| 301 | John W. McGowan | | Oil & Gas Operator | Jun 1991 |
| 302 | Johnson Oil & Gas Corporation | | Oil & Gas Operator | Feb 1994 |
| 303 | Jones Company | | Oil & Gas Operator | Dec 1990 |
| 304 | Jones Company, LTD. | Albany, TX 76430 | Oil & Gas Operator | May 1999 |
| 305 | Jones Exploration Company | | Oil & Gas Operator | Jun 1985 |
| 306 | Jordan Oil Company, Inc. | Lake Charles, LA 70602 | Oil & Gas Operator | Dec 2019 |
| 307 | Joseph C. Leckelt | | Oil Operator | Aug 1995 |
| 308 | Julil Energy, LLC | Richmond, TX 77406 | Oil & Gas Operator | Dec 2024 |
| 309 | Jva Operating Company | Midland, TX 79710 | Oil & Gas Operator | Oct 2021 |
| 310 | Kaiser-Francis Oil Company | Tulsa, OK 74121 | Oil & Gas Operator | Oct 2025 |
| 311 | Kaneb Energy Company | | Oil & Gas Operator | Jan 1986 |
| 312 | Kaneb Oil & Gas Company | | Oil & Gas Operator | Nov 1985 |
| 313 | Kaneb Operg Co. LTD. PTN. | | Oil & Gas Operator | Aug 1988 |
| 314 | Kash Oil And Gas, Inc | | Oil & Gas Operator | Oct 2020 |
| 315 | Kelley Oil Corporation | Houston, TX 77002 | Oil & Gas Operator | Jan 2002 |
| 316 | Kerr-McGee Corporation | Dallas, TX 75380 | Oil & Gas Operator | May 2025 |
| 317 | Kewanee Oil Company | Houston, TX 77001 | Oil & Gas Operator | Aug 1978 |
| 318 | Key Operating Co., Inc. | Duncan, OK 73534-1284 | Oil & Gas Operator | Jan 2025 |
| 319 | Kimbark Oil & Gas Company | Denver, CO 80203 | Oil & Gas Operator | May 2007 |
| 320 | Knight Resources LLC | | Oil & Gas Operator | Dec 2013 |
| 321 | Koch Gateway Pipeline Company | | Oil & Gas Operator | Feb 2001 |
| 322 | L P C Energy, Inc. | | Oil & Gas Operator | Mar 1985 |
| 323 | L. B. Simmons Energy, Inc. | Midland, TX BAD ADDR | Oil & Gas Operator | Oct 1996 |
| 324 | L.L. Oil Company | Freer, TX 78357 | Oil & Gas Operator | Oct 2025 |
| 325 | La Intrastate Gas Co LLC | | Oil Operator | Apr 2004 |
| 326 | La Mesa Production, Inc. | | Oil & Gas Operator | Apr 2004 |
| 327 | La. Nap. Inc. Lanlock Res Inc | | Oil Operator | Feb 1995 |
| 328 | Labelle Petroleum, Inc. | | Oil & Gas Operator | Oct 1990 |
| 329 | Ladd Petroleum Corp. | Denver, CO 80202 | Oil & Gas Operator | Oct 2004 |
| 330 | Lafayette Oilfield Contractors, Inc. | | Oil Operator | Dec 2024 |
| 331 | Lamar Oil & Gas, Inc. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Oct 2025 |
| 332 | Lamson Petroleum Corporation | | Oil & Gas Operator | Mar 1993 |
| 333 | Lamson/Crocker Petroleum Corp. | | Oil & Gas Operator | May 1988 |
| 334 | Layline Petroleum I, LLC | Houston, TX 77024 | Oil & Gas Operator | May 2013 |
| 335 | Lear Petroleum Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | Aug 1999 |
| 336 | Lee Mills | | Oil Operator | Feb 1992 |
| 337 | Lee Roy Daigle | | Oil Operator | Dec 1992 |
| 338 | Legendary Oil Co., Inc. | | Oil Operator | Feb 2004 |
| 339 | Legendary Well Service, Inc. | | Oil Operator | Jan 1996 |
| 340 | Leggett Petroleum, L.L.C. | | Oil & Gas Operator | Dec 2020 |
| 341 | LGS Exploration, Inc. | | Oil & Gas Operator | Jan 1991 |
| 342 | Liberty Oil And Gas Corp. | Olney, IL 62450-2489 | Oil & Gas Operator | Dec 2021 |
| 343 | Liberty Resources, Inc. | | Oil & Gas Operator | Dec 2024 |
| 344 | Linder Oil Company,A Partnership | Shreveport, LA 71136 | Oil & Gas Operator | Oct 2025 |
| 345 | Littlefield Oil & Gas Company | | Oil & Gas Operator | Jan 1990 |
| 346 | Llog Expl. Co. | Metairie, LA 70005 | Oil & Gas Operator | Jan 2003 |
| 347 | Llog Exploration & Prod Co | | Oil & Gas Operator | Jul 2000 |
| 348 | Llox, L.L.C. | Covington, LA 70433 | Oil & Gas Operator | Oct 2025 |
| 349 | Longhorn Oil & Gas Company | | Oil & Gas Operator | Sep 1982 |
| 350 | Louisiana Gas System, Inc. | | Oil Operator | Apr 2004 |
| 351 | Louisiana Intrastate Gas Corp. | | Oil Operator | Feb 1994 |
| 352 | Loyd E. Simar | | Oil & Gas Operator | Aug 2001 |
| 353 | Machin & Associates, Inc. | Longview, TX 75606 | Oil & Gas Operator | Oct 2025 |
| 354 | Mack Energy Co. | Duncan, OK 73534 | Oil & Gas Operator | Jul 2025 |
| 355 | Maddox Oil & Gas, Inc. | | Oil Operator | Apr 1983 |
| 356 | Magnolia Production Company LLC | | Oil & Gas Operator | Nov 2024 |
| 357 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 358 | Mar-Low Corporation | | Oil & Gas Operator | Mar 1992 |
| 359 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Aug 2025 |
| 360 | Marine Cont. & Supply Inc. | | Oil & Gas Operator | Nov 1985 |
| 361 | Marlin Exploration, Inc. | | Oil & Gas Operator | Oct 2006 |
| 362 | Marline Petroleum Corporation | | Oil & Gas Operator | Dec 1985 |
| 363 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 364 | Marsh Engineering, Inc. | | Oil & Gas Operator | Dec 1990 |
| 365 | Martin Exploration Co. | | Oil & Gas Operator | Apr 1986 |
| 366 | Master Well Works, Inc. | | Oil Operator | Dec 2024 |
| 367 | Matzinger Petroleum Co. | | Oil & Gas Operator | Jan 1991 |
| 368 | May Petroleum, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Nov 1998 |
| 369 | Maybrier Brothers | | Oil Operator | Apr 2006 |
| 370 | Maybrier Production, L.L.C. | | Oil Operator | Oct 2022 |
| 371 | McClinton & 4-M Invest Inc | | Oil & Gas Operator | Aug 1992 |
| 372 | McClinton & Mosing | | Oil & Gas Operator | Oct 1977 |
| 373 | McCord Oil Co. And T. Walker | | Oil & Gas Operator | Dec 1985 |
| 374 | McCord-Goodrich Oil Company | | Oil & Gas Operator | Oct 1991 |
| 375 | McCormick Operating Company | | Oil & Gas Operator | Mar 1984 |
| 376 | McCormick Operating PRTNSHP | | Oil & Gas Operator | Sep 1985 |
| 377 | McCulloch Oil Corp.-Ids | | Oil & Gas Operator | Dec 1981 |
| 378 | McFarland Energy, Inc. | New Orleans, LA 70160 | Oil & Gas Operator | Dec 2009 |
| 379 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 380 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Oct 2025 |
| 381 | McIntyre Oil Company | | Oil & Gas Operator | Jan 1992 |
| 382 | McMoran-Transco | | Oil & Gas Operator | Aug 1979 |
| 383 | McOr Oil & Gas Corp | Houston, TX 77002 | Oil & Gas Operator | Oct 2013 |
| 384 | McOr Oil Development, Inc. | | Oil & Gas Operator | Feb 1990 |
| 385 | McRae Exploration, Inc. | | Oil & Gas Operator | Mar 1984 |
| 386 | MCZ, Inc. | Houston, TX 77026 | Oil & Gas Operator | Sep 1990 |
| 387 | Medders Oil Company | Wichita Falls, TX 76308 | Oil & Gas Operator | Oct 2025 |
| 388 | Mesa Operating LTD Partnership | Amarillo, TX 79189 | Oil & Gas Operator | May 1994 |
| 389 | MFP Petroleum LTD. Partnership | Oklahoma City, OK 73142 | Oil & Gas Operator | Nov 2017 |
| 390 | Michael W Mills | | Oil Operator | Jul 2007 |
| 391 | Michel T. Halbouty Energy Co. | | Oil & Gas Operator | Nov 1986 |
| 392 | Michigan-Wisconsin Pipe Line Co | | Oil & Gas Operator | Dec 1983 |
| 393 | Midstates Petroleum Company LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2018 |
| 394 | Midstates Petroleum Corp. | | Oil & Gas Operator | Dec 2008 |
| 395 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 396 | Minden Oil & Gas, Inc. | | Oil & Gas Operator | May 1985 |
| 397 | Miss-Lou Operating LLC | | Oil & Gas Operator | Jul 2025 |
| 398 | Miss-Lou Petroleum LLC | | Oil & Gas Operator | Jun 2011 |
| 399 | Mobil E&P North America Inc. | | Oil & Gas Operator | Jan 1994 |
| 400 | Mobil Oil E & P Southeast Inc | | Oil & Gas Operator | Sep 2013 |