| 501 | Smith, R. E. Interests, Inc. | Houston, TX 77027 | Oil & Gas Operator | Mar 1998 |
| 502 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 503 | Sogc, Inc. | Salt Lake Cty, UT 84131 | Oil & Gas Operator | Feb 2025 |
| 504 | Sojitz Energy Venture, Inc. | Houston, TX 77042 | Oil & Gas Operator | Feb 2018 |
| 505 | Sojourner Drilling Corporation | Abilene, TX 79604 | Oil & Gas Operator | Apr 2025 |
| 506 | Soldier Creek Energy, LLC | Edmond, OK 73013 | Oil & Gas Operator | Apr 2025 |
| 507 | Sonat Exploration Co. | Houston, TX 77251 | Oil & Gas Operator | Dec 2021 |
| 508 | Sonat Exploration Company -Tyler | Houston, TX 77251 | Oil & Gas Operator | Dec 1999 |
| 509 | Sonat Exploration Company-MCR | Houston, TX 77251 | Oil & Gas Operator | Dec 1999 |
| 510 | Southcoast Production Inc | Houston, TX 77010 | Oil & Gas Operator | Apr 2025 |
| 511 | Southwest Operating, Inc.-Tyler | Tyler, TX 75701 | Oil & Gas Operator | Apr 2025 |
| 512 | Southwest Royalties Inc | Midland, TX 79710 | Oil & Gas Operator | Apr 2025 |
| 513 | Spartan Operating Company, Inc. | Tyler, TX 75702 | Oil & Gas Operator | Feb 2013 |
| 514 | Spindletop Oil & Gas Co. | Dallas, TX 75230 | Oil & Gas Operator | Apr 2025 |
| 515 | Sponte Operating, Inc. | Dallas, TX 75313 | Oil & Gas Operator | Apr 2025 |
| 516 | SSC, Inc. | Lubbock, TX 79408 | Oil & Gas Operator | Apr 2025 |
| 517 | St. Mary Land & Exploration Co | Denver, CO 80201 | Oil & Gas Operator | Jun 2010 |
| 518 | Sterling Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Dec 2015 |
| 519 | Strand Energy, L.C. | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 520 | Strat Land Exploration Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2025 |
| 521 | Stroube Energy Corporation | Dallas, TX 75248 | Oil & Gas Operator | Jan 2012 |
| 522 | Stroud Energy, LTD. | Fort Worth, TX 76102 | Oil & Gas Operator | Jun 2006 |
| 523 | Stroud Oil Properties, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | May 2013 |
| 524 | Stuart Oil & Gas | Longview, TX 75606 | Oil & Gas Operator | Apr 2025 |
| 525 | Sun River Operating, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Apr 2025 |
| 526 | Sundown Energy LP | Dallas, TX 75248 | Oil & Gas Operator | Apr 2025 |
| 527 | Sunland Production Company, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jan 2025 |
| 528 | Sunwest Operating Company L.L.C. | Englewood, CO 80155 | Oil & Gas Operator | Aug 2002 |
| 529 | SW Operating, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Sep 2000 |
| 530 | Sydri Operating, LLC | Dallas, TX 75231 | Oil & Gas Operator | Apr 2025 |
| 531 | T & G Oil, Inc. | White Oak, TX 75693 | Oil & Gas Operator | Dec 2010 |
| 532 | Tanos Exploration II, LLC | Tyler, TX 75701 | Oil & Gas Operator | Sep 2023 |
| 533 | Tanos Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Oct 2018 |
| 534 | TC Oil And Gas, LLC | Denton, TX 76205 | Oil Operator | Apr 2025 |
| 535 | Te-Ray Resources, Inc. | Oklahoma City, OK 73108 | Oil & Gas Operator | Mar 2015 |
| 536 | Te-Ray Resources, LLC | Oklahoma City, OK 73142 | Oil & Gas Operator | Apr 2025 |
| 537 | Teco Operating Company | Athens, TX 75751 | Oil & Gas Operator | Jun 2001 |
| 538 | Tesoro E&P Company, L.P. | San Antonio, TX 78216 | Oil & Gas Operator | Jan 2000 |
| 539 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Apr 2025 |
| 540 | Texaco Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2017 |
| 541 | Texakoma E & P, LLC | Plano, TX 75024 | Oil & Gas Operator | Apr 2025 |
| 542 | Texakoma Operating, L.P. | Plano, TX 75024 | Oil & Gas Operator | Jan 2025 |
| 543 | Texas American Resources Company | Austin, TX 78701 | Oil & Gas Operator | Apr 2025 |
| 544 | Texas Crude Operator, Inc. | Houston, TX 77098 | Oil & Gas Operator | Aug 2017 |
| 545 | Texas Utilities Fuel Co. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2018 |
| 546 | Texas Utilities Mining Co. | Dallas, TX 75201 | Oil & Gas Operator | May 1995 |
| 547 | Texeast Operating Co., Inc. | Farmers BRNCH, TX 75234 | Oil Operator | Apr 2025 |
| 548 | Texican Crude & Hydrocarbons LLC | Houston, TX 77002 | Oil Operator | Sep 2023 |
| 549 | Texla Energy Products LLC | Houston, TX 77002 | Oil Operator | Sep 2020 |
| 550 | Texokan Operating, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Apr 2025 |
| 551 | TGNR East Texas II LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 552 | TGNR East Texas LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 553 | TGX Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2004 |
| 554 | Thorp Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Feb 2014 |
| 555 | Three J Energy, Inc. | Seguin, TX 78155 | Oil & Gas Operator | Apr 2025 |
| 556 | Thunder Oil & Gas, LLC | Ardmore, OK 73402 | Oil & Gas Operator | Jan 2025 |
| 557 | Thunderbird (Texas) Resources LP | Edmond, OK 73025 | Oil & Gas Operator | Apr 2019 |
| 558 | Tidemark Exploration Inc | Tulsa, OK 74120 | Oil & Gas Operator | Apr 2019 |
| 559 | TK Drilling Corp. | Tulsa, OK 74133 | Oil & Gas Operator | Jan 2025 |
| 560 | TMR Exploration, Inc. | Bossier City, LA 71171 | Oil & Gas Operator | Apr 2025 |
| 561 | Torch Energy Services, Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2011 |
| 562 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 563 | Total E&P USA, Inc. | Houston, TX 77210 | Oil & Gas Operator | Nov 2011 |
| 564 | Totalfinaelf E&P USA Inc | Houston, TX 77024 | Oil & Gas Operator | Jul 2007 |
| 565 | Tower Resources Inc | Conroe, TX 77304 | Oil & Gas Operator | Apr 2025 |
| 566 | Tracy Production | Lindale, TX 75771 | Oil & Gas Operator | Apr 2025 |
| 567 | Tri-State Exploration & Prod Inc | Marshall, TX 75671 | Oil & Gas Operator | Aug 2003 |
| 568 | Trich Production, Inc. | Longview, TX 75606 | Oil & Gas Operator | Jan 2025 |
| 569 | Trico Oil & Gas Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Apr 2025 |
| 570 | Triple J Investments Inc | Longview, TX 75606 | Oil & Gas Operator | Feb 2023 |
| 571 | Triple M Saltwater Disposal, LP | Kilgore, TX 75663 | Oil Operator | Apr 2025 |
| 572 | Trivium Operating, LLC | Fort Worth, TX 76107 | Oil & Gas Operator | Apr 2025 |
| 573 | Truth Resources LP | Houston, TX 77090 | Oil Operator | Sep 2021 |
| 574 | Tryco Exploration, LLC | Plano, TX 75026 | Oil & Gas Operator | Nov 2006 |
| 575 | Twojo, Inc. | Longview, TX 75601 | Oil & Gas Operator | Nov 1996 |
| 576 | Tyler Oil & Gas Inc. | Tyler, TX 75702 | Oil & Gas Operator | Sep 2004 |
| 577 | Uhc Petroleum Corporation | Rocksprings, TX 78880 | Oil & Gas Operator | Apr 2025 |
| 578 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 579 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 580 | Uosi Operating, Inc. | Lovelady, TX 75851 | Oil & Gas Operator | Apr 2025 |
| 581 | Ursus Oil And Gas | Tyler, TX 75703 | Oil & Gas Operator | Apr 2025 |
| 582 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Apr 2025 |
| 583 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Dec 2024 |
| 584 | Vaughan Operating Company, LLC | Shreveport, LA 71101 | Oil & Gas Operator | Jun 2009 |
| 585 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Jan 2025 |
| 586 | Vintage Petroleum, LLC | Houston, TX 77210 | Oil & Gas Operator | Dec 2019 |
| 587 | Viola Prod., Inc. | Dallas, TX 75251 | Oil & Gas Operator | Apr 2025 |
| 588 | Walker, Tigner | Shreveport, LA 71138 | Oil & Gas Operator | Feb 2005 |
| 589 | Watkins Production Company | Dallas, TX 75229 | Oil & Gas Operator | Feb 2008 |
| 590 | West Mountain Operating Co, Inc. | Longview, TX 75604 | Oil & Gas Operator | Feb 2019 |
| 591 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 592 | Whitaker Properties, L. P. | Carthage, TX 75633 | Oil & Gas Operator | Sep 1997 |
| 593 | Whitaker, Fred | Carthage, TX 75633 | Gas Operator | Mar 2001 |
| 594 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Apr 2025 |
| 595 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 596 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 597 | Whittier Operating Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2007 |
| 598 | Wildhorse Resources MNGT Co, LLC | Oklahoma City, OK 73154 | Oil & Gas Operator | May 2019 |
| 599 | Wildhorse Resources, LLC | Houston, TX 77279 | Oil & Gas Operator | Feb 2015 |
| 600 | Will-Drill Operating, L.L.C. | Shreveport, LA 71105 | Oil & Gas Operator | Apr 2025 |