| 201 | City Of Santa Fe Springs | | Oil Operator | Dec 2007 |
| 202 | City Oil Corp. Oper. For | | Oil & Gas Operator | Dec 1989 |
| 203 | Claremont Energy | | Gas Operator | Dec 1993 |
| 204 | Clarence R. Barnett Inc. | | Oil & Gas Operator | Jul 2025 |
| 205 | Clean Energy Systems Placerita Inc. | | Oil & Gas Operator | Nov 2025 |
| 206 | Clearfield Energy Resources & Management Inc. | | Oil & Gas Operator | Dec 1998 |
| 207 | Clint H. Woodington | | Oil Operator | Dec 1994 |
| 208 | Clofas Case Oil Co. | | Oil & Gas Operator | Nov 2025 |
| 209 | Clyde B. Baker Opr. | | Gas Operator | Dec 1995 |
| 210 | Cmo Inc. | | Oil Operator | Dec 2025 |
| 211 | Coal Oil Inc. | | Oil & Gas Operator | Dec 1997 |
| 212 | Coast Supply Company LTD. | | Oil & Gas Operator | Dec 1991 |
| 213 | Coastal Oil & Gas Corp | Houston, TX 77252 | Oil & Gas Operator | Dec 2009 |
| 214 | Cockriel Petroleum | | Oil & Gas Operator | Dec 1993 |
| 215 | Coelho & Case Oil Company | | Oil & Gas Operator | Dec 1997 |
| 216 | Coffee Petroleum | | Oil & Gas Operator | Nov 2025 |
| 217 | Columbine Associates | | Oil & Gas Operator | Dec 2025 |
| 218 | Commander Oil Company LTD. | | Oil & Gas Operator | Dec 2021 |
| 219 | Compass Global Resources LLC | | Oil & Gas Operator | Dec 2015 |
| 220 | Concho Petroleum | | Oil & Gas Operator | Dec 1994 |
| 221 | Concordia Resources Inc. | | Oil & Gas Operator | Dec 2025 |
| 222 | Condor Oil Company Inc. | | Oil & Gas Operator | Dec 2000 |
| 223 | Conoco Inc | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 224 | Cooper & Brain Inc. | | Oil & Gas Operator | Dec 2025 |
| 225 | Core Energy LLC | | Oil & Gas Operator | Dec 2025 |
| 226 | Corona Development Co. Inc. | | Oil Operator | Dec 1989 |
| 227 | Costa Loma LTD. | | Oil & Gas Operator | Nov 2025 |
| 228 | Courtland City Lights Assoc. | | Oil Operator | Dec 2005 |
| 229 | Coyote Oil Company. LTD. | | Oil & Gas Operator | Dec 1997 |
| 230 | Coyote Oil LLC | | Oil Operator | Jan 2018 |
| 231 | Crain Orchards Inc. | | Gas Operator | Nov 2025 |
| 232 | Crazy J Oil LLC | | Oil & Gas Operator | Dec 2025 |
| 233 | Cree Oil LLC | | Oil & Gas Operator | Dec 2025 |
| 234 | Crest Oil & Gas Management Corp. | | Oil & Gas Operator | Nov 2025 |
| 235 | CRG Properties LTD. | | Oil & Gas Operator | Dec 2013 |
| 236 | Crimson Resource Management Corp. | | Oil & Gas Operator | Dec 2025 |
| 237 | Crupper Operating & Trading Company | | Oil & Gas Operator | Dec 1996 |
| 238 | D D Natural Resources LLC | | Oil & Gas Operator | Dec 2025 |
| 239 | D. A. Stark | | Oil Operator | Dec 1990 |
| 240 | D. E. Craggs Inc. | | Gas Operator | Dec 1993 |
| 241 | D. J. Hatfield | | Oil & Gas Operator | Dec 1994 |
| 242 | D. J. Pickrell Operator | | Gas Operator | Dec 2012 |
| 243 | D. W. Elliott Operating Acct | | Oil & Gas Operator | Dec 1991 |
| 244 | Dalen Resources Oil & Gas Co | Dallas, TX 75206 | Oil & Gas Operator | Jun 2010 |
| 245 | Damson Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Mar 2005 |
| 246 | Daniel B. Robinett | | Oil & Gas Operator | Dec 1990 |
| 247 | David Radcliff | | Oil & Gas Operator | Dec 2014 |
| 248 | Davis Davis & Davis | | Oil & Gas Operator | Dec 1988 |
| 249 | Davis Investment LLC | | Oil & Gas Operator | Dec 1998 |
| 250 | Daybreak Oil And Gas, Inc. | | Oil & Gas Operator | Dec 2025 |
| 251 | DBF Partners | | Oil Operator | Dec 1986 |
| 252 | Dcor, L.L.C. | | Oil & Gas Operator | Dec 2025 |
| 253 | Decalta International Corp | Denver, CO 80202 | Oil & Gas Operator | Mar 2015 |
| 254 | Dekalb Energy Company | Oklahoma City, OK 73134 | Oil & Gas Operator | Oct 1996 |
| 255 | Del Amo Energy Co. | | Oil & Gas Operator | Dec 1987 |
| 256 | Delta Sierra Oil & Gas LLC | | Gas Operator | Jan 2018 |
| 257 | Denali Oil & Gas Management LLC | Houston, TX 77060 | Oil & Gas Operator | Dec 2012 |
| 258 | Department Of Conservation | | Oil Operator | Dec 2005 |
| 259 | Depco Inc. | Denver, CO 80202 | Oil & Gas Operator | Apr 2014 |
| 260 | Deuel Pet. Co. Inc. | | Oil & Gas Operator | Dec 2005 |
| 261 | Deuel Petroleum Calif. Inc. | | Oil & Gas Operator | Dec 2001 |
| 262 | Deuel Petroleum Company Inc. | | Oil & Gas Operator | Dec 1999 |
| 263 | Diversified Resources LLC | | Gas Operator | Nov 2025 |
| 264 | DKM Offshore Energy Inc. | | Oil & Gas Operator | Dec 1993 |
| 265 | DLM Ventures | | Oil & Gas Operator | Dec 2004 |
| 266 | DLM Ventures LLC | | Oil & Gas Operator | Dec 2004 |
| 267 | Doc Oil Corp. | | Oil Operator | Dec 2006 |
| 268 | Dole Enterprises Inc. | | Oil & Gas Operator | Dec 2025 |
| 269 | Dominguez Energy L.P. | | Oil & Gas Operator | Dec 2000 |
| 270 | Dominguez Properties | | Oil & Gas Operator | Dec 1991 |
| 271 | Donald C Slawson Expl Co. Inc | | Oil & Gas Operator | Dec 2020 |
| 272 | Donald Len Barreth | | Oil & Gas Operator | Dec 1991 |
| 273 | Dos Lobos Oil Co. | | Oil Operator | Dec 1999 |
| 274 | Dos Rios Inc. | | Gas Operator | Dec 2025 |
| 275 | Double Barrel Oil Co. | | Oil Operator | Dec 1978 |
| 276 | Douglas W. Baker Trustee | | Oil & Gas Operator | Dec 1993 |
| 277 | Douglas Whitney | | Oil Operator | Dec 2004 |
| 278 | Dow Chemical Co. | | Oil & Gas Operator | Dec 1997 |
| 279 | Drilling & Production Co. | | Oil & Gas Operator | Dec 2025 |
| 280 | Drilling Exploration & Operating Co. Inc. | | Oil & Gas Operator | Dec 2025 |
| 281 | Driltrol | | Oil & Gas Operator | Dec 1984 |
| 282 | Dwayne'S Engineering | | Oil Operator | Nov 2025 |
| 283 | Dynamic Production, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 2026 |
| 284 | E & B Natural Resources Management Corporation | Hays, KS 67601 | Oil & Gas Operator | Dec 2025 |
| 285 | E & S Production Corp. | | Oil & Gas Operator | Dec 1988 |
| 286 | E & T Limited Liability Co. | | Oil & Gas Operator | Nov 2025 |
| 287 | E-Z Serve Of Ca Inc. | | Oil Operator | Dec 1989 |
| 288 | E. C. Green | | Gas Operator | Dec 1989 |
| 289 | Earth Basics Contracting Corp. | | Oil & Gas Operator | Dec 2001 |
| 290 | Eastern Pacific Oil Co. | | Oil & Gas Operator | Dec 1998 |
| 291 | Ecology Auto Wrecking | | Oil Operator | Dec 2005 |
| 292 | Edison Beneficial Reuse | | Oil & Gas Operator | Nov 2025 |
| 293 | Ehb Oil Company | | Oil Operator | Dec 2001 |
| 294 | El Dorado Exploration Co. | | Oil Operator | Dec 1999 |
| 295 | El Segundo Oil LLC | | Oil Operator | Nov 2025 |
| 296 | Elf Aquitaine Inc | Houston, TX 77002 | Oil & Gas Operator | May 1991 |
| 297 | Elk Slough Pipeline Co. | | Oil & Gas Operator | Dec 1999 |
| 298 | Elliott Underground LLC | | Oil Operator | Dec 2025 |
| 299 | Emil & Ruby Plegel | | Oil Operator | Dec 1989 |
| 300 | Emil W. Plegel | | Oil & Gas Operator | Nov 2025 |