| 201 | Clarence R. Barnett Inc. | | Oil & Gas Operator | Apr 2025 |
| 202 | Clean Energy Systems Placerita Inc. | | Oil & Gas Operator | Apr 2025 |
| 203 | Clearfield Energy Resources & Management Inc. | | Oil & Gas Operator | Dec 1998 |
| 204 | Clint H. Woodington | | Oil Operator | Dec 1994 |
| 205 | Clofas Case Oil Co. | | Oil & Gas Operator | Apr 2025 |
| 206 | Cmo Inc. | | Oil Operator | May 2025 |
| 207 | Coal Oil Inc. | | Oil & Gas Operator | Dec 1997 |
| 208 | Coast Supply Company LTD. | | Oil & Gas Operator | Dec 1991 |
| 209 | Coastal Oil & Gas Corporation | Houston, TX 77252 | Oil & Gas Operator | Dec 2009 |
| 210 | Cockriel Petroleum | | Oil & Gas Operator | Dec 1993 |
| 211 | Coelho & Case Oil Company | | Oil & Gas Operator | Dec 1997 |
| 212 | Coffee Petroleum | | Oil & Gas Operator | Apr 2025 |
| 213 | Columbine Associates | | Oil & Gas Operator | May 2025 |
| 214 | Commander Oil Company LTD. | | Oil & Gas Operator | Dec 2021 |
| 215 | Compass Global Resources LLC | | Oil & Gas Operator | Dec 2015 |
| 216 | Concho Petroleum | | Oil & Gas Operator | Dec 1994 |
| 217 | Concordia Resources Inc. | | Oil & Gas Operator | May 2025 |
| 218 | Condor Oil Company Inc. | | Oil & Gas Operator | Dec 2000 |
| 219 | Conoco Inc. | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 220 | Cooper & Brain Inc. | | Oil & Gas Operator | Apr 2025 |
| 221 | Core Energy LLC | | Oil & Gas Operator | May 2025 |
| 222 | Corona Development Co. Inc. | | Oil Operator | Dec 1989 |
| 223 | Costa Loma LTD. | | Oil & Gas Operator | Apr 2025 |
| 224 | Courtland City Lights Assoc. | | Oil Operator | Dec 2005 |
| 225 | Coyote Oil Company. LTD. | | Oil & Gas Operator | Dec 1997 |
| 226 | Coyote Oil LLC | | Oil Operator | Jan 2018 |
| 227 | Crain Orchards Inc. | | Gas Operator | May 2025 |
| 228 | Crazy J Oil LLC | | Oil & Gas Operator | May 2025 |
| 229 | Cree Oil LLC | | Oil & Gas Operator | May 2025 |
| 230 | Crest Oil & Gas Management Corp. | | Oil & Gas Operator | Apr 2025 |
| 231 | CRG Properties LTD. | | Oil & Gas Operator | Dec 2013 |
| 232 | Crimson Resource Management Corp. | | Oil & Gas Operator | May 2025 |
| 233 | Crupper Operating & Trading Company | | Oil & Gas Operator | Dec 1996 |
| 234 | D D Natural Resources LLC | | Oil & Gas Operator | May 2025 |
| 235 | D. A. Stark | | Oil Operator | Dec 1990 |
| 236 | D. E. Craggs Inc. | | Gas Operator | Dec 1993 |
| 237 | D. J. Hatfield | | Oil & Gas Operator | Dec 1994 |
| 238 | D. J. Pickrell Operator | | Gas Operator | Dec 2012 |
| 239 | D. W. Elliott Operating Acct | | Oil & Gas Operator | Dec 1991 |
| 240 | Dalen Resources Oil & Gas Co. | Dallas, TX 75206 | Oil & Gas Operator | Jun 2010 |
| 241 | Damson Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Mar 2005 |
| 242 | Daniel B. Robinett | | Oil & Gas Operator | Dec 1990 |
| 243 | David Radcliff | | Oil & Gas Operator | Dec 2014 |
| 244 | Davis Davis & Davis | | Oil & Gas Operator | Dec 1988 |
| 245 | Davis Investment LLC | | Oil & Gas Operator | Dec 1998 |
| 246 | Daybreak Oil And Gas, Inc. | | Oil & Gas Operator | May 2025 |
| 247 | DBF Partners | | Oil Operator | Dec 1986 |
| 248 | Dcor, L.L.C. | Dallas, TX 75225 | Oil & Gas Operator | May 2025 |
| 249 | Decalta International Corp | Denver, CO 80202 | Oil & Gas Operator | Mar 2015 |
| 250 | Dekalb Energy Company | Oklahoma City, OK 73134 | Oil & Gas Operator | Oct 1996 |
| 251 | Del Amo Energy Co. | | Oil & Gas Operator | Dec 1987 |
| 252 | Delta Sierra Oil & Gas LLC | | Gas Operator | Jan 2018 |
| 253 | Denali Oil & Gas Management, LLC | Houston, TX 77060 | Oil & Gas Operator | Dec 2012 |
| 254 | Department Of Conservation | | Oil Operator | Dec 2005 |
| 255 | Depco Inc. | Denver, CO 80202 | Oil & Gas Operator | Apr 2014 |
| 256 | Deuel Pet. Co. Inc. | | Oil & Gas Operator | Dec 2005 |
| 257 | Deuel Petroleum Calif. Inc. | | Oil & Gas Operator | Dec 2001 |
| 258 | Deuel Petroleum Company Inc. | | Oil & Gas Operator | Dec 1999 |
| 259 | Diversified Resources LLC | | Gas Operator | Apr 2025 |
| 260 | DKM Offshore Energy Inc. | | Oil & Gas Operator | Dec 1993 |
| 261 | DLM Ventures | | Oil & Gas Operator | Dec 2004 |
| 262 | DLM Ventures LLC | | Oil & Gas Operator | Dec 2004 |
| 263 | Doc Oil Corp. | | Oil Operator | Dec 2006 |
| 264 | Dole Enterprises Inc. | | Oil & Gas Operator | May 2025 |
| 265 | Dominguez Energy L.P. | | Oil & Gas Operator | Dec 2000 |
| 266 | Dominguez Properties | | Oil & Gas Operator | Dec 1991 |
| 267 | Donald C Slawson Expl Co. Inc | | Oil & Gas Operator | Dec 2020 |
| 268 | Donald Len Barreth | | Oil & Gas Operator | Dec 1991 |
| 269 | Dos Lobos Oil Co. | | Oil Operator | Dec 1999 |
| 270 | Dos Rios Inc. | | Gas Operator | Jun 2025 |
| 271 | Double Barrel Oil Co. | | Oil Operator | Dec 1978 |
| 272 | Douglas W. Baker Trustee | | Oil & Gas Operator | Dec 1993 |
| 273 | Douglas Whitney | | Oil Operator | Dec 2004 |
| 274 | Drilling & Production Co. | | Oil & Gas Operator | May 2025 |
| 275 | Drilling Exploration & Operating Co. Inc. | | Oil & Gas Operator | Apr 2025 |
| 276 | Driltrol | | Oil & Gas Operator | Dec 1984 |
| 277 | Dwayne'S Engineering | | Oil Operator | Apr 2025 |
| 278 | Dynamic Production, Inc. | Fort Worth, TX 76106 | Oil & Gas Operator | Jul 2025 |
| 279 | E & B Natural Resources Management Corporation | Hays, KS 67601 | Oil & Gas Operator | May 2025 |
| 280 | E & S Production Corp. | | Oil & Gas Operator | Dec 1988 |
| 281 | E & T Limited Liability Co. | | Oil & Gas Operator | Apr 2025 |
| 282 | E-Z Serve Of Ca Inc. | | Oil Operator | Dec 1989 |
| 283 | E. C. Green | | Gas Operator | Dec 1989 |
| 284 | Earth Basics Contracting Corp. | | Oil & Gas Operator | Dec 2001 |
| 285 | Eastern Pacific Oil Co. | | Oil & Gas Operator | Dec 1998 |
| 286 | Ecology Auto Wrecking | | Oil Operator | Dec 2005 |
| 287 | Edison Beneficial Reuse | | Oil & Gas Operator | Apr 2025 |
| 288 | Ehb Oil Company | | Oil Operator | Dec 2001 |
| 289 | El Dorado Exploration Co. | | Oil Operator | Dec 1999 |
| 290 | El Segundo Oil LLC | | Oil Operator | Apr 2025 |
| 291 | Elf Aquitaine Inc | Houston, TX 77002 | Oil & Gas Operator | May 1991 |
| 292 | Elk Slough Pipeline Co. | | Oil & Gas Operator | Dec 1999 |
| 293 | Elliott Underground LLC | | Oil Operator | Jun 2025 |
| 294 | Emil & Ruby Plegel | | Oil Operator | Dec 1989 |
| 295 | Emil W. Plegel | | Oil & Gas Operator | Apr 2025 |
| 296 | Emjayco L. P. | | Oil Operator | Dec 2020 |
| 297 | Enerfin Resources Northwest Limited Partnership | | Oil & Gas Operator | Jan 2022 |
| 298 | Energy Development Of California Inc. | | Oil & Gas Operator | Dec 2004 |
| 299 | Energy Production & Sales Co. | | Oil & Gas Operator | Dec 1999 |
| 300 | Engineers Oil Company | | Oil & Gas Operator | May 2025 |