| 301 | Lightning Oil Company | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 302 | Live Oak Gas Company | Dallas, TX 75251 | Oil & Gas Operator | May 2025 |
| 303 | LMP Exploration Operating, LLC | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Feb 2008 |
| 304 | LMP Petroleum, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Jan 2010 |
| 305 | Loin Energy Corporation | La Grange, TX 78945 | Oil & Gas Operator | May 2025 |
| 306 | Louisiana Energy Consultant Inc. | Kilgore, TX 75663 | Oil & Gas Operator | May 2025 |
| 307 | LT Oil LLC | San Marcos, TX 78666 | Oil Operator | May 2025 |
| 308 | Lundberg Operating Corporation | Dallas, TX 75225 | Oil & Gas Operator | Oct 2002 |
| 309 | Lytle Creek Operating, Inc. | Abilene, TX 79606 | Oil & Gas Operator | May 2025 |
| 310 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 311 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 312 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 313 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 314 | Mandarin Oil & Gas Company | Austin, TX 78714 | Oil & Gas Operator | May 2025 |
| 315 | Marathon Oil Ef LLC | Houston, TX 77252 | Oil & Gas Operator | May 2025 |
| 316 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 317 | Marrow, N. S. | Austin, TX 78703 | Oil & Gas Operator | Aug 2012 |
| 318 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | May 2025 |
| 319 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 320 | Matrix Production Company | Sugar Land, TX 77478 | Oil & Gas Operator | Mar 2025 |
| 321 | Maverick Drilling Co., Inc. | Austin, TX 78729 | Oil & Gas Operator | Mar 2015 |
| 322 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 323 | McCullis Resources Co., Inc. | Littleton, CO 80161 | Oil & Gas Operator | Mar 2025 |
| 324 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 325 | McGuffin, Joe Jr. | Christoval, TX 76935 | Oil & Gas Operator | May 2025 |
| 326 | McGuffin, Joe S. Inc. | Mathis, TX 78368 | Gas Operator | May 2025 |
| 327 | McLelland Engineering & MGMT. | Houston, TX 77042 | Oil & Gas Operator | Mar 1999 |
| 328 | McMahon Operating Co., L.C. | Pampa, TX 79066 | Oil & Gas Operator | Dec 2004 |
| 329 | Meeker & Company | Fort Worth, TX 76102 | Oil & Gas Operator | May 2025 |
| 330 | Mego Resources, LLC | Taft, TX 78390 | Oil & Gas Operator | May 2025 |
| 331 | Meridian Resource & Expl LLC,The | Houston, TX 77094 | Oil & Gas Operator | Nov 2012 |
| 332 | Merrimac Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | Aug 1999 |
| 333 | Mesa Chica Corp. | San Antonio, TX 78278 | Oil & Gas Operator | May 2018 |
| 334 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 335 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 336 | MGM Well Service, Inc. | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Oct 2004 |
| 337 | Mid-Continent Energy, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2020 |
| 338 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 339 | Millennium Exploration Co. LLC | San Antonio, TX 78232 | Oil & Gas Operator | May 2025 |
| 340 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 341 | Miner, R. C. Inc. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Apr 2002 |
| 342 | Miner, R. C. Oil, Inc. | MC Queeney, TX 78123 | Oil & Gas Operator | May 2025 |
| 343 | Miramar Petroleum, Inc. | Corpus Chrsti, TX 78463 | Oil & Gas Operator | Sep 2017 |
| 344 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | May 2025 |
| 345 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 346 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 347 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | May 2025 |
| 348 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 349 | Morris, W. Dale Inc. | Mineral Wells, TX 76068 | Oil & Gas Operator | May 2025 |
| 350 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 351 | Moy, Gary | Falls City, TX 78113 | Oil & Gas Operator | Nov 1998 |
| 352 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 353 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Feb 2025 |
| 354 | Murphy Production Corp. | Austin, TX 78731 | Oil & Gas Operator | Sep 2013 |
| 355 | Navajo Exploration, Inc. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | May 2025 |
| 356 | Nelson, James L. | Pettus, TX 78146 | Oil & Gas Operator | May 2025 |
| 357 | Neuhaus, V. F. Properties, Inc. | Palmhurst, TX 78573 | Oil & Gas Operator | Dec 2022 |
| 358 | New Horizon Investments LTD. | George West, TX 78022 | Oil & Gas Operator | May 2025 |
| 359 | Newfield Exploration Company | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2017 |
| 360 | Newman Operating Company | Freer, TX 78357 | Oil & Gas Operator | Jun 2021 |
| 361 | Newton Corp.,The | Dallas, TX 75251 | Oil & Gas Operator | May 2025 |
| 362 | Nog Production & Operating LLC | Goliad, TX 77963 | Oil & Gas Operator | May 2025 |
| 363 | Nolen Oil & Gas | Beeville, TX 78102 | Oil & Gas Operator | May 2025 |
| 364 | Norcen Explorer, Inc. | Houston, TX 77079 | Oil & Gas Operator | May 1998 |
| 365 | Nordan Trust, The | San Antonio, TX 78205 | Oil & Gas Operator | Nov 2003 |
| 366 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | May 2025 |
| 367 | North Shore Energy, L.L.C. | Austin, TX 78750 | Oil & Gas Operator | May 2025 |
| 368 | Null, W. M. & San Patricio Corp. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Aug 1994 |
| 369 | O'Connor & Hewitt, LTD. | Victoria, TX 77901 | Oil & Gas Operator | Jun 1998 |
| 370 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 371 | Odegard Energy, Inc. | Houston, TX 77024 | Oil & Gas Operator | Jul 2020 |
| 372 | Oil & Gas Acquisition Group Inc | Austin, TX 78716 | Oil & Gas Operator | May 2003 |
| 373 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 374 | Omega Energy, LLC | Corpus Chrsti, TX 78418 | Oil & Gas Operator | May 2025 |
| 375 | One Tec Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Nov 2007 |
| 376 | Origin Production Company, Inc. | New Braunfels, TX 78132 | Oil & Gas Operator | May 2025 |
| 377 | Origin Production Group LLC | Luling, TX 78648 | Oil Operator | May 2025 |
| 378 | Osr Oil & Gas Company | Victoria, TX 77902 | Oil & Gas Operator | Jul 2000 |
| 379 | Osyka Oil & Gas, Inc. | Metairie, LA 70004 | Oil & Gas Operator | May 2025 |
| 380 | Osyka Permian, LLC | Houston, TX 77079 | Oil & Gas Operator | May 2025 |
| 381 | Outline Oil Company LLC | Beeville, TX 78104 | Oil Operator | May 2025 |
| 382 | Outline Oil Corp. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 383 | Owl Creek Production Co., Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2006 |
| 384 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 385 | Oztx Oil & Gas, L.L.C. | Ozona, TX 76943 | Oil & Gas Operator | May 2025 |
| 386 | Pace Production Co. | San Angelo, TX 76902 | Oil & Gas Operator | May 2025 |
| 387 | Paleo Oil Company LLC | Corpus Chrsti, TX 78411 | Oil & Gas Operator | May 2025 |
| 388 | Paloma Operating, LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 389 | Pantera Energy Company | Amarillo, TX 79101 | Oil & Gas Operator | May 2025 |
| 390 | Paragon Energy, Inc. | Dallas, TX 75244 | Oil & Gas Operator | May 2025 |
| 391 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 392 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 393 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 394 | Patricia Oil Company | Tuleta, TX 78162 | Oil Operator | Sep 2008 |
| 395 | Patterson Energy Corporation | Dallas, TX 75205 | Oil & Gas Operator | May 2025 |
| 396 | Payne Producing Co. | Fredericksbrg, TX 78624 | Oil & Gas Operator | Jun 2008 |
| 397 | Payne, B.R. Oil & Gas, Inc. | Corpus Chrsti, TX 78411 | Oil & Gas Operator | Feb 2006 |
| 398 | Pearl, Bill H. Productions, Inc. | Corpus Chrsti, TX 78460 | Oil & Gas Operator | May 2025 |
| 399 | Pegasus Petroleum Corporation | Corpus Chrsti, TX 78476 | Oil & Gas Operator | May 2025 |
| 400 | Pennzenergy Exp. & Prod., L.L.C. | Houston, TX 77210 | Oil & Gas Operator | Mar 2000 |