| 301 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 302 | Mina Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Feb 2012 |
| 303 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | May 2025 |
| 304 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 305 | Modena Operating LLC | Houston, TX 77057 | Oil & Gas Operator | May 2025 |
| 306 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | May 2025 |
| 307 | Mohican Oil & Gas, L.L.C. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Apr 2013 |
| 308 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 309 | Momentum Oil & Gas, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | May 2015 |
| 310 | Momentum Production Corp. | Baytown, TX 77521 | Oil & Gas Operator | May 2025 |
| 311 | Morningstar Gas, Inc. | Las Vegas, NV 89117 | Gas Operator | May 2025 |
| 312 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 313 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 314 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 315 | Mueller Exploration, Inc. | Portland, TX 78374 | Oil & Gas Operator | May 2025 |
| 316 | Mustang Oil & Gas Corporation | Wichita Falls, TX 76308 | Oil & Gas Operator | Jul 2021 |
| 317 | Nadcf Recovery Group, Inc. | Chapin, SC 29036 | Oil & Gas Operator | May 2025 |
| 318 | Navajo Exploration, Inc. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | May 2025 |
| 319 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Nov 2024 |
| 320 | Neuhaus, V. F. Properties, Inc. | Palmhurst, TX 78573 | Oil & Gas Operator | Dec 2022 |
| 321 | Neumin Production Company | Point Comfort, TX 77978 | Oil & Gas Operator | May 2025 |
| 322 | Newfield Exploration Company | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2017 |
| 323 | Newgulf Petroleum, LLC | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2017 |
| 324 | Newman Operating Company | Freer, TX 78357 | Oil & Gas Operator | Jun 2021 |
| 325 | Newton Corp.,The | Dallas, TX 75251 | Oil & Gas Operator | May 2025 |
| 326 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | May 2025 |
| 327 | Nordan Trust, The | San Antonio, TX 78205 | Oil & Gas Operator | Nov 2003 |
| 328 | Okie Operating Company, LTD. | Tulsa, OK 74103 | Oil & Gas Operator | May 2025 |
| 329 | Okla. Magic Circle Energy Corp. | Shawnee, OK 74801 | Oil & Gas Operator | Jul 2004 |
| 330 | Olsen Energy Inc. | Boerne, TX 78006 | Oil & Gas Operator | May 2025 |
| 331 | Omimex Petroleum Inc | Fort Worth, TX 76120 | Oil & Gas Operator | Aug 2022 |
| 332 | Opex Energy, LLC | Houston, TX 77042 | Oil & Gas Operator | Mar 2008 |
| 333 | Orx Resources, L.L.C. | Houston, TX 77067 | Oil & Gas Operator | May 2025 |
| 334 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 335 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Mar 2025 |
| 336 | Osborn,W.B. Oil & Gas Operations | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 337 | Overton Park Oil & Gas LP | Fort Worth, TX 76109 | Oil & Gas Operator | May 2025 |
| 338 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 339 | Pace Oil And Gas Company | Austin, TX 78715 | Oil & Gas Operator | May 2025 |
| 340 | Paladin-Hayes, L.L.C. | Austin, TX 78746 | Oil & Gas Operator | Dec 1999 |
| 341 | Palmer Petroleum Inc. | Shreveport, LA 71105 | Oil & Gas Operator | May 2025 |
| 342 | Panther Creek Resources, LLC | Denver, CO 80202 | Oil & Gas Operator | May 2012 |
| 343 | Paradis Investments, L.L.C. | Bellaire, TX 77401 | Oil Operator | Jun 2020 |
| 344 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 345 | Patterson Energy Corporation | Dallas, TX 75205 | Oil & Gas Operator | May 2025 |
| 346 | Pearl Energy, L.L.C. | Austin, TX 78746 | Oil & Gas Operator | Apr 2002 |
| 347 | Pearl, Bill H. Productions, Inc. | Corpus Chrsti, TX 78460 | Oil & Gas Operator | May 2025 |
| 348 | Pegasus Petroleum Corporation | Corpus Chrsti, TX 78476 | Oil & Gas Operator | May 2025 |
| 349 | Peoples Energy Prod.-TX, L.P. | Houston, TX 77002 | Oil & Gas Operator | Sep 2007 |
| 350 | Petra Oleum Corp. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 351 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 352 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 353 | Petrodome Operating, LLC | Houston, TX 77265 | Oil & Gas Operator | Jan 2025 |
| 354 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 355 | PG&E Resources Company | Houston, TX 77042 | Oil & Gas Operator | May 1995 |
| 356 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 357 | Philpott Oil & Gas Co Inc | Atwood, KS 67730 | Oil Operator | Aug 2010 |
| 358 | Pioneer Natural Res. USA, Inc. | Irving, TX 75038 | Oil & Gas Operator | May 2025 |
| 359 | Pitco Investments, LTD. | Scottsdale, AZ 85261 | Oil & Gas Operator | Jan 2013 |
| 360 | Plains Exploration & Prod. Co. | Houston, TX 77002 | Oil & Gas Operator | Jul 2013 |
| 361 | Platinum Oil & Gas, L.L.C. | San Juan, TX 78589 | Oil & Gas Operator | May 2025 |
| 362 | Pogo Producing Company LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 363 | Prevail Energy, Inc | Corpus Chrsti, TX 78469 | Oil & Gas Operator | May 2025 |
| 364 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | May 2025 |
| 365 | Proline Energy Resources Inc | Sugar Land, TX 77479 | Oil & Gas Operator | May 2025 |
| 366 | Prolithic Energy Company, L.P. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Aug 2002 |
| 367 | Pyle Petroleum | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Dec 1996 |
| 368 | Pyle Petroleum, Inc. | Tyler, TX 75703 | Oil & Gas Operator | May 2025 |
| 369 | Quintana Pet. Corp. | Refugio, TX 78377 | Oil & Gas Operator | Dec 2000 |
| 370 | Quisto Expl. & Production, L.C. | Sugar Land, TX 77478 | Oil & Gas Operator | Aug 1998 |
| 371 | Ram Operating Company, Inc. | Houston, TX 77002 | Oil & Gas Operator | Sep 2012 |
| 372 | Rand - Paulson Oil Company, Inc. | Houston, TX 77063 | Oil & Gas Operator | Feb 1999 |
| 373 | Rand Energy Company | Houston, TX 77063 | Oil & Gas Operator | May 2025 |
| 374 | Raptor Resources, Inc. | Austin, TX 78701 | Oil & Gas Operator | May 2025 |
| 375 | Redman Operating Company | Houston, TX 77042 | Oil & Gas Operator | May 2008 |
| 376 | Reh Energy, Inc. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | May 2025 |
| 377 | Remco Oil & Gas Production,Inc. | Rio Grande Ci, TX 78582 | Oil & Gas Operator | Nov 2021 |
| 378 | Resaca Resources, L.L.C. | Austin, TX 78746 | Oil & Gas Operator | May 2025 |
| 379 | Reserve Operating Corp. | Houston, TX 77040 | Oil & Gas Operator | May 2025 |
| 380 | Resource Expl & Prod, Inc. | Salado, TX 76571 | Oil & Gas Operator | May 2025 |
| 381 | Ress Production Co. | Farmington, NM 87499 | Oil & Gas Operator | May 2025 |
| 382 | Reveille Resources | Houston, TX 77084 | Oil & Gas Operator | Apr 2011 |
| 383 | Reveille Resources (Texas), Inc. | Houston, TX 77084 | Oil & Gas Operator | Jan 2013 |
| 384 | Richman Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Jul 2006 |
| 385 | Ricochet Energy, Inc. | San Antonio, TX 78258 | Oil & Gas Operator | May 2025 |
| 386 | Riddle Engineering Corp. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2011 |
| 387 | Ridge Petroleum Inc. | Tyler, TX 75701 | Oil & Gas Operator | May 2025 |
| 388 | Rincon Petroleum Corporation | Corpus Chrsti, TX 78427 | Oil & Gas Operator | May 2025 |
| 389 | Rlu Oil & Gas, Inc. | Devine, TX 78016 | Oil & Gas Operator | May 2025 |
| 390 | Rlu Operating, LLC | Devine, TX 78016 | Oil & Gas Operator | May 2025 |
| 391 | Rme Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Nov 2016 |
| 392 | RNS Oil Co. | Rio Grande Ci, TX 78582 | Oil Operator | May 2025 |
| 393 | Roc Operating, Inc. | Plano, TX 75093 | Oil & Gas Operator | Oct 2008 |
| 394 | Rock Energy Resources, Inc. | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 395 | Rodessa Operating Company | Corpus Chrsti, TX 78426 | Oil & Gas Operator | May 2025 |
| 396 | Ross Gas And Oil, LTD. Co. | Dripping SPGS, TX 78620 | Oil & Gas Operator | May 2025 |
| 397 | Rowden Oil & Gas, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Jun 2023 |
| 398 | Royal Oil & Gas Corp. | Indiana, PA 15701 | Oil & Gas Operator | Apr 2014 |
| 399 | Royal Production Company, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 400 | Rse, Inc. | Houston, TX 77077 | Oil & Gas Operator | Sep 2000 |