| 301 | Nelson Oil & Gas, Inc. | | Oil & Gas Operator | Aug 1995 |
| 302 | New Century Exploration, Inc. | Spring, TX 77379 | Oil & Gas Operator | Jul 2025 |
| 303 | Noram Field Services Corp. | | Oil Operator | Apr 1999 |
| 304 | Northeast Resources | | Oil & Gas Operator | Jan 1992 |
| 305 | O'Brien Energy Company | Shreveport, LA 71136 | Oil & Gas Operator | Sep 2019 |
| 306 | O'Brien Operating Company | | Oil & Gas Operator | Dec 2004 |
| 307 | O. B. Mobley | | Oil & Gas Operator | Jul 1989 |
| 308 | O. G., Inc. | | Oil & Gas Operator | Nov 1992 |
| 309 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 310 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 311 | Oracle Oil, LLC | | Oil & Gas Operator | Jul 2013 |
| 312 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 313 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 314 | Ozark Production Company, Inc. | | Oil & Gas Operator | Jan 2025 |
| 315 | Pacific Enterprises Oil Co USA | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 316 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 317 | Paloma Natural Gas, LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2024 |
| 318 | Par Minerals Corporation | Shreveport, LA 71101 | Oil & Gas Operator | Jul 2025 |
| 319 | Par Oil Corporation | | Oil & Gas Operator | Sep 1990 |
| 320 | Pearl Resources Inc. | | Oil & Gas Operator | Jul 1990 |
| 321 | Pend Oreille Oil & Gas Company | | Oil & Gas Operator | Sep 1989 |
| 322 | Pennzenergy Explor & Prod LLC | | Oil & Gas Operator | Dec 1999 |
| 323 | Pennzoil Exploration & Production Co. | Carthage, TX 75633 | Oil & Gas Operator | Mar 2008 |
| 324 | Peoples Energy Prod.-TX, L.P. | Houston, TX 77002 | Oil & Gas Operator | Sep 2007 |
| 325 | Petro-Chem Operating Company, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jul 2025 |
| 326 | Petro-Lewis Corp. | | Oil & Gas Operator | Feb 1994 |
| 327 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 328 | Petrosearch, Inc. | | Oil Operator | Jul 1992 |
| 329 | Phillips Energy, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2018 |
| 330 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 331 | Phoenix Operating Company, Inc. | Shreveport, LA 71161 | Oil & Gas Operator | Mar 2015 |
| 332 | Phoenix Opr Co Inc-Oc Yacht 85 | | Oil Operator | Dec 1992 |
| 333 | Phoenix Opr Co Inc-Rvside '85 | | Oil Operator | Dec 1992 |
| 334 | Pinnacle Operating Company, Inc. | Shreveport, LA 71135 | Oil & Gas Operator | Jul 2025 |
| 335 | Placid Oil Company | Houston, TX 77227 | Oil & Gas Operator | Mar 2008 |
| 336 | Pogo Producing Company | Houston, TX 77002 | Oil & Gas Operator | Jan 2008 |
| 337 | Premier Natural Resources II,LLC | Tulsa, OK 74105 | Oil & Gas Operator | Feb 2015 |
| 338 | Pritchard Engineering | | Oil & Gas Operator | Mar 1989 |
| 339 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Apr 2025 |
| 340 | Quantent Energy Partners Operating LLC | | Gas Operator | Dec 2024 |
| 341 | Questar Expl. And Prod. Co. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jul 2011 |
| 342 | R H Energy Co Inc | | Oil & Gas Operator | Sep 1989 |
| 343 | R. & F. Land Company | | Oil & Gas Operator | Jan 2000 |
| 344 | R360 Environmental Solutions Of La, LLC | | Oil Operator | Jan 2025 |
| 345 | Ralph L. Leaderbrand | | Oil & Gas Operator | Dec 1996 |
| 346 | Rauch, Shaw & Laird, Inc. | | Oil & Gas Operator | Mar 1995 |
| 347 | Rauch-Shaw Assoc. Inc. & Laird | | Oil & Gas Operator | Mar 1991 |
| 348 | Raybo, Inc. | | Oil Operator | Dec 1990 |
| 349 | Red River Oil & Gas Inc. | | Oil & Gas Operator | May 2012 |
| 350 | Regency Field Services LLC | Dallas, TX 75201 | Oil Operator | Jul 2017 |
| 351 | Regency Intrastate Gas LLC | | Oil Operator | Feb 2009 |
| 352 | Reliant Energy Field SVS Inc. | | Oil Operator | Sep 2002 |
| 353 | Resources Investment Corp | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 354 | Riverstone Energy Operating, LLC | Houston, TX 77090 | Oil & Gas Operator | Jul 2025 |
| 355 | Riviera Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 356 | Roberson Farm Equipment, Inc. | | Oil Operator | Mar 1989 |
| 357 | Rocky Mount Gas Gathering,LLC | | Oil Operator | Apr 2001 |
| 358 | Rosbottom Production Corp | Shreveport, LA 71134 | Oil & Gas Operator | Dec 2017 |
| 359 | Rosewood Resources (Poc), Inc. | | Oil & Gas Operator | Dec 1984 |
| 360 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Jul 2025 |
| 361 | S. G. Myers, Jr. | | Oil & Gas Operator | May 2005 |
| 362 | Sabine Corporation | Oklahoma City, OK 73116 | Oil & Gas Operator | Jul 1996 |
| 363 | Sammy D. Thrash | | Oil & Gas Operator | May 2012 |
| 364 | Sammy D. Thrash, LLC | | Oil & Gas Operator | May 2019 |
| 365 | Sample Exploration | | Oil & Gas Operator | Jul 2002 |
| 366 | Samson Contour Energy E&P, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Sep 2017 |
| 367 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 368 | San Miguel Oil & Gas, Inc. | | Oil & Gas Operator | Jan 1993 |
| 369 | Sandhill Production Inc | Shongaloo, LA 71072 | Oil & Gas Operator | Dec 2019 |
| 370 | Santa Fe Snyder Corporation | Houston, TX 77024 | Oil & Gas Operator | Oct 2000 |
| 371 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 372 | Seagull Mid-South Inc | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 373 | Seagull Operating Co., Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jan 2025 |
| 374 | Shaw-Laird, LLC | | Oil & Gas Operator | Jan 2017 |
| 375 | Shell Oil Company | Houston, TX 77210 | Oil & Gas Operator | Apr 2015 |
| 376 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 377 | Shenandoah Oil Corporation | | Oil & Gas Operator | Jun 1979 |
| 378 | Shuler Drilling Co., Inc. | El Dorado, AR 71730 | Oil & Gas Operator | Jan 2025 |
| 379 | Simmons Oil Corporation | | Oil Operator | Jan 1989 |
| 380 | Simpson Well Service, Inc. | | Oil Operator | Dec 1996 |
| 381 | Skinner Energy Management, Inc. | Shreveport, LA 71135 | Oil & Gas Operator | Jan 2011 |
| 382 | Sklar & Phillips Oil Co. | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2000 |
| 383 | Sklar Exploration Company LLC | Shreveport, LA 71101 | Oil & Gas Operator | Jul 2025 |
| 384 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Jul 2025 |
| 385 | Smackover Drilling Company Inc | Shreveport, LA 71104 | Oil & Gas Operator | Dec 2024 |
| 386 | Smith Operating And MGMT Co. | Shreveport, LA 71161 | Oil & Gas Operator | Jun 2023 |
| 387 | SND Operating, L.L.C. | Kilgore, TX 75663 | Oil & Gas Operator | Jul 2025 |
| 388 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 389 | Sonat Exploration Co. | Houston, TX 77251 | Oil & Gas Operator | Dec 2021 |
| 390 | Southern Management Services | | Oil Operator | May 2017 |
| 391 | Southern Star Operating, Inc. | | Oil & Gas Operator | Jun 2010 |
| 392 | Southwest Operating Inc. | | Oil & Gas Operator | Dec 2024 |
| 393 | Southwestern Electric Power Co | Dallas, TX 75266 | Oil & Gas Operator | Dec 1989 |
| 394 | Special Energy Corporation | Stillwater, OK 74076 | Oil & Gas Operator | Jul 2025 |
| 395 | Spicy Daugx Operators Louisiana LLC | | Oil & Gas Operator | Nov 2024 |
| 396 | St. Mary Land & Exploration Co | Denver, CO 80201 | Oil & Gas Operator | Jun 2010 |
| 397 | Story Oil And Gas Inc | Magnolia, AR 71753 | Oil & Gas Operator | Jan 2025 |
| 398 | Stroud Petroleum, Inc. | Shreveport, LA 71162 | Oil & Gas Operator | Jul 2025 |
| 399 | Suburban Propane Expl Co, Inc. | | Oil & Gas Operator | Jun 1983 |
| 400 | Suburban Propane Gas Corp. | | Oil & Gas Operator | Sep 1980 |