| 301 | Killam Oil Company | Laredo, TX 78042 | Oil & Gas Operator | Mar 1994 |
| 302 | Kimmeridge Texas Gas, LLC | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 303 | Kinder Morgan Tejas Pipeline LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 304 | Kovar Operating, LLC | Victoria, TX 77901 | Oil & Gas Operator | Sep 2021 |
| 305 | Koven Production Co. | San Antonio, TX 78232 | Oil & Gas Operator | Aug 2003 |
| 306 | L.O.G. Energy Exploration, LTD. | Laredo, TX 78041 | Oil & Gas Operator | Oct 2025 |
| 307 | L.T.D. Explorations Inc. | Alice, TX 78333 | Oil & Gas Operator | Oct 2025 |
| 308 | Lacy, F. B. Inc. | Houston, TX 77055 | Oil & Gas Operator | Sep 1997 |
| 309 | Lakeshore Operating, LLC | Wichita, KS 67203 | Oil & Gas Operator | Oct 2025 |
| 310 | Lakewood Operating, LTD. | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 311 | Laredo Energy | Houston, TX 77002 | Oil & Gas Operator | Jun 2016 |
| 312 | Laredo Energy Operating, LLC | Houston, TX 77024 | Oil & Gas Operator | Nov 2022 |
| 313 | Laredo Energy, LP | Houston, TX 77040 | Oil & Gas Operator | Oct 2003 |
| 314 | Lawbar Petroleum, Inc. | Tuleta, TX 78162 | Oil & Gas Operator | Aug 2003 |
| 315 | Legend Natural Gas II, LP | Houston, TX 77094 | Oil & Gas Operator | Feb 2015 |
| 316 | Legend Natural Gas III, LP | Houston, TX 77094 | Oil & Gas Operator | Feb 2015 |
| 317 | Lewis Petro Properties, Inc. | San Antonio, TX 78216 | Oil & Gas Operator | Oct 2025 |
| 318 | LGDC Corporation | Shreveport, LA 71101 | Oil & Gas Operator | Oct 2025 |
| 319 | Linn Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Jan 2019 |
| 320 | Linn Operating, Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2017 |
| 321 | Llog Exploration Offshore, Inc. | Covington, LA 70433 | Oil & Gas Operator | Aug 2004 |
| 322 | LMP Petroleum, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Jan 2010 |
| 323 | Lobo Energy, Inc. | Laredo, TX 78044 | Oil & Gas Operator | Nov 1996 |
| 324 | Lobo Operating, Inc. | Houston, TX 77077 | Oil & Gas Operator | Dec 2024 |
| 325 | Lobo Resources, LTD. | Houston, TX 77077 | Oil & Gas Operator | Apr 1994 |
| 326 | LTS Oil & Gas A | Lubbock, TX 79424 | Oil & Gas Operator | Oct 2025 |
| 327 | Luca Resources Group, LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 328 | Luttrell, T. Bruce Oil & Gas Opr | Freer, TX 78357 | Oil & Gas Operator | Mar 2008 |
| 329 | Lynd, J. L., Inc. | Austin, TX 78716 | Oil & Gas Operator | Sep 2009 |
| 330 | M & R Exploration Company | Houston, TX 77074 | Oil & Gas Operator | Aug 2003 |
| 331 | Maggert Energy Corp. | Spring, TX 77387 | Gas Operator | Jun 1998 |
| 332 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 333 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 334 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 335 | Maguire Oil Company | Dallas, TX 75270 | Oil & Gas Operator | Mar 2015 |
| 336 | Manley, John D. III, Oper., Inc | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Feb 2016 |
| 337 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Aug 2025 |
| 338 | Marmik Oil Company | El Dorado, AR 71730 | Oil & Gas Operator | Jan 2015 |
| 339 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 340 | Martin Oil & Gas | Freer, TX 78357 | Oil & Gas Operator | May 2025 |
| 341 | Martin Oil & Gas Inc. | Freer, TX 78357 | Oil & Gas Operator | Oct 2025 |
| 342 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 343 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 344 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 345 | Mayo Oil Co. | San Antonio, TX 78209 | Oil & Gas Operator | Feb 2019 |
| 346 | MB Energy, LLC | San Antonio, TX 78233 | Oil & Gas Operator | Oct 2025 |
| 347 | McCombs Energy LLC | Houston, TX 77056 | Oil & Gas Operator | Jan 2006 |
| 348 | McDonnold Operating, Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 349 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 350 | McGuffin, Joe Jr. | Christoval, TX 76935 | Oil & Gas Operator | Oct 2025 |
| 351 | McLelland Engineering & MGMT. | Houston, TX 77042 | Oil & Gas Operator | Mar 1999 |
| 352 | McRae & Henry LTD | Golden, CO 80401 | Oil & Gas Operator | May 2022 |
| 353 | McRae, Nathan Rathburn | Hebbronville, TX 78361 | Oil & Gas Operator | Apr 1994 |
| 354 | Medallion Oil Company | Houston, TX 77251 | Oil & Gas Operator | Jan 2012 |
| 355 | Memorial Production Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 356 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 357 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 358 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 359 | Merritt Operating, Inc. | Mineola, TX 75773 | Oil & Gas Operator | Oct 2025 |
| 360 | Mesa Operating LTD Partnership | Amarillo, TX 79189 | Oil & Gas Operator | May 1994 |
| 361 | Metano Energy, LP | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2008 |
| 362 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 363 | MGM Oil & Gas Company | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 364 | Michael Petr. & Hurd Ent., LTD. | Houston, TX 77056 | Oil & Gas Operator | Oct 1993 |
| 365 | Michael Petroleum Corporation | Houston, TX 77040 | Oil & Gas Operator | Dec 2001 |
| 366 | Middle Bay Production Co. Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2014 |
| 367 | Middleton Oil Company | Houston, TX 77006 | Oil & Gas Operator | Oct 2025 |
| 368 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 369 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 370 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 371 | Minuja Oil And Gas LLC | Corpus Christi, TX 78401 | Oil & Gas Operator | Sep 1996 |
| 372 | Mir-Tex Energy Corp. | Mirando City, TX 78369 | Oil & Gas Operator | Aug 2003 |
| 373 | Miramar Petroleum, Inc. | Corpus Chrsti, TX 78463 | Oil & Gas Operator | Sep 2017 |
| 374 | Mirando Crude Oil Co. | Luling, TX 78648 | Oil & Gas Operator | Jul 1994 |
| 375 | Mirando Resource, L.L.C. | Freer, TX 78357 | Oil & Gas Operator | Oct 2025 |
| 376 | Mitsui E&P USA LLC | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 377 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 378 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 379 | Mohican Oil & Gas, L.L.C. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Apr 2013 |
| 380 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 381 | Monitor O&G, L.L.C. | Frisco, TX 75034 | Oil & Gas Operator | Jan 2016 |
| 382 | Morgan Enterprises, Inc. | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 383 | Morsey Oil & Gas Corporation | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 384 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 385 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 386 | Moy, Gary | Falls City, TX 78113 | Oil & Gas Operator | Nov 1998 |
| 387 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 388 | Mustang Oil & Gas Corporation | Wichita Falls, TX 76308 | Oil & Gas Operator | Jul 2021 |
| 389 | MV Purchasing LLC | Wichita, KS 67206 | Oil & Gas Operator | Dec 2019 |
| 390 | Nbi Services, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | Oct 2025 |
| 391 | Nearburg Producing Company | Dallas, TX 75380 | Oil & Gas Operator | Oct 2025 |
| 392 | Neumin Production Company | Point Comfort, TX 77978 | Oil & Gas Operator | Oct 2025 |
| 393 | Newfield Exploration Company | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2017 |
| 394 | Newman Operating Company | Freer, TX 78357 | Oil & Gas Operator | Jun 2021 |
| 395 | Nitro Oil & Gas, LLC | Cuero, TX 77954 | Oil & Gas Operator | Oct 2025 |
| 396 | North American Reserve Corp. | Houston, TX 77060 | Oil & Gas Operator | Oct 2010 |
| 397 | North Central Oil Corp | Houston, TX 77252 | Oil & Gas Operator | Dec 2005 |
| 398 | Null, W.M. Operations, Inc. | Corpus Chrsti, TX 78475 | Oil & Gas Operator | Jun 2002 |
| 399 | Oak Energy, LLC | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 400 | Oakwood Energy, Inc. | Jourdanton, TX 78026 | Oil & Gas Operator | Mar 2023 |