| 201 | Decker Operating Co., L.L.C. | Houston, TX 77008 | Oil & Gas Operator | Oct 2025 |
| 202 | Decleva, Paul | Wichita Falls, TX 76302 | Oil & Gas Operator | Dec 2020 |
| 203 | Deco | Kilgore, TX 75662 | Oil & Gas Operator | Jan 1999 |
| 204 | Dedica Energy Corporation | Mattoon, IL 61938 | Oil & Gas Operator | Mar 2008 |
| 205 | Dee'S Oil | Wellington, TX 79095 | Oil & Gas Operator | Mar 2008 |
| 206 | Dee-Jay Exploration Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Oct 2025 |
| 207 | Deen Drilling Company | Archer City, TX 76351 | Oil & Gas Operator | Oct 2025 |
| 208 | Deep Gully Oil LLC | Houston, TX 77292 | Oil Operator | Oct 2025 |
| 209 | Deep Reef Industries | Amarillo, TX 79101 | Oil & Gas Operator | Jan 2004 |
| 210 | Deep Rock Resources, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Oct 2025 |
| 211 | Defranco Oil Account | Wichita Falls, TX 76307 | Oil & Gas Operator | Feb 2004 |
| 212 | Deg Energy, Inc. | Magnolia, TX 77354 | Oil & Gas Operator | Feb 2007 |
| 213 | Deguello Operating LLC | Kilgore, TX 75663 | Oil & Gas Operator | Oct 2025 |
| 214 | Dekalb Energy Company | Oklahoma City, OK 73134 | Oil & Gas Operator | Oct 1996 |
| 215 | Del Mar | Holliday, TX 76366 | Oil & Gas Operator | Oct 2025 |
| 216 | Del Mar Energy, Inc. | Van Alstyne, TX 75495 | Oil & Gas Operator | Oct 2025 |
| 217 | Del Mar Exploration Company | Houston, TX 77006 | Oil & Gas Operator | Jan 2014 |
| 218 | Del Petroleum Corporation | Dallas, TX 75219 | Oil & Gas Operator | Jan 2012 |
| 219 | Del Rio Production Co. | Gainesville, TX 76240 | Oil Operator | Mar 2019 |
| 220 | Delaware Davis Petroleum Corp. | Houston, TX 77056 | Oil & Gas Operator | Jan 2000 |
| 221 | Delaware Ecco Petroleum Inc. | Rockwall, TX 75087 | Oil & Gas Operator | Jul 2001 |
| 222 | Delcar, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 1995 |
| 223 | Delco Operating Company LP | Houston, TX 77056 | Oil & Gas Operator | May 2020 |
| 224 | Delek Energy Systems Us Inc | Denver, CO 80202 | Oil & Gas Operator | Oct 2011 |
| 225 | Delfin Operating, LLC | Dallas, TX 75243 | Oil & Gas Operator | Oct 2025 |
| 226 | Delgado, Emil A | San Antonio, TX 78223 | Oil & Gas Operator | Sep 2016 |
| 227 | Delhi Gas Pipeline Corporation | Palestine, TX 75802 | Oil & Gas Operator | Feb 1998 |
| 228 | Delmar Operating, Inc. | Houston, TX 77010 | Oil & Gas Operator | Oct 1996 |
| 229 | Delong, Horace | Pleasanton, TX 78064 | Oil & Gas Operator | Oct 2025 |
| 230 | Delray Oil, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 231 | Delta C02, LLC | Breckenridge, TX 76424 | Oil & Gas Operator | Jul 2021 |
| 232 | Delta Exploration Company Inc | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 233 | Delta Exploration, LLC | Fredericksbrg, TX 78624 | Oil Operator | Oct 2025 |
| 234 | Delta Oil | Holliday, TX 76366 | Oil & Gas Operator | Sep 2005 |
| 235 | Delta Oil & Gas Company | Breckenridge, TX 76424 | Oil & Gas Operator | Apr 2003 |
| 236 | Delta Oil & Gas LTD. | Breckenridge, TX 76424 | Oil & Gas Operator | Oct 2025 |
| 237 | Delta Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Dec 2024 |
| 238 | Deltex Minerals Inc. | Peachtree Cty, GA 30269 | Oil & Gas Operator | Oct 2025 |
| 239 | Delwintex Oil & Gas Prop., Inc. | Lubbock, TX 79423 | Oil & Gas Operator | Aug 2003 |
| 240 | Demand Energy, Inc. | Abilene, TX 79601 | Oil & Gas Operator | Jul 1999 |
| 241 | Demers - Fleming | Wichita Falls, TX 76305 | Oil & Gas Operator | Mar 2008 |
| 242 | Demers Oil Production | Byers, TX 76357 | Oil & Gas Operator | Apr 2002 |
| 243 | Demoss, L. V. | Graham, TX 76450 | Oil & Gas Operator | May 2004 |
| 244 | Den Cal, Inc. | Borger, TX 79007 | Oil & Gas Operator | Oct 2025 |
| 245 | Den-Kay Corp. | Plano, TX 75074 | Oil Operator | Aug 2009 |
| 246 | Denali Exploration, Inc. | Amarillo, TX 79109 | Oil & Gas Operator | Nov 2018 |
| 247 | Denali Oil & Gas Management, LLC | Houston, TX 77060 | Oil & Gas Operator | Dec 2012 |
| 248 | Denali Petroleum, LLC | Arlington, TX 76006 | Oil Operator | Mar 2021 |
| 249 | Denbury Management, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Dec 1999 |
| 250 | Denbury Onshore, LLC | Plano, TX 75024 | Oil & Gas Operator | Oct 2025 |
| 251 | Denbury Resources Inc. | Plano, TX 75024 | Oil & Gas Operator | Dec 2003 |
| 252 | Denhart & Denhart | Brownwood, TX 76804 | Oil & Gas Operator | Dec 2001 |
| 253 | Denman-Friesen Co. | Lufkin, TX 75901 | Oil & Gas Operator | Nov 2006 |
| 254 | Dennis & Broun | Bullard, TX 75757 | Oil & Gas Operator | Sep 2003 |
| 255 | Dennis & Davis Oil Co. | Nocona, TX 76255 | Oil & Gas Operator | Oct 2025 |
| 256 | Dennis, Don | Grady, OK 73545 | Oil & Gas Operator | Mar 1998 |
| 257 | Denny'S Inc. | Horseshoe Bay, TX 78657 | Oil & Gas Operator | Dec 2000 |
| 258 | Denoco Inc. | Plano, TX 75086 | Oil & Gas Operator | Mar 2008 |
| 259 | Denovo Oil & Gas, Inc. | Houston, TX 77210 | Oil & Gas Operator | May 1995 |
| 260 | Denpac Corporation | Colorado SPGS, CO 80922 | Oil & Gas Operator | Oct 2025 |
| 261 | Denteco Oil Company LLC | Abilene, TX 79604 | Oil & Gas Operator | Oct 2025 |
| 262 | Denton Exploration, Inc. | Dallas, TX 75219 | Oil & Gas Operator | Oct 2025 |
| 263 | Denton Oil & Gas | Argyle, TX 76226 | Oil Operator | Dec 2014 |
| 264 | Denver Energy Exploration,LLC | Canyon Lake, TX 78133 | Oil Operator | Oct 2025 |
| 265 | Derby Oil Of Texas | Ventura, CA 93003 | Oil & Gas Operator | May 1996 |
| 266 | Derrick Exploration, Inc. | Amarillo, TX 79105 | Oil & Gas Operator | Jan 2003 |
| 267 | Derrick Oil & Gas, Inc. | Rosharon, TX 77583 | Oil & Gas Operator | Aug 2003 |
| 268 | Derwen Operating Company | Houston, TX 77098 | Gas Operator | Dec 2009 |
| 269 | Desana Development Corporation | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 270 | Desco Oil Company | Houston, TX 77056 | Oil & Gas Operator | Feb 2017 |
| 271 | Desert Production, Inc. | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 272 | Desert States Energy, Inc. | Hobbs, NM 88240 | Oil & Gas Operator | Aug 1995 |
| 273 | Devilbiss Contracting, Inc. | Carrizo SPGS, TX 78834 | Oil & Gas Operator | Oct 2005 |
| 274 | Devine, C. R., Inc. | Houston, TX 77292 | Oil & Gas Operator | Feb 2018 |
| 275 | Devon Energy Corp (Nevada) | Oklahoma City, OK 73102 | Oil & Gas Operator | Feb 2017 |
| 276 | Devon Energy Operating Co., L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Jun 2009 |
| 277 | Devon Energy Operating Corp | Oklahoma City, OK 73102 | Oil & Gas Operator | Apr 2013 |
| 278 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 279 | Devon Gas Services, L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Nov 2015 |
| 280 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 281 | Devon SFS Operating Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2008 |
| 282 | Devx Operating Company | Frisco, TX 75034 | Oil & Gas Operator | Feb 2004 |
| 283 | Dewbre Petroleum Corporation | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Oct 2025 |
| 284 | Dewbre, Jerry C., Trustee | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Oct 2025 |
| 285 | Dewco Exploration | Coleman, TX 76834 | Oil & Gas Operator | Nov 2007 |
| 286 | DFG Energy Company LLC | Eastland, TX 76448 | Oil & Gas Operator | Oct 2025 |
| 287 | DG&E/Slocum, Limited Partnership | Dallas, TX 75206 | Oil & Gas Operator | Oct 2025 |
| 288 | DH Operating, Inc. | Gordon, TX 76453 | Oil & Gas Operator | Oct 2025 |
| 289 | DH Production | Albany, TX 76430 | Oil Operator | Dec 2005 |
| 290 | DHC, Inc. | Midland, TX 79710 | Oil & Gas Operator | Dec 1997 |
| 291 | Di Energy Inc. | Houston, TX 77067 | Oil & Gas Operator | Jan 2004 |
| 292 | Diamond "S" Oil, Inc. | Houston, TX 77065 | Oil & Gas Operator | Apr 1994 |
| 293 | Diamond A Inc. | Tulsa, OK 74137 | Oil & Gas Operator | Jun 2001 |
| 294 | Diamond Energy Operating Company | Tulsa, OK 74137 | Oil & Gas Operator | Mar 2005 |
| 295 | Diamond Energy Services, LP | Tulsa, OK 74103 | Oil Operator | Oct 2025 |
| 296 | Diamond Energy, Inc. | Sherman, TX 75091 | Oil & Gas Operator | Oct 2025 |
| 297 | Diamond G Production | FT Stockton, TX 79735 | Oil & Gas Operator | Oct 2025 |
| 298 | Diamond M DRLG & Expl Co. | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 299 | Diamond M Oil Co., Inc. | Monahans, TX 79756 | Oil & Gas Operator | Oct 2025 |
| 300 | Diamond Mineral Investments Inc. | Bangs, TX 76823 | Gas Operator | Feb 2008 |