| 301 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 302 | MRD Operating LLC | | Oil & Gas Operator | Dec 2016 |
| 303 | MRT Exploration Co | | Oil & Gas Operator | Feb 1983 |
| 304 | N Central Casing Pullers, Inc. | | Oil & Gas Operator | May 1994 |
| 305 | Nabors Drilling Company, Inc. | | Oil & Gas Operator | Sep 1977 |
| 306 | Nadel And Gussman Ruston, LLC | | Oil & Gas Operator | Dec 2024 |
| 307 | Nasser Oil & Gas, Inc. | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 1998 |
| 308 | Nelson Oil & Gas, Inc. | | Oil & Gas Operator | Aug 1995 |
| 309 | New Century Exploration, Inc. | Spring, TX 77379 | Oil & Gas Operator | Feb 2026 |
| 310 | Noram Field Services Corp. | | Oil Operator | Apr 1999 |
| 311 | Northeast Resources | | Oil & Gas Operator | Jan 1992 |
| 312 | O'Brien Energy Company | Shreveport, LA 71136 | Oil & Gas Operator | Sep 2019 |
| 313 | O'Brien Operating Company | Shreveport, LA 71164 | Oil & Gas Operator | Dec 2004 |
| 314 | O. B. Mobley | | Oil & Gas Operator | Jul 1989 |
| 315 | O. G., Inc. | | Oil & Gas Operator | Nov 1992 |
| 316 | Ocean Energy Inc | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 317 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2025 |
| 318 | Oracle Oil, LLC | | Oil & Gas Operator | Jul 2013 |
| 319 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 320 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Feb 2026 |
| 321 | Ozark Production Company, Inc. | | Oil & Gas Operator | Jan 2025 |
| 322 | Pacific Enterprises Oil Co USA | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 323 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 324 | Paloma Natural Gas, LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2024 |
| 325 | Par Minerals Corporation | Shreveport, LA 71101 | Oil & Gas Operator | Feb 2026 |
| 326 | Par Oil Corporation | | Oil & Gas Operator | Sep 1990 |
| 327 | Pearl Resources Inc. | | Oil & Gas Operator | Jul 1990 |
| 328 | Pend Oreille Oil & Gas Company | | Oil & Gas Operator | Sep 1989 |
| 329 | Pennzenergy Explor & Prod LLC | | Oil & Gas Operator | Dec 1999 |
| 330 | Pennzoil Exploration & Production Co. | Carthage, TX 75633 | Oil & Gas Operator | Mar 2008 |
| 331 | Peoples Energy Prod.-TX, L.P. | Houston, TX 77002 | Oil & Gas Operator | Sep 2007 |
| 332 | Petro-Chem Operating Company, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Feb 2026 |
| 333 | Petro-Lewis Corp. | | Oil & Gas Operator | Feb 1994 |
| 334 | Petro-Search, Inc. | | Oil Operator | Jul 1992 |
| 335 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 336 | Phillips Energy, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2018 |
| 337 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 338 | Phoenix Operating Company, Inc. | Shreveport, LA 71161 | Oil & Gas Operator | Mar 2015 |
| 339 | Phoenix Opr Co Inc-Oc Yacht 85 | | Oil Operator | Dec 1992 |
| 340 | Phoenix Opr Co Inc-Rvside '85 | | Oil Operator | Dec 1992 |
| 341 | Pinnacle Operating Company, Inc. | Shreveport, LA 71135 | Oil & Gas Operator | Feb 2026 |
| 342 | Placid Oil Company | Houston, TX 77227 | Oil & Gas Operator | Mar 2008 |
| 343 | Pogo Producing Company | Houston, TX 77002 | Oil & Gas Operator | Jan 2008 |
| 344 | Premier Natural Resources II,LLC | Tulsa, OK 74105 | Oil & Gas Operator | Feb 2015 |
| 345 | Pritchard Engineering | | Oil & Gas Operator | Mar 1989 |
| 346 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Nov 2025 |
| 347 | Quantent Energy Partners Operating LLC | | Gas Operator | Dec 2024 |
| 348 | Questar Expl. And Prod. Co. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jul 2011 |
| 349 | R & F Land Co., Inc. | | Oil & Gas Operator | Jan 2000 |
| 350 | R H Energy Co Inc | | Oil & Gas Operator | Sep 1989 |
| 351 | R360 Environmental Solutions Of La, LLC | | Oil Operator | Jan 2025 |
| 352 | Ralph L. Leaderbrand | | Oil & Gas Operator | Dec 1996 |
| 353 | Rauch, Shaw & Laird, Inc. | | Oil & Gas Operator | Mar 1995 |
| 354 | Rauch-Shaw Assoc. Inc. & Laird | | Oil & Gas Operator | Mar 1991 |
| 355 | Raybo, Inc. | | Oil Operator | Dec 1990 |
| 356 | Red River Gas Company | | Oil & Gas Operator | May 2000 |
| 357 | Red River Oil & Gas Inc. | | Oil & Gas Operator | May 2012 |
| 358 | Regency Field Services LLC | Dallas, TX 75201 | Oil Operator | Jul 2017 |
| 359 | Regency Intrastate Gas LLC | | Oil Operator | Feb 2009 |
| 360 | Reliant Energy Field SVS Inc. | | Oil Operator | Sep 2002 |
| 361 | Resources Investment Corp | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 362 | Riverstone Energy Operating, LLC | Houston, TX 77090 | Oil & Gas Operator | Feb 2026 |
| 363 | Riviera Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 364 | Roberson Farm Equipment, Inc. | | Oil Operator | Mar 1989 |
| 365 | Rocky Mount Gas Gathering,LLC | | Oil Operator | Apr 2001 |
| 366 | Rosbottom Production Corp | Shreveport, LA 71134 | Oil & Gas Operator | Dec 2017 |
| 367 | Rosewood Resources (Poc), Inc. | | Oil & Gas Operator | Dec 1984 |
| 368 | Rosewood Resources Inc | Dallas, TX 75201 | Oil & Gas Operator | Feb 2026 |
| 369 | S. G. Myers, Jr. | | Oil & Gas Operator | May 2005 |
| 370 | Sabine Corporation | Oklahoma City, OK 73116 | Oil & Gas Operator | Jul 1996 |
| 371 | Sammy D. Thrash | | Oil & Gas Operator | May 2012 |
| 372 | Sammy D. Thrash, LLC | | Oil & Gas Operator | May 2019 |
| 373 | Sample Exploration | | Oil & Gas Operator | Jul 2002 |
| 374 | Samson Contour Energy E&P, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Sep 2017 |
| 375 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2025 |
| 376 | San Miguel Oil & Gas, Inc. | | Oil & Gas Operator | Jan 1993 |
| 377 | Sandhill Production Inc | Shongaloo, LA 71072 | Oil & Gas Operator | Dec 2019 |
| 378 | Santa Fe Snyder Corporation | Houston, TX 77024 | Oil & Gas Operator | Oct 2000 |
| 379 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 380 | Seagull Mid-South Inc | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 381 | Seagull Operating Co., Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jan 2025 |
| 382 | Shaw-Laird, LLC | | Oil & Gas Operator | Jan 2017 |
| 383 | Shell Oil Co. | Houston, TX 77001 | Oil & Gas Operator | Jun 1985 |
| 384 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 385 | Shenandoah Oil Corporation | | Oil & Gas Operator | Jun 1979 |
| 386 | Shuler Drilling Co., Inc. | El Dorado, AR 71730 | Oil & Gas Operator | Jan 2025 |
| 387 | Shuler DRLG Co &Roy Guffey Oil | | Oil & Gas Operator | Sep 1992 |
| 388 | Simmons Oil Corp | | Oil Operator | Jan 1989 |
| 389 | Simpson Well Service, Inc. | | Oil Operator | Dec 1996 |
| 390 | Skinner Energy Management, Inc. | Shreveport, LA 71135 | Oil & Gas Operator | Jan 2011 |
| 391 | Sklar & Phillips Oil Co. | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2000 |
| 392 | Sklar Exploration Company LLC | Shreveport, LA 71101 | Oil & Gas Operator | Feb 2026 |
| 393 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Feb 2026 |
| 394 | Smackover Drilling Co. Inc. | Shreveport, LA 71105 | Oil & Gas Operator | Jan 2025 |
| 395 | Smith Operating And MGMT Co. | Shreveport, LA 71161 | Oil & Gas Operator | Jun 2023 |
| 396 | SND Operating, L.L.C. | Kilgore, TX 75663 | Oil & Gas Operator | Feb 2026 |
| 397 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 398 | Sonat Exploration Co. | Houston, TX 77251 | Oil & Gas Operator | Dec 2021 |
| 399 | Southern Management Services | | Oil Operator | May 2017 |
| 400 | Southern Star Operating, Inc. | | Oil & Gas Operator | Jun 2010 |