| 301 | Marion Corporation | | Oil & Gas Operator | Jan 2001 |
| 302 | Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Feb 2026 |
| 303 | Marsh Operating Company | Dallas, TX 75221 | Oil & Gas Operator | Dec 2025 |
| 304 | Marshall Oil Corporation | Oklahoma City, OK 73154 | Oil & Gas Operator | Apr 2017 |
| 305 | Matador E & P Company Inc | | Oil & Gas Operator | May 2020 |
| 306 | Maverick Brothers Resources LLC | Enid, OK 73701 | Oil & Gas Operator | Jan 2026 |
| 307 | McNic Oil & Gas Midcontinent | Oklahoma City, OK 73154-0526 | Oil & Gas Operator | May 2024 |
| 308 | Meade Energy Corporation | Oklahoma City, OK 73118-4015 | Oil & Gas Operator | Feb 2026 |
| 309 | Meadowbrook Oil Corporation Of Ok Inc | Del City, OK 73115-3608 | Oil & Gas Operator | Feb 2026 |
| 310 | Mep Operating LLC | Houston, TX 77056-2733 | Oil & Gas Operator | Aug 2025 |
| 311 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 312 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Apr 2026 |
| 313 | Mge Resources, Inc. | Perryton, TX 79070 | Oil & Gas Operator | Jan 2026 |
| 314 | Mid Center Oil Company | | Oil & Gas Operator | Mar 2014 |
| 315 | Mid-Con Central Expl Co | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2014 |
| 316 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2026 |
| 317 | Midland TMG Inc. | Midland, TX 79705 | Oil & Gas Operator | Apr 2017 |
| 318 | Midnight Hour LLC | Enid, OK 73702 | Oil & Gas Operator | Apr 2020 |
| 319 | Mija LLC | Oklahoma City, OK 73151 | Oil & Gas Operator | Feb 2026 |
| 320 | Milmac Operating Company | Lubbock, TX 79408-2976 | Oil & Gas Operator | Sep 2004 |
| 321 | Mogo Operating, LLC | Norman, OK 73069 | Oil & Gas Operator | Feb 2026 |
| 322 | Monroe Natural Gas Inc | Norman, OK 73071 | Oil & Gas Operator | Feb 2026 |
| 323 | Moore Richard L | Morris, OK 74445 | Oil Operator | Aug 2013 |
| 324 | Morrison Oil Company | Bartlesville, OK 74003 | Oil Operator | Mar 2015 |
| 325 | MT Energy LLC | Waskom, TX 75692 | Oil & Gas Operator | Apr 2026 |
| 326 | Muirfield Resources Company | Tulsa, OK 74101-3166 | Oil & Gas Operator | Jun 2024 |
| 327 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 328 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Apr 2026 |
| 329 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 330 | Nadel And Gussman LLC | Tulsa, OK 74119 | Oil & Gas Operator | Apr 2026 |
| 331 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 332 | National Oil Company | Garden City, KS 67846 | Oil & Gas Operator | Jun 2024 |
| 333 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 334 | Nbi Services, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | Apr 2026 |
| 335 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Aug 2025 |
| 336 | Neok Production Company LLC | Nowata, OK 74048 | Oil & Gas Operator | Feb 2026 |
| 337 | Nexstreem Corporation | | Oil & Gas Operator | Dec 2020 |
| 338 | Nject Disposal LLC | Houston, TX 77027 | Oil Operator | Mar 2017 |
| 339 | NM&O Operating Company | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2025 |
| 340 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Apr 2026 |
| 341 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Apr 2026 |
| 342 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | Apr 2026 |
| 343 | Nortex Gas & Oil Co | Tulsa, OK 74135 | Oil & Gas Operator | Sep 1993 |
| 344 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Apr 2026 |
| 345 | Notting Hill Energy LLC | Fort Worth, TX 76101 | Oil & Gas Operator | Apr 2026 |
| 346 | Nova Energy Corporation | Denver, CO 80201 | Oil & Gas Operator | Jun 2003 |
| 347 | Nye Oil Company | Oklahoma City, OK 73118-1245 | Oil & Gas Operator | Jun 2004 |
| 348 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 349 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 350 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 351 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Jan 2026 |
| 352 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Feb 2026 |
| 353 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 354 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 355 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 356 | Oneok Gas Transportation Co | Tulsa, OK 74121-2089 | Oil & Gas Operator | Oct 2014 |
| 357 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 358 | Opal Operating Company LLC | Edmond, OK 73013 | Oil & Gas Operator | Apr 2026 |
| 359 | Overflow Energy, LLC | Perryton, TX 79070 | Oil & Gas Operator | Apr 2026 |
| 360 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Feb 2026 |
| 361 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Apr 2026 |
| 362 | Oxley Petroleum | Tulsa, OK 74119-3609 | Oil & Gas Operator | Jan 2020 |
| 363 | Oxley Petroleum Company | Oklahoma City, OK 73118-1044 | Oil & Gas Operator | Sep 2017 |
| 364 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Apr 2026 |
| 365 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 366 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 367 | Paloma Operating Co Inc | Houston, TX 77002-5220 | Oil & Gas Operator | Feb 2026 |
| 368 | Pardee Production Co. | Skiatook, OK 74070 | Oil & Gas Operator | Mar 2021 |
| 369 | Park Avenue Exploration Corp | Oklahoma City, OK 73102-5604 | Oil & Gas Operator | Sep 2011 |
| 370 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 371 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 372 | Payne Exploration Company | Crescent, OK 73028 | Oil & Gas Operator | Jan 2026 |
| 373 | Penn VIrginia MC Operating Co LLC | Houston, TX 77084-7213 | Oil & Gas Operator | Sep 2025 |
| 374 | Pennzoil Company | Midland, TX 79710-0090 | Oil & Gas Operator | Mar 2000 |
| 375 | Pennzoil Explor & Prod Co | Houston, TX 77002 | Oil & Gas Operator | Mar 2000 |
| 376 | Petro Speed Inc | Norman, OK 73069-8116 | Oil & Gas Operator | Mar 2015 |
| 377 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 378 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 379 | Petroleum Investment Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 1998 |
| 380 | Petroleum Properties MGMT. Co. | Oklahoma City, OK 73118 | Oil & Gas Operator | Dec 2014 |
| 381 | Petromark Energy LLC | Oklahoma City, OK 73116-7634 | Oil & Gas Operator | Jun 2000 |
| 382 | Petroquest Energy, L.L.C. | Lafayette, LA 70505 | Oil & Gas Operator | Apr 2026 |
| 383 | Philcon Development Co. | Amarillo, TX 79101 | Oil & Gas Operator | Sep 2014 |
| 384 | Pioneer Resources Prod LP | Irving, TX 75039-3745 | Oil & Gas Operator | Feb 2005 |
| 385 | Piper Operating LLC | Stigler, OK 74462 | Oil & Gas Operator | Feb 2026 |
| 386 | Pitco Production Company | Tulsa, OK 74170-2320 | Oil & Gas Operator | May 2013 |
| 387 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 388 | Plymouth Exploration LLC | Tulsa, OK 74119-1031 | Oil & Gas Operator | Dec 2025 |
| 389 | Pogo Producing Company LLC | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 390 | Powerline Energy Corporation | Arlington, TX 76015 | Oil & Gas Operator | Apr 2026 |
| 391 | Prentice, Napier & Green, Inc. | Oklahoma City, OK 73142 | Oil & Gas Operator | Feb 2026 |
| 392 | Presidio Petroleum LLC | Canadian, TX 79014 | Oil & Gas Operator | Apr 2026 |
| 393 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2026 |
| 394 | Primary Natural Resources III LLC | Tulsa, OK 74136-6351 | Oil & Gas Operator | Jan 2026 |
| 395 | Primary Natural Resources Inc. | Tulsa, OK 74136-6351 | Oil & Gas Operator | Mar 2023 |
| 396 | Primexx Operating Corporation | Dallas, TX 75206 | Oil & Gas Operator | Mar 2024 |
| 397 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 398 | Prospective Investment & Trading | Scottsdale, AZ 85261-4190 | Oil & Gas Operator | Jun 2016 |
| 399 | Proven Reserves Management, Inc. | Dallas, TX 75370 | Oil & Gas Operator | Jan 2026 |
| 400 | Pyro Energy Corp | Kingwood, TX 77339-2102 | Oil & Gas Operator | Mar 1998 |