| 501 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 502 | Sanchez Oil & Gas Corporation | Houston, TX 77056 | Oil & Gas Operator | Apr 2026 |
| 503 | Sanchez-O'Brien Oil & Gas Corp | Houston, TX 77057 | Oil & Gas Operator | May 1998 |
| 504 | Sandridge Exploration And Production LLC | Oklahoma City, OK 73104 | Oil & Gas Operator | Apr 2026 |
| 505 | Santa Fe Energy Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 506 | Santa Fe Snyder Corporation | Houston, TX 77024 | Oil & Gas Operator | Oct 2000 |
| 507 | Sarita Energy Resources, LTD. | Houston, TX 77277 | Oil & Gas Operator | Apr 2026 |
| 508 | Saxet Oil Corporation | Midland, TX 79708 | Oil & Gas Operator | Apr 2026 |
| 509 | Scana Petroleum Resources Inc | Houston, TX 77002 | Oil & Gas Operator | Jun 2013 |
| 510 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | Apr 2026 |
| 511 | Scythian, LTD. | Midland, TX 79701 | Oil & Gas Operator | Dec 2020 |
| 512 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 513 | Seagull Midcon Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 514 | SFM Holdings, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Jul 1995 |
| 515 | Sharp Image Energy, Inc. | Big Spring, TX 79721 | Oil & Gas Operator | Apr 2026 |
| 516 | Shell Western E&P | Houston, TX 77001 | Oil & Gas Operator | Apr 2026 |
| 517 | Sheridan Production Company, LLC | Houston, TX 77056 | Oil & Gas Operator | Jan 2026 |
| 518 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | Apr 2026 |
| 519 | Shinnery Oil Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | Apr 2026 |
| 520 | Siegfried R H Inc | Tulsa, OK 74104 | Oil & Gas Operator | Mar 2008 |
| 521 | Simpson Bros. Oil Co. | Odessa, TX 79760 | Oil & Gas Operator | Jan 2001 |
| 522 | Simpson Bros. Oil Co.-Odessa | Odessa, TX 79760 | Oil & Gas Operator | Jan 2001 |
| 523 | Simpson Oil Company | Odessa, TX 79760 | Oil & Gas Operator | Oct 2004 |
| 524 | Slant Operating, LLC | Lafayette, LA 70503 | Oil & Gas Operator | Apr 2026 |
| 525 | SMC Oil & Gas, Inc. | Midland, TX 79710 | Oil & Gas Operator | Apr 2026 |
| 526 | Smith Brothers Oil & Gas, Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2026 |
| 527 | Smith Pipe Of Abilene | Abilene, TX 79608 | Oil & Gas Operator | Apr 2026 |
| 528 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 529 | Sonat Exploration Co. | Houston, TX 77251 | Oil & Gas Operator | Dec 2021 |
| 530 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 531 | Southwest Royalties, Inc. | Midland, TX 79710 | Oil & Gas Operator | Apr 2026 |
| 532 | Southwestern Energy Prod Co | Houston, TX 77032 | Oil & Gas Operator | Jun 2015 |
| 533 | Special Energy Corp. | Stillwater, OK 74076 | Oil & Gas Operator | Apr 2026 |
| 534 | Spindletop Drilling Co. | Dallas, TX 75230 | Oil & Gas Operator | Apr 2026 |
| 535 | Spiral Energy Corp. | Midland, TX 79705 | Oil & Gas Operator | Dec 2019 |
| 536 | Stallion Energy, Inc. | Houston, TX 77060 | Oil & Gas Operator | Oct 2017 |
| 537 | Stanolind Production LLC | Midland, TX 79702 | Oil & Gas Operator | Dec 2020 |
| 538 | Stephens, Autry C. | Midland, TX 79701 | Oil & Gas Operator | Mar 2023 |
| 539 | Summit Exploration, L.L.C. | Tulsa, OK 74119 | Oil & Gas Operator | Mar 2008 |
| 540 | Sundown Energy LP | Dallas, TX 75248 | Oil & Gas Operator | Apr 2026 |
| 541 | Sutton, Robert E., Inc. | Odessa, TX 79760 | Oil & Gas Operator | Mar 1997 |
| 542 | Sweet Crude Operating LLC | Brenham, TX 77834 | Oil & Gas Operator | Apr 2026 |
| 543 | T.G.B., Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2026 |
| 544 | Tamarack Petroleum Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | Apr 2026 |
| 545 | Targa Midstream Services LLC | Houston, TX 77002 | Oil Operator | Mar 2023 |
| 546 | Targa Pipeline Mid-Continent LLC | Sulphur, LA 70665 | Oil & Gas Operator | Jun 2018 |
| 547 | Taurus Exploration U.S.A., Inc. | Midland, TX 79705 | Oil & Gas Operator | Nov 1998 |
| 548 | Taylor Two Energy, LLC | Big Spring, TX 79720 | Oil & Gas Operator | Aug 2019 |
| 549 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | Apr 2026 |
| 550 | Tejas Permian Operating, LLC | Midland, TX 79702 | Oil & Gas Operator | Apr 2026 |
| 551 | Tejones Operating Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2026 |
| 552 | Terrace Petroleum Corporation | Midland, TX 79701 | Oil & Gas Operator | Jul 2013 |
| 553 | Texaco E & P Inc. | Houston, TX 77099 | Oil & Gas Operator | Apr 2026 |
| 554 | Texan Petroleum Corporation | Dallas, TX 75204 | Oil & Gas Operator | Oct 2004 |
| 555 | Texas Crude, Inc. | Houston, TX 77256 | Oil & Gas Operator | Oct 1995 |
| 556 | Texas Investments | San Angelo, TX 76904 | Oil & Gas Operator | Mar 2008 |
| 557 | Texas Secondary Oil Corporation | Devine, TX 78016 | Oil & Gas Operator | Apr 2026 |
| 558 | Thomas Exploration & Devel., Inc | Jourdanton, TX 78026 | Oil & Gas Operator | Apr 2026 |
| 559 | Thompson, J. Cleo | Dallas, TX 75201 | Oil & Gas Operator | May 2024 |
| 560 | Three Rivers Operating Co II LLC | Austin, TX 78735 | Oil & Gas Operator | Mar 2017 |
| 561 | Three Rivers Operating Co LLC | Austin, TX 78735 | Oil & Gas Operator | Mar 2017 |
| 562 | Titan Resources I, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2000 |
| 563 | TMBR/Sharp Drilling, Inc. | Midland, TX 79703 | Oil & Gas Operator | Feb 2004 |
| 564 | Topat Oil Corporation | Midland, TX 79701 | Oil & Gas Operator | Sep 2017 |
| 565 | Tracer Energy, Inc. | Graham, TX 76450 | Oil & Gas Operator | Nov 1998 |
| 566 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Apr 2026 |
| 567 | Trend Exploration Company | Midland, TX 79701 | Oil & Gas Operator | Mar 2008 |
| 568 | Trilogy Operating, Inc. | Midland, TX 79708 | Oil & Gas Operator | Apr 2026 |
| 569 | Trinidad Energy, LLC | Midland, TX 79708 | Oil & Gas Operator | Apr 2026 |
| 570 | Triple "N" Services, Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2026 |
| 571 | Tripp & Sons, LLC | Odessa, TX 79768 | Oil & Gas Operator | Apr 2026 |
| 572 | Tritex Production Co. | Iowa Park, TX 76367 | Oil & Gas Operator | Jan 2013 |
| 573 | Trout Oil Company, Inc. | Odessa, TX 79762 | Oil & Gas Operator | Apr 2026 |
| 574 | TXP, Incorporated | San Angelo, TX 76906 | Oil & Gas Operator | Apr 2026 |
| 575 | Txu Lone Star Pipeline | Dallas, TX 75201 | Oil & Gas Operator | Oct 2003 |
| 576 | U S Energy Corp. Of Amer. Inc. | Cisco, TX 76437 | Oil & Gas Operator | Apr 2026 |
| 577 | U. S. Operating, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Jul 2025 |
| 578 | Uhc Petroleum Corporation | Rocksprings, TX 78880 | Oil & Gas Operator | Apr 2026 |
| 579 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 580 | Universal Resources Corp. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jan 2000 |
| 581 | V-F Petroleum Inc. | Midland, TX 79702 | Oil & Gas Operator | Apr 2026 |
| 582 | Valla Energy Corporation | Odessa, TX 79762 | Oil & Gas Operator | Aug 2003 |
| 583 | Vanguard Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Aug 2019 |
| 584 | Vanguard Permian, LLC | Houston, TX 77057 | Oil & Gas Operator | Nov 2018 |
| 585 | Vencer Energy, LLC | Abilene, TX 79602 | Oil & Gas Operator | Dec 2023 |
| 586 | Ventex Operating Corp. | Addison, TX 75001 | Oil & Gas Operator | Apr 2026 |
| 587 | Venus Exploration, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2013 |
| 588 | Veritas Energy LLC | San Antonio, TX 78231 | Oil & Gas Operator | Apr 2026 |
| 589 | Vernor, Milburn | Uvalde, TX 78801 | Oil & Gas Operator | Aug 2008 |
| 590 | Vision Natural Resources, LP | Midland, TX 79708 | Oil & Gas Operator | Apr 2026 |
| 591 | Vital Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 2026 |
| 592 | W.H.D., Inc. | Euless, TX 76039 | Oil & Gas Operator | Aug 1998 |
| 593 | Wagner & Brown, LTD. | Midland, TX 79702 | Oil & Gas Operator | Aug 2014 |
| 594 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 595 | Walbet, Inc. | Monahans, TX 79756 | Oil & Gas Operator | Apr 2026 |
| 596 | Wallace Oil & Gas Inc | Oklahoma City, OK 73156 | Oil & Gas Operator | Apr 2026 |
| 597 | Warren American Oil Co | Tulsa, OK 74147 | Oil & Gas Operator | Feb 2026 |
| 598 | Wash, Robert C. Inc. | Forsan, TX 79733 | Oil & Gas Operator | Apr 2026 |
| 599 | Watusi Energy LLC | Midland, TX 79710 | Oil & Gas Operator | Apr 2026 |
| 600 | West Texas Oil And Gas Corp. | Houston, TX 77056 | Oil & Gas Operator | Feb 2014 |