| 401 | R H Energy Co Inc | | Oil & Gas Operator | Sep 1989 |
| 402 | R. D. Briscoe, Inc. | | Oil & Gas Operator | Nov 2024 |
| 403 | R/C Holdings, Inc. | | Oil & Gas Operator | Dec 1991 |
| 404 | Ralph L. Leaderbrand | | Oil & Gas Operator | Dec 1996 |
| 405 | Ram Energy LLC (Ok) | | Oil & Gas Operator | Feb 2018 |
| 406 | Ram Management Company, Inc. | | Oil & Gas Operator | Sep 1984 |
| 407 | RCV Investments, LLC | | Oil & Gas Operator | Jan 2025 |
| 408 | RDT Properties, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Oct 2012 |
| 409 | Redd Production Of Mansfield | | Oil & Gas Operator | Jan 1991 |
| 410 | Redmon Oil Company, Inc., The | Plano, TX 75023 | Oil & Gas Operator | Jul 2026 |
| 411 | Regency Field Services LLC | Dallas, TX 75201 | Oil Operator | Jul 2017 |
| 412 | Reliant Energy Field SVS Inc. | | Oil Operator | Sep 2002 |
| 413 | Remuda Oil & Gas Corp. | | Oil & Gas Operator | Aug 1987 |
| 414 | Remuda Operating Company | Midland, TX 79711 | Oil & Gas Operator | Jul 2026 |
| 415 | Retsal Drilling Co. | | Oil & Gas Operator | Jan 1984 |
| 416 | Retsal Production Company | | Oil & Gas Operator | Mar 1986 |
| 417 | Revilo Exploration, Inc. | Richardson, TX 75081 | Oil & Gas Operator | Jul 2021 |
| 418 | Reynolds Drilling Co., Inc. | Shreveport, LA 71105 | Oil & Gas Operator | Jul 2026 |
| 419 | Richard C. Hinds | | Oil Operator | Jan 2025 |
| 420 | Rising Star Energy-Oper Co., LLC | | Oil & Gas Operator | Nov 2006 |
| 421 | River Rouge Minerals | | Oil & Gas Operator | Dec 2024 |
| 422 | Robert S. Barnwell, III | | Oil & Gas Operator | Oct 1984 |
| 423 | Rockcliff Operating La LLC | | Oil & Gas Operator | Jul 2022 |
| 424 | Ron Knott & Associates,Inc. | | Oil & Gas Operator | Aug 1989 |
| 425 | Rosbottom Production Corp | Shreveport, LA 71134 | Oil & Gas Operator | Dec 2017 |
| 426 | Rosewood Resources Inc | Dallas, TX 75201 | Oil & Gas Operator | Jul 2026 |
| 427 | Ross & Glenn Petroleum Inc. | | Oil & Gas Operator | Aug 1984 |
| 428 | Ross Exploration,Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2013 |
| 429 | Roughneck L.L.C. | | Oil Operator | Jan 2025 |
| 430 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 431 | Sabre Operating, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Jul 2026 |
| 432 | Sage Energy Company | San Antonio, TX 78215 | Oil & Gas Operator | Jul 2026 |
| 433 | Sample Exploration | | Oil & Gas Operator | Jul 2002 |
| 434 | Samson Contour Energy E&P, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Sep 2017 |
| 435 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2026 |
| 436 | Sananco Energy Corp | Naples, FL 33941 | Oil & Gas Operator | Jul 2013 |
| 437 | Sawyer Drilling & Service Inc. | | Oil & Gas Operator | Oct 2004 |
| 438 | Sawyer Energy, Inc. | | Oil & Gas Operator | May 1997 |
| 439 | Saye Petroleum, Inc. | | Oil & Gas Operator | Apr 1995 |
| 440 | Seagull Operating Co., Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jan 2025 |
| 441 | Sepulvado Oilfield Service Inc | | Oil & Gas Operator | Jul 2010 |
| 442 | Shoreline Exploration, Inc. | | Oil & Gas Operator | Jul 1990 |
| 443 | Shoreline Petroleum Corp. | Channelview, TX 77530 | Oil & Gas Operator | Sep 2003 |
| 444 | Shufflin Energy | | Oil & Gas Operator | Sep 2011 |
| 445 | Sierra Industries, Inc. | | Oil & Gas Operator | Apr 1989 |
| 446 | Silver Oak Operating, Inc. | Longview, TX 75601 | Oil & Gas Operator | Dec 2009 |
| 447 | Silver Oak Operating, LLC | Longview, TX 75604 | Oil & Gas Operator | Jul 2026 |
| 448 | Silver Pines Energy Corp. | Houston, TX 77005 | Oil & Gas Operator | Apr 2026 |
| 449 | Skelly Oil Co | | Oil & Gas Operator | Mar 2005 |
| 450 | Skinner Energy Management, Inc. | Shreveport, LA 71135 | Oil & Gas Operator | Jan 2011 |
| 451 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Jul 2026 |
| 452 | Smith Operating And MGMT Co. | Shreveport, LA 71161 | Oil & Gas Operator | Jun 2023 |
| 453 | SND Operating, L.L.C. | Kilgore, TX 75663 | Oil & Gas Operator | Jul 2026 |
| 454 | Sonat Exploration Co. | Houston, TX 77251 | Oil & Gas Operator | Dec 2021 |
| 455 | South La. Production Co., Inc. | | Oil & Gas Operator | Jun 1982 |
| 456 | Southern Natural Gas Co | Houston, TX 77001 | Oil & Gas Operator | Dec 2011 |
| 457 | Southern Water Disposal, LLC | | Oil & Gas Operator | Jan 2025 |
| 458 | Special Energy Corp. | Stillwater, OK 74076 | Oil & Gas Operator | Jul 2026 |
| 459 | Spicy Daugx Operators Louisiana LLC | | Oil & Gas Operator | Nov 2024 |
| 460 | Spyglass Oil & Gas LLC | | Oil & Gas Operator | Dec 2024 |
| 461 | St. Mary Land & Exploration Co | Denver, CO 80201 | Oil & Gas Operator | Jun 2010 |
| 462 | Strat Land Exploration Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2026 |
| 463 | Stroud Petroleum, Inc. | Shreveport, LA 71162 | Oil & Gas Operator | Jul 2026 |
| 464 | Stroud Production LLC | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2024 |
| 465 | Summit Energy,Inc | Littleton, CO 80127 | Oil & Gas Operator | Aug 2013 |
| 466 | Summit Gas LLC | | Oil & Gas Operator | Oct 2011 |
| 467 | Sun Exploration & Production Co | | Oil & Gas Operator | Jan 1990 |
| 468 | Sun Resources Texas, Inc. | Longview, TX 75606 | Oil & Gas Operator | Dec 2024 |
| 469 | Sundance Energy Corporation | | Oil & Gas Operator | Jan 2025 |
| 470 | Sunland Production Company, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Apr 2026 |
| 471 | Superior Operating LLC | | Oil Operator | May 2020 |
| 472 | Swepi LP | Houston, TX 77079 | Oil & Gas Operator | Jul 2020 |
| 473 | SWN Production (Louisiana), LLC | | Oil & Gas Operator | Dec 2024 |
| 474 | T-M Well Service, L.L.C. | Jefferson, TX 75657 | Oil & Gas Operator | Dec 2024 |
| 475 | T. C. Morrow Oil Co. | | Oil & Gas Operator | Apr 1991 |
| 476 | T. L. James & Co., Inc. | | Oil & Gas Operator | Oct 1992 |
| 477 | T. M. Hopkins | | Oil & Gas Operator | Aug 2007 |
| 478 | Talco Midstream Assets, LTD. | | Oil Operator | May 2017 |
| 479 | Target Oil & Gas, Inc. | | Oil & Gas Operator | Nov 2011 |
| 480 | Tatco, Inc. | | Oil & Gas Operator | May 1991 |
| 481 | TD & Associates, Inc. | | Oil & Gas Operator | Jun 1998 |
| 482 | Teal Petroleum Co. | | Oil & Gas Operator | Sep 1978 |
| 483 | Tellurian Operating LLC | | Oil & Gas Operator | Jun 2024 |
| 484 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Dec 2025 |
| 485 | Tennessee Gas Pipeline Company, LLC | | Oil Operator | Dec 2024 |
| 486 | Tepee Petroleum Company, Inc. | Houston, TX 77098 | Oil & Gas Operator | Feb 2014 |
| 487 | Terra Resources, Inc. | Casper, WY 82601 | Oil & Gas Operator | Jun 1990 |
| 488 | Terral D Hinds | | Oil Operator | Mar 2012 |
| 489 | Tex/Con Oil & Gas Company | Houston, TX 77074 | Oil & Gas Operator | Feb 2001 |
| 490 | Texaco Producing Inc. | Rock Springs, WY 82901 | Oil & Gas Operator | Dec 2000 |
| 491 | Texas General Petroleum Corp | | Oil & Gas Operator | Aug 1984 |
| 492 | Texas Oil & Gas Corporation | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 493 | The Goro Corporation | | Oil & Gas Operator | Jul 1978 |
| 494 | The Hunter Company, Inc. | | Oil & Gas Operator | Sep 1985 |
| 495 | The Romanoff Corporation | | Oil & Gas Operator | Nov 1989 |
| 496 | Thornton & Brooks, Inc. | | Oil & Gas Operator | Oct 1990 |
| 497 | Tide West Oil Company | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2021 |
| 498 | TMR Exploration, Inc. | Bossier City, LA 71171 | Oil & Gas Operator | Sep 2025 |
| 499 | Tola Production Company | Dallas, TX 75367 | Oil & Gas Operator | Jul 2026 |
| 500 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |