| 501 | Rio-Tex, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 502 | Rittenhouse Oil & Gas Co. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 503 | Rki Exploration & Production LLC | Tulsa, OK 74172 | Oil & Gas Operator | May 2025 |
| 504 | Roanoke Corporation | Fort Worth, TX 76102 | Oil & Gas Operator | Oct 1995 |
| 505 | Robertson Resources, Inc. | Midland, TX 79708 | Oil & Gas Operator | May 2025 |
| 506 | Roca Resource Company, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 507 | Rockport Energy Solutions LLC | Austin, TX 78730 | Oil & Gas Operator | May 2025 |
| 508 | Roosth Production Co. | Tyler, TX 75711 | Oil & Gas Operator | May 2025 |
| 509 | Rosetta Resources Operating LP | San Antonio, TX 78216 | Oil & Gas Operator | May 2025 |
| 510 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 511 | Rover Petroleum Operating, LLC | Plano, TX 75075 | Oil & Gas Operator | May 2025 |
| 512 | Roxanna Oil Company | Oklahoma City, OK 73120-2717 | Oil Operator | Aug 2016 |
| 513 | Royalty Operating, Inc. | Richardson, TX 75081 | Oil & Gas Operator | Nov 2007 |
| 514 | Rrig Exploration, LLC | Fort Worth, TX 76147 | Oil & Gas Operator | May 2025 |
| 515 | Rubicon Oil & Gas, LLC | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 516 | Ruwco Oil And Gas Corp. | Austin, TX 78701 | Oil & Gas Operator | Aug 2021 |
| 517 | S & P Energy | Benbrook, TX 76126 | Oil & Gas Operator | Oct 1994 |
| 518 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 519 | Sabre Operating, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | May 2025 |
| 520 | Saga Pet. LTD Liability Co Of Co | Midland, TX 79701 | Oil & Gas Operator | Apr 2004 |
| 521 | Saga Petroleum LLC Of Colorado | Norman, OK 73072 | Oil & Gas Operator | May 2025 |
| 522 | Sage Energy Company | San Antonio, TX 78215 | Oil & Gas Operator | May 2025 |
| 523 | Saguaro Petroleum, LLC | Midland, TX 79705 | Oil & Gas Operator | May 2025 |
| 524 | Sahara Operating Company | Midland, TX 79704 | Oil & Gas Operator | May 2025 |
| 525 | Samson Exploration LLC | Tulsa, OK 74101 | Oil & Gas Operator | Mar 2025 |
| 526 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 527 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 528 | Samson Lone Star, LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2025 |
| 529 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2025 |
| 530 | Sandridge Exploration And Production LLC | Oklahoma City, OK 73104 | Oil & Gas Operator | May 2025 |
| 531 | Saturn Oil And Development Corp. | Carlsbad, NM 88220 | Oil & Gas Operator | May 2025 |
| 532 | Savannah Ross And Company, LLC | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 533 | Sbog, LLC | Granbury, TX 76048 | Oil & Gas Operator | Feb 2021 |
| 534 | Schmid Properties Inc | Hico, TX 76457 | Oil & Gas Operator | May 2025 |
| 535 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | May 2025 |
| 536 | Scythian, LTD. | Midland, TX 79701 | Oil & Gas Operator | Dec 2020 |
| 537 | Seaboard Oil Company | Midland, TX 79710 | Oil & Gas Operator | Mar 2008 |
| 538 | Seaboard Operating Co. | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 539 | Seguro Oil And Gas, LLC | Midland, TX 79702 | Oil & Gas Operator | Jul 2024 |
| 540 | Sha-Jam Operating Corp. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 541 | Shaida, John H. | Wichita, KS 67226 | Oil & Gas Operator | May 2025 |
| 542 | Shale Energy LLC | Jeffersonville, KY 40337 | Oil Operator | Dec 2018 |
| 543 | Shell Western E&P | Houston, TX 77001 | Oil & Gas Operator | May 2025 |
| 544 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 545 | Shenandoah Petroleum Corporation | Midland, TX 79705 | Oil & Gas Operator | May 2025 |
| 546 | Sheridan Production Company, LLC | Houston, TX 77056 | Oil & Gas Operator | Feb 2025 |
| 547 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | May 2025 |
| 548 | Shinnery Oil Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 549 | Shoreham Oil & Gas Company, Inc. | Katy, TX 77492 | Oil & Gas Operator | May 2025 |
| 550 | Siete Oil And Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Aug 2003 |
| 551 | Siltstone Resources Op II, LLC | Wilmington, DE 19801 | Oil & Gas Operator | May 2025 |
| 552 | Silverback Operating, LLC | San Antonio, TX 78257 | Oil & Gas Operator | Oct 2016 |
| 553 | Simon, W. D. Oil Co. | Kermit, TX 79745 | Oil & Gas Operator | May 2025 |
| 554 | Slack, R. C. | Pecos, TX 79772 | Oil & Gas Operator | Jul 2000 |
| 555 | Sledge Bros. Oil Co. | Midland, TX 79702 | Oil & Gas Operator | Mar 2016 |
| 556 | SMC Oil & Gas, Inc. | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 557 | Snow Oil & Gas Inc. | Andrews, TX 79714 | Oil & Gas Operator | May 2025 |
| 558 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 559 | Solis Partners, L.L.C. | Midland, TX 79707 | Oil & Gas Operator | Feb 2025 |
| 560 | Sonat Exploration Co. - Midland | Houston, TX 77251 | Oil & Gas Operator | Mar 1999 |
| 561 | Sonat Exploration Company -Tyler | Houston, TX 77251 | Oil & Gas Operator | Dec 1999 |
| 562 | Sonoran Energy Inc. | Addison, TX 75001 | Oil & Gas Operator | May 2025 |
| 563 | Southern Union Exploration Co. | Austin, TX 78701 | Oil & Gas Operator | Feb 2002 |
| 564 | Southwest Royalties Inc | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 565 | Spiller Operating Co., Inc. | Round Rock, TX 78665 | Oil & Gas Operator | May 2015 |
| 566 | SSC, Inc. | Lubbock, TX 79408 | Oil & Gas Operator | May 2025 |
| 567 | Staley Operating Co. | Midland, TX 79702 | Oil & Gas Operator | Jan 2022 |
| 568 | Stallion Energy, Inc. | Houston, TX 77060 | Oil & Gas Operator | Oct 2017 |
| 569 | Stanolind Operating Corp. | Midland, TX 79701 | Oil & Gas Operator | Apr 2008 |
| 570 | Steward Energy, LLC | Frisco, TX 75034 | Oil & Gas Operator | Nov 2014 |
| 571 | Stickney Oil & Gas, Inc. | Midland, TX 79704 | Oil & Gas Operator | Nov 2014 |
| 572 | Stickney, F. C., Inc. | Midland, TX 79704 | Oil & Gas Operator | Oct 1998 |
| 573 | Strand Energy, L.C. | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 574 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | May 2025 |
| 575 | Synergex Inc | Oklahoma City, OK 73134 | Oil & Gas Operator | Feb 2025 |
| 576 | Synergy Oil & Gas, Inc. (A) | Houston, TX 77024 | Oil & Gas Operator | Aug 2001 |
| 577 | T & C Oil, Inc. | Lubbock, TX 79424 | Oil & Gas Operator | Apr 2024 |
| 578 | T-N-T Engineering, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | May 2025 |
| 579 | Tall City Operations III LLC | Midland, TX 79702 | Oil & Gas Operator | Jun 2023 |
| 580 | Talus Inc | Graham, TX 76450-1210 | Oil & Gas Operator | Feb 2017 |
| 581 | Tamarack Petroleum Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 582 | Tap Rock Operating, LLC | Golden, CO 80401 | Oil & Gas Operator | May 2025 |
| 583 | Targa Midstream Services LLC | Houston, TX 77002 | Oil Operator | Mar 2023 |
| 584 | Taurus Exploration U.S.A., Inc. | Midland, TX 79705 | Oil & Gas Operator | Nov 1998 |
| 585 | Taylor, Ben J. Inc. | Fort Worth, TX 76185 | Oil & Gas Operator | Feb 2022 |
| 586 | TC Oil And Gas, LLC | Denton, TX 76205 | Oil Operator | May 2025 |
| 587 | Tejas Permian Operating, LLC | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 588 | Teke Production LLC | Houston, TX 77269 | Oil Operator | May 2025 |
| 589 | Tema Oil And Gas Company | Houston, TX 77084 | Oil & Gas Operator | May 2025 |
| 590 | Tema Oil And Gas, LLC | Houston, TX 77040 | Oil & Gas Operator | Apr 2000 |
| 591 | Tess Oil Company | Borger, TX 79008 | Oil & Gas Operator | Mar 2008 |
| 592 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | May 2025 |
| 593 | Texasgulf Inc. | Newgulf, TX 77462 | Oil & Gas Operator | Jul 1994 |
| 594 | Texland-Rector & Schumacher | Fort Worth, TX 76102 | Oil & Gas Operator | Nov 2000 |
| 595 | Thompson, J. Cleo | Dallas, TX 75201 | Oil & Gas Operator | May 2024 |
| 596 | Three Rivers Oper Co III LLC | Austin, TX 78735 | Oil & Gas Operator | Nov 2017 |
| 597 | Three Rivers Operating Co LLC | Austin, TX 78735 | Oil & Gas Operator | Mar 2017 |
| 598 | Three-B Oil Company, The | Monahans, TX 79756 | Oil & Gas Operator | May 2025 |
| 599 | Titan Energy, Inc. | Austin, TX 78703 | Oil & Gas Operator | May 2025 |
| 600 | Titan Resources I, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2000 |