| 401 | Reef Exploration, Inc. (A-1) | Richardson, TX 75080 | Oil & Gas Operator | Oct 2006 |
| 402 | Remuda Operating Company | Midland, TX 79711 | Oil & Gas Operator | May 2025 |
| 403 | Rendova Oil Company, Inc. | Midland, TX 79702 | Oil & Gas Operator | Oct 2002 |
| 404 | Reneau, Nelda York | Snyder, TX 79549 | Oil & Gas Operator | May 2025 |
| 405 | Rhodes Drilling Company | Abilene, TX 79608 | Oil & Gas Operator | Sep 2000 |
| 406 | Rhombus Operating Co., LTD | Littleton, CO 80160 | Oil & Gas Operator | Feb 2025 |
| 407 | Richardson, Bud II | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 408 | Ridglea Energy I, LLC | Spring, TX 77379 | Oil & Gas Operator | May 2025 |
| 409 | Rio Exploration Company | San Antonio, TX 78209 | Gas Operator | Dec 2005 |
| 410 | Rister, Dewey | Avoca, TX 79503 | Oil & Gas Operator | May 2025 |
| 411 | RMB Operating LLC | Lubbock, TX 79493 | Oil & Gas Operator | May 2025 |
| 412 | Robertson Resources, Inc. | Midland, TX 79708 | Oil & Gas Operator | May 2025 |
| 413 | Roca Production, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | May 2025 |
| 414 | Roca Resource Company, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 415 | Rollo Resources, LLC | Granbury, TX 76049 | Gas Operator | May 2025 |
| 416 | Rose Exploration, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Feb 2002 |
| 417 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 418 | Ross Engineering, Inc. | Abilene, TX 79601 | Oil & Gas Operator | May 2025 |
| 419 | Rover Petroleum Operating, LLC | Plano, TX 75075 | Oil & Gas Operator | May 2025 |
| 420 | Royal Texas Petroleum | Lago VIsta, TX 78645 | Oil & Gas Operator | May 2025 |
| 421 | Rust Oil Corp. | Fort Worth, TX 76108 | Oil & Gas Operator | May 2025 |
| 422 | Ruwco Oil And Gas Corp. | Austin, TX 78701 | Oil & Gas Operator | Aug 2021 |
| 423 | Ryder Scott Oil Company | Wichita Falls, TX 76307 | Oil & Gas Operator | Dec 2005 |
| 424 | Ryholland Fielder, Inc | Delray Beach, FL 33446 | Oil & Gas Operator | May 2025 |
| 425 | S & J Operating Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Mar 2015 |
| 426 | S.B. Street Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 427 | Sabre Oil And Gas Corp. | Houston, TX 77063 | Oil & Gas Operator | May 2025 |
| 428 | Sabre Operating, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | May 2025 |
| 429 | Sage Energy Company | San Antonio, TX 78215 | Oil & Gas Operator | May 2025 |
| 430 | Salida Exploration, LLC | Abilene, TX 79603 | Oil & Gas Operator | May 2025 |
| 431 | Salt Creek Production, Inc. | Big Spring, TX 79721 | Oil & Gas Operator | May 2025 |
| 432 | San Patricio Corporation | Dinero, TX 78350 | Oil & Gas Operator | Sep 2003 |
| 433 | Sanchez-O'Brien Oil & Gas Corp | Houston, TX 77057 | Oil & Gas Operator | May 1998 |
| 434 | Santa Fe Energy Oper. Part., LP | Houston, TX 77057 | Oil & Gas Operator | Dec 1994 |
| 435 | Sapient Energy Corp | Oklahoma City, OK 73154 | Oil & Gas Operator | Jan 2002 |
| 436 | Sauder Management Company | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2025 |
| 437 | Savannah Ross And Company, LLC | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 438 | Schalk Oil Company, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | May 2025 |
| 439 | Schiff, H. G. & Co. | Dallas, TX 75206 | Oil & Gas Operator | Jul 1993 |
| 440 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | May 2025 |
| 441 | Scythian, LTD. | Midland, TX 79701 | Oil & Gas Operator | Dec 2020 |
| 442 | Shackelford Oil Co | Midland, TX 79707 | Oil & Gas Operator | Mar 2025 |
| 443 | Sheridan Production Company, LLC | Houston, TX 77056 | Oil & Gas Operator | Feb 2025 |
| 444 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | May 2025 |
| 445 | Simon, W. D. Oil Co. | Kermit, TX 79745 | Oil & Gas Operator | May 2025 |
| 446 | Sinclair Exploration Company | Abilene, TX 79604 | Oil & Gas Operator | Nov 1998 |
| 447 | SMC Oil & Gas, Inc. | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 448 | Smith Pipe Of Abilene | Abilene, TX 79608 | Oil & Gas Operator | May 2025 |
| 449 | Sojourner Drilling Corporation | Abilene, TX 79604 | Oil & Gas Operator | May 2025 |
| 450 | Southcoast Resources, LLC | Fort Worth, TX 76116 | Oil & Gas Operator | Dec 2015 |
| 451 | Southern Exploration, Inc. | Fort Worth, TX 76137 | Oil & Gas Operator | Aug 2023 |
| 452 | Southern Union Exploration Co. | Austin, TX 78701 | Oil & Gas Operator | Feb 2002 |
| 453 | Southlake Exploration, Inc. | Southlake, TX 76092 | Oil & Gas Operator | May 2025 |
| 454 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 455 | Southwest Royalties Inc | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 456 | Spence Energy Company | Dallas, TX 75360 | Oil & Gas Operator | May 2025 |
| 457 | Spenergy Corp. | Midland, TX 79701 | Oil & Gas Operator | Dec 1999 |
| 458 | Spiller Operating Co., Inc. | Round Rock, TX 78665 | Oil & Gas Operator | May 2015 |
| 459 | Spindletop Oil & Gas Co. | Dallas, TX 75230 | Oil & Gas Operator | May 2025 |
| 460 | SRG Oil Corporation | Abilene, TX 79604 | Oil & Gas Operator | Apr 1994 |
| 461 | Staley, Jack C. | Wichita Falls, TX 76308 | Oil & Gas Operator | Jan 2000 |
| 462 | Stallion Energy, Inc. | Houston, TX 77060 | Oil & Gas Operator | Oct 2017 |
| 463 | Stamper Operating Co., Inc. | Jacksboro, TX 76458 | Oil & Gas Operator | May 2025 |
| 464 | Star Production, Inc. | Dallas, TX 75360 | Oil & Gas Operator | May 2025 |
| 465 | Stasney Well Service, LLC | Albany, TX 76430 | Oil & Gas Operator | May 2025 |
| 466 | Stearns Operating Company | Abilene, TX 79604 | Oil & Gas Operator | Oct 1993 |
| 467 | Stephens & Johnson Operating Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2025 |
| 468 | Stovall Operating Co. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 469 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | May 2025 |
| 470 | Sullivan, Hollis R. Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2009 |
| 471 | Sulphur River Exploration, Inc. | Dallas, TX 75244 | Oil & Gas Operator | May 2025 |
| 472 | Summit Resources MGMT., LLC. | Edmond, OK 73083 | Oil & Gas Operator | May 2025 |
| 473 | Sunlight Exploration, Inc. | Canyon, TX 79015 | Oil & Gas Operator | May 2025 |
| 474 | Supreme Energy Company, Inc. | Abilene, TX 79601 | Oil & Gas Operator | May 2025 |
| 475 | Swenson, Clifford E. | Henrietta, TX 76365 | Oil & Gas Operator | May 2025 |
| 476 | T2 Operating Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 477 | Tacor Resources Inc | Midland, TX 79705 | Oil & Gas Operator | May 2025 |
| 478 | Tahoe Exploration Inc. | Abilene, TX 79608 | Oil & Gas Operator | Mar 2016 |
| 479 | Tamarack Petroleum Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 480 | Tarpon Oil Company | Fort Worth, TX 76107 | Oil & Gas Operator | Mar 2017 |
| 481 | TC Oil And Gas, LLC | Denton, TX 76205 | Oil Operator | May 2025 |
| 482 | TCF Energy, Inc. | Midland, TX 79704 | Oil & Gas Operator | Dec 2004 |
| 483 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | May 2025 |
| 484 | Telesis Operating Co. | Fort Worth, TX 76116 | Oil & Gas Operator | May 2025 |
| 485 | Tema Oil And Gas Company | Houston, TX 77084 | Oil & Gas Operator | May 2025 |
| 486 | Terrell Oil & Gas Production Co. | Hamlin, TX 79520 | Oil & Gas Operator | May 2025 |
| 487 | Tex-Ok Energy, LTD Partnership | Cody, WY 82414 | Oil & Gas Operator | May 2025 |
| 488 | Tex-R Energy, Inc. | Abilene, TX 79608 | Oil & Gas Operator | Feb 2021 |
| 489 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | May 2025 |
| 490 | Texas Energy Sources, Inc. | Midland, TX 79708 | Oil & Gas Operator | Mar 2008 |
| 491 | Texas Royalty Corp. | Austin, TX 78746 | Oil & Gas Operator | May 2025 |
| 492 | Texland-Rector & Schumacher | Fort Worth, TX 76102 | Oil & Gas Operator | Nov 2000 |
| 493 | Texsun Operating Company Limited | Abilene, TX 79601 | Oil & Gas Operator | Mar 1996 |
| 494 | Texzona Oil & Gas, Inc. | Abilene, TX 79608 | Oil & Gas Operator | Dec 1997 |
| 495 | Thompson, Richard W. Inc. | Plano, TX 75024 | Oil & Gas Operator | May 2025 |
| 496 | Three Rivers Operating Co LLC | Austin, TX 78735 | Oil & Gas Operator | Mar 2017 |
| 497 | Titan Energy, Inc. | Austin, TX 78703 | Oil & Gas Operator | May 2025 |
| 498 | TKP Petroleum, Inc. | Lubbock, TX 79464 | Oil & Gas Operator | May 2025 |
| 499 | Tonk Creek Oil Company | Aspermont, TX 79502 | Oil & Gas Operator | May 2025 |
| 500 | Tri-Tex Exploration LTD | Abilene, TX 79608 | Oil Operator | Apr 2019 |