| 301 | Colorado Oil Co., Inc. | | Oil & Gas Operator | Dec 1977 |
| 302 | Colt Energy Inc | Iola, KS 66749 | Oil & Gas Operator | Dec 2025 |
| 303 | Colt Production Corp. Inc. | | Oil & Gas Operator | Jul 1996 |
| 304 | Columbia Gas Dev. Corp. | | Oil & Gas Operator | Apr 1996 |
| 305 | Columbia Gulf Transmission Co. | | Oil Operator | Dec 2014 |
| 306 | Columbia Gulf Transmission Company, LLC | | Oil Operator | Jan 2025 |
| 307 | Columbia Minerals Corp., Inc. | | Oil & Gas Operator | May 1996 |
| 308 | Columbia Petroleum Corp. | | Oil & Gas Operator | Jun 1982 |
| 309 | Comco Of Louisiana, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jun 2000 |
| 310 | Commerce Energy, Inc. | | Oil & Gas Operator | Dec 1999 |
| 311 | Commonwealth Energy, Inc. | Weston, WV 26452-0000 | Oil & Gas Operator | Dec 2021 |
| 312 | Compadres, Inc. | | Oil & Gas Operator | Dec 1988 |
| 313 | Compass Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Apr 2026 |
| 314 | Comstock Offshore, LLC | | Oil & Gas Operator | Nov 2004 |
| 315 | Comstock Oil & Gas -- La, Inc. | | Oil & Gas Operator | Mar 2005 |
| 316 | Comstock Oil & Gas--La, LLC | | Oil & Gas Operator | Dec 2024 |
| 317 | Concor Petroleum, Inc. | | Oil & Gas Operator | Feb 1983 |
| 318 | Concord Operating Incorporated | Horseshoe Bay, TX 78657 | Oil & Gas Operator | Dec 2008 |
| 319 | Concord Resources, LLC | | Oil & Gas Operator | Nov 2000 |
| 320 | Condor Energy, Inc. | Great Bend, KS 67530 | Oil & Gas Operator | Nov 2019 |
| 321 | Condor Petroleum Corporation | | Oil & Gas Operator | Aug 2020 |
| 322 | Confed Oil Incorporated | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2008 |
| 323 | Conley P Smith Operating Co. | | Oil & Gas Operator | Jun 1995 |
| 324 | Conn Energy Group, LLC | | Oil & Gas Operator | Apr 2024 |
| 325 | Conoco Inc | Houston, TX 77252 | Oil & Gas Operator | Mar 2015 |
| 326 | ConocoPhillips Company | Midland, TX 79701 | Oil & Gas Operator | Apr 2026 |
| 327 | Conquest Exploration Co. | | Oil & Gas Operator | Mar 1992 |
| 328 | Conquest Petroleum Inc | | Oil & Gas Operator | Nov 2014 |
| 329 | Consolidated Energy Inv., Inc. | | Oil & Gas Operator | Oct 2013 |
| 330 | Consolidated Energy Res., Inc. | | Oil Operator | Jun 1992 |
| 331 | Consolidated Resources, Inc. | | Oil & Gas Operator | May 2004 |
| 332 | Contango Operators, Inc. | Houston, TX 77098 | Oil & Gas Operator | Dec 2022 |
| 333 | Contango Operators, LLC | | Oil & Gas Operator | Nov 2024 |
| 334 | Contango Resources Company | | Oil & Gas Operator | Mar 2009 |
| 335 | Contango Resources, Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 336 | Continental Oil & Gas Co. Inc. | | Oil & Gas Operator | Jul 1997 |
| 337 | Continental Operating Co. | Houston, TX 77024 | Oil & Gas Operator | Apr 2026 |
| 338 | Continental Resources, Inc. | Oklahoma City, OK 73126 | Oil & Gas Operator | Apr 2026 |
| 339 | Contour Energy E & P, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 340 | Contour Energy E & P, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Aug 2003 |
| 341 | Converse Oil Corp. | | Oil Operator | Dec 2010 |
| 342 | Cook Production LLC | | Oil Operator | Jan 2025 |
| 343 | Coquina Oil Corporation | Houston, TX 77227 | Oil & Gas Operator | Mar 2015 |
| 344 | Cordex Petroleums, Inc. | | Oil & Gas Operator | Jun 1996 |
| 345 | Corenergy Operating Group, LLC | Houston, TX 77074 | Oil & Gas Operator | Apr 2026 |
| 346 | Cornell Oil Company | | Oil & Gas Operator | May 1985 |
| 347 | Cornerstone Gas Processing Inc | | Oil Operator | Jan 1999 |
| 348 | Cornerstone Natural Gas Co. | | Oil Operator | Oct 1999 |
| 349 | Coronado Energy E&P Company, LLC | Houston, TX 77252 | Oil & Gas Operator | Dec 2010 |
| 350 | Coronado Oil & Minerals Co. | | Oil & Gas Operator | Sep 1980 |
| 351 | Corpus Christi Oil & Gas Co. | | Oil & Gas Operator | Dec 1991 |
| 352 | Cortex Energy, Inc. | Wichita, KS 67217 | Oil & Gas Operator | Dec 2024 |
| 353 | Corum Production Co.-Tepco | | Oil & Gas Operator | Dec 1989 |
| 354 | Corum Production Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2026 |
| 355 | Costa Energy, LLC | Irving, TX 75063 | Oil & Gas Operator | Apr 2026 |
| 356 | Costilla Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 357 | Coteau Energy LLC | | Oil & Gas Operator | Dec 2024 |
| 358 | Cotton Petroleum Corporation | Tulsa, OK 74102 | Oil & Gas Operator | Jan 2005 |
| 359 | Cougar Exploration, Inc. | | Oil & Gas Operator | Jun 1988 |
| 360 | Courtney Oil Co. | | Oil Operator | Dec 1998 |
| 361 | Coushatta Oil & Gas Inc. | | Oil & Gas Operator | Jan 2007 |
| 362 | Covey Energy, Inc. | | Oil & Gas Operator | Jun 1998 |
| 363 | Covey Park Gas LLC | | Oil & Gas Operator | Aug 2019 |
| 364 | Cox & Perkins Exploration, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2026 |
| 365 | Cox Oil & Gas Inc | Dallas, TX 75201 | Oil & Gas Operator | Mar 2014 |
| 366 | Cox Operating, L.L.C. | | Oil & Gas Operator | Jan 2024 |
| 367 | Cox Resources Corporation | Dallas, TX 75244 | Oil & Gas Operator | Mar 2015 |
| 368 | Coy W. Hale | | Oil Operator | Nov 2024 |
| 369 | CPBG, LLC | | Oil Operator | Oct 2019 |
| 370 | Cpi 5, L.L.C | | Oil Operator | Dec 2023 |
| 371 | Cpi Operating Co. | | Oil & Gas Operator | Mar 2003 |
| 372 | Cpi Operating Company, LLC | | Oil Operator | Jan 2025 |
| 373 | Cra International, LTD | | Oil & Gas Operator | Mar 1983 |
| 374 | Crab Run Gas Company | | Oil & Gas Operator | Feb 1982 |
| 375 | Crain & Dore Production Co Inc | | Oil & Gas Operator | Oct 1990 |
| 376 | Cranford Exploration, Inc. | | Oil & Gas Operator | Jul 2002 |
| 377 | Crawford Energy Operating Co | Houston, TX 77056 | Oil & Gas Operator | Aug 2008 |
| 378 | Crawford Hughes Operating Co. | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 2026 |
| 379 | Crebbs Oil Company | Batson, TX 77519 | Oil & Gas Operator | Jun 2024 |
| 380 | Credo Petroleum Corporation | Denver, CO 80202 | Oil & Gas Operator | Jan 2013 |
| 381 | Creek Operating Company, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Sep 1998 |
| 382 | Creole Operating, LLC | | Oil & Gas Operator | Dec 2024 |
| 383 | Crescent Drilling Company, Inc. | | Gas Operator | Dec 2024 |
| 384 | Crescent DRLG & DVLPMNT, Inc. | | Oil & Gas Operator | Oct 1992 |
| 385 | Crescent Energy Company | | Oil Operator | May 1993 |
| 386 | Crescent Pass Energy, LLC | Houston, TX 77070 | Oil & Gas Operator | Apr 2026 |
| 387 | Creslenn Oil Co | | Oil & Gas Operator | Nov 1998 |
| 388 | Crest Resources & Expl. Corp. | Houston, TX 77079 | Oil & Gas Operator | Dec 1998 |
| 389 | Crestmont Operating LLC | New York, NY 10151 | Oil Operator | Apr 2026 |
| 390 | Crimson Explor Operating, Inc. | | Oil & Gas Operator | Dec 2009 |
| 391 | Criswell E. White | | Gas Operator | Jun 2015 |
| 392 | Cross Development Co. | | Oil Operator | Dec 1989 |
| 393 | Cross Development-MMHS PRTSHP. | | Oil Operator | May 1987 |
| 394 | Cross Development1984-1 PRTSHP | | Oil & Gas Operator | Sep 1990 |
| 395 | Cross Timbers Operating Company | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2025 |
| 396 | Crossroads Energy Development, LLC | | Oil Operator | Mar 2018 |
| 397 | Crosstex Lig, LLC | | Oil Operator | Mar 2014 |
| 398 | Crosstex Processing SVCS, LLC | | Oil Operator | Mar 2014 |
| 399 | Crosstex Treating Services, L.P. | | Oil Operator | Sep 2009 |
| 400 | Crow-Eason | | Oil & Gas Operator | Feb 1984 |