| 401 | Dorchester Resources LP | Oklahoma City, OK 73154-8879 | Oil & Gas Operator | Aug 2021 |
| 402 | Dore Corporation | Amarillo, TX 79119 | Gas Operator | Jun 2010 |
| 403 | Dore Energy Co., LTD. | Amarillo, TX 79101 | Gas Operator | Sep 2026 |
| 404 | Dorfman Production Company | Beloit, OH 44609 | Oil & Gas Operator | Sep 2026 |
| 405 | Dorland, D. L. | Midland, TX 79701 | Oil & Gas Operator | Aug 2003 |
| 406 | Dorland, D. L. Estate Of | Midland, TX 79702 | Oil & Gas Operator | Nov 1994 |
| 407 | Dorland, D. L. Inc. | Midland, TX 79701 | Oil & Gas Operator | Jul 1994 |
| 408 | Dorondoco Operating Co., Inc. | Brownwood, TX 76801 | Oil & Gas Operator | May 1994 |
| 409 | Dorough, Lee Operations | Orlando, FL 32801 | Oil & Gas Operator | Sep 2026 |
| 410 | Dorr, John R. | Pecos, TX 79772 | Oil & Gas Operator | Sep 2026 |
| 411 | Dos Cicadas | Miles, TX 76861 | Oil & Gas Operator | Sep 2026 |
| 412 | Double Barrel Oil LLC | Brenham, TX 77834 | Oil & Gas Operator | Sep 2026 |
| 413 | Double Barrel Operating Limited Liability Company | Wichita Falls, TX 76308 | Oil Operator | Sep 2026 |
| 414 | Double C Operating LLC | Abilene, TX 79602 | Oil Operator | Sep 2026 |
| 415 | Double C Production, LLC | Canyon Lake, TX 78133 | Oil Operator | Sep 2026 |
| 416 | Double Diamond Energy Corp. | Granbury, TX 76048 | Gas Operator | Apr 2013 |
| 417 | Double Diamond Petroleum, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Sep 2026 |
| 418 | Double E Oil & Gas, L. P. | Electra, TX 76360 | Oil & Gas Operator | Sep 2026 |
| 419 | Double Eagle Exploration Inc | Windthorst, TX 76389 | Oil Operator | Apr 2026 |
| 420 | Double Eagle Oil Co. | Marshall, TX 75670 | Oil & Gas Operator | Jan 2002 |
| 421 | Double Eagle Operating, LLC | Fort Worth, TX 76107 | Oil & Gas Operator | Sep 2026 |
| 422 | Double Eagle Petroleum Corp | Evansville, IN 47725 | Oil & Gas Operator | Sep 2026 |
| 423 | Double Eight Oil Company LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Sep 2026 |
| 424 | Double J Enterprises | Loving, TX 76460 | Oil Operator | Sep 2026 |
| 425 | Double J Operating Company, Inc. | San Antonio, TX 78205 | Oil Operator | Jan 2008 |
| 426 | Double K Production | Graham, TX 76450 | Oil & Gas Operator | Sep 2014 |
| 427 | Double L Contractors, LLC | Carthage, TX 75633 | Oil Operator | Sep 2026 |
| 428 | Double L Operating | Graham, TX 76450 | Oil & Gas Operator | Nov 2018 |
| 429 | Double M Petroproperties, Inc. | Haskell, TX 79521 | Oil & Gas Operator | Sep 2026 |
| 430 | Double Play Oil & Gas | Portland, TX 78374 | Oil & Gas Operator | Dec 2001 |
| 431 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | Sep 2026 |
| 432 | Double R Oil Co. | Charlotte, TX 78011 | Oil & Gas Operator | May 2010 |
| 433 | Double S Liberty Energy, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Sep 2026 |
| 434 | Double S Operating Co. | Wichita Falls, TX 76308 | Oil & Gas Operator | Sep 2026 |
| 435 | Double T Energy LLC | Lenorah, TX 79749 | Oil Operator | Sep 2026 |
| 436 | Double U Oil Co. | San Antonio, TX 78217 | Oil & Gas Operator | Feb 1996 |
| 437 | Double U Oil Co., LTD. | San Antonio, TX 78217 | Oil & Gas Operator | May 2000 |
| 438 | Dougherty Properties | Beeville, TX 78104 | Oil & Gas Operator | Jun 1997 |
| 439 | Doughtie Operating Company, LLC | MC Queeney, TX 78123 | Oil & Gas Operator | Mar 2023 |
| 440 | Douglas Investments Inc | Fort Worth, TX 76137 | Oil Operator | Jan 2020 |
| 441 | Douglas Petroleum Inc. | Spring, TX 77379 | Oil & Gas Operator | Nov 2010 |
| 442 | Douglas, Norvel Trust | Hot Springs V, AR 71909 | Oil & Gas Operator | Aug 2013 |
| 443 | Dove Creek Energy, Inc. | Fort Worth, TX 76121 | Oil & Gas Operator | Sep 2026 |
| 444 | Dove Creek Resources, LLC | Arlington, TX 76012 | Oil Operator | Sep 2026 |
| 445 | Dove Drilling, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Nov 1997 |
| 446 | Dove Mineral | Abilene, TX 79601 | Oil & Gas Operator | Dec 2010 |
| 447 | Dowden, T. L. | Henderson, TX 75652 | Oil & Gas Operator | Sep 2026 |
| 448 | Dowell Oil & Gas | Stephenville, TX 76401 | Oil & Gas Operator | Sep 2026 |
| 449 | Down-Hole Pump Service Co., Inc. | Fort Worth, TX 76109 | Oil & Gas Operator | Sep 2026 |
| 450 | Downing Well Service, Inc. | Devine, TX 78016 | Oil & Gas Operator | Sep 2026 |
| 451 | Downman Jones Oil Operators, Inc | Brookshire, TX 77423 | Oil & Gas Operator | Jan 2007 |
| 452 | DP Permian Operator, LLC | Houston, TX 77024 | Oil & Gas Operator | Aug 2024 |
| 453 | DP Well Works I, LLC | Salt Lake Cty, UT 84103 | Oil & Gas Operator | Sep 2026 |
| 454 | DPMP Energy LLC | Prosper, TX 75078 | Oil & Gas Operator | Dec 2023 |
| 455 | Drachen Energy Co. | San Antonio, TX 78258 | Oil Operator | Sep 2026 |
| 456 | Drachen Oil Company | San Antonio, TX 78258 | Oil & Gas Operator | Sep 2026 |
| 457 | Draco Energy, Inc. | Midland, TX 79701 | Oil & Gas Operator | Sep 2026 |
| 458 | Draco Production Company | Tulsa, OK 74133 | Oil & Gas Operator | Jul 2012 |
| 459 | Dragon Operating, LLC | Tulsa, OK 74137 | Oil Operator | Sep 2026 |
| 460 | Dragoon Oil & Gas Co. | Fort Worth, TX 76147 | Oil & Gas Operator | May 2015 |
| 461 | Drain Oil Co. | Fritch, TX 79036 | Oil & Gas Operator | Jul 2009 |
| 462 | Drain Oil Co. LLC | Fritch, TX 79036 | Oil & Gas Operator | Sep 2026 |
| 463 | Drake Oil & Gas, LLC | Wichita Falls, TX 76308 | Oil Operator | Sep 2026 |
| 464 | Drake Petroleum, LLC | Cypress, TX 77429 | Oil & Gas Operator | Jun 2023 |
| 465 | Dreher, George R. | Midland, TX 79702 | Oil & Gas Operator | Jan 2018 |
| 466 | Drennan Oil L.L.C. | Ballinger, TX 76821 | Oil & Gas Operator | Sep 2026 |
| 467 | Drennan, D. E. | Graham, TX 76450 | Oil & Gas Operator | Dec 2011 |
| 468 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |
| 469 | DRH Properties LLC | Wichita Falls, TX 76308 | Oil & Gas Operator | Dec 2014 |
| 470 | Driftwood Energy Operating, LLC | Dallas, TX 75219 | Oil & Gas Operator | Dec 2022 |
| 471 | Drill Partners Management, LLC | Houston, TX 77056 | Oil & Gas Operator | Nov 2010 |
| 472 | Drillers Energy Search, Inc | Denver, CO 80202 | Oil & Gas Operator | Aug 1996 |
| 473 | Drillmar Energy, Inc. | Houston, TX 77079 | Oil & Gas Operator | Nov 2014 |
| 474 | Drillmar Operating Company | Houston, TX 77019 | Oil & Gas Operator | Jun 2013 |
| 475 | Drillogix Exploration LLC | Breckenridge, TX 76424 | Oil Operator | Sep 2026 |
| 476 | Drilmor, Inc. | Midland, TX 79701 | Oil & Gas Operator | Feb 1998 |
| 477 | Driscoll S.W.D. Inc. | San Antonio, TX 78229 | Oil & Gas Operator | Sep 2026 |
| 478 | DRS Exploration Inc. | San Antonio, TX 78209 | Oil & Gas Operator | May 1999 |
| 479 | Drum Oil & Gas, Inc. | Liberty, TX 77575 | Oil & Gas Operator | Sep 2026 |
| 480 | Drum, Delton | Liberty, TX 77575 | Oil & Gas Operator | Jul 2005 |
| 481 | Dry Creek Operating, LLC | Fort Worth, TX 76109 | Oil & Gas Operator | Sep 2026 |
| 482 | Dry Fork Production Co | Wichita Falls, TX 76301 | Oil Operator | Apr 2003 |
| 483 | Dry Fork Production Co., LLC | Wichita Falls, TX 76307 | Oil & Gas Operator | Sep 2026 |
| 484 | DSB Energy, LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Sep 2026 |
| 485 | DSM Exploration Inc | Oklahoma City, OK 73154 | Oil & Gas Operator | May 1996 |
| 486 | DSR Oil & Gas, Inc. | Monahans, TX 79756 | Oil & Gas Operator | Sep 2026 |
| 487 | DSTJ Corporation | Montgomery, TX 77316 | Oil & Gas Operator | Mar 2001 |
| 488 | DSW Production Corp. | Houston, TX 77265 | Oil & Gas Operator | Sep 2026 |
| 489 | DSX Operating Co. | Amarillo, TX 79105 | Oil & Gas Operator | Mar 2008 |
| 490 | Dte Gas Resources, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Nov 2007 |
| 491 | Dte Gas Resources, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 2014 |
| 492 | Dual Production Partners, LLC | Nacogdoches, TX 75963 | Oil & Gas Operator | Sep 2026 |
| 493 | Dual Quiver Oil & Gas Op, LLC | Flower Mound, TX 75027 | Oil & Gas Operator | Sep 2026 |
| 494 | Ducky Oil Corporation | Fort Worth, TX 76120 | Oil & Gas Operator | Sep 2026 |
| 495 | Duderstadt, A. R. | Boling, TX 77420 | Oil & Gas Operator | Sep 2026 |
| 496 | Dudley Oil Co. | Crane, TX 79731 | Oil & Gas Operator | Jan 2006 |
| 497 | Dugan Production Corp | Farmington, NM 87499 | Oil & Gas Operator | Jul 2026 |
| 498 | Dugger, Glenn | Alice, TX 78332 | Oil & Gas Operator | Nov 2013 |
| 499 | Duke Operating Company | Graham, TX 76450 | Oil Operator | Sep 2026 |
| 500 | Duke, M. L. | Snyder, TX 79549 | Oil & Gas Operator | Mar 2008 |