| 401 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 402 | Ranken Energy Corporation | Edmond, OK 73013 | Oil & Gas Operator | Apr 2025 |
| 403 | Ravil Inc | Edmond, OK 73013 | Gas Operator | Nov 1998 |
| 404 | RCK Oil And Gas LLC | Denton, TX 76207 | Oil & Gas Operator | Apr 2025 |
| 405 | Red Mountain Operating LLC | Oklahoma City, OK 73118-1253 | Oil & Gas Operator | Apr 2024 |
| 406 | Red Rocks Oil & Gas Operating LLC | Oklahoma City, OK 73103-4821 | Oil & Gas Operator | May 2025 |
| 407 | Redbud E & P, Inc. | Giddings, TX 78942 | Oil & Gas Operator | Jul 2025 |
| 408 | Redwine Resources Inc | Dallas, TX 75225 | Oil & Gas Operator | Feb 2015 |
| 409 | Reid Williams Operating Inc | Shreveport, LA 71106-6223 | Oil & Gas Operator | Apr 2025 |
| 410 | Revere Corporation | Fort Smith, AR 72902-0908 | Oil & Gas Operator | Feb 2015 |
| 411 | Revilo Exploration, Inc. | Richardson, TX 75081 | Oil & Gas Operator | Jul 2021 |
| 412 | Riley Exploration Operating Co LLC | Blanchard, OK 73010-8024 | Gas Operator | Jun 2017 |
| 413 | Rio VIsta Operating LLC | Eufaula, OK 74432-0789 | Gas Operator | Apr 2025 |
| 414 | River City Resources Inc | Tulsa, OK 74119 | Oil & Gas Operator | Nov 1997 |
| 415 | Riverfront Exploration LLC | Fort Smith, AR 72901 | Gas Operator | Apr 2025 |
| 416 | Riviera Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 417 | RL&B Energy LLC | Wichita Falls, TX 76230 | Oil & Gas Operator | Apr 2025 |
| 418 | Roberson Oil Company | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 419 | Rockwell Drilling Company | New York, NY 10013 | Oil & Gas Operator | Dec 2005 |
| 420 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Jul 2025 |
| 421 | Rover Operating, LLC | Chicago, IL 60606 | Oil & Gas Operator | May 2025 |
| 422 | Royalty Petroleum Company | Oklahoma City, OK 73120 | Gas Operator | Feb 2002 |
| 423 | Rush Creek Operating LLC | McKinney, TX 75070 | Oil & Gas Operator | Jul 2025 |
| 424 | S & J Operating Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Mar 2015 |
| 425 | Sabco Operating Company, LLC | Houston, TX 77056 | Oil & Gas Operator | Jun 2018 |
| 426 | Sabre Operating, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Jul 2025 |
| 427 | Samson Gas Producing Company | Tulsa, OK 74103 | Oil & Gas Operator | May 2001 |
| 428 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 429 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 430 | San Francisco-Okla Pet Ex Inc | | Oil & Gas Operator | Apr 2014 |
| 431 | Sandra Corporation (The) | Pampa, TX 79066-2474 | Gas Operator | Oct 1996 |
| 432 | Sanguine Gas Exploration, LLC | Tulsa, OK 74119 | Oil & Gas Operator | Jul 2025 |
| 433 | Santa Fe Minerals, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Sep 2013 |
| 434 | Santa Fe Operating LLC | Frisco, TX 75034 | Gas Operator | Jul 2025 |
| 435 | Santa Fe-Andover Oil Co | Tulsa, OK 74172 | Oil & Gas Operator | Sep 2000 |
| 436 | Scana Exploration Company | Houston, TX 77002 | Oil & Gas Operator | Dec 1999 |
| 437 | Scana Petroleum Resources Inc | Houston, TX 77002 | Oil & Gas Operator | Jun 2013 |
| 438 | Schmid Properties Inc | Hico, TX 76457 | Oil & Gas Operator | Jul 2025 |
| 439 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 440 | Seagull Mid-South Inc | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 441 | Seagull Midcon Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 442 | Sedna Energy LLC | Blanchard, OK 73010-8043 | Gas Operator | Apr 2017 |
| 443 | Sellmeyer Frank | San Rafael, CA 94901-1339 | Oil Operator | Dec 2014 |
| 444 | Seneca Oil Company | Tulsa, OK 74121-1518 | Oil & Gas Operator | Jan 2015 |
| 445 | Sheridan Production Company, LLC | Houston, TX 77056 | Oil & Gas Operator | Apr 2025 |
| 446 | Shields Energy Inc | Fort Smith, AR 72901-4607 | Oil & Gas Operator | Apr 2025 |
| 447 | Shields Operating, Inc | Fort Smith, AR 72901-3834 | Oil & Gas Operator | Oct 2021 |
| 448 | Siegfried R H Inc | Tulsa, OK 74104 | Oil & Gas Operator | Mar 2008 |
| 449 | Silver Pines Energy Corp. | Houston, TX 77005 | Oil & Gas Operator | Apr 2025 |
| 450 | Sinclair Oil & Gas Company | Salt Lake Cty, UT 84130 | Oil & Gas Operator | Jul 2025 |
| 451 | Six "E" Trading Company | Henryetta, OK 74801 | Oil & Gas Operator | Sep 2020 |
| 452 | SJM Inc | Tulsa, OK 74133-1757 | Gas Operator | Apr 2006 |
| 453 | Slawson, Donald C. | Wichita, KS 67202 | Oil & Gas Operator | Oct 2024 |
| 454 | Sloan Petroleum Service Inc | Guthrie, OK 73044 | Oil & Gas Operator | May 2025 |
| 455 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Jul 2025 |
| 456 | Smith Energy Company LLC | Purcell, OK 73080-4772 | Oil & Gas Operator | May 2015 |
| 457 | Snyder Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2015 |
| 458 | Sogc, Inc. | Salt Lake Cty, UT 84131 | Oil & Gas Operator | May 2025 |
| 459 | Sorrels J R Dba Cheyenne Oil Properties | Ponca City, OK 74601 | Oil & Gas Operator | Jul 2022 |
| 460 | Southern Resources Inc | Oklahoma City, OK 73118-4821 | Oil & Gas Operator | May 2025 |
| 461 | Southern Union Exploration Co. | Austin, TX 78701 | Oil & Gas Operator | Feb 2002 |
| 462 | Spartan Resources LLC | Oklahoma City, OK 73116 | Oil & Gas Operator | May 2025 |
| 463 | Spess Oil Company Inc | Cleveland, OK 74020-4617 | Oil & Gas Operator | May 2025 |
| 464 | Spring Resources, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Jul 2007 |
| 465 | St. Mary Operating Company | Denver, CO 80203 | Oil & Gas Operator | Mar 2019 |
| 466 | Staab Alan R | Tulsa, OK 74114-4213 | Oil & Gas Operator | Sep 2010 |
| 467 | Stalwart Energy Co | Tulsa, OK 74103-3518 | Oil & Gas Operator | Apr 2014 |
| 468 | Stephens Production Company | The Woodlands, TX 77381 | Oil & Gas Operator | May 2025 |
| 469 | Stover Company | Tulsa, OK 74152-0786 | Oil & Gas Operator | Jan 2013 |
| 470 | Strike Energy LLC | Burneyville, OK 73430 | Oil Operator | May 2025 |
| 471 | Struthers Oil & Gas Corp | Tulsa, OK 74133 | Oil & Gas Operator | Jan 2013 |
| 472 | Summit Energy, Inc. | Littleton, CO 80127 | Oil & Gas Operator | Aug 2013 |
| 473 | Sundown Energy LP | Dallas, TX 75248 | Oil & Gas Operator | Jul 2025 |
| 474 | Sunterra Energy Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Dec 2009 |
| 475 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 476 | SWN Production LLC | Spring, TX 77389-4954 | Oil & Gas Operator | Feb 2022 |
| 477 | Sydson D'Oro Expl. Co. | Houston, TX 77079 | Oil & Gas Operator | Jan 1992 |
| 478 | T C Craighead & Company LLC | Ardmore, OK 73401 | Oil & Gas Operator | Aug 2019 |
| 479 | Tag Team Resources LLC | Eufaula, OK 74432 | Oil & Gas Operator | Apr 2025 |
| 480 | Tau Ventures | Tulsa, OK 74105-1026 | Oil & Gas Operator | Apr 2025 |
| 481 | Taylor R C Companies Inc | Oklahoma City, OK 73118-4015 | Oil & Gas Operator | May 2021 |
| 482 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Apr 2025 |
| 483 | Texaco Expl. And Prod. Inc. | Houston, TX 77236 | Oil & Gas Operator | May 2025 |
| 484 | Texaco Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2017 |
| 485 | Texas Meridian Operating Co. Inc | Houston, TX 77079 | Oil & Gas Operator | Oct 1993 |
| 486 | Texinia Corp | Dallas, TX 75201 | Oil & Gas Operator | Jun 2015 |
| 487 | Texinia Limited Partnership | Dallas, TX 75201 | Gas Operator | Jan 2017 |
| 488 | Texinia Oil & Gas Inc. | Dallas, TX 75214 | Oil & Gas Operator | Apr 2025 |
| 489 | Texland Petroleum Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2003 |
| 490 | Thomas J L Engineering Inc | Edmond, OK 73003-0026 | Oil & Gas Operator | Jul 2016 |
| 491 | Tide West Oil Company | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2021 |
| 492 | Tidemark Exploration | Tulsa, OK 74170 | Oil & Gas Operator | May 2005 |
| 493 | Tiger Trucks Inc | Seminole, OK 74868 | Oil & Gas Operator | May 2025 |
| 494 | Tilford Pinson Exploration LLC | Edmond, OK 73003 | Oil & Gas Operator | Apr 2025 |
| 495 | TK Drilling Corp. | Tulsa, OK 74133 | Oil & Gas Operator | Apr 2025 |
| 496 | Totalfinaelf E&P USA Inc | Houston, TX 77024 | Oil & Gas Operator | Jul 2007 |
| 497 | Trafalgar House Oil & Gas Inc. | Houston, TX 77002-7346 | Oil & Gas Operator | Jan 1992 |
| 498 | Transfuel Resources Co | Houston, TX 77215 | Oil & Gas Operator | Aug 2013 |
| 499 | Transok LLC | Oklahoma City, OK 73124-0300 | Oil & Gas Operator | Jul 2020 |
| 500 | Travis Peak Resources LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |