| 301 | Kemper Operating Co. | Abilene, TX 79605 | Oil & Gas Operator | Nov 2015 |
| 302 | Kerr-McGee Corporation | Dallas, TX 75380 | Oil & Gas Operator | Jan 2025 |
| 303 | Kerr-McGee Oil & Gas Onshore LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2017 |
| 304 | Kidd Production Co. | Luling, TX 78648 | Oil & Gas Operator | Apr 2025 |
| 305 | Killam Oil Co., LTD. | Laredo, TX 78042 | Oil & Gas Operator | Apr 2025 |
| 306 | King Energy Resources | Kerrville, TX 78029 | Oil & Gas Operator | Apr 2025 |
| 307 | Kinlaw Oil Corporation | Dallas, TX 75380 | Oil & Gas Operator | Apr 2025 |
| 308 | Klutts, Carlos J. | Austin, TX 78711 | Oil & Gas Operator | Apr 2002 |
| 309 | Kodiak Drilling, Inc. | Borger, TX 79008 | Oil & Gas Operator | Aug 2003 |
| 310 | Kouatli, Aiman M. | Caldwell, TX 77836 | Oil & Gas Operator | Apr 2025 |
| 311 | KRC Operating, LLC | Corpus Chrsti, TX 78412 | Oil & Gas Operator | Apr 2025 |
| 312 | Ksabe Energy Partners, LLC | Oklahoma City, OK 73106 | Oil Operator | Apr 2025 |
| 313 | L & J Exploration, LLC | Carrizo SPGS, TX 78834 | Oil & Gas Operator | Apr 2025 |
| 314 | Lake Ronel Oil Company | Tyler, TX 75710 | Oil & Gas Operator | Jul 2017 |
| 315 | Lasalle Marine Corporation | Houston, TX 77056 | Oil Operator | Aug 2003 |
| 316 | Lawbar Petroleum, Inc. | Tuleta, TX 78162 | Oil & Gas Operator | Aug 2003 |
| 317 | Leexus Oil LLC | Giddings, TX 78942 | Oil & Gas Operator | Apr 2025 |
| 318 | Legacy Corporation, The | Cedar Park, TX 78613 | Oil & Gas Operator | Jun 2004 |
| 319 | Lehnertz, G. M. | Tyler, TX 75702 | Oil & Gas Operator | Dec 1998 |
| 320 | Lewis Petro Properties, Inc. | San Antonio, TX 78216 | Oil & Gas Operator | Apr 2025 |
| 321 | Libom Oil Company | Elmsford, NY 10523 | Oil & Gas Operator | Aug 2003 |
| 322 | Light Resources | San Antonio, TX 78278 | Oil & Gas Operator | Aug 2013 |
| 323 | Lillis, Michael D. | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 324 | Lissner, Lindy | Jourdanton, TX 78026 | Oil & Gas Operator | Apr 2025 |
| 325 | Little & Whyte Operating, Inc. | Tyler, TX 75711 | Oil & Gas Operator | Mar 2008 |
| 326 | Live Oak Gas Company | Dallas, TX 75251 | Oil & Gas Operator | Apr 2025 |
| 327 | LMP Petroleum, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Jan 2010 |
| 328 | Lomak Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Aug 1998 |
| 329 | Lone Star Operating Company | Pearsall, TX 78061 | Oil & Gas Operator | Apr 2025 |
| 330 | Lonestar Operating, LLC | Houston, TX 77084 | Oil & Gas Operator | Nov 2022 |
| 331 | Longhorn Mineral Corporation | Bellaire, TX 77401 | Oil & Gas Operator | May 2018 |
| 332 | Lovelady, I. W. | Albuquerque, NM 87111 | Oil & Gas Operator | Jan 1996 |
| 333 | LP Operating, LLC | Boerne, TX 78006 | Oil & Gas Operator | Apr 2025 |
| 334 | LTS Oil & Gas A | Lubbock, TX 79424 | Oil & Gas Operator | Apr 2025 |
| 335 | Lucas Energy, Inc. | Houston, TX 77067 | Oil & Gas Operator | Feb 2017 |
| 336 | Lynch, W. W. | San Antonio, TX 78205 | Oil & Gas Operator | Jul 2006 |
| 337 | Magna Oil & Gas Corporation | Irving, TX 75017 | Oil & Gas Operator | Feb 2016 |
| 338 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2025 |
| 339 | Magnum Petroleum, Inc. | Palm Desert, CA 92260 | Oil & Gas Operator | Nov 2013 |
| 340 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 341 | Manti Exploration Operating LLC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Feb 2015 |
| 342 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | Apr 2025 |
| 343 | Mantle Oil & Gas, LLC | Friendswood, TX 77546 | Oil & Gas Operator | Apr 2025 |
| 344 | Marathon Oil Company | Houston, TX 77024 | Oil & Gas Operator | Feb 2025 |
| 345 | Marathon Oil Ef LLC | Houston, TX 77252 | Oil & Gas Operator | Apr 2025 |
| 346 | Mariah Energy Corp. | Austin, TX 78716 | Oil & Gas Operator | Apr 1999 |
| 347 | Mascot Oil Company | Schulenburg, TX 78956 | Oil & Gas Operator | Apr 2025 |
| 348 | Matador Production Company | Dallas, TX 75240 | Oil & Gas Operator | Apr 2025 |
| 349 | Maverick Energy Group, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 350 | Maverick Prod. Co., Inc. | Houston, TX 77056 | Oil & Gas Operator | Apr 2025 |
| 351 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 352 | May Investments, Inc. | New Boston, TX 75570 | Oil & Gas Operator | Aug 2003 |
| 353 | Mayo Oil Co. | San Antonio, TX 78209 | Oil & Gas Operator | Feb 2019 |
| 354 | Mazco Energy LLC | San Antonio, TX 78266 | Oil & Gas Operator | Apr 2025 |
| 355 | McA Petroleum Corporation | Flatonia, TX 78941 | Oil & Gas Operator | Apr 2025 |
| 356 | McCombs Energy LLC | Houston, TX 77056 | Oil & Gas Operator | Jan 2006 |
| 357 | McDaniel Company, Inc., The | Dallas, TX 75230 | Oil & Gas Operator | Apr 2025 |
| 358 | McDay Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | Apr 2025 |
| 359 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 360 | McMinn Operating Company, Inc. | Hempstead, TX 77445 | Oil & Gas Operator | Apr 2025 |
| 361 | Megaenergy Operating, Inc. | Edmond, OK 73034 | Oil & Gas Operator | Jul 2015 |
| 362 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 363 | Mescalero Energy, Inc. | San Antonio, TX 78231 | Oil & Gas Operator | Aug 2003 |
| 364 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 365 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 366 | Mid Texas Natural Gas | Kyle, TX 78640 | Oil & Gas Operator | May 2019 |
| 367 | Midas Resources, Inc. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Apr 2025 |
| 368 | Miesch Exploration Corporation | Dallas, TX 75229 | Oil & Gas Operator | Nov 2002 |
| 369 | Mina Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Feb 2012 |
| 370 | Mineral Development, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Aug 1996 |
| 371 | Mineral Resources, Incorporated | Lewisville, TX 75029 | Oil & Gas Operator | Apr 2025 |
| 372 | Mobile Production Systems, Inc. | Austin, TX 78711 | Oil & Gas Operator | Feb 1995 |
| 373 | Moody Oil Co. | Pearsall, TX 78061 | Oil & Gas Operator | Apr 2025 |
| 374 | Mosaic Texas LLC | Dallas, TX 75205 | Oil & Gas Operator | Apr 2025 |
| 375 | Moy, Gary | Falls City, TX 78113 | Oil & Gas Operator | Nov 1998 |
| 376 | Mueller Exploration, Inc. | Portland, TX 78374 | Oil & Gas Operator | Apr 2025 |
| 377 | Nails Operating Company LLC | Hondo, TX 78861 | Oil Operator | Apr 2025 |
| 378 | Nelms Bros. Oil Properties Inc. | Austin, TX 78711 | Oil & Gas Operator | Jun 1996 |
| 379 | Neumann Oil & Gas, LLC | Bigfoot, TX 78005 | Oil Operator | Apr 2025 |
| 380 | Neumann, Alfred | Bigfoot, TX 78005 | Oil & Gas Operator | Aug 2003 |
| 381 | Newton Corp.,The | Dallas, TX 75251 | Oil & Gas Operator | Apr 2025 |
| 382 | Nichols,Edwin S Explorations Inc | Graham, TX 76450 | Oil & Gas Operator | Apr 2025 |
| 383 | Nijean, Inc. | Shawnee, OK 74802 | Oil & Gas Operator | Feb 2012 |
| 384 | Noonday Exploration, LLC | Tyler, TX 75711 | Oil & Gas Operator | Apr 2024 |
| 385 | North Central Oil Corp. | Houston, TX 77252 | Oil & Gas Operator | Dec 2005 |
| 386 | North Star Energy, Inc. | Strawn, TX 76475 | Oil & Gas Operator | Jan 2010 |
| 387 | Nutek Oil Inc | San Antonio, TX 78254 | Oil & Gas Operator | Feb 2006 |
| 388 | Ogog Operating, LLC | Dallas, TX 75367 | Oil & Gas Operator | Apr 2025 |
| 389 | Oilex Int'L Investments, Inc. | Luling, TX 78648 | Oil & Gas Operator | Apr 2025 |
| 390 | Okla. Magic Circle Energy Corp. | Shawnee, OK 74801 | Oil & Gas Operator | Jul 2004 |
| 391 | Olmos Partners, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Apr 2025 |
| 392 | Omber Petroleum & Energy Corp. | New Braunfels, TX 78131 | Oil & Gas Operator | Apr 2025 |
| 393 | Omimex Petroleum Inc | Fort Worth, TX 76120 | Oil & Gas Operator | Aug 2022 |
| 394 | Omni Operating Company(A) | Dallas, TX 75370 | Oil & Gas Operator | Apr 2025 |
| 395 | Origin Production Company, Inc. | New Braunfels, TX 78132 | Oil & Gas Operator | Apr 2025 |
| 396 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 397 | Overly Operating Co. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2013 |
| 398 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Apr 2025 |
| 399 | Pace Oil And Gas Company | Austin, TX 78715 | Oil & Gas Operator | Apr 2025 |
| 400 | Peak Energy Corporation | Plano, TX 75093 | Oil & Gas Operator | Oct 2018 |