| 501 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 502 | Samson Lone Star, LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2025 |
| 503 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2025 |
| 504 | SBS Oil Company | Austin, TX 78749 | Oil & Gas Operator | May 2025 |
| 505 | Schiff, H. G. & Co. | Dallas, TX 75206 | Oil & Gas Operator | Jul 1993 |
| 506 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | May 2025 |
| 507 | Scully And Smith Oil Corporation | Salado, TX 76571 | Oil & Gas Operator | Feb 1995 |
| 508 | Scythian, LTD. | Midland, TX 79701 | Oil & Gas Operator | Dec 2020 |
| 509 | Seely Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | May 2025 |
| 510 | Senkel, Wesley, Inc. | Graham, TX 76450 | Oil & Gas Operator | Apr 2007 |
| 511 | Sequoia Fossil Fuels, Inc. | Albany, TX 76430 | Oil & Gas Operator | May 2025 |
| 512 | Sequoia Natural Gas, Inc. | Albany, TX 76430 | Oil & Gas Operator | May 2025 |
| 513 | Sharp Image Energy, Inc. | Big Spring, TX 79721 | Oil & Gas Operator | May 2025 |
| 514 | Sheets Exploration Co., Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Jul 2016 |
| 515 | Shiloh Oil Company LLC | Williston, FL 32696 | Oil & Gas Operator | May 2025 |
| 516 | Shoshone Oil Company | Dallas, TX 75244 | Oil & Gas Operator | May 1994 |
| 517 | Simpson Oil & Land Co. | Fort Worth, TX 76102 | Oil & Gas Operator | May 2025 |
| 518 | Singleton Investments, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Oct 2012 |
| 519 | Sky Development Corporation | Graham, TX 76450 | Oil & Gas Operator | Mar 2008 |
| 520 | Sky Resources, Inc. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 521 | Skyway Energy LLC | Leesburg, OH 34748 | Oil & Gas Operator | Dec 2020 |
| 522 | Smith Pipe Of Abilene | Abilene, TX 79608 | Oil & Gas Operator | May 2025 |
| 523 | Smith, W. Don | Breckenridge, TX 76424 | Oil & Gas Operator | Aug 2001 |
| 524 | Snow Oil Company | Nocona, TX 76255 | Oil Operator | May 2025 |
| 525 | Snyder Drilling Corp. | Albany, TX 76430 | Oil & Gas Operator | May 2025 |
| 526 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 527 | So Operating Company | Cisco, TX 76437 | Oil & Gas Operator | May 2025 |
| 528 | Southeastern Resources Corp. | Mansfield, TX 76063 | Oil & Gas Operator | Feb 2004 |
| 529 | Southern Alliance Oil Corp. | Grapevine, TX 76099 | Oil & Gas Operator | May 2025 |
| 530 | Southlake Exploration, Inc. | Southlake, TX 76092 | Oil & Gas Operator | May 2025 |
| 531 | Southwest Royalties Inc | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 532 | Spartan Oil Corporation | Abilene, TX 79601 | Oil & Gas Operator | Aug 2003 |
| 533 | Squyres Oil Co., Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Nov 2024 |
| 534 | SSC, Inc. | Lubbock, TX 79408 | Oil & Gas Operator | May 2025 |
| 535 | Sta-Kel Incorporated | Graham, TX 76450 | Oil & Gas Operator | Dec 2000 |
| 536 | Stamper Operating Co., Inc. | Jacksboro, TX 76458 | Oil & Gas Operator | May 2025 |
| 537 | Star Production, Inc. | Dallas, TX 75360 | Oil & Gas Operator | May 2025 |
| 538 | Stasney, H. R. & Sons, LTD. | Albany, TX 76430 | Oil & Gas Operator | May 2025 |
| 539 | Statex Operating, LLC | Dallas, TX 75229 | Oil & Gas Operator | Mar 2007 |
| 540 | Statex Petroleum Inc | Dallas, TX 75229 | Oil & Gas Operator | Dec 2000 |
| 541 | STB Energy Inc. | Tulsa, OK 74105 | Oil & Gas Operator | Jul 2008 |
| 542 | Stephens & Johnson Operating Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2025 |
| 543 | Stephenson Oil & Gas, Inc. | Eastland, TX 76448 | Oil & Gas Operator | Sep 1999 |
| 544 | Stivers Inc | Graham, TX 76450 | Oil & Gas Operator | May 2003 |
| 545 | Stober Oil And Gas Services, LLC | Breckenridge, TX 76424 | Oil & Gas Operator | May 2025 |
| 546 | Stonebriar Oil LLC | Frisco, TX 75034 | Oil & Gas Operator | May 2025 |
| 547 | Stoneburner Exploration, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Oct 1997 |
| 548 | Stovall Operating Co. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 549 | Stratagas, Inc. | Rowlett, TX 75088 | Oil & Gas Operator | May 2006 |
| 550 | Street, Spencer B., Jr. | Graham, TX 76450 | Oil & Gas Operator | Mar 1998 |
| 551 | Sunbelt Salvage | Eastland, TX 76448 | Oil & Gas Operator | Sep 1998 |
| 552 | Sundial Resources, Inc. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 553 | Sunterra Energy Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Dec 2009 |
| 554 | Supreme Energy Company, Inc. | Abilene, TX 79601 | Oil & Gas Operator | May 2025 |
| 555 | Sweetwater Drilling Co., Inc. | Fort Worth, TX 76116 | Oil & Gas Operator | May 2025 |
| 556 | T-N-T Engineering, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | May 2025 |
| 557 | Tahoe Exploration Inc. | Abilene, TX 79608 | Oil & Gas Operator | Mar 2016 |
| 558 | Talus Inc | Graham, TX 76450-1210 | Oil & Gas Operator | Feb 2017 |
| 559 | Targa Midstream Services LLC | Houston, TX 77002 | Oil Operator | Mar 2023 |
| 560 | Taylor, Dutch | Graham, TX 76450 | Oil & Gas Operator | Jan 2016 |
| 561 | TCT Operating Company, Inc. | Johnson City, TX 78636 | Oil & Gas Operator | Feb 2017 |
| 562 | Team Operating, L.L.C. | Pinehurst, TX 77362 | Oil & Gas Operator | May 2025 |
| 563 | Telesis Operating Co. | Fort Worth, TX 76116 | Oil & Gas Operator | May 2025 |
| 564 | Tempo Resources GP, LLC | Mineral Wells, TX 76068 | Oil & Gas Operator | Apr 2013 |
| 565 | Tenison Oil Company | Abilene, TX 79605 | Oil & Gas Operator | May 2025 |
| 566 | Tex-Ann Oil & Gas Services, Inc. | Abilene, TX 79608 | Oil & Gas Operator | May 2025 |
| 567 | Texas Shallow Oil & Gas, LLC | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 568 | Texas United Geoproduction, Inc. | Abilene, TX 79606 | Oil & Gas Operator | May 2025 |
| 569 | Texxol Operating Company, Inc. | Fort Worth, TX 76108 | Oil & Gas Operator | May 2025 |
| 570 | Thornton, Michael D. | Breckenridge, TX 76424 | Oil & Gas Operator | Nov 1995 |
| 571 | Three P Operating Co.,GP, L.L.C. | Newcastle, TX 76372 | Oil & Gas Operator | May 2025 |
| 572 | Three P Operating Company | Newcastle, TX 76372 | Oil & Gas Operator | Nov 2007 |
| 573 | Three Rivers Operating Co LLC | Austin, TX 78735 | Oil & Gas Operator | Mar 2017 |
| 574 | Threshold Development Company | Fort Worth, TX 76109 | Oil & Gas Operator | Aug 2016 |
| 575 | Throckmorton Oil, Inc. | Throckmorton, TX 76483 | Oil & Gas Operator | Mar 2008 |
| 576 | Thunder Oil & Gas, LLC | Ardmore, OK 73402 | Oil & Gas Operator | Feb 2025 |
| 577 | Thunder Resources LLC | Graham, TX 76450 | Oil Operator | May 2025 |
| 578 | Tiara Resources, Inc. | Fort Worth, TX 76179 | Oil & Gas Operator | Apr 1998 |
| 579 | Tiki Oil & Gas, LLC | Cisco, TX 76437 | Oil Operator | May 2025 |
| 580 | Timn Oil Co. | Lubbock, TX 79424 | Oil & Gas Operator | Aug 1997 |
| 581 | Titan Energy, Inc. | Austin, TX 78703 | Oil & Gas Operator | May 2025 |
| 582 | TKP Petroleum, Inc. | Lubbock, TX 79464 | Oil & Gas Operator | May 2025 |
| 583 | Todd, J R Oil & Investments, Inc | Dallas, TX 75206 | Oil & Gas Operator | Jun 2002 |
| 584 | Tower Resources Inc | Conroe, TX 77304 | Oil & Gas Operator | May 2025 |
| 585 | Trace Energy Management Inc | Weatherford, TX 76086 | Oil & Gas Operator | May 2025 |
| 586 | Tracer Energy, Inc. | Graham, TX 76450 | Oil & Gas Operator | Nov 1998 |
| 587 | Tracer Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 588 | Tracker Resource Dev III, LLC | Englewood, CO 80112 | Oil & Gas Operator | Jul 2021 |
| 589 | Trailblazer Energy LLC | Plano, TX 75075 | Oil & Gas Operator | Feb 2025 |
| 590 | Treco Oil Company | Albany, TX 76430 | Oil & Gas Operator | May 2025 |
| 591 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | May 2025 |
| 592 | Triple Singleton, Inc. | Santa Fe, TX 77510 | Oil & Gas Operator | Dec 2020 |
| 593 | Tritex Production Co. | Iowa Park, TX 76367 | Oil & Gas Operator | Jan 2013 |
| 594 | Trust Oil Co. | Pine, CO 80470 | Oil & Gas Operator | May 2025 |
| 595 | Trutex Operating, LLC | Haltom City, TX 76117 | Oil & Gas Operator | May 2025 |
| 596 | Tug Oil & Gas, L.L.C. | Breckenridge, TX 76424 | Oil & Gas Operator | May 2025 |
| 597 | Twin Oaks Construction Company | Irving, TX 75063 | Oil & Gas Operator | May 2025 |
| 598 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | May 2025 |
| 599 | United Energy Partners, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2008 |
| 600 | Upham Oil & Gas Company | Mineral Wells, TX 76068 | Oil & Gas Operator | May 2025 |