| 501 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 502 | San Angelo Cetco, Inc. | San Angelo, TX 76901 | Oil & Gas Operator | Mar 1998 |
| 503 | Satanta Oil Company | Midland, TX 79704 | Oil & Gas Operator | Feb 2026 |
| 504 | Schlachter Operating Corporation | Dallas, TX 75225 | Oil & Gas Operator | Feb 2026 |
| 505 | Schmid Properties, Inc. | Hico, TX 76457 | Oil & Gas Operator | Feb 2026 |
| 506 | Scope Operating Company | Fort Worth, TX 76102 | Oil & Gas Operator | Aug 2003 |
| 507 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | Feb 2026 |
| 508 | SD Royale Energy, Inc. | San Diego, CA 92159 | Oil & Gas Operator | Feb 2026 |
| 509 | SDB Oil & Gas, LLC | Pasadena, TX 77502 | Oil Operator | Feb 2026 |
| 510 | Sedona Oil & Gas Corporation | Dallas, TX 75231 | Oil & Gas Operator | Feb 2026 |
| 511 | Sellers Lease Service, Inc. | Flatonia, TX 78941 | Oil & Gas Operator | Feb 2026 |
| 512 | Sequoia Fossil Fuels, Inc. | Albany, TX 76430 | Oil & Gas Operator | Feb 2026 |
| 513 | Seven Cross Operating, LLC | Santa Anna, TX 76878 | Oil & Gas Operator | Feb 2026 |
| 514 | Sha-Jam Operating Corp. | Midland, TX 79701 | Oil & Gas Operator | Feb 2026 |
| 515 | Shamrock Minerals Corporation | Merkel, TX 79536 | Oil & Gas Operator | Nov 1998 |
| 516 | Sharp Image Energy, Inc. | Big Spring, TX 79721 | Oil & Gas Operator | Feb 2026 |
| 517 | Shelby, Michael H. | Shreveport, LA 71101 | Oil & Gas Operator | Feb 2026 |
| 518 | Shenandoah Oil, Inc. (I) | Midland, TX 79710 | Oil & Gas Operator | Apr 1996 |
| 519 | Shifflett Operating Company | Snyder, TX 79550 | Oil & Gas Operator | Feb 2026 |
| 520 | Shoco Production LLC | Kilgore, TX 75663 | Oil & Gas Operator | Feb 2026 |
| 521 | Shoco Production, L.P. | Kilgore, TX 75663 | Oil & Gas Operator | May 2020 |
| 522 | Shoshone Oil Company | Dallas, TX 75244 | Oil & Gas Operator | May 1994 |
| 523 | Simpson Oil & Land Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 2026 |
| 524 | Simpson Operating Services, LP | Ballinger, TX 76821 | Oil & Gas Operator | Feb 2026 |
| 525 | Sims, John S. | Lawn, TX 79530 | Oil & Gas Operator | Aug 2003 |
| 526 | Six Oil Producers | Abilene, TX 79601 | Oil & Gas Operator | Sep 2002 |
| 527 | Smail, James R. | Big Prairie, OH 44611 | Oil & Gas Operator | Dec 1998 |
| 528 | Smalley, Bill | Albany, TX 76430 | Oil & Gas Operator | Jul 2001 |
| 529 | Smith Pipe Of Abilene | Abilene, TX 79608 | Oil & Gas Operator | Feb 2026 |
| 530 | Snow Oil & Gas Inc. | Andrews, TX 79714 | Oil & Gas Operator | Feb 2026 |
| 531 | Sojourner Drilling Corporation | Abilene, TX 79604 | Oil & Gas Operator | Feb 2026 |
| 532 | Southcoast Resources, LLC | Fort Worth, TX 76116 | Oil & Gas Operator | Dec 2015 |
| 533 | Southeastern Resources Corp. | Mansfield, TX 76063 | Oil & Gas Operator | Feb 2004 |
| 534 | Southern Exploration, Inc. | Fort Worth, TX 76137 | Oil & Gas Operator | Aug 2023 |
| 535 | Southern Union Exploration Co. | Austin, TX 78701 | Oil & Gas Operator | Feb 2002 |
| 536 | Southwest Gas Systems, Inc. | Spring, TX 77379 | Oil & Gas Operator | Feb 2026 |
| 537 | Southwest Royalties, Inc. | Midland, TX 79710 | Oil & Gas Operator | Feb 2026 |
| 538 | Sovereign Petroleum Company, LLC | Oklahoma City, OK 73120 | Oil & Gas Operator | Jul 2013 |
| 539 | Spence Energy Company | Dallas, TX 75360 | Oil & Gas Operator | Feb 2026 |
| 540 | SPH Development, LLC | Wichita Falls, TX 76308 | Oil & Gas Operator | Nov 2022 |
| 541 | Spicer Oil Company, Inc. | Dallas, TX 75225 | Oil & Gas Operator | Dec 2008 |
| 542 | Sproul, C. R. Inc. | Eldorado, TX 76936 | Oil & Gas Operator | Aug 2000 |
| 543 | SRG Oil Corporation | Abilene, TX 79604 | Oil & Gas Operator | Apr 1994 |
| 544 | St. Mary Energy Company | Houston, TX 77079 | Oil & Gas Operator | Aug 2008 |
| 545 | Standard Oil Tools, Inc. | College Sta, TX 77845 | Oil & Gas Operator | Feb 2026 |
| 546 | Star Production, Inc. | Dallas, TX 75360 | Oil & Gas Operator | Feb 2026 |
| 547 | Stearns Operating Company | Abilene, TX 79604 | Oil & Gas Operator | Oct 1993 |
| 548 | Stephens & Johnson Operating Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | Feb 2026 |
| 549 | Stetson Petroleum Corp. | Rollins, MT 59931 | Oil & Gas Operator | Feb 2026 |
| 550 | Stovall Operating Co. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 551 | Street, Spencer B., Jr. | Graham, TX 76450 | Oil & Gas Operator | Mar 1998 |
| 552 | Stroube Energy Corporation | Dallas, TX 75248 | Oil & Gas Operator | Jan 2012 |
| 553 | Stubblefield Energy Company | Abilene, TX 79604 | Oil & Gas Operator | Feb 2026 |
| 554 | Subsurface Energy Corp. | Coleman, TX 76834 | Oil & Gas Operator | Feb 2026 |
| 555 | Subsurface Exploration | Coleman, TX 76834 | Oil & Gas Operator | Apr 2006 |
| 556 | Subsurface Production, Inc. | Coleman, TX 76834 | Oil & Gas Operator | Feb 2026 |
| 557 | Susanna Corporation | Breckenridge, TX 76424 | Oil & Gas Operator | Feb 2026 |
| 558 | Swartz Oil Company | San Angelo, TX 76906 | Oil & Gas Operator | Feb 2026 |
| 559 | Sweetwater Drilling Co., Inc. | Fort Worth, TX 76116 | Oil & Gas Operator | Feb 2026 |
| 560 | Sweetwater Production, Inc. | San Angelo, TX 76906 | Oil & Gas Operator | Feb 2026 |
| 561 | Synergy Oil & Gas, Inc. (A) | Houston, TX 77024 | Oil & Gas Operator | Aug 2001 |
| 562 | Synergy Production Company | Houston, TX 77024 | Oil & Gas Operator | Jan 1996 |
| 563 | T-N-T Engineering, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | Feb 2026 |
| 564 | T.G. Energy Co. | Abilene, TX 79602 | Oil & Gas Operator | Mar 2008 |
| 565 | Tactical Oil & Gas, LLC | Odessa, TX 79768 | Oil & Gas Operator | Feb 2026 |
| 566 | Tallgrass Production Company LLC | Santa Anna, TX 76878 | Oil & Gas Operator | Mar 2014 |
| 567 | Tam2 Squared Operating, LLC | Rockwall, TX 75032 | Oil & Gas Operator | Feb 2026 |
| 568 | Tankersley, D. C. | Abilene, TX 79601 | Oil & Gas Operator | Sep 2002 |
| 569 | Taylor, Frank Well Service | Cross Plains, TX 76443 | Oil & Gas Operator | Aug 2003 |
| 570 | TCS Petroleum Co., LLC | Abilene, TX 79608 | Oil & Gas Operator | Feb 2026 |
| 571 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | Feb 2026 |
| 572 | Tech Resources, Inc. | Georgetown, TX 78628 | Oil & Gas Operator | Dec 2001 |
| 573 | Telesis Operating Co. | Fort Worth, TX 76116 | Oil & Gas Operator | Feb 2026 |
| 574 | Tema Oil And Gas Company | Houston, TX 77084 | Oil & Gas Operator | Feb 2026 |
| 575 | Tema Oil And Gas, LLC | Houston, TX 77040 | Oil & Gas Operator | Apr 2000 |
| 576 | Tenison Oil Company | Abilene, TX 79605 | Oil & Gas Operator | Nov 2025 |
| 577 | Tepco Resources, Inc. | Houston, TX 77027 | Oil & Gas Operator | Sep 2004 |
| 578 | Tepco, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 1999 |
| 579 | Texas International Resource LLC | Allen, TX 75013 | Oil Operator | Feb 2026 |
| 580 | Texas Operating & Consult., LLC | Abilene, TX 79608 | Oil & Gas Operator | Feb 2018 |
| 581 | Texas United Geoproduction, Inc. | Abilene, TX 79606 | Oil & Gas Operator | Feb 2026 |
| 582 | Texco Operating Co. | San Antonio, TX 78209 | Gas Operator | Aug 2003 |
| 583 | Texical, Inc. | Katy, TX 77491 | Oil & Gas Operator | Feb 2026 |
| 584 | Texlark Exploration Company, Inc | Plano, TX 75074 | Oil & Gas Operator | Sep 2001 |
| 585 | Texxol Operating Company, Inc. | Fort Worth, TX 76108 | Oil & Gas Operator | Feb 2026 |
| 586 | Texzona Oil & Gas, Inc. | Abilene, TX 79608 | Oil & Gas Operator | Dec 1997 |
| 587 | Thomas Oil And Gas Inc. | San Angelo, TX 76906 | Oil & Gas Operator | May 2019 |
| 588 | Thompson, Richard W. Inc. | Plano, TX 75024 | Oil & Gas Operator | Feb 2026 |
| 589 | Thornton Oil Co. | Abilene, TX 79603 | Oil & Gas Operator | Aug 2003 |
| 590 | Thunderbolt Oil & Gas, Inc. | Abilene, TX 79605 | Oil & Gas Operator | Feb 2004 |
| 591 | Tidwell Production Company | Sonora, TX 76950 | Oil & Gas Operator | Feb 2026 |
| 592 | TK Operating | Cross Plains, TX 76443 | Oil & Gas Operator | Feb 2026 |
| 593 | TKP Petroleum, Inc. | Lubbock, TX 79464 | Oil & Gas Operator | Feb 2026 |
| 594 | Tor Energy, LLC | Temple, TX 76501 | Oil & Gas Operator | Feb 2026 |
| 595 | Townsend Company | Abilene, TX 79608 | Oil & Gas Operator | Dec 2021 |
| 596 | Tracer Energy, Inc. | Graham, TX 76450 | Oil & Gas Operator | Nov 1998 |
| 597 | Tracer Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 598 | Tracker Mineral | Clyde, TX 79510 | Oil & Gas Operator | Feb 2026 |
| 599 | Transcontinental Shale L.L.C. | Austin, TX 78717 | Oil & Gas Operator | Feb 2016 |
| 600 | Transfuel Resources Co | Houston, TX 77215 | Oil & Gas Operator | Aug 2013 |