| 301 | Kenergy-Wainoco | | Oil & Gas Operator | Mar 1981 |
| 302 | Key Energy Of Colorado, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2016 |
| 303 | Key Operating Co., Inc. | Duncan, OK 73534-1284 | Oil & Gas Operator | Jan 2025 |
| 304 | Kilroy Co. Of Texas, Inc. | | Oil & Gas Operator | Jun 1991 |
| 305 | Kirby Exploration Co | Houston, TX 77251 | Oil & Gas Operator | Jan 2014 |
| 306 | Kirby Exploration Co Of Texas | | Oil & Gas Operator | Nov 1993 |
| 307 | Koch Gateway Pipeline Company | | Oil & Gas Operator | Feb 2001 |
| 308 | L P C Energy, Inc. | | Oil & Gas Operator | Mar 1985 |
| 309 | La Gas Dev Corp/Araxas | | Oil & Gas Operator | Dec 2001 |
| 310 | La Intrastate Gas Co LLC | | Oil Operator | Apr 2004 |
| 311 | La. Land & Expl. Co. | | Oil & Gas Operator | Dec 2010 |
| 312 | Lafayette Oilfield Contractors, Inc. | | Oil Operator | Dec 2024 |
| 313 | Lake Racourci Gath Sys, LLC | | Oil Operator | May 2004 |
| 314 | Lamson Petroleum Corporation | | Oil & Gas Operator | Mar 1993 |
| 315 | Lamson/Crocker Petroleum Corp. | | Oil & Gas Operator | May 1988 |
| 316 | Lamson/Onshore Petroleum Corp. | | Oil & Gas Operator | Sep 1985 |
| 317 | Lanoco, Inc. | | Oil & Gas Operator | Sep 2002 |
| 318 | Las Services, Inc. | | Oil & Gas Operator | Oct 1997 |
| 319 | Lea Exploration, Inc. | | Oil & Gas Operator | Nov 1989 |
| 320 | Lear Petroleum Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | Aug 1999 |
| 321 | Leigh Operating Co | Dallas, TX 75205 | Oil & Gas Operator | Mar 2008 |
| 322 | Levinson Partners Corporation | Denver, CO 80202 | Oil & Gas Operator | Jul 1995 |
| 323 | Liberty Oil And Gas Corp. | Olney, IL 62450-2489-2489 | Oil & Gas Operator | Dec 2021 |
| 324 | Liberty Resources, Inc. | | Oil & Gas Operator | Dec 2024 |
| 325 | Lignum Oil Company | | Oil & Gas Operator | Dec 1989 |
| 326 | Linder Oil Company,A Partnership | Shreveport, LA 71136 | Oil & Gas Operator | Mar 2025 |
| 327 | Lko Operating LLC | | Oil & Gas Operator | Feb 2017 |
| 328 | Llog Expl. Co. | Metairie, LA 70005 | Oil & Gas Operator | Jan 2003 |
| 329 | Llog Exploration & Prod Co | | Oil & Gas Operator | Jul 2000 |
| 330 | Llog Exploration Company, LLC | | Oil & Gas Operator | Dec 2024 |
| 331 | Llog Production Company | Metairie, LA 70005 | Oil & Gas Operator | Apr 1995 |
| 332 | Llox, L.L.C. | Covington, LA 70433 | Oil & Gas Operator | Mar 2025 |
| 333 | LNG Gathering Company | | Oil Operator | Oct 2024 |
| 334 | Lobo Operating, Inc. | Houston, TX 77077 | Oil & Gas Operator | Dec 2024 |
| 335 | Louisiana Gas Development Corp | | Oil & Gas Operator | Jan 2025 |
| 336 | Louisiana Gas System, Inc. | | Oil Operator | Apr 2004 |
| 337 | Louisiana Intrastate Gas Corp. | | Oil Operator | Feb 1994 |
| 338 | Louisiana Resources Co | | Oil Operator | May 1992 |
| 339 | Lucky Lad Energy, LLC | Magnolia, TX 77353 | Oil & Gas Operator | Mar 2025 |
| 340 | Lynal, Inc. | | Oil & Gas Operator | Oct 1988 |
| 341 | Lyons Petroleum, Inc. | | Oil & Gas Operator | Oct 1988 |
| 342 | M & M Investments | | Oil & Gas Operator | May 1990 |
| 343 | M. F. McCain, Inc. | | Oil & Gas Operator | Jul 1987 |
| 344 | Mack Energy Co. | Duncan, OK 73534 | Oil & Gas Operator | Jan 2025 |
| 345 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Mar 2025 |
| 346 | Manna Minerals, Inc. | | Oil & Gas Operator | Apr 1989 |
| 347 | Manti Exploration Operating LLC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Feb 2015 |
| 348 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | Mar 2025 |
| 349 | Map Drilling Company | | Oil & Gas Operator | Apr 2012 |
| 350 | Mar-Low Corporation | | Oil & Gas Operator | Mar 1992 |
| 351 | Marathon Oil Company | Houston, TX 77024 | Oil & Gas Operator | Jan 2025 |
| 352 | Mariner Energy, Inc. | Houston, TX 77042 | Oil & Gas Operator | Nov 2010 |
| 353 | Maritech Resources, LLC | | Oil & Gas Operator | May 2011 |
| 354 | Mark L Shidler Inc | Houston, TX 77055 | Oil & Gas Operator | Jan 2025 |
| 355 | Mark Producing, Inc. | Houston, TX 77057 | Oil & Gas Operator | Dec 1987 |
| 356 | Marline Oil Corporation | Houston, TX 77002 | Oil & Gas Operator | Dec 1989 |
| 357 | Marline Petroleum Corporation | | Oil & Gas Operator | Dec 1985 |
| 358 | Marshall Exploration, Inc. | | Oil & Gas Operator | Jun 1992 |
| 359 | Marshall Prod. & Energy Inc. | | Oil & Gas Operator | Jan 1992 |
| 360 | Martin Exploration Co. | | Oil & Gas Operator | Apr 1986 |
| 361 | Masters Resources, L.L.C. | Houston, TX 77079 | Oil & Gas Operator | Dec 2008 |
| 362 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 363 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 364 | McAlester Fuel Co | Houston, TX 77042 | Oil & Gas Operator | Jan 2010 |
| 365 | McCormick-Bintliff-Pettit | | Oil & Gas Operator | Feb 1984 |
| 366 | McCormick-Terra-Bintliff | | Oil & Gas Operator | Dec 1979 |
| 367 | McGowen Resources Co., Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2003 |
| 368 | McMoran Oil & Gas LLC | New Orleans, LA 70160 | Oil & Gas Operator | Oct 2021 |
| 369 | McRae Oil Corporation | | Oil & Gas Operator | Mar 1984 |
| 370 | Medallion Petroleum, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2015 |
| 371 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 372 | Memorial Exploration Company | Saint Louis, MO 63105 | Oil & Gas Operator | Aug 1996 |
| 373 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 374 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Mar 2025 |
| 375 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 376 | Michel T. Halbouty Energy Co. | | Oil & Gas Operator | Nov 1986 |
| 377 | Mid-Continent Energy, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2020 |
| 378 | Middle Bay Production Co. Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2014 |
| 379 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 380 | Miller Oil Field Services, Inc | | Oil Operator | Feb 1990 |
| 381 | Miller S.W.D., Inc. | | Oil Operator | Oct 2002 |
| 382 | Minatome Corpora | | Oil & Gas Operator | Sep 1987 |
| 383 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 384 | Mobil E&P N.A.-Pel-Tex | | Oil & Gas Operator | Dec 1993 |
| 385 | Mobil E&P North America Inc. | | Oil & Gas Operator | Jan 1994 |
| 386 | Mobil Oil E & P Southeast Inc | | Oil & Gas Operator | Sep 2013 |
| 387 | Mobil Oil E&P Se Inc - Pel-Tex | | Oil & Gas Operator | Dec 2005 |
| 388 | Monterey Pipeline Co. | | Oil Operator | Aug 1993 |
| 389 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 390 | Mullins & Prichard | | Oil & Gas Operator | May 1992 |
| 391 | Murphy Exp & Prod Co.-USA | | Oil & Gas Operator | May 2014 |
| 392 | Murphy Exploration & Prod. Co. | Houston, TX 77094 | Oil & Gas Operator | Jun 2011 |
| 393 | N And B Exploration, Inc. | | Oil & Gas Operator | Jun 1993 |
| 394 | Navitas Resources, LLC | | Oil & Gas Operator | May 2016 |
| 395 | Nerco Oil & Gas, Inc. | | Oil & Gas Operator | Dec 1996 |
| 396 | Neumin Production Company | Point Comfort, TX 77978 | Oil & Gas Operator | Mar 2025 |
| 397 | Newfield Exploration Company | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2017 |
| 398 | Newmont Oil Company | Houston, TX 77002 | Oil & Gas Operator | Sep 1988 |
| 399 | Nexen Petroleum U.S.A. Inc. | Houston, TX 77024 | Oil & Gas Operator | Jul 2012 |
| 400 | Nicco Operating Co. | | Oil & Gas Operator | May 1990 |