| 301 | California Oil Co | | Oil & Gas Operator | Aug 1965 |
| 302 | California Oil Independents | | Oil & Gas Operator | Dec 2025 |
| 303 | California Petroleum Group Inc. | | Oil Operator | Jul 2026 |
| 304 | California Resources Elk Hills LLC | | Oil & Gas Operator | Jul 2026 |
| 305 | California Resources Long Beach Inc. | | Oil & Gas Operator | Jul 2026 |
| 306 | California Resources Production Corporation | | Oil & Gas Operator | Jul 2026 |
| 307 | California Southern Oil Co. | | Oil Operator | Dec 2000 |
| 308 | California Time Petroleum, Inc | | Oil Operator | Mar 1986 |
| 309 | California/Nevada Developments LLC | | Oil Operator | Dec 2001 |
| 310 | Calistoga Energy Reserves, LLC | Houston, TX 77063 | Oil & Gas Operator | Sep 2026 |
| 311 | Calk Oil Company | Lytle, TX 78052 | Oil Operator | Sep 2026 |
| 312 | Calk Operating, LLC | Lytle, TX 78052 | Oil Operator | Sep 2026 |
| 313 | Calk, Roger D. | Lytle, TX 78052 | Oil & Gas Operator | Sep 2026 |
| 314 | Call Farms, Inc. | Batavia, NY 14020 | Gas Operator | Dec 2025 |
| 315 | Call Harold Charles | Dewey, OK 74029 | Oil Operator | May 2026 |
| 316 | Call, Harold L | | Oil Operator | Mar 2015 |
| 317 | Callahan, Stephen Et Al | Navarre, FL 32566 | Oil & Gas Operator | Dec 2022 |
| 318 | Callander & Kimbrel Inc | Cerluean, KY 42215 | Oil & Gas Operator | Dec 1989 |
| 319 | Callarman, David | Cisco, TX 76437 | Oil & Gas Operator | Sep 2026 |
| 320 | Callaway Oil & Gas LLC | Gillette, WY 82717 | Oil & Gas Operator | Jun 2026 |
| 321 | Callaway Production Co., Inc. | Midland, TX 79701 | Oil & Gas Operator | Jan 1996 |
| 322 | Calley, Bob | Midland, TX 79702 | Oil & Gas Operator | Aug 2003 |
| 323 | Callie Oil Company LLC | Perry, OK 73077 | Oil & Gas Operator | Jun 2026 |
| 324 | Callon (Eagle Ford) LLC | Houston, TX 77042 | Oil & Gas Operator | Jun 2023 |
| 325 | Callon (Permian) LLC | Houston, TX 77042 | Oil & Gas Operator | Jul 2024 |
| 326 | Callon Offshore Production, Inc. | Natchez, MS 39121 | Oil & Gas Operator | Dec 2005 |
| 327 | Callon Oil Co, Cambell | | Oil & Gas Operator | Oct 1984 |
| 328 | Callon Permian II, LLC | Houston, TX 77056 | Oil & Gas Operator | Jul 2024 |
| 329 | Callon Petroleum Company | Natchez, MS 39120 | Oil & Gas Operator | Jan 2000 |
| 330 | Callon Petroleum Operating Co | Houston, TX 77042 | Oil & Gas Operator | Jul 2024 |
| 331 | Calnrg Operating LLC | | Oil & Gas Operator | Jul 2026 |
| 332 | Calpetco-Herbst Expl. Inc. | | Gas Operator | Jan 1990 |
| 333 | Calpine Natural Gas Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2002 |
| 334 | Calpine Natural Gas Company L.P. | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 335 | Calpine Natural Gas L.P. | Houston, TX 77002 | Oil & Gas Operator | Dec 2005 |
| 336 | Calresources LLC | | Oil & Gas Operator | Dec 1996 |
| 337 | Caltex Energy Co. | Luling, TX 78648 | Oil & Gas Operator | Sep 2026 |
| 338 | Caltico Oil Corp. | | Oil Operator | Dec 2025 |
| 339 | Calto Operating Company, Inc. | Dallas, TX 75225 | Oil & Gas Operator | May 2004 |
| 340 | Calumet Lubricants Company | | Oil Operator | Dec 1993 |
| 341 | Calumet Oil Company | Oklahoma City, OK 73114 | Oil & Gas Operator | Feb 2019 |
| 342 | Calumet Refining Co. | | Oil Operator | May 1991 |
| 343 | Calvert Drilling Co. | Oklahoma City, OK 73154 | Oil & Gas Operator | Jan 1992 |
| 344 | Calvert Exploration Co | | Oil & Gas Operator | Apr 1993 |
| 345 | Calvert Operating LLC | Oklahoma City, OK 73118 | Oil Operator | Apr 2026 |
| 346 | Calvin Explorati | | Oil & Gas Operator | Oct 1991 |
| 347 | Calvin F Tennison | Granbury, TX 76049 | Oil & Gas Operator | Apr 2007 |
| 348 | Calvin Noah, LLC | Valley Center, KS 67147 | Oil Operator | Apr 2026 |
| 349 | Calyx Energy III LLC | Tulsa, OK 74136-4226 | Oil & Gas Operator | May 2026 |
| 350 | Calyx Energy LLC | Tulsa, OK 74146-3807 | Oil & Gas Operator | Feb 2020 |
| 351 | Calyx Exploration & Production | | Oil & Gas Operator | Jul 1991 |
| 352 | Cam Company | Breckenridge, TX 76424 | Oil & Gas Operator | Sep 2004 |
| 353 | Cam Development | | Oil & Gas Operator | Dec 1990 |
| 354 | Camar Exploration | | Oil Operator | Jan 1989 |
| 355 | Cambern, Rex | Montgomery, TX 77356 | Oil Operator | Jan 1996 |
| 356 | Cambria Corporation | Great Bend, KS 67530 | Oil & Gas Operator | Dec 2019 |
| 357 | Cambria Oil Company | Casper, WY 82601 | Oil & Gas Operator | Dec 1996 |
| 358 | Cambrian Hunter Inc | Jefferson, OH 44047 | Oil & Gas Operator | Dec 2025 |
| 359 | Cambrian Management LTD | McCaulley, TX 79534 | Oil & Gas Operator | Sep 2026 |
| 360 | Cambrian Oil Inc | Odessa, TX 79760 | Oil & Gas Operator | Aug 1996 |
| 361 | Cambridge Energy Corporation | | Oil & Gas Operator | Jul 2003 |
| 362 | Cambridge Production, Inc. | Amarillo, TX 79120 | Oil & Gas Operator | Nov 2020 |
| 363 | Cambron, Paul L. | Ness City, KS 67560 | Oil & Gas Operator | Dec 2019 |
| 364 | Camco Resources, Inc. | | Oil Operator | Aug 1991 |
| 365 | Camco Saltwater Transport | George West, TX 78022 | Oil Operator | Feb 2015 |
| 366 | Camco Saltwater Transport,L.L.C. | George West, TX 78022 | Oil Operator | Oct 2025 |
| 367 | Camco, Inc | Columbia, KY 42728 | Oil Operator | Dec 2023 |
| 368 | Camden Oil & Gas, Inc. | Farmers BRNCH, TX 75234 | Oil & Gas Operator | Dec 2005 |
| 369 | Camden Reserves, Inc. | Houston, TX 77019 | Oil & Gas Operator | Mar 2011 |
| 370 | Camden Resources, Inc. | Farmers BRNCH, TX 75234 | Oil & Gas Operator | Apr 2008 |
| 371 | Camden Resources, LLC | Blanchard, OK 73010 | Oil & Gas Operator | Dec 2015 |
| 372 | Camelot Oil And Gas, LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2003 |
| 373 | Cameron & Kincaid | Zanesville, OH 43701 | Oil & Gas Operator | Dec 1986 |
| 374 | Cameron Brothers | Zanesville, OH 43701 | Oil & Gas Operator | Dec 1995 |
| 375 | Cameron Development Co., Inc. | | Oil & Gas Operator | Mar 1988 |
| 376 | Cameron Energy Co | Sheffield, PA 16347-2642 | Oil & Gas Operator | Dec 2025 |
| 377 | Cameron Engineering, Inc | Montgomery, TX 77356 | Oil & Gas Operator | Jun 2003 |
| 378 | Cameron Exploration, Inc. | Longview, TX 75604 | Oil & Gas Operator | Sep 2026 |
| 379 | Cameron LNG, LLC | | Oil Operator | Jan 2025 |
| 380 | Cameron Oil & Gas Company | | Gas Operator | Dec 2016 |
| 381 | Cameron Oil & Gas Inc | Hobbs, NM 88240 | Oil & Gas Operator | Mar 2026 |
| 382 | Cameron Production Co Inc | Zanesville, OH 43701 | Oil & Gas Operator | Dec 2025 |
| 383 | Cameron Properties | Columbus, OH 43220 | Oil & Gas Operator | Dec 1996 |
| 384 | Cameron, Paul E., Jr., Inc. | Montgomery, TX 77356 | Oil & Gas Operator | May 2015 |
| 385 | Camex Operating Company | | Oil & Gas Operator | Dec 2024 |
| 386 | Camex, Inc. | | Oil & Gas Operator | Jun 1992 |
| 387 | Caminar Oil & Gas, LLC | Abilene, TX 79602 | Oil & Gas Operator | Aug 2024 |
| 388 | Camino Natural Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2026 |
| 389 | Camino Real Technologies Inc | Temple, TX 76502 | Oil Operator | Sep 2026 |
| 390 | Camio Enterprises, LLC | Augusta, KS 67010 | Oil Operator | Mar 2026 |
| 391 | Camio Oil Co. | | Oil Operator | Dec 2004 |
| 392 | Camio Oil Compan | | Oil & Gas Operator | Apr 1991 |
| 393 | Camo Oil LLC | Stillwater, OK 74074 | Oil & Gas Operator | Jun 2026 |
| 394 | Camoil, Inc. | Columbus, TX 78934 | Oil & Gas Operator | Sep 2026 |
| 395 | Campana Petroleum Company | Midland, TX 79705 | Oil & Gas Operator | Sep 2026 |
| 396 | Campanella, George L | Great Falls, MT 59403 | Oil & Gas Operator | Jan 2026 |
| 397 | Campbell & Assoc.-Ring | | Oil Operator | Nov 1980 |
| 398 | Campbell & Associates | | Oil & Gas Operator | Aug 1987 |
| 399 | Campbell & Hedrick | Midland, TX 79702 | Oil & Gas Operator | Jun 2014 |
| 400 | Campbell B R | Ardmore, OK 73401 | Oil & Gas Operator | Oct 2002 |