| 401 | Rcy Mineral Group, Inc. | El Campo, TX 77437 | Oil Operator | Jul 2010 |
| 402 | Red Wolf Oil Company, Inc. | Brenham, TX 77833 | Oil & Gas Operator | Oct 2025 |
| 403 | Reddy Disposals, LLC | Beeville, TX 78104 | Oil Operator | Oct 2025 |
| 404 | Reichmann Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Oct 2025 |
| 405 | Remora Management, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | Oct 2025 |
| 406 | Remora Operating LLC | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 407 | Reo Operating LLC | Austin, TX 78747 | Oil & Gas Operator | Oct 2025 |
| 408 | Republic Resources, LLC. | San Antonio, TX 78212 | Oil & Gas Operator | Oct 2025 |
| 409 | Resaca Resources, L.L.C. | Austin, TX 78746 | Oil & Gas Operator | Oct 2025 |
| 410 | Resource Expl & Prod, Inc. | Salado, TX 76571 | Oil & Gas Operator | Oct 2025 |
| 411 | Richardson, Marshall T. | Midfield, TX 77458 | Oil & Gas Operator | Oct 2025 |
| 412 | Richman Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Jul 2006 |
| 413 | Rife Oil Properties Inc | Fort Worth, TX 76107 | Oil & Gas Operator | Oct 2025 |
| 414 | Rincon Petroleum Corporation | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Oct 2025 |
| 415 | Riseden Services, Inc. | Houston, TX 77256 | Oil & Gas Operator | Sep 1997 |
| 416 | Rlu Operating, LLC | Devine, TX 78016 | Oil & Gas Operator | Oct 2025 |
| 417 | Rme Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Nov 2016 |
| 418 | Rodeo Resources, L.L.C. | Houston, TX 77079 | Oil & Gas Operator | Dec 2024 |
| 419 | Rodessa Operating Company | Corpus Chrsti, TX 78426 | Oil & Gas Operator | Oct 2025 |
| 420 | Roil Production Company | Houston, TX 77056 | Gas Operator | Sep 2005 |
| 421 | Rosenthal, Stanley H. | Bay City, TX 77404 | Oil & Gas Operator | Dec 2020 |
| 422 | Roule Production Company | Bay City, TX 77414 | Oil & Gas Operator | Feb 1997 |
| 423 | Royalty Land & Dev. Co., Inc. | Wolfforth, TX 79382 | Oil & Gas Operator | Oct 2025 |
| 424 | Rse, Inc. | Houston, TX 77077 | Oil & Gas Operator | Sep 2000 |
| 425 | Rudman Partnership, The | Dallas, TX 75201 | Oil & Gas Operator | Dec 2014 |
| 426 | Rumble Energy LLC | Skiatook, OK 74070 | Oil & Gas Operator | Oct 2025 |
| 427 | Rusk Energy Operating LLC | Houston, TX 77040 | Oil & Gas Operator | Oct 2025 |
| 428 | Saba Energy Of Texas Inc | Houston, TX 77042 | Oil & Gas Operator | Jul 2007 |
| 429 | Sabco Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2011 |
| 430 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 431 | Samson Exploration LLC | Tulsa, OK 74101 | Oil & Gas Operator | Aug 2025 |
| 432 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 433 | Samson Lone Star, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2025 |
| 434 | San Isidro Development Co, L. C. | Sandia, TX 78383 | Oil & Gas Operator | Oct 2025 |
| 435 | Sanchez Oil & Gas Corporation | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 436 | Sanchez-O'Brien Oil & Gas Corp | Houston, TX 77057 | Oil & Gas Operator | May 1998 |
| 437 | Sandalwood Exploration, L.P. | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 438 | Sandel Energy, Inc. | Huntsville, TX 77342 | Oil & Gas Operator | Apr 2004 |
| 439 | Sandel Operating Company | Huntsville, TX 77340 | Oil & Gas Operator | Oct 2025 |
| 440 | Santos USA Corp. | Houston, TX 77042 | Oil & Gas Operator | Dec 2008 |
| 441 | Satex Energy, Inc. | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2003 |
| 442 | Saxet Energy, LTD. | Houston, TX 77057 | Oil & Gas Operator | Mar 2004 |
| 443 | Scana Petroleum Resources Inc | Houston, TX 77002 | Oil & Gas Operator | Jun 2013 |
| 444 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 445 | Seneca Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Dec 2017 |
| 446 | Shana Petroleum Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2002 |
| 447 | Sharpe Energy Company | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 448 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 449 | Sheridan Energy,Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2000 |
| 450 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | Oct 2025 |
| 451 | Shoco Production LLC | Kilgore, TX 75663 | Oil & Gas Operator | Oct 2025 |
| 452 | Shoco Production, L.P. | Kilgore, TX 75663 | Oil & Gas Operator | May 2020 |
| 453 | Shubuta Oil Corporation | Houston, TX 77056 | Oil & Gas Operator | Sep 1998 |
| 454 | Siana Oil & Gas | Conroe, TX 77305 | Oil & Gas Operator | Oct 2025 |
| 455 | Sierra Minerals, Inc. | Rockdale, TX 76567 | Oil & Gas Operator | Oct 2025 |
| 456 | Skrivanos Engineering, Inc. | Shreveport, LA 71164 | Oil & Gas Operator | Dec 2011 |
| 457 | Smith Energy 1986a Partnership | Alvin, TX 77511 | Oil & Gas Operator | Feb 2010 |
| 458 | Smith Petroleum Company | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 459 | Smith Production Inc. | The Woodlands, TX 77381 | Oil & Gas Operator | Oct 2025 |
| 460 | South Bay Resources, L.L.C. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 461 | South Texas Limited Partnership | Houston, TX 77060 | Oil & Gas Operator | Feb 1994 |
| 462 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 463 | Southwestern Energy Prod Co | Houston, TX 77032 | Oil & Gas Operator | Jun 2015 |
| 464 | Spicewood Operating Company, LLC | Austin, TX 78746 | Oil & Gas Operator | Oct 2025 |
| 465 | Spur Operating Co. | Austin, TX 78701 | Oil & Gas Operator | Oct 2025 |
| 466 | Square Mile Energy, L.L.C. | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 467 | Sterling Expl. & Prod. Co., LLC | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 468 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | Oct 2025 |
| 469 | Sue-Ann Operating, L.C. | Victoria, TX 77903 | Oil & Gas Operator | Oct 2025 |
| 470 | Sue-Ann Production Company | Victoria, TX 77903 | Oil & Gas Operator | Mar 2008 |
| 471 | Suemaur Expl. & Prod., LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jun 2024 |
| 472 | Sun Resources Texas, Inc. | Longview, TX 75606 | Oil & Gas Operator | Dec 2024 |
| 473 | Suncoast Technical Services Inc | Dallas, TX 75251 | Oil & Gas Operator | Oct 2025 |
| 474 | Sure Flow Oil & Gas, Inc. | Victoria, TX 77902 | Oil & Gas Operator | Oct 2025 |
| 475 | SV Energy Company, LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Mar 2017 |
| 476 | Sydri Operating, LLC | Dallas, TX 75231 | Oil & Gas Operator | Oct 2025 |
| 477 | Synergy Oil & Gas, Inc. (A) | Houston, TX 77024 | Oil & Gas Operator | Aug 2001 |
| 478 | Synergy Production Company | Houston, TX 77024 | Oil & Gas Operator | Jan 1996 |
| 479 | Tag Operating Company, Inc. | Houston, TX 77092 | Oil & Gas Operator | Oct 2025 |
| 480 | Tecpetrol Operating LLC | Houston, TX 77027 | Oil & Gas Operator | Dec 2015 |
| 481 | Tenison Oil Company | Abilene, TX 79605 | Oil & Gas Operator | Jun 2025 |
| 482 | Tepco, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 1999 |
| 483 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Oct 2025 |
| 484 | Texakoma E & P, LLC | Plano, TX 75024 | Oil & Gas Operator | Oct 2025 |
| 485 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 486 | Texakoma Operating, L.P. | Plano, TX 75024 | Oil & Gas Operator | Mar 2025 |
| 487 | Texas Crude Energy, Inc. | Houston, TX 77256 | Oil & Gas Operator | Oct 2012 |
| 488 | Texas Fuel Company | Galveston, TX 77550 | Oil & Gas Operator | Oct 2025 |
| 489 | Texas Gulf Gas Corporation | Fayetteville, TX 78940 | Oil & Gas Operator | Jun 2005 |
| 490 | Texas Independent Explor., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 491 | Texas Meridian Res. Expl., Inc. | Houston, TX 77079 | Oil & Gas Operator | Jun 1998 |
| 492 | Texas Western Energy Corporation | Portland, TX 78374 | Oil & Gas Operator | Nov 2002 |
| 493 | Texegy Operating Company LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Dec 2024 |
| 494 | Texian Operating Company, LLC | Irving, TX 75063 | Oil & Gas Operator | Oct 2025 |
| 495 | Texstar North America, Inc. | Waynesboro, MS 39367 | Oil & Gas Operator | Aug 1994 |
| 496 | Titan Energy Operating LLC | Houston, TX 77056 | Oil Operator | Jan 2016 |
| 497 | Tiza Energy, Inc. | Austin, TX 78715 | Oil & Gas Operator | Oct 2025 |
| 498 | TNR Petroleum, Inc. | Austin, TX 78747 | Oil & Gas Operator | Sep 1999 |
| 499 | Tracer Energy, Inc. | Graham, TX 76450 | Oil & Gas Operator | Nov 1998 |
| 500 | Traton Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Mar 2019 |