| 301 | Harsh International Inc | | Oil & Gas Operator | Dec 2013 |
| 302 | Hathaway Operators, Inc | | Oil & Gas Operator | Dec 2000 |
| 303 | Hayes Oil & Gas Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2005 |
| 304 | Headington Oil Company, L.P. | Dallas, TX 75231 | Oil & Gas Operator | Mar 2008 |
| 305 | Heartland Oil & Gas Company | | Oil & Gas Operator | Jun 2000 |
| 306 | Hec Petroleum, Inc | Midland, TX 79705 | Oil & Gas Operator | Mar 2006 |
| 307 | Helena Resources Inc | Lakewood, CO 80215 | Oil & Gas Operator | Jun 2025 |
| 308 | High Plains Energy LLC | | Oil & Gas Operator | May 2017 |
| 309 | High River Resources Operating LLC | Farmington, NM 87401 | Oil & Gas Operator | May 2025 |
| 310 | Highpoint Energy LLC | | Oil & Gas Operator | Nov 2022 |
| 311 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Jul 2025 |
| 312 | Holcomb Oil & Gas Inc | Farmington, NM 87401 | Oil & Gas Operator | Jun 2025 |
| 313 | Homestead Oil Inc | | Oil & Gas Operator | Jan 2018 |
| 314 | Horseshoe Operating Inc | Midland, TX 79701 | Oil & Gas Operator | Jan 2023 |
| 315 | Houston Exploration Co, The | Houston, TX 77002 | Oil & Gas Operator | Apr 2017 |
| 316 | Howell Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 2015 |
| 317 | HRC Operating, LLC | Denver, CO 80202 | Oil & Gas Operator | Nov 2017 |
| 318 | HRM Resources II, LLC | Denver, CO 80202 | Oil & Gas Operator | Jan 2022 |
| 319 | HRM Resources III LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2022 |
| 320 | HRM Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Aug 2015 |
| 321 | HS Resources, Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2005 |
| 322 | Hubbard Creek Coal Gas LLC | | Gas Operator | Jun 2025 |
| 323 | Hubbs III, LLC | | Oil & Gas Operator | Mar 2024 |
| 324 | Huber Corporation* J M | | Oil & Gas Operator | Feb 2008 |
| 325 | Huntington Energy LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Jul 2025 |
| 326 | Hyndrex Resources | | Oil & Gas Operator | Apr 2018 |
| 327 | Impetro Resources LLC | | Oil & Gas Operator | May 2025 |
| 328 | Incremental Oil & Gas (Florence) LLC | | Oil & Gas Operator | Jun 2025 |
| 329 | Industrial Gas Services Inc | Wheat Ridge, CO 80033 | Oil & Gas Operator | Feb 2023 |
| 330 | Infinity Oil & Gas Of Wyoming Inc | | Oil Operator | Dec 2007 |
| 331 | Inspire Oil And Gas Inc. | Katy, TX 77449 | Oil & Gas Operator | Jul 2025 |
| 332 | Intermountain Oil Co | | Oil & Gas Operator | Nov 2003 |
| 333 | Investment Equipment LLC | FT Morgan, CO 80701 | Oil & Gas Operator | May 2025 |
| 334 | J-W Operating Company | Christoval, TX 76935 | Oil & Gas Operator | Jul 2025 |
| 335 | Jackson, Donald W. | Borger, TX 79008 | Oil & Gas Operator | Dec 2001 |
| 336 | Javernick Oil | | Oil Operator | May 2025 |
| 337 | Jelco G V Inc | | Gas Operator | Dec 2005 |
| 338 | Jenex Petroleum Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Jul 2025 |
| 339 | Jetta Operating Company Inc | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2025 |
| 340 | Joeckel* Raymond N | | Oil Operator | Mar 2000 |
| 341 | Jones Energy, LTD. | Austin, TX 78746 | Oil & Gas Operator | Sep 2013 |
| 342 | Journey Operating, L.L.C. | Sugar Land, TX 77496 | Oil & Gas Operator | Aug 2006 |
| 343 | Juniper Resources Inc | | Oil Operator | Sep 2004 |
| 344 | JWC Operating LLC | | Oil & Gas Operator | May 2025 |
| 345 | K P Kauffman Company Inc | Denver, CO 80203 | Oil & Gas Operator | May 2025 |
| 346 | K W B Oil Property MGMT Inc | | Oil & Gas Operator | Jun 2000 |
| 347 | Kaiser-Francis Oil Company | Tulsa, OK 74121 | Oil & Gas Operator | Jul 2025 |
| 348 | KC Resources Inc | Snowmass VLG., CO 81615 | Oil & Gas Operator | Apr 2025 |
| 349 | KCS Resources, Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2009 |
| 350 | Keener Oil & Gas Company | Tulsa, OK 74119-4416 | Oil & Gas Operator | May 2025 |
| 351 | Kennec Trustee* Frank | | Gas Operator | Apr 2008 |
| 352 | Kerr-McGee Oil & Gas Onshore LP | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 353 | Kestrel Resources, Inc. | Dallas, TX 75204 | Oil & Gas Operator | Jan 2017 |
| 354 | KGH Operating Company | Billings, MT 59115 | Oil & Gas Operator | May 2025 |
| 355 | Kinder Morgan Co2 Company, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jun 2025 |
| 356 | Klabzuba Oil & Gas Inc | Denver, CO 80202 | Oil & Gas Operator | Aug 2012 |
| 357 | KLT Gas Inc | Woodlands, TX 77380 | Oil & Gas Operator | Sep 2004 |
| 358 | Koch Exploration Company, LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2019 |
| 359 | Kodiak Petroleum, Inc. | Englewood, CO 80155 | Oil & Gas Operator | Mar 2025 |
| 360 | Kriti Exploration, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2012 |
| 361 | KT Resources LLC | | Oil & Gas Operator | May 2025 |
| 362 | KTM Operating LLC | | Oil & Gas Operator | May 2025 |
| 363 | Kuenzler & Flora Reserve Company | | Oil Operator | Mar 2025 |
| 364 | Kugler* Dean & Joe Dba D-J Oil Company | | Oil & Gas Operator | Sep 2019 |
| 365 | Kykon Oil & Gas, Inc. | Billings, MT 59103 | Oil & Gas Operator | Feb 2009 |
| 366 | L B Exploration Inc | Wichita, KS 67205 | Oil & Gas Operator | Jun 2025 |
| 367 | Lamar Oil & Gas Exploration | | Gas Operator | Oct 2013 |
| 368 | Lance Oil & Gas Company Inc | Kirtland, NM 87417 | Oil & Gas Operator | Mar 2013 |
| 369 | Laramie Energy II LLC | Denver, CO 80202 | Oil & Gas Operator | Sep 2015 |
| 370 | Laramie Energy LLC | | Oil & Gas Operator | Aug 2013 |
| 371 | Lasso Oil & Gas LLC | | Oil & Gas Operator | Jul 2022 |
| 372 | Leben* Theodore I Dba Leben Oil Companies | | Oil Operator | Jun 2002 |
| 373 | Legado DJ, LLC | | Oil Operator | Jul 2011 |
| 374 | Lewis & Clark Exploration Company | | Oil Operator | Jan 2005 |
| 375 | Lilis Energy Inc | Denver, CO 80203 | Oil & Gas Operator | Aug 2017 |
| 376 | Linn Bros Oil & Gas Inc | Fruita, CO 81521 | Oil & Gas Operator | Jun 2025 |
| 377 | Linn Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Jan 2019 |
| 378 | Locin Oil Corporation | Katy, TX 77494 | Oil & Gas Operator | Jul 2025 |
| 379 | Loeb LLC* Herman L | | Oil & Gas Operator | Jun 2025 |
| 380 | Logos Operating LLC | Farmington, NM 87401 | Oil & Gas Operator | May 2025 |
| 381 | Lone Mountain Production Company | | Oil & Gas Operator | Jan 2016 |
| 382 | Longs Peak Resources LLC | Houston, TX 77019 | Oil & Gas Operator | May 2025 |
| 383 | Lorentz Oil & Gas LLC | Edmond, OK 73034-7266 | Oil & Gas Operator | Apr 2025 |
| 384 | Lowry Exploration Inc | Tulsa, OK 74119 | Oil & Gas Operator | Apr 2025 |
| 385 | Ludwick* James L | | Gas Operator | Apr 2004 |
| 386 | Luff Exploration Company | Denver, CO 80203 | Oil & Gas Operator | May 2025 |
| 387 | Lundvall Oil & Gas Inc | | Oil & Gas Operator | Jan 2023 |
| 388 | Lyco Energy Corporation | Dallas, TX 75206 | Oil & Gas Operator | Jun 2015 |
| 389 | Lyster Oil Company Inc | | Oil & Gas Operator | Nov 2020 |
| 390 | M E III Corporation | | Oil & Gas Operator | Apr 2022 |
| 391 | Machii-Ross Petroleum Co | | Oil & Gas Operator | Apr 2014 |
| 392 | Magpie Operating, Inc | | Oil & Gas Operator | May 2025 |
| 393 | Mallon Oil Company | Denver, CO 80202 | Oil & Gas Operator | Jun 2005 |
| 394 | Manzano LLC | Roswell, NM 88202 | Oil & Gas Operator | Jul 2025 |
| 395 | Maralex Resources Inc | Ignacio, CO 81137 | Oil & Gas Operator | May 2025 |
| 396 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | May 2025 |
| 397 | Markus Production, Inc | | Oil & Gas Operator | Mar 2021 |
| 398 | Markwest Resources Inc | Englewood, CO 801125004 | Oil & Gas Operator | Jun 2003 |
| 399 | Matrix Energy LLC | | Oil & Gas Operator | Apr 2013 |
| 400 | Matrix Oil Corporation | | Oil & Gas Operator | May 2025 |