| 301 | Diamond Oil & Gas LLC | Casper, WY 82604 | Oil & Gas Operator | Aug 2025 |
| 302 | Diamond Oil And Gas, Inc. | Kalamazoo, MI 49001 | Oil & Gas Operator | Oct 2025 |
| 303 | Diamond Operating, LLC | Wichita Falls, TX 76308 | Oil & Gas Operator | Aug 2010 |
| 304 | Diamond S Energy Company | Fort Worth, TX 76132 | Oil & Gas Operator | Oct 2025 |
| 305 | Diamond S Masada LLC | Magnolia, TX 77354 | Oil & Gas Operator | Oct 2025 |
| 306 | Diamondback E&P LLC | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 307 | Diamondback Oil Partners LLP | Arvada, CO 80004 | Oil & Gas Operator | Dec 2016 |
| 308 | Diamondback Operating, LP | Tulsa, OK 74132 | Gas Operator | Oct 2025 |
| 309 | Diamondback Resources LLC | Midland, TX 79705 | Oil & Gas Operator | May 2018 |
| 310 | Diasu Oil & Gas Co., Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2016 |
| 311 | Dick Lindsay Oil Company, Inc. | Graham, TX 76450 | Oil Operator | Oct 2025 |
| 312 | Dickson Petroleum, Inc. | Midland, TX 79710 | Oil & Gas Operator | May 2000 |
| 313 | Digital Operating Company LLC | Boerne, TX 78006 | Oil & Gas Operator | Oct 2025 |
| 314 | Diler Development Inc. | Garland, TX 75043 | Oil & Gas Operator | Oct 2025 |
| 315 | Dillard & Dillard Inc. | Holliday, TX 76366 | Oil & Gas Operator | Oct 2025 |
| 316 | Dillard, A. W., Jr. | Midland, TX 79701 | Oil & Gas Operator | Jan 1995 |
| 317 | Diller Oil Company | Baird, TX 79504 | Oil Operator | Oct 2025 |
| 318 | Dillon, H. L., Jr. | Houston, TX 77027 | Oil & Gas Operator | Mar 1996 |
| 319 | Dime Box Oil Company | Austin, TX 78759 | Oil & Gas Operator | Mar 2008 |
| 320 | Dimmit County SWD, LLC | Carrizo SPGS, TX 78834 | Oil Operator | Oct 2025 |
| 321 | Dimock Operating Company | Frisco, TX 75034 | Oil & Gas Operator | Oct 2025 |
| 322 | Dimock Petroleum | Dallas, TX 75205 | Oil Operator | Apr 2014 |
| 323 | Dinero Oil Corporation | Corpus Chrsti, TX 78460 | Oil & Gas Operator | Nov 1999 |
| 324 | Dinero Operating Co | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 325 | Dino Operating LLC | Throckmorton, TX 76483 | Oil Operator | Oct 2025 |
| 326 | Dirks Petroleum Company | Beeville, TX 78104 | Oil & Gas Operator | Oct 2025 |
| 327 | Dirks, R. W. | Tuleta, TX 78162 | Oil & Gas Operator | May 1999 |
| 328 | Dirks, R.W. Pet. Eng. Inc. | Tuleta, TX 78162 | Oil & Gas Operator | Jul 1999 |
| 329 | Dirnett, Inc. | Tuleta, TX 78162 | Oil & Gas Operator | Oct 2025 |
| 330 | Discorbis Oil Company | San Antonio, TX 78217 | Oil & Gas Operator | Jul 2019 |
| 331 | Discovery Energy Corp. CC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2025 |
| 332 | Discovery Natural Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 333 | Discovery Operating Inc | Midland, TX 79705 | Oil & Gas Operator | Oct 2025 |
| 334 | Discovery Petroleum, L.L.C. | Alice, TX 78333 | Oil & Gas Operator | Oct 2025 |
| 335 | Dittman, D. W. | Big Lake, TX 76932 | Oil & Gas Operator | Mar 2007 |
| 336 | Diversified Operating Corp. | Golden, CO 80401 | Oil & Gas Operator | Oct 2012 |
| 337 | Diversified Production LLC | Keithville, LA 71047 | Oil & Gas Operator | Oct 2025 |
| 338 | Diversity Petroleum, LP | Rockwall, TX 75087 | Oil & Gas Operator | Aug 2010 |
| 339 | Dixie Drilling Company, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Nov 2011 |
| 340 | Dixie Lake Operating, LLC | Longview, TX 75606 | Gas Operator | Oct 2025 |
| 341 | Dixon Exploration Inc | Abilene, TX 79604 | Oil & Gas Operator | Oct 2019 |
| 342 | Dixon, N. D. | Midland, TX 79702 | Oil & Gas Operator | Feb 2003 |
| 343 | DJ & T Services, LLC | Abilene, TX 79601 | Oil & Gas Operator | Oct 2025 |
| 344 | DJ Exploration, Inc. | San Antonio, TX 78257 | Oil & Gas Operator | Oct 2025 |
| 345 | DJ Resources Inc | Bowie, TX 76230 | Oil & Gas Operator | Nov 2017 |
| 346 | DJD Drilling Corporation | Graham, TX 76450 | Oil Operator | Jan 2010 |
| 347 | DJH Investments, Inc. | Houston, TX 77024 | Oil Operator | Oct 2025 |
| 348 | DJH Oil & Gas LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 349 | DJM Beasley Well Service | Tuscola, TX 79562 | Oil Operator | Oct 2025 |
| 350 | DKM Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Sep 2011 |
| 351 | DKMR Oil Company, Inc. | Muenster, TX 76252 | Oil & Gas Operator | Apr 2017 |
| 352 | DKW Energy, Inc. | Sherman Oaks, CA 91403 | Oil & Gas Operator | Oct 2025 |
| 353 | DLB Oil & Gas, Inc. | Big Lake, TX 76932 | Oil & Gas Operator | Oct 2025 |
| 354 | DLM Energy | Houston, TX 77058 | Oil & Gas Operator | Sep 1994 |
| 355 | DM Backhoe Service | Graham, TX 76450 | Oil & Gas Operator | Oct 2025 |
| 356 | DML Exploration, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 357 | DMS Oil Company | Houston, TX 77042 | Oil & Gas Operator | Aug 2025 |
| 358 | DMV Pipeline LLC | Lipan, TX 76462 | Oil & Gas Operator | Oct 2025 |
| 359 | DNR Oil And Gas, Inc. | Englewood, CO 80155 | Oil & Gas Operator | Aug 2025 |
| 360 | Dobbs Petroleum Co. | Abilene, TX 79606 | Oil & Gas Operator | Oct 2025 |
| 361 | Doc Oil | Brownwood, TX 76801 | Oil & Gas Operator | Oct 2019 |
| 362 | Doc'S Tank Trucks | Jacksboro, TX 76458 | Oil Operator | Jun 2007 |
| 363 | Dodson Prairie Oil & Gas LLC | San Antonio, TX 78205 | Gas Operator | Oct 2025 |
| 364 | Dodson, Inc. | San Antonio, TX 78232 | Oil & Gas Operator | Oct 1998 |
| 365 | Dodson, Wayne Consultants, Inc. | Snyder, TX 79549 | Oil & Gas Operator | Jul 2003 |
| 366 | Doege, Donald | La Vernia, TX 78121 | Oil & Gas Operator | Oct 2025 |
| 367 | Doege, Harry | La Vernia, TX 78121 | Oil & Gas Operator | Aug 2003 |
| 368 | Doggy Oil Corp | Decatur, GA 30031 | Oil & Gas Operator | Oct 2025 |
| 369 | Dogwood Operating Company, Inc. | Houston, TX 77069 | Oil & Gas Operator | Oct 2025 |
| 370 | Dolberry Energy Resources Corp. | Dallas, TX 75252 | Oil Operator | Oct 2025 |
| 371 | Dolch Production, Inc. | San Antonio, TX 78248 | Oil & Gas Operator | Jul 1996 |
| 372 | Dolphin Petroleum | Alice, TX 78333 | Oil & Gas Operator | Jun 2008 |
| 373 | Dolphin Petroleum, LP | Alice, TX 78333 | Oil & Gas Operator | Oct 2025 |
| 374 | Domestic Crude | Graham, TX 76450 | Oil & Gas Operator | Jul 2000 |
| 375 | Dominion Corporation | Houston, TX 77001 | Oil & Gas Operator | Dec 2010 |
| 376 | Dominion Exploration & Production Inc | Houston, TX 77060 | Oil & Gas Operator | Apr 2015 |
| 377 | Dominion Minerals Corporation | Houston, TX 77014 | Oil & Gas Operator | Nov 2009 |
| 378 | Dominion Natural Resources LLC | Dallas, TX 75367 | Oil & Gas Operator | Oct 2025 |
| 379 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 380 | Dominion Operating, LLC | Midland, TX 79708 | Oil Operator | Mar 2018 |
| 381 | Dominion Production Company, LLC | Tampa, FL 33606 | Oil & Gas Operator | Oct 2025 |
| 382 | Domino Operations, Inc. | Abilene, TX 79603 | Oil & Gas Operator | Oct 2025 |
| 383 | Domino Prod Services Inc | Bellville, TX 77418 | Oil & Gas Operator | Feb 2004 |
| 384 | Dominus Energy, Inc | Austin, TX 78737 | Oil & Gas Operator | Dec 2020 |
| 385 | Dominy Oil Co., Inc. | Fort Worth, TX 76185 | Oil & Gas Operator | Oct 1999 |
| 386 | Don Bar Investment Company | Windthorst, TX 76389 | Oil & Gas Operator | Feb 2004 |
| 387 | Don Peterson Company, LLC - | Loving, TX 76460 | Oil Operator | Oct 2025 |
| 388 | Don-Dale, Inc. | Clarksville, TX 75426 | Oil & Gas Operator | Aug 2003 |
| 389 | Donalu Oil | Pampa, TX 79066 | Oil & Gas Operator | Oct 2025 |
| 390 | Donna-Lynne Oil Co. | George West, TX 78022 | Oil & Gas Operator | Jun 2018 |
| 391 | Donnell Pipe & Supply Co/TX Corp | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2008 |
| 392 | Donnell, Bill | Graham, TX 76450 | Oil & Gas Operator | May 1995 |
| 393 | Donnell, Louis, Jr. | South Bend, TX 76481 | Oil & Gas Operator | Mar 2008 |
| 394 | Donoco Oil Company | La Vernia, TX 78121 | Oil & Gas Operator | Oct 2025 |
| 395 | Doolaree Corporation | Sherman, TX 75091 | Oil & Gas Operator | Oct 2025 |
| 396 | Dooley, Jeff | Breckenridge, TX 76424 | Oil & Gas Operator | Jul 2012 |
| 397 | Dora Inc | Levelland, TX 79336 | Oil & Gas Operator | Jul 2019 |
| 398 | Dorado Drilling, Inc. | Gulfport, MS 39501 | Oil & Gas Operator | Oct 2025 |
| 399 | Dorado Oil Company | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2013 |
| 400 | Dorado Operating Inc. | Dallas, TX 75225 | Oil & Gas Operator | Apr 2011 |