| 501 | Rock Well Petroleum (U.S.), Inc. | Canada, 00100 | Oil & Gas Operator | Sep 2014 |
| 502 | Rockport Energy Solutions LLC | Austin, TX 78730 | Oil & Gas Operator | Oct 2025 |
| 503 | Roemer Oil Company | Denver, CO 80202 | Oil & Gas Operator | Nov 1998 |
| 504 | Rogers, M. L. | Midland, TX 79701 | Oil & Gas Operator | Sep 2014 |
| 505 | RP Operating, L.L.C. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 506 | RRP Operating LLC | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |
| 507 | S & M Drilling, LLC | Wichita Falls, TX 76308 | Oil Operator | Sep 2023 |
| 508 | S.B. Street Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | Oct 2025 |
| 509 | Sabinal Energy Operating, LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Oct 2025 |
| 510 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 511 | Sable Permian Resources Land,LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2019 |
| 512 | Sable Permian Resources, LLC | Houston, TX 77002 | Oil & Gas Operator | Feb 2021 |
| 513 | Sabre Operating, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Oct 2025 |
| 514 | Sahara Operating Company | Midland, TX 79704 | Oil & Gas Operator | Oct 2025 |
| 515 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 516 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 517 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 518 | Samson Lone Star, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2025 |
| 519 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2025 |
| 520 | San Marco Petroleum Inc | Denver, CO 80293 | Oil & Gas Operator | Jun 2025 |
| 521 | Sandia Production Co., Inc. | Corrales, NM 87048 | Oil & Gas Operator | Oct 2025 |
| 522 | Sandor Petroleum Corporation | Crane, TX 79731 | Oil & Gas Operator | Oct 2025 |
| 523 | Sandridge Exploration And Production LLC | Oklahoma City, OK 73104 | Oil & Gas Operator | Oct 2025 |
| 524 | Santa Fe Energy Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 525 | Santa Fe Snyder Corporation | Houston, TX 77024 | Oil & Gas Operator | Oct 2000 |
| 526 | Sarita Energy Resources, LTD. | Houston, TX 77277 | Oil & Gas Operator | Oct 2025 |
| 527 | Schlachter Operating Corporation | Dallas, TX 75225 | Oil & Gas Operator | Oct 2025 |
| 528 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 529 | Scythian, LTD. | Midland, TX 79701 | Oil & Gas Operator | Dec 2020 |
| 530 | Seaboard Oil Company | Midland, TX 79710 | Oil & Gas Operator | Mar 2008 |
| 531 | Seaboard Operating Co. | Midland, TX 79710 | Oil & Gas Operator | Oct 2025 |
| 532 | Seco Production Company | Midland, TX 79708 | Oil & Gas Operator | Aug 2003 |
| 533 | Seguro Oil And Gas, LLC | Midland, TX 79702 | Oil & Gas Operator | Jul 2024 |
| 534 | Select Water Solutions, LLC | Gainesville, TX 76240 | Oil Operator | Jun 2025 |
| 535 | Sem Operating Company LLC | Houston, TX 77042 | Oil & Gas Operator | Oct 2025 |
| 536 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 537 | Shirley, B. J. | Lawn, TX 79530 | Oil & Gas Operator | Mar 2008 |
| 538 | Silver Creek Oil & Gas, LLC | Flower Mound, TX 75022 | Oil & Gas Operator | Oct 2025 |
| 539 | Simata Energy, LLC | Midland, TX 79708 | Oil & Gas Operator | Oct 2025 |
| 540 | Sledge, H. G., Inc. | Midland, TX 79701 | Oil & Gas Operator | Dec 2016 |
| 541 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Oct 2025 |
| 542 | SMC Oil & Gas, Inc. | Midland, TX 79710 | Oil & Gas Operator | Oct 2025 |
| 543 | Smith Pipe Of Abilene | Abilene, TX 79608 | Oil & Gas Operator | Oct 2025 |
| 544 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 545 | Sol Oil Co., L.C. | Crane, TX 79731 | Oil Operator | Oct 2025 |
| 546 | Southern Mineral Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2001 |
| 547 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 548 | Southwest Royalties Inc | Midland, TX 79710 | Oil & Gas Operator | Oct 2025 |
| 549 | Spade Energy L.L.C. | Wichita Falls, TX 76310 | Oil & Gas Operator | Oct 2025 |
| 550 | St. Mary Land & Exploration Co | Denver, CO 80201 | Oil & Gas Operator | Jun 2010 |
| 551 | Staley Operating Co. | Midland, TX 79702 | Oil & Gas Operator | Jan 2022 |
| 552 | Stallion Energy, Inc. | Houston, TX 77060 | Oil & Gas Operator | Oct 2017 |
| 553 | Stanolind Operating Corp. | Midland, TX 79701 | Oil & Gas Operator | Apr 2008 |
| 554 | STB Energy Inc. | Tulsa, OK 74105 | Oil & Gas Operator | Jul 2008 |
| 555 | Stephens, Autry C. | Midland, TX 79701 | Oil & Gas Operator | Mar 2023 |
| 556 | Stout Energy Inc. | Midland, TX 79708 | Oil & Gas Operator | Oct 2025 |
| 557 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | Oct 2025 |
| 558 | Summit Petroleum LLC | Midland, TX 79705 | Oil & Gas Operator | Oct 2025 |
| 559 | Sundown Energy LP | Dallas, TX 75248 | Oil & Gas Operator | Oct 2025 |
| 560 | Swanson, Tom | Electra, TX 76360 | Oil & Gas Operator | Oct 2004 |
| 561 | Swanson, Tommy Oil Co. | Electra, TX 76360 | Oil & Gas Operator | Mar 2017 |
| 562 | Swartz Oil Company | San Angelo, TX 76906 | Oil & Gas Operator | Oct 2025 |
| 563 | T.G.B., Inc. | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 564 | T2 Operating Corporation | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 565 | Tamarack Petroleum Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 566 | Targa Midstream Services LLC | Houston, TX 77002 | Oil Operator | Mar 2023 |
| 567 | Targa Pipeline Mid-Continent LLC | Sulphur, LA 70665 | Oil & Gas Operator | Jun 2018 |
| 568 | Taurus Exploration U.S.A., Inc. | Midland, TX 79705 | Oil & Gas Operator | Nov 1998 |
| 569 | Taylor, J. S. Inc. | Lewisville, TX 75057 | Oil & Gas Operator | Oct 2025 |
| 570 | Taylor-McIlhenny Oper. Co., Inc. | Lewisville, TX 75029 | Oil & Gas Operator | Jan 1996 |
| 571 | Tema Oil And Gas Company | Houston, TX 77084 | Oil & Gas Operator | Oct 2025 |
| 572 | Terrace Petroleum Corporation | Midland, TX 79701 | Oil & Gas Operator | Jul 2013 |
| 573 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Oct 2025 |
| 574 | Texaco Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2017 |
| 575 | Texas Vanguard Oil Company | Austin, TX 78720 | Oil & Gas Operator | Jan 2014 |
| 576 | Texland Petroleum Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2003 |
| 577 | Texland Petroleum, L.P. | Fort Worth, TX 76107 | Oil & Gas Operator | Oct 2025 |
| 578 | Texland-Rector & Schumacher | Fort Worth, TX 76102 | Oil & Gas Operator | Nov 2000 |
| 579 | Thompson, J. Cleo | Dallas, TX 75201 | Oil & Gas Operator | May 2024 |
| 580 | Three Rivers Operating Co II LLC | Austin, TX 78735 | Oil & Gas Operator | Mar 2017 |
| 581 | Three Rivers Operating Co LLC | Austin, TX 78735 | Oil & Gas Operator | Mar 2017 |
| 582 | Three-B Oil Company, The | Monahans, TX 79756 | Oil & Gas Operator | Oct 2025 |
| 583 | Tidwell Production Company | Sonora, TX 76950 | Oil & Gas Operator | Oct 2025 |
| 584 | Tindle Petroleum LLC | Midland, TX 79701 | Oil & Gas Operator | Jan 2023 |
| 585 | Tipperary Oil & Gas Corp | Denver, CO 80202 | Oil & Gas Operator | May 2014 |
| 586 | Titan Resources I, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2000 |
| 587 | TMBR/Sharp Drilling, Inc. | Midland, TX 79703 | Oil & Gas Operator | Feb 2004 |
| 588 | Topat Oil Corporation | Midland, TX 79701 | Oil & Gas Operator | Sep 2017 |
| 589 | Tres Roughneckas WTX LLC | MC Camey, TX 79752 | Oil Operator | Oct 2025 |
| 590 | Trey Services, Inc. | Midland, TX 79711 | Oil & Gas Operator | Dec 1996 |
| 591 | Triesco, Inc. | Midland, TX 79702 | Oil & Gas Operator | Jun 1996 |
| 592 | Trigo Oil And Gas, LLC | Amarillo, TX 79101 | Oil & Gas Operator | Mar 2022 |
| 593 | Triple "N" Services, Inc. | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 594 | Triple Crown Resources, LLC | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 595 | Tripledee Drilling Co Inc | Ardmore, OK 73402-1888 | Oil & Gas Operator | Dec 2015 |
| 596 | Tripp & Sons, LLC | Odessa, TX 79768 | Oil & Gas Operator | Oct 2025 |
| 597 | TRP Operating LLC | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 598 | True Oil Company LLC | Midland, TX 79701 | Oil & Gas Operator | Mar 2016 |
| 599 | TS Oil, LLC | Fort Worth, TX 76114 | Oil & Gas Operator | Oct 2025 |
| 600 | TSF Operating | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |