| 301 | Horizon Natural Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2019 |
| 302 | Horizon Oil & Gas Co. | Dallas, TX 75221 | Oil & Gas Operator | Jan 2005 |
| 303 | Huber J M Corp | Edison, NJ 08837 | Oil & Gas Operator | Apr 2025 |
| 304 | Hugoton Energy Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2019 |
| 305 | Huitt Joe A | Tulsa, OK 74103 | Oil & Gas Operator | May 2001 |
| 306 | Hulsey Larry O & Co | Graham, TX 76046 | Oil & Gas Operator | Jun 2012 |
| 307 | Hunt Engineering Inc | Norman, OK 73069-4093 | Oil & Gas Operator | Feb 2019 |
| 308 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 309 | Huntington Energy LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Apr 2025 |
| 310 | Hunton Oil & Gas Corporation | Oklahoma City, OK 73154-0191 | Oil & Gas Operator | May 2019 |
| 311 | Hy-Carb Energy Inc | | Oil & Gas Operator | Feb 2009 |
| 312 | Indian Oil Company | Gainesville, TX 76241 | Oil & Gas Operator | Apr 2025 |
| 313 | Infinity Hydrocarbons LLC | Houston, TX 77079 | Oil & Gas Operator | Aug 2022 |
| 314 | Internorth Inc | Tulsa, OK 74136 | Oil & Gas Operator | Apr 2014 |
| 315 | Iochem Corporation | Oklahoma City, OK 73118-7483 | Oil & Gas Operator | Jan 2025 |
| 316 | Irex Corporation | Englewood, CO 80111 | Oil & Gas Operator | May 2000 |
| 317 | J & R Transports Inc | Woodward, OK 73802 | Oil & Gas Operator | Dec 2006 |
| 318 | J-Brex Company | Amarillo, TX 79101 | Oil & Gas Operator | Apr 2025 |
| 319 | January Investments LLC | Norman, OK 73069-8224 | Oil & Gas Operator | Feb 2025 |
| 320 | Jay Petroleum Inc | Oklahoma City, OK 73154-0526 | Oil & Gas Operator | Mar 2019 |
| 321 | JCR, Jr - Operating, Inc. | Amarillo, TX 79114 | Oil & Gas Operator | Apr 2022 |
| 322 | Jec Operating LLC | Oklahoma City, OK 73114-2717 | Oil & Gas Operator | Jan 2025 |
| 323 | Jenex Operating Company | The Woodlands, TX 77380-164280209 | Oil & Gas Operator | May 2019 |
| 324 | Jerry Sanner Oil Properties Inc | Enid, OK 73701 | Oil & Gas Operator | Feb 2025 |
| 325 | Jet Oil Co12/Ofb See 18649 | | Oil & Gas Operator | Jul 2007 |
| 326 | Jetta Operating Company Inc | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2025 |
| 327 | Jma Energy Company LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Feb 2025 |
| 328 | Jma Resources, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Jan 2025 |
| 329 | JN Production LLP | Guthrie, OK 73028 | Oil & Gas Operator | Jan 2025 |
| 330 | Johnson E Lyle | Oklahoma City, OK 73142 | Oil & Gas Operator | Jan 2025 |
| 331 | Johnson Exploration Company | Oklahoma City, OK 73102-7008 | Oil & Gas Operator | Jun 2015 |
| 332 | Jolen Operating Company | Oklahoma City, OK 73102 | Oil & Gas Operator | Jan 2025 |
| 333 | Jones Energy LLC | Oklahoma City, OK 73134 | Oil & Gas Operator | Jan 2025 |
| 334 | K & F Oil Co. | Olney, TX 76374 | Oil & Gas Operator | Dec 2021 |
| 335 | K & M Oil Company LLC | Hennessey, OK 73742 | Oil & Gas Operator | Jan 2025 |
| 336 | K O G Production LLC | Freedom, OK 73842 | Oil & Gas Operator | Feb 2025 |
| 337 | K S Oil Company Inc | Norman, OK 73072-7480 | Oil & Gas Operator | Feb 2025 |
| 338 | Kaiser-Francis Oil Company | Tulsa, OK 74121 | Oil & Gas Operator | Apr 2025 |
| 339 | KC Resources Inc | Snowmass VLG., CO 81615 | Oil & Gas Operator | Jan 2025 |
| 340 | KCS Medallion Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Nov 2018 |
| 341 | Kelloil Inc | Fort Worth, TX 76116-5600 | Oil & Gas Operator | Mar 2015 |
| 342 | Kennedy & Mitchell, Inc. | Houston, TX 77084 | Oil & Gas Operator | Aug 2013 |
| 343 | Kenneth W. Cory, LTD. | Bellaire, TX 77401 | Oil & Gas Operator | Jan 2025 |
| 344 | Kepasa Corp | Oklahoma City, OK 73106 | Oil & Gas Operator | Jan 2025 |
| 345 | Kepco Operating, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2024 |
| 346 | Kepco. Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2015 |
| 347 | Kerr McGee Rocky MTN Corp | Denver, CO 80202-5736 | Oil & Gas Operator | Mar 2015 |
| 348 | Kerr-McGee Corporation | Dallas, TX 75380 | Oil & Gas Operator | Jan 2025 |
| 349 | Kerr-McGee Oil & Gas Onshore LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2017 |
| 350 | Kerr-McGee Oil & Gas Onshore LP | Houston, TX 77046 | Oil & Gas Operator | Apr 2025 |
| 351 | Key Production Company, Inc. | Longview, TX 75606 | Oil & Gas Operator | Jan 2025 |
| 352 | Kimball Production Co. | Houston, TX 77042 | Oil & Gas Operator | Jul 2002 |
| 353 | Kingfisher Resources Inc | Clinton, OK 73601 | Oil & Gas Operator | Feb 2025 |
| 354 | Kirkpatrick Oil Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Apr 2025 |
| 355 | Klingensmith Fred T Etal | Sapulpa, OK 74066 | Oil & Gas Operator | Nov 2007 |
| 356 | KNG Producers | Dumas, TX 79029 | Oil & Gas Operator | Oct 2009 |
| 357 | Koch Oil Company | | Oil & Gas Operator | May 2017 |
| 358 | KRS Oil Company | Frisco, TX 75034 | Oil & Gas Operator | Apr 2020 |
| 359 | KT Energy Inc | Enid, OK 73702-2365 | Oil & Gas Operator | Jan 2025 |
| 360 | L & L Smith Energy Corporation | Muskogee, OK 74403-8479 | Oil & Gas Operator | Jan 2023 |
| 361 | L & R Energy Corporation | Spearman, TX 79081 | Oil & Gas Operator | Nov 2014 |
| 362 | Ladd Petroleum Corp. | Denver, CO 80202 | Oil & Gas Operator | Oct 2004 |
| 363 | Lamamco Drilling Company | Skiatook, OK 74070 | Oil & Gas Operator | Jan 2025 |
| 364 | Lammerts Robert P | Oklahoma City, OK 73102 | Oil & Gas Operator | Jan 2002 |
| 365 | Landers & Waldman Inc | Okemah, OK 74859-0660 | Oil & Gas Operator | May 2013 |
| 366 | Lariat Petroleum Inc | Tulsa, OK 74119 | Oil & Gas Operator | Sep 2024 |
| 367 | Larkspur Operating LLC | Oklahoma City, OK 73034 | Oil & Gas Operator | Jan 2025 |
| 368 | Latigo Oil And Gas Inc | Woodward, OK 73801 | Oil & Gas Operator | Feb 2025 |
| 369 | LCB Resources LLC | Kingfisher, OK 73750-2322 | Oil & Gas Operator | Feb 2025 |
| 370 | Leede Oil & Gas Inc. | Greenwood VLG, CO 80111 | Oil & Gas Operator | Aug 2003 |
| 371 | Legacy Reserves Operating LP | Denver, CO 80201 | Oil & Gas Operator | Apr 2025 |
| 372 | Lime Rock Resources II-A, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2025 |
| 373 | Lindenmuth & Associates Inc | Austin, TX 78703 | Oil & Gas Operator | Aug 2024 |
| 374 | Litzenberger Exploration | Waynoka, OK 73860 | Oil & Gas Operator | Jul 1996 |
| 375 | Litzenberger Exploration Inc | Waynoka, OK 73860 | Oil & Gas Operator | Feb 2025 |
| 376 | Lobo Exploration Company | Yukon, OK 73099 | Oil & Gas Operator | Jan 2025 |
| 377 | Locin Oil Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 378 | Louis Dreyfus Gas Marketing | Oklahoma City, OK 73134 | Oil & Gas Operator | Mar 2018 |
| 379 | LX4 LLC | Gage, OK 73843 | Oil Operator | Dec 2024 |
| 380 | Lynx Energy Company, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2008 |
| 381 | M & M Exploration, Inc. | Westminster, CO 80031 | Oil & Gas Operator | Feb 2025 |
| 382 | M E Klein & Associates LLC | Washington, OK 73093-4663 | Oil & Gas Operator | Feb 2025 |
| 383 | Mac Laskey Kelly Oilfield | El Dorado, KS 67042 | Oil & Gas Operator | Feb 2025 |
| 384 | Mack Energy Co. | Duncan, OK 73534 | Oil & Gas Operator | Feb 2025 |
| 385 | Mackellar Inc | Oklahoma City, OK 73116-7101 | Oil & Gas Operator | Feb 2025 |
| 386 | Maguire James Q Inc | Norman, OK 73070-1748 | Oil & Gas Operator | Jun 2011 |
| 387 | Malson Oil Company | Crawford, OK 73638 | Oil & Gas Operator | Dec 2016 |
| 388 | Manuel Corporation | Wichita, KS 67206 | Oil & Gas Operator | Jan 2025 |
| 389 | Marathon Oil Company | Houston, TX 77024 | Oil & Gas Operator | Feb 2025 |
| 390 | Marjo Operating Company Inc | Tulsa, OK 741010729 | Oil & Gas Operator | Jan 2025 |
| 391 | Marjo Operating Mid-Continent LLC | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2025 |
| 392 | Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Jan 2025 |
| 393 | Marshall Oil Corporation | Oklahoma City, OK 73154 | Oil & Gas Operator | Apr 2017 |
| 394 | Matador E & P Company Inc | | Oil & Gas Operator | May 2020 |
| 395 | Mathews & Casselman Oil Inc | Morris, OK 74445 | Oil & Gas Operator | Dec 2021 |
| 396 | Maverick Brothers Resources LLC | Enid, OK 73701 | Oil & Gas Operator | Jan 2025 |
| 397 | May Petroleum, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Nov 1998 |
| 398 | McCool John E | Youngsville, PA 16371 | Oil & Gas Operator | Jan 2025 |
| 399 | McNic Oil & Gas Midcontinent | Oklahoma City, OK 73154-0526 | Oil & Gas Operator | May 2024 |
| 400 | McOr Oil & Gas Corp | Houston, TX 77002 | Oil & Gas Operator | Oct 2013 |