| 301 | Manti Exploration Operating LLC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Feb 2015 |
| 302 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | Jul 2025 |
| 303 | Marathon Oil Ef LLC | Houston, TX 77252 | Oil & Gas Operator | Jul 2025 |
| 304 | Mark IV Energy | San Antonio, TX 78213 | Oil & Gas Operator | Apr 1993 |
| 305 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 306 | Maverick Energy & Dev. Corp. | Austin, TX 78746 | Oil & Gas Operator | Jul 2025 |
| 307 | McCombs Energy LLC | Houston, TX 77056 | Oil & Gas Operator | Jan 2006 |
| 308 | McGowen Resources Co., Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2003 |
| 309 | McLain Exploration, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Mar 2008 |
| 310 | McLeod, George L. Inc. | Houston, TX 77079 | Oil & Gas Operator | Sep 2002 |
| 311 | Mego Resources, LLC | Taft, TX 78390 | Oil & Gas Operator | Jul 2025 |
| 312 | Merta, Mike | Alice, TX 78333 | Oil & Gas Operator | Aug 2005 |
| 313 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 314 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 315 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2025 |
| 316 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 317 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 318 | Mo-Jon, Inc. | Edroy, TX 78352 | Oil & Gas Operator | May 1999 |
| 319 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 320 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |
| 321 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Jul 2025 |
| 322 | Montgomery Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2007 |
| 323 | Morgan Enterprises, Inc. | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 324 | Moy, Gary | Falls City, TX 78113 | Oil & Gas Operator | Nov 1998 |
| 325 | MPG Petroleum | San Antonio, TX 78217 | Oil & Gas Operator | Aug 2003 |
| 326 | MPG Petroleum, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2025 |
| 327 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 328 | Munoco Co. | El Dorado, AR 71730 | Oil & Gas Operator | Jul 2021 |
| 329 | Munson, David M. Inc. | Dallas, TX 75251 | Oil & Gas Operator | Jul 2025 |
| 330 | Murphy Expl. & Prod. Co. - USA | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 331 | Murphy Exploration & Prod. Co. | Houston, TX 77094 | Oil & Gas Operator | Jun 2011 |
| 332 | Murphy Exploration & Production | Houston, TX 77024 | Oil Operator | Dec 2024 |
| 333 | Nails Operating Company LLC | Hondo, TX 78861 | Oil Operator | Jul 2025 |
| 334 | Natural Reserves Group, Inc. | Houston, TX 77057 | Oil & Gas Operator | Jun 1993 |
| 335 | NBL Permian LLC | Houston, TX 77070 | Oil & Gas Operator | Aug 2018 |
| 336 | Ncey Holdings, LLC | Houston, TX 77056 | Oil & Gas Operator | Jun 2013 |
| 337 | New Horizon Investments LTD. | George West, TX 78022 | Oil & Gas Operator | Jul 2025 |
| 338 | Newfield Exploration Company | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2017 |
| 339 | Newgulf Petroleum, LLC | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2017 |
| 340 | Newman Operating Company | Freer, TX 78357 | Oil & Gas Operator | Jun 2021 |
| 341 | Nexen Petroleum U.S.A. Inc. | Houston, TX 77024 | Oil & Gas Operator | Jul 2012 |
| 342 | Nitro Oil & Gas, LLC | Cuero, TX 77954 | Oil & Gas Operator | Jul 2025 |
| 343 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Jul 2025 |
| 344 | Nueces Minerals Company | Dallas, TX 75251 | Oil & Gas Operator | May 2021 |
| 345 | Nupower Energy, LLC | Houston, TX 77058 | Oil & Gas Operator | Jul 2025 |
| 346 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 347 | Oilton Resources, Inc. | Laredo, TX 78041 | Oil & Gas Operator | Jul 2025 |
| 348 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | Jul 2025 |
| 349 | Omega Energy, LLC | Corpus Chrsti, TX 78418 | Oil & Gas Operator | Jul 2025 |
| 350 | Orca Operating Company LLC | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 351 | Orion Energen Inc. | Austin, TX 78731 | Oil & Gas Operator | Jul 2023 |
| 352 | Orx Resources, L.L.C. | Houston, TX 77067 | Oil & Gas Operator | Jul 2025 |
| 353 | Outline Oil Company LLC | Beeville, TX 78104 | Oil Operator | Jul 2025 |
| 354 | Overly Operating Co. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2013 |
| 355 | P. R. L. Oil Company | Albany, TX 76430 | Oil & Gas Operator | Apr 2008 |
| 356 | Pace Oil And Gas Company | Austin, TX 78715 | Oil & Gas Operator | Jul 2025 |
| 357 | Pace Production Co. | San Angelo, TX 76902 | Oil & Gas Operator | Jul 2025 |
| 358 | Padon, Frank B. Oil Oper., Inc. | Houston, TX 77227 | Oil & Gas Operator | Nov 1998 |
| 359 | Paisano Minerals Company | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Aug 2003 |
| 360 | Paleo Oil Company LLC | Corpus Chrsti, TX 78411 | Oil & Gas Operator | Jul 2025 |
| 361 | Palmer Petroleum Inc. | Shreveport, LA 71105 | Oil & Gas Operator | Jul 2025 |
| 362 | Paloma Operating, LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2025 |
| 363 | Paradis Investments, L.L.C. | Bellaire, TX 77401 | Oil Operator | Jun 2020 |
| 364 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 365 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 366 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 367 | Patterson Energy Corporation | Dallas, TX 75205 | Oil & Gas Operator | Jul 2025 |
| 368 | Patterson, Ben M., Jr. | San Antonio, TX 78216 | Oil & Gas Operator | Mar 2003 |
| 369 | Payrock II, LLC | Houston, TX 77007 | Oil & Gas Operator | Dec 2020 |
| 370 | Pearl, Bill H. Productions, Inc. | Corpus Chrsti, TX 78460 | Oil & Gas Operator | Jul 2025 |
| 371 | Pedeco, Inc. | Casper, WY 82601 | Oil & Gas Operator | Mar 2008 |
| 372 | Pegasus Operating, Inc. | Coldspring, TX 77331 | Oil & Gas Operator | Jul 2025 |
| 373 | Pentad Development Corp. (A) | Dallas, TX 75201 | Oil & Gas Operator | Mar 1993 |
| 374 | Perdido Energy, LLC | Houston, TX 77251 | Oil & Gas Operator | Jul 2025 |
| 375 | Petra Oleum Corp. | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 376 | Petro-Guard Production,L.L.C. | Houston, TX 77063 | Oil & Gas Operator | Dec 2024 |
| 377 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 378 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | Jul 2025 |
| 379 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 380 | Petrolero Corp. | San Antonio, TX 78205 | Oil & Gas Operator | Feb 1998 |
| 381 | Petroleum Production Engineering | Fulton, TX 78358 | Oil Operator | Feb 2019 |
| 382 | Petrotx Operating, LLC | Kingwood, TX 77339 | Oil & Gas Operator | Jul 2025 |
| 383 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 384 | Phoenix Fund, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | Jun 2000 |
| 385 | Pintex Operating Inc. | Corpus Chrsti, TX 78478 | Oil & Gas Operator | Feb 2005 |
| 386 | Pioneer Exploration Company | Houston, TX 77090 | Oil & Gas Operator | May 2025 |
| 387 | Pioneer Exploration, LLC | Houston, TX 77090 | Oil & Gas Operator | May 2025 |
| 388 | Pioneer Exploration, LTD. | Houston, TX 77090 | Oil & Gas Operator | Sep 2008 |
| 389 | Pioneer Natural Res. USA, Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |
| 390 | Pioneer Resources Producing, L.P | Irving, TX 75039 | Oil & Gas Operator | Feb 2001 |
| 391 | Placer Oil Co. | Sugar Land, TX 77479 | Oil & Gas Operator | Apr 2008 |
| 392 | Placid Oil Company | Houston, TX 77227 | Oil & Gas Operator | Mar 2008 |
| 393 | Plains Marketing, LP | Cushing, OK 74023 | Oil Operator | Jan 2012 |
| 394 | Plains Production Inc | Wichita Falls, TX 76308 | Oil & Gas Operator | Dec 1995 |
| 395 | Pmo | Garland, TX 75040 | Oil & Gas Operator | Feb 2018 |
| 396 | Portal Energy Corporation | Dallas, TX 75201 | Oil & Gas Operator | Mar 1993 |
| 397 | Preferred Pipeline Corp. | Victoria, TX 77902 | Oil & Gas Operator | Jun 2025 |
| 398 | Premier Operating Company | Tulsa, OK 74153 | Gas Operator | Nov 1996 |
| 399 | Premium Exploration Company | Early, TX 76803 | Oil & Gas Operator | Jul 2025 |
| 400 | Primera Energy, LLC | Longview, TX 75606 | Oil & Gas Operator | Mar 2016 |