| 501 | Quicksilver Resources Inc | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2018 |
| 502 | R K Petroleum Corp. | Midland, TX 79708 | Oil & Gas Operator | May 2024 |
| 503 | R. B. Oil Company | Monahans, TX 79756 | Oil & Gas Operator | Nov 1996 |
| 504 | Rad Oil Company | Snyder, TX 79549 | Oil & Gas Operator | Mar 2025 |
| 505 | Raider Oil & Gas Company | MC Camey, TX 79752 | Oil & Gas Operator | Mar 2025 |
| 506 | Ram Energy LLC | Tulsa, OK 74152 | Oil & Gas Operator | Dec 2024 |
| 507 | Ram Operating Company, Inc. | Houston, TX 77002 | Oil & Gas Operator | Sep 2012 |
| 508 | Ram Operating Inc. | Browns, IL 62818 | Oil & Gas Operator | Aug 2008 |
| 509 | Rampart Petroleum, Incorporated | Buffalo Gap, TX 79508 | Oil & Gas Operator | Jan 2009 |
| 510 | Ramtex Energy LLC | Tulsa, OK 74114 | Oil & Gas Operator | Mar 2025 |
| 511 | Ranger 40 Petroleum, LLC | Fairfield, CT 06824 | Oil & Gas Operator | Mar 2025 |
| 512 | Rasmussen, Tom | San Angelo, TX 76904 | Oil & Gas Operator | Mar 2025 |
| 513 | Rattler Midstream Operating LLC | Midland, TX 79701 | Oil Operator | Mar 2025 |
| 514 | Ratts, Robert V. Inc. | Bedford, TX 76021 | Oil & Gas Operator | Aug 2003 |
| 515 | Raw Oil & Gas, Inc. | Lubbock, TX 79401 | Oil & Gas Operator | Mar 2025 |
| 516 | Raw Production | Kermit, TX 79745 | Oil & Gas Operator | Mar 2025 |
| 517 | Rayden | Midland, TX 79711 | Oil & Gas Operator | Mar 2025 |
| 518 | RBD-Shelby Agency | Dallas, TX 75283 | Oil & Gas Operator | Dec 1993 |
| 519 | Reata Resources | Kermit, TX 79745 | Oil & Gas Operator | Sep 2007 |
| 520 | Red Willow Production, LLC | Ignacio, CO 81137 | Oil & Gas Operator | Oct 2015 |
| 521 | Rein Pusher Operating LLC | Brenham, TX 77834 | Oil & Gas Operator | Mar 2025 |
| 522 | Remnant Oil Operating, LLC | Midland, TX 79704 | Oil & Gas Operator | Jul 2024 |
| 523 | Remuda Operating Company | Midland, TX 79711 | Oil & Gas Operator | Mar 2025 |
| 524 | Reo Operating LLC | Austin, TX 78747 | Oil & Gas Operator | Mar 2025 |
| 525 | Resaca Operating Company | Houston, TX 77010 | Oil & Gas Operator | Sep 2013 |
| 526 | Resource Operating Company | Abilene, TX 79601 | Oil & Gas Operator | Jul 1997 |
| 527 | Restore Operating LLC | Andrews, TX 79714 | Oil & Gas Operator | Mar 2025 |
| 528 | Rhombus Operating Co., LTD | Littleton, CO 80160 | Oil & Gas Operator | Mar 2025 |
| 529 | Rhonda Operating Company | Midland, TX 79710 | Oil & Gas Operator | Aug 2017 |
| 530 | Riata Energy Inc | Oklahoma City, OK 73101 | Oil & Gas Operator | Apr 2008 |
| 531 | Richardson, Bud II | Graham, TX 76450 | Oil & Gas Operator | Mar 2025 |
| 532 | Ridge Petroleum Inc. | Tyler, TX 75701 | Oil & Gas Operator | Mar 2025 |
| 533 | Ring Energy, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2025 |
| 534 | Rki Exploration & Production LLC | Tulsa, OK 74172 | Oil & Gas Operator | Mar 2025 |
| 535 | Robertson Resources, Inc. | Midland, TX 79708 | Oil & Gas Operator | Mar 2025 |
| 536 | Roc Operating, Inc. | Plano, TX 75093 | Oil & Gas Operator | Oct 2008 |
| 537 | Roca Operating, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2025 |
| 538 | Rockland Oil Company | Addison, TX 75001 | Oil & Gas Operator | Dec 2024 |
| 539 | Rodan, Inc. | Wink, TX 79789 | Oil & Gas Operator | Mar 2025 |
| 540 | Roden Oil Company | Midland, TX 79702 | Oil & Gas Operator | Feb 2008 |
| 541 | Roswell Operating, LLC | Midland, TX 79702 | Oil & Gas Operator | Oct 2019 |
| 542 | Rover Operating Inc | Richardson, TX 75080 | Oil & Gas Operator | Apr 2000 |
| 543 | Roy Jackson Energy Operating, LLC | Midland, TX 79701 | Oil & Gas Operator | Mar 2025 |
| 544 | Royal Oil LTD. Co. | Hobbs, NM 88241 | Oil & Gas Operator | Mar 1996 |
| 545 | RSP Permian, LLC | Midland, TX 79701 | Oil & Gas Operator | Jul 2018 |
| 546 | Ruckus Energy Operating, LLC | San Antonio, TX 78257 | Oil & Gas Operator | Mar 2025 |
| 547 | Rust Oil Corp. | Fort Worth, TX 76108 | Oil & Gas Operator | Mar 2025 |
| 548 | S & P Energy | Benbrook, TX 76126 | Oil & Gas Operator | Oct 1994 |
| 549 | Saba Energy Of Texas Inc | Houston, TX 77042 | Oil & Gas Operator | Jul 2007 |
| 550 | Saber Oil & Gas Ventures, LLC | Midland, TX 79701 | Oil & Gas Operator | Mar 2025 |
| 551 | Sabinal Energy Operating, LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Mar 2025 |
| 552 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 553 | Saddleback Exploration, LLC | Oklahoma City, OK 73134 | Oil & Gas Operator | Apr 2024 |
| 554 | Sage Energy Company | San Antonio, TX 78215 | Oil & Gas Operator | Mar 2025 |
| 555 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 556 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Dec 2024 |
| 557 | Sandridge Exploration And Production LLC | Oklahoma City, OK 73104 | Oil & Gas Operator | Mar 2025 |
| 558 | Sapient Energy Corp | Oklahoma City, OK 73154 | Oil & Gas Operator | Jan 2002 |
| 559 | Saxet Oil Corporation | Midland, TX 79708 | Oil & Gas Operator | Mar 2025 |
| 560 | Schlachter Operating Corporation | Dallas, TX 75225 | Oil & Gas Operator | Mar 2025 |
| 561 | Schlachter, David A. | Dallas, TX 75225 | Oil & Gas Operator | Apr 2015 |
| 562 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | Mar 2025 |
| 563 | Scythian, LTD. | Midland, TX 79701 | Oil & Gas Operator | Dec 2020 |
| 564 | SDG Resources L.P. | Montrose, CO 81402 | Oil & Gas Operator | May 2006 |
| 565 | SDX Resources, Inc. | Midland, TX 79705 | Oil & Gas Operator | Mar 2025 |
| 566 | Sea Sand Oil Company | Fort Worth, TX 76185 | Oil & Gas Operator | Jun 1995 |
| 567 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 568 | Seanard Energy Company | Baton Rouge, LA 70808 | Oil & Gas Operator | Jul 2002 |
| 569 | Seco Production Company | Midland, TX 79708 | Oil & Gas Operator | Aug 2003 |
| 570 | Seguro Oil And Gas, LLC | Midland, TX 79702 | Oil & Gas Operator | Jul 2024 |
| 571 | Seven Falls Company | Dallas, TX 75201 | Oil & Gas Operator | May 2008 |
| 572 | Shaida, John H. | Wichita, KS 67226 | Oil & Gas Operator | Mar 2025 |
| 573 | Shelby, Michael H. | Shreveport, LA 71101 | Oil & Gas Operator | Mar 2025 |
| 574 | Shell Trading Us Company | Houston, TX 77210 | Oil & Gas Operator | Dec 2024 |
| 575 | Shell Western E&P | Houston, TX 77001 | Oil & Gas Operator | Mar 2025 |
| 576 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 577 | Sheridan Production Company, LLC | Houston, TX 77056 | Oil & Gas Operator | Dec 2024 |
| 578 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | Mar 2025 |
| 579 | Shifflett Operating Company | Snyder, TX 79550 | Oil & Gas Operator | Mar 2025 |
| 580 | Silver Hill Energy Partners, LLC | Dallas, TX 75219 | Oil & Gas Operator | Feb 2017 |
| 581 | Simon, W. D. Oil Co. | Kermit, TX 79745 | Oil & Gas Operator | Mar 2025 |
| 582 | Simpson Bros. Oil Co. | Odessa, TX 79760 | Oil & Gas Operator | Jan 2001 |
| 583 | Simpson Oil Company | Odessa, TX 79760 | Oil & Gas Operator | Oct 2004 |
| 584 | Slack, R. C. | Pecos, TX 79772 | Oil & Gas Operator | Jul 2000 |
| 585 | Slant Operating, LLC | Lafayette, LA 70503 | Oil & Gas Operator | Mar 2025 |
| 586 | SMC Oil & Gas, Inc. | Midland, TX 79710 | Oil & Gas Operator | Mar 2025 |
| 587 | Smith & Marrs Inc. | Lubbock, TX 79424 | Oil & Gas Operator | Apr 2021 |
| 588 | Sogo III LLC | Midland, TX 79702 | Oil & Gas Operator | Jul 2017 |
| 589 | Southern Operating, LLC | Midland, TX 79710 | Oil & Gas Operator | Mar 2025 |
| 590 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 591 | Southwest Royalties Inc | Midland, TX 79710 | Oil & Gas Operator | Mar 2025 |
| 592 | Special Energy Corporation | Stillwater, OK 74076 | Oil & Gas Operator | Mar 2025 |
| 593 | Spindletop Drilling Co. | Dallas, TX 75230 | Oil & Gas Operator | Mar 2025 |
| 594 | Staley Operating Co. | Midland, TX 79702 | Oil & Gas Operator | Jan 2022 |
| 595 | Stanolind Operating Corp. | Midland, TX 79701 | Oil & Gas Operator | Apr 2008 |
| 596 | Stanolind Operating LLC | Midland, TX 79702 | Oil & Gas Operator | Apr 2021 |
| 597 | Stanolind Production LLC | Midland, TX 79702 | Oil & Gas Operator | Dec 2020 |
| 598 | Stephens, Autry C. | Midland, TX 79701 | Oil & Gas Operator | Mar 2023 |
| 599 | Stevens & Tull, Inc. | Midland, TX 79702 | Oil & Gas Operator | Jun 2000 |
| 600 | Stickney Oil & Gas, Inc. | Midland, TX 79704 | Oil & Gas Operator | Nov 2014 |