operator | Jan 2019 |
| 531 | Walker R J Oil Co Inc | | Oil & Gas Operator | May 2003 |
| 532 | Wallace Oil & Gas Inc | Oklahoma City, OK 73156 | Oil & Gas Operator | Apr 2025 |
| 533 | Walters Oil Company | Elmore City, OK 73433-9505 | Oil & Gas Operator | Feb 2025 |
| 534 | Ward Gas Marketing Inc | Enid, OK 73702 | Oil & Gas Operator | Sep 2011 |
| 535 | Ward Petroleum Corporation | Enid, OK 73702 | Oil & Gas Operator | Jan 2025 |
| 536 | Weinkauf Petroleum, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2025 |
| 537 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 538 | Wildhorse Operating Company | Ardmore, OK 73402 | Oil & Gas Operator | Apr 2025 |
| 539 | Williams Roger F | Tulsa, OK 74152-0951 | Oil & Gas Operator | May 2013 |
| 540 | Windward Development LLC | Tulsa, OK 74136-7007 | Oil & Gas Operator | Jul 2019 |
| 541 | Wynn-Crosby Operating LP | Dallas, TX 75201 | Oil & Gas Operator | Jan 2025 |
| 542 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2025 |
| 543 | Yarhola Production Company | Drumright, OK 74030 | Oil & Gas Operator | Feb 2025 |
| 544 | Yingling Oil, Inc. | Oklahoma City, OK 73118 | Oil & Gas Operator | Dec 2000 |
| 545 | Young H Inc | Edmond, OK 73013 | Oil & Gas Operator | Oct 1993 |