| 401 | St. Mary Energy Company | Houston, TX 77079 | Oil & Gas Operator | Aug 2008 |
| 402 | St. Mary Land & Exploration Co | Denver, CO 80201 | Oil & Gas Operator | Jun 2010 |
| 403 | St. Mary Operating Company | Denver, CO 80203 | Oil & Gas Operator | Mar 2019 |
| 404 | Stahl Petroleum Co. | Amarillo, TX 79118 | Oil & Gas Operator | Aug 2003 |
| 405 | Staley, Jack C. | Wichita Falls, TX 76308 | Oil & Gas Operator | Jan 2000 |
| 406 | Stallion Energy, Inc. | Houston, TX 77060 | Oil & Gas Operator | Oct 2017 |
| 407 | Statoil Oil & Gas LP | Austin, TX 78730 | Oil & Gas Operator | Oct 2018 |
| 408 | Stephens & Johnson Operating Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2025 |
| 409 | Sting Exploration Company | Tulsa, OK 74120 | Oil Operator | Sep 2004 |
| 410 | Striper Oil, Inc. | Dallas, TX 75379 | Oil & Gas Operator | Apr 2002 |
| 411 | Summit Exploration, L.L.C. | Tulsa, OK 74119 | Oil & Gas Operator | Mar 2008 |
| 412 | Summit Overseas Expl., Inc. | Denver, CO 80226 | Oil & Gas Operator | Apr 2007 |
| 413 | Sundown Energy, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Jan 2025 |
| 414 | Supa Energy, Inc. | Shamrock, TX 79079 | Oil & Gas Operator | May 2025 |
| 415 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 416 | T-Y Development Corp | Perryton, TX 79070 | Oil & Gas Operator | May 2025 |
| 417 | Talon Oil & Gas LLC | Dallas, TX 75243 | Oil & Gas Operator | Dec 2010 |
| 418 | Talus Inc | Graham, TX 76450-1210 | Oil & Gas Operator | Feb 2017 |
| 419 | Tapstone Energy LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Mar 2025 |
| 420 | Tascosa Petroleum Corporation | Amarillo, TX 79105 | Oil & Gas Operator | May 2025 |
| 421 | Taubert & Steed | Wichita Falls, TX 76301 | Oil & Gas Operator | Aug 2001 |
| 422 | Tecolote Energy Operating, LLC | Fort Worth, TX 76107 | Oil & Gas Operator | Jan 2024 |
| 423 | Templar Operating LLC | Oklahoma City, OK 73142 | Oil & Gas Operator | Feb 2025 |
| 424 | Tesoro E&P Company, L.P. | San Antonio, TX 78216 | Oil & Gas Operator | Jan 2000 |
| 425 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | May 2025 |
| 426 | Texakoma E & P, LLC | Plano, TX 75024 | Oil & Gas Operator | May 2025 |
| 427 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 428 | Texakoma Operating, L.P. | Plano, TX 75024 | Oil & Gas Operator | Jan 2025 |
| 429 | The Operating Co. | Pampa, TX 79065 | Oil & Gas Operator | Sep 2007 |
| 430 | Tide West Oil Company | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2021 |
| 431 | Toklan Oil And Gas Corporation | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2025 |
| 432 | Top O'Texas Energy, L.P. | Pampa, TX 79066 | Oil & Gas Operator | May 2025 |
| 433 | Trans Terra Corp., International | Amarillo, TX 79159 | Oil & Gas Operator | Feb 2009 |
| 434 | Transtexas Gas Corporation | Houston, TX 77265 | Oil & Gas Operator | Aug 2005 |
| 435 | Trejim Operators, LLC | Pampa, TX 79065 | Oil & Gas Operator | May 2025 |
| 436 | Triple J Oil Co. | Pampa, TX 79065 | Oil & Gas Operator | Aug 1996 |
| 437 | Triton Operating LLC | Wichita Falls, TX 76310 | Oil & Gas Operator | May 2025 |
| 438 | Unbridled Resources, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 439 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 440 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | May 2025 |
| 441 | Universal Resources Corp. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jan 2000 |
| 442 | Upland Resources, Inc. | Canadian, TX 79014 | Oil & Gas Operator | Dec 2009 |
| 443 | Uplift Production Company, Inc. | Shamrock, TX 79079 | Oil & Gas Operator | Feb 1999 |
| 444 | Validus Energy II Midcon LLC | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 445 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | Jan 2025 |
| 446 | Vega Energy Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Sep 2015 |
| 447 | Viking Ventures, LLC | Garland, TX 75044 | Oil & Gas Operator | Mar 2009 |
| 448 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Feb 2025 |
| 449 | Viola Production Inc | Dallas, TX 75251 | Oil & Gas Operator | May 2025 |
| 450 | W & T Offshore, L.L.C. | Houston, TX 77046 | Gas Operator | Jan 1999 |
| 451 | Wallace Oil & Gas Inc | Oklahoma City, OK 73156 | Oil & Gas Operator | May 2025 |
| 452 | Walls, G. M. & Frances, Inc. | Pampa, TX 79066 | Oil & Gas Operator | May 2025 |
| 453 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 454 | Wheeler Oil Co. (A) | Amarillo, TX 79114 | Gas Operator | Apr 2001 |
| 455 | White Operating Company | Oklahoma City, OK 73159-7136 | Oil & Gas Operator | Mar 2025 |
| 456 | White Pine Petroleum Corporation | Wichita, KS 67202 | Oil & Gas Operator | Dec 2019 |
| 457 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 458 | Whittington, G. R. | Amarillo, TX 79109 | Oil & Gas Operator | Jan 1994 |
| 459 | Whittington, G. R. Estate | Amarillo, TX 79109 | Oil & Gas Operator | Mar 2008 |
| 460 | Wilchar, DR. R. B. | Fort Worth, TX 76185 | Oil & Gas Operator | Jan 2007 |
| 461 | Wildcat Cement Co. | Shamrock, TX 79079 | Oil & Gas Operator | May 2015 |
| 462 | Windsor Energy Group LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Aug 2021 |
| 463 | Wischkaemper, James K. | Shamrock, TX 79079 | Oil & Gas Operator | Aug 2023 |
| 464 | Wischkaemper, Kenneth | Shamrock, TX 79079 | Oil & Gas Operator | May 2025 |
| 465 | Wise Exploration | Perrin, TX 76486 | Oil & Gas Operator | May 2025 |
| 466 | Wo Operating Company | Tulsa, OK 74159 | Oil & Gas Operator | May 2025 |
| 467 | Wolf Creek Exploration Company | Amarillo, TX 79159 | Oil & Gas Operator | Aug 2000 |
| 468 | Wright Trucking, Inc. | Weatherford, OK 73096 | Oil & Gas Operator | Feb 2019 |
| 469 | WTG Exploration | Midland, TX 79705 | Oil & Gas Operator | May 2025 |
| 470 | Wynn-Crosby Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2005 |
| 471 | Wynn-Crosby Operating, LTD. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 472 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 473 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 474 | Zephyr Lone Star Oper Co.,L.L.C. | Oklahoma City, OK 73118 | Oil & Gas Operator | May 2025 |