| 301 | McKenzie Petroleum Company | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 302 | McKinney Operating Company | Canadian, TX 79014 | Gas Operator | May 2002 |
| 303 | McNic Oil & Gas Midcontinent | Oklahoma City, OK 73154-0526 | Oil & Gas Operator | May 2024 |
| 304 | Meade Energy Corporation | Oklahoma City, OK 73118-4015 | Oil & Gas Operator | Feb 2026 |
| 305 | Medallion Petroleum, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2015 |
| 306 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 307 | Merex Resources, Inc. | Amarillo, TX 79159 | Oil & Gas Operator | Sep 2019 |
| 308 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Apr 2026 |
| 309 | Merrick Ward S Inc | Ardmore, OK 73402 | Oil & Gas Operator | Feb 2001 |
| 310 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 311 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Apr 2026 |
| 312 | Mid-Con Energy Operating, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | May 2020 |
| 313 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2026 |
| 314 | Middle Bay Production Co. Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2014 |
| 315 | Midgard Energy Company | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2014 |
| 316 | Midwestern Exploration Company | Edmond, OK 73013 | Oil & Gas Operator | May 2025 |
| 317 | Mikco Inc | Tulsa, OK 74133 | Oil & Gas Operator | May 2001 |
| 318 | Montgomery Exploration Co LTD | Dallas, TX 75204-2634 | Oil & Gas Operator | Jan 2026 |
| 319 | Morrison International Energy Inc | Oklahoma City, OK 73189-0537 | Oil & Gas Operator | Feb 2025 |
| 320 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Jan 2026 |
| 321 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 322 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Apr 2026 |
| 323 | N L S Inc | Kimberling City, MO 65686 | Oil & Gas Operator | Aug 2016 |
| 324 | Nadel And Gussman LLC | Tulsa, OK 74119 | Oil & Gas Operator | Apr 2026 |
| 325 | National Cooperative RFG Assoc | McPherson, KS 67460-1404 | Oil & Gas Operator | Oct 2025 |
| 326 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 327 | National Oil Co Ohio The | Columbus, OH 43215 | Oil & Gas Operator | Sep 1999 |
| 328 | National Oil Company | Garden City, KS 67846 | Oil & Gas Operator | Jun 2024 |
| 329 | Natural Gas Anadarko Company | Perryton, TX 79070 | Oil & Gas Operator | Apr 2026 |
| 330 | Natural Gas Compression Corp | Cleveland, OK 74020 | Oil & Gas Operator | Jan 2025 |
| 331 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 332 | Neas Operating | Pampa, TX 79065 | Oil & Gas Operator | Oct 2011 |
| 333 | New London Oil Inc. | Houston, TX 77253 | Oil & Gas Operator | Aug 2002 |
| 334 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Apr 2026 |
| 335 | Novy Oil & Gas, Inc. | Goddard, KS 67052 | Oil & Gas Operator | Feb 2026 |
| 336 | O'Brien Energy Resources Corp | Portsmouth, NH 03801 | Oil & Gas Operator | Apr 2026 |
| 337 | O'Neill Properties, LTD. | Midland, TX 79702 | Oil & Gas Operator | Apr 2026 |
| 338 | Oakland Petroleum Oper Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2026 |
| 339 | Oexco, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2015 |
| 340 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Apr 2026 |
| 341 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 342 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Jan 2026 |
| 343 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 344 | Oky Investments, Inc. | Edmond, OK 73013 | Oil & Gas Operator | Sep 2021 |
| 345 | Olympia Oil Inc | Edmond, OK 73083-7088 | Oil & Gas Operator | Jul 2020 |
| 346 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 347 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 348 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 349 | Onshore Royalties LLC | Houston, TX 77269 | Oil & Gas Operator | Feb 2026 |
| 350 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 351 | Oxley Petroleum | Tulsa, OK 74119-3609 | Oil & Gas Operator | Jan 2020 |
| 352 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Apr 2026 |
| 353 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Apr 2026 |
| 354 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 355 | Pal Energy LLC | Guymon, OK 73942-1950 | Gas Operator | Aug 2009 |
| 356 | Pal Kids Inc | Coronado, CA 92118 | Oil & Gas Operator | Nov 2000 |
| 357 | Panada Exploration, Inc. | Tulsa, OK 74135 | Oil & Gas Operator | Jun 1996 |
| 358 | Panenergy Services Inc | Houston, TX 77525 | Oil & Gas Operator | May 2001 |
| 359 | Panhandle Eastern Pipeline Company LP | Houston, TX 77002-6803 | Oil & Gas Operator | Oct 1999 |
| 360 | Pantera Energy Company | Amarillo, TX 79101 | Oil & Gas Operator | Apr 2026 |
| 361 | Paradox Petroleum Company | Amarillo, TX 79114-7587 | Oil & Gas Operator | Dec 1998 |
| 362 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 363 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 364 | Patrick RJ Operating Co | Liberal, KS 67905-1157 | Oil & Gas Operator | Nov 2014 |
| 365 | Payne Exploration Company | Crescent, OK 73028 | Oil & Gas Operator | Jan 2026 |
| 366 | Payne W C Family Trust | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Mar 2015 |
| 367 | Pennmark Resources Company | Edmond, OK 73013 | Oil & Gas Operator | Feb 2026 |
| 368 | Pepin Oil Co | Stillwater, OK 74076 | Oil & Gas Operator | Oct 2013 |
| 369 | Pet-Ex Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Dec 2025 |
| 370 | Petro Speed Inc | Norman, OK 73069-8116 | Oil & Gas Operator | Mar 2015 |
| 371 | Petroleum Exploration Company LTD LP | Breckenridge, TX 76424 | Oil & Gas Operator | Feb 2026 |
| 372 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 373 | Petroleum Production MGMT., Inc. | Kansas City, MO 64112 | Oil & Gas Operator | Apr 2026 |
| 374 | Petroleum Reserve Corporation | Plymouth MTNG, PA 19462 | Oil & Gas Operator | May 2008 |
| 375 | Phoenix Petrocorp, Inc. | McKinney, TX 75070 | Oil & Gas Operator | Feb 2026 |
| 376 | Pic Inc | Ponca City, OK 74602 | Oil & Gas Operator | Jan 2013 |
| 377 | Pioneer Exploration Company | Houston, TX 77090 | Oil & Gas Operator | Feb 2026 |
| 378 | Pioneer Natural Res. USA, Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2026 |
| 379 | Plains Petroleum Operating Co | Denver, CO 80202 | Oil & Gas Operator | Dec 2014 |
| 380 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 381 | Pogo Panhandle 2004, L.P. | Houston, TX 77002 | Oil & Gas Operator | Oct 2017 |
| 382 | Powerline Energy Corporation | Arlington, TX 76015 | Oil & Gas Operator | Apr 2026 |
| 383 | Prentice, Napier & Green, Inc. | Oklahoma City, OK 73142 | Oil & Gas Operator | Feb 2026 |
| 384 | Presidio Petroleum LLC | Canadian, TX 79014 | Oil & Gas Operator | Apr 2026 |
| 385 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2026 |
| 386 | Primary Fuels Inc | Midland, TX 79701-4410 | Oil & Gas Operator | Mar 1991 |
| 387 | Prime Operating Company | Midland, TX 79705 | Oil & Gas Operator | Apr 2026 |
| 388 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 389 | Producers Operating Co Inc | Amarillo, TX 79105 | Oil & Gas Operator | Apr 2026 |
| 390 | Protege Energy LLC | Tulsa, OK 74135 | Oil & Gas Operator | Jan 2018 |
| 391 | Proven Reserves Management, Inc. | Dallas, TX 75370 | Oil & Gas Operator | Jan 2026 |
| 392 | Psec Inc | Tulsa, OK 74102-0871 | Oil & Gas Operator | Dec 2016 |
| 393 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Jan 2026 |
| 394 | Quail Oil & Gas LC | Garden City, KS 67846 | Oil & Gas Operator | Jan 2026 |
| 395 | Questa Energy Corporation | Amarillo, TX 79159 | Oil & Gas Operator | Apr 2026 |
| 396 | R C Taylor Operating Company LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Feb 2026 |
| 397 | R D T Properties | Tulsa, OK 74105-7122 | Oil & Gas Operator | Sep 2017 |
| 398 | Rama Operating Company Inc | Stafford, KS 67578 | Oil & Gas Operator | Feb 2026 |
| 399 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 400 | Ranch Oil Company | West Linn, OR 97068 | Oil & Gas Operator | Mar 2026 |