| 201 | Lightning Oil Company | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 202 | Loin Energy Corporation | La Grange, TX 78945 | Oil & Gas Operator | May 2025 |
| 203 | Lonestar Operating, LLC | Houston, TX 77084 | Oil & Gas Operator | Nov 2022 |
| 204 | LTS Oil & Gas A | Lubbock, TX 79424 | Oil & Gas Operator | May 2025 |
| 205 | M IV Ops., Inc. | San Antonio, TX 78217 | Oil & Gas Operator | Mar 1998 |
| 206 | Magnum Engineering Company | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 207 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 208 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Mar 2025 |
| 209 | Mariah Energy Corp. | Austin, TX 78716 | Oil & Gas Operator | Apr 1999 |
| 210 | Martineau Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Jan 2025 |
| 211 | Matador Production Company | Dallas, TX 75240 | Oil & Gas Operator | May 2025 |
| 212 | Matrix Petroleum, LLC | Houston, TX 77077 | Oil & Gas Operator | May 2025 |
| 213 | May Investments, Inc. | New Boston, TX 75570 | Oil & Gas Operator | Aug 2003 |
| 214 | MB Energy, LLC | San Antonio, TX 78233 | Oil & Gas Operator | May 2025 |
| 215 | McCulliss Resources Co Inc | Littleton, CO 80161-3248 | Oil & Gas Operator | Jun 2009 |
| 216 | McDaniel Company, Inc., The | Dallas, TX 75230 | Oil & Gas Operator | May 2025 |
| 217 | McDay Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | May 2025 |
| 218 | McEna Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2005 |
| 219 | Merrion Oil & Gas Corp | Farmington, NM 87401 | Oil & Gas Operator | Mar 2025 |
| 220 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 221 | Mid Texas Natural Gas | Kyle, TX 78640 | Oil & Gas Operator | May 2019 |
| 222 | Miesch Exploration Corporation | Dallas, TX 75229 | Oil & Gas Operator | Nov 2002 |
| 223 | Millennium Petro-Physics, Inc. | Corpus Chrsti, TX 78480 | Oil & Gas Operator | May 2025 |
| 224 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 225 | Mina Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Feb 2012 |
| 226 | Miramar Petroleum, Inc. | Corpus Chrsti, TX 78463 | Oil & Gas Operator | Sep 2017 |
| 227 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | May 2025 |
| 228 | Mitsui E&P USA LLC | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 229 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 230 | Mobile Production Systems, Inc. | Austin, TX 78711 | Oil & Gas Operator | Feb 1995 |
| 231 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | May 2025 |
| 232 | Mohican Oil & Gas, L.L.C. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Apr 2013 |
| 233 | MPG Petroleum | San Antonio, TX 78217 | Oil & Gas Operator | Aug 2003 |
| 234 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 235 | Murphy Expl. & Prod. Co. - USA | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 236 | Murphy Exploration & Prod. Co. | Houston, TX 77094 | Oil & Gas Operator | Jun 2011 |
| 237 | MV Purchasing LLC | Wichita, KS 67206 | Oil & Gas Operator | Dec 2019 |
| 238 | Navajo Exploration, Inc. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | May 2025 |
| 239 | Neumin Production Company | Point Comfort, TX 77978 | Oil & Gas Operator | May 2025 |
| 240 | Newton Corp.,The | Dallas, TX 75251 | Oil & Gas Operator | May 2025 |
| 241 | Null, W. M. & San Patricio Corp. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Aug 1994 |
| 242 | Null, W.M. Operations, Inc. | Corpus Chrsti, TX 78475 | Oil & Gas Operator | Jun 2002 |
| 243 | Oilton Resources, Inc. | Laredo, TX 78041 | Oil & Gas Operator | May 2025 |
| 244 | Okla. Magic Circle Energy Corp. | Shawnee, OK 74801 | Oil & Gas Operator | Jul 2004 |
| 245 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 246 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 247 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Mar 2025 |
| 248 | Outline Oil Corp. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 249 | Overly Operating Co. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2013 |
| 250 | P.B. Blue Dot Properties | Wexford, PA 15090 | Oil & Gas Operator | May 2025 |
| 251 | Panther Creek Resources, LLC | Denver, CO 80202 | Oil & Gas Operator | May 2012 |
| 252 | Patterson, Ben M., Jr. | San Antonio, TX 78216 | Oil & Gas Operator | Mar 2003 |
| 253 | Payrock II, LLC | Houston, TX 77007 | Oil & Gas Operator | Dec 2020 |
| 254 | Pearl, Bill H. Productions, Inc. | Corpus Chrsti, TX 78460 | Oil & Gas Operator | May 2025 |
| 255 | Pearsall Partners | Dallas, TX 75201 | Oil & Gas Operator | Mar 1993 |
| 256 | Penroc Oil Corp. | Hobbs, NM 88241 | Oil & Gas Operator | Feb 2025 |
| 257 | Penrod Oil Company Of Texas, Inc | Milano, TX 76556 | Oil & Gas Operator | May 2025 |
| 258 | Perdido Energy, LLC | Houston, TX 77251 | Oil & Gas Operator | May 2025 |
| 259 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 260 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 261 | Petrolero Corp. | San Antonio, TX 78205 | Oil & Gas Operator | Feb 1998 |
| 262 | Petroleum Management, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | May 2025 |
| 263 | Petroquest Energy, L.L.C. | Lafayette, LA 70505 | Oil & Gas Operator | May 2025 |
| 264 | Phillips, Jack L. Co. | Gladewater, TX 75647 | Oil & Gas Operator | May 2025 |
| 265 | Pioneer Natural Res. USA, Inc. | Irving, TX 75038 | Oil & Gas Operator | May 2025 |
| 266 | Plains Marketing, LP | Cushing, OK 74023 | Oil Operator | Jan 2012 |
| 267 | Plano Petroleum Corporation | McKinney, TX 75070 | Oil & Gas Operator | Jan 2025 |
| 268 | Pressly Oil Interest, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 269 | Progas Properties, Inc. | New Braunfels, TX 78132 | Oil & Gas Operator | May 2025 |
| 270 | Proline Energy Resources Inc | Sugar Land, TX 77479 | Oil & Gas Operator | May 2025 |
| 271 | Pursuit Oil & Gas STX, LLC | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 272 | Pursuit Oil & Gas, LLC | Houston, TX 77024 | Gas Operator | Sep 2019 |
| 273 | PXP Gulf Coast Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 274 | PXP Texas Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2007 |
| 275 | Pyle Petroleum, Inc. | Tyler, TX 75703 | Oil & Gas Operator | May 2025 |
| 276 | Quest Research & Dev. Corp. | Weatherford, TX 76086 | Oil & Gas Operator | May 2025 |
| 277 | Quintana Minerals Corporation | Houston, TX 77002 | Oil & Gas Operator | Jan 2003 |
| 278 | Quintana Pet. Corp. | Refugio, TX 78377 | Oil & Gas Operator | Dec 2000 |
| 279 | Quintana Petroleum Services | Houston, TX 77253 | Oil & Gas Operator | Jul 1997 |
| 280 | R.D. Oil Company | Austin, TX 78755 | Oil & Gas Operator | May 2025 |
| 281 | Ram Operating Inc. | Browns, IL 62818 | Oil & Gas Operator | Aug 2008 |
| 282 | Regal Petroleum Services | Euless, TX 76039 | Oil & Gas Operator | Aug 2002 |
| 283 | Repsol Eagle Ford North, LLC | The Woodlands, TX 77381 | Oil & Gas Operator | Jul 2023 |
| 284 | Repsol Oil & Gas USA, LLC | The Woodlands, TX 77381 | Oil & Gas Operator | May 2025 |
| 285 | Rexcom, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 286 | Ridgemar Energy Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | May 2025 |
| 287 | Riley Exploration, LLC | Blanchard, OK 73010 | Oil & Gas Operator | May 2025 |
| 288 | Rim Operating, Inc. | Englewood, CO 80112 | Oil & Gas Operator | May 2025 |
| 289 | Rio Bravo Royalty Co. | Bandera, TX 78003 | Oil & Gas Operator | Aug 2003 |
| 290 | Rio Exploration Company | San Antonio, TX 78209 | Gas Operator | Dec 2005 |
| 291 | Rio-Tex, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 292 | Ritchie, H. G. Jr. | Taft, TX 78390 | Oil & Gas Operator | May 2025 |
| 293 | Rocc Operating, LLC | Houston, TX 77084 | Oil & Gas Operator | May 2025 |
| 294 | Roland Carlson LLC | Austin, TX 78705 | Gas Operator | May 2025 |
| 295 | Roma Oil And Gas, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 296 | Rosetta Resources Operating LP | San Antonio, TX 78216 | Oil & Gas Operator | May 2025 |
| 297 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 298 | Royal Oil & Gas Corp. | Indiana, PA 15701 | Oil & Gas Operator | Apr 2014 |
| 299 | Royal Petroleum Corp. | Dallas, TX 75229 | Oil & Gas Operator | Jan 2025 |
| 300 | Rutherford Oil Corporation | Houston, TX 77046 | Oil & Gas Operator | Jun 2019 |