| 301 | Hadson Petroleum Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2015 |
| 302 | Halcon Holdings Inc | Ada, OK 74820 | Oil & Gas Operator | Jan 2026 |
| 303 | Halcyon Natural Gas LLC | Oklahoma City, OK 73116-9111 | Oil & Gas Operator | Nov 2025 |
| 304 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 305 | Hamon Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Dec 2011 |
| 306 | Harding & Shelton Inc | Oklahoma City, OK 73104-2410 | Oil & Gas Operator | Jan 2026 |
| 307 | Harding And Shelton Exploration LLC | Oklahoma City, OK 73101-1557 | Oil & Gas Operator | Jan 2026 |
| 308 | Harken Exploration Company | Houston, TX 77079 | Oil & Gas Operator | Mar 2008 |
| 309 | Hawkins Oil & Gas Inc | Tulsa, OK 74103 | Oil & Gas Operator | Dec 2016 |
| 310 | Hazlewood Oil & Gas Co Inc | Oklahoma City, OK 73139-9353 | Oil & Gas Operator | Apr 2022 |
| 311 | HCG Energy Corporation & Subs | | Oil & Gas Operator | Mar 2015 |
| 312 | HCM | Dallas, TX 75206 | Oil & Gas Operator | Mar 2015 |
| 313 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 314 | Headington Oil Company LLC | Dallas, TX 75204 | Oil & Gas Operator | Apr 2016 |
| 315 | Heartland Environmental Services | Watonga, OK 73080 | Oil & Gas Operator | May 1999 |
| 316 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Dec 2025 |
| 317 | Hennessey Oil & Gas LLC | Hennessey, OK 73742-0212 | Oil & Gas Operator | Sep 2024 |
| 318 | Henry Gungoll Operating Inc | Enid, OK 73703 | Oil & Gas Operator | Feb 2026 |
| 319 | Henry Rennick | | Oil Operator | Feb 2026 |
| 320 | Hep Oil Company, LTD. | Gainesville, TX 76240 | Oil & Gas Operator | Mar 2012 |
| 321 | Hep Oil GP, LLC | Gainesville, TX 76241 | Oil & Gas Operator | Mar 2015 |
| 322 | Hess Corporation | Houston, TX 77010 | Oil & Gas Operator | Aug 2017 |
| 323 | Hi-Kat Petroleum Company | Liberal, KS 67905-1261 | Oil & Gas Operator | May 2014 |
| 324 | Hiawatha Exploration Company | Oklahoma City, OK 73116-7326 | Oil & Gas Operator | Mar 2009 |
| 325 | Hill John H | Dallas, TX 75240-7077 | Oil & Gas Operator | Jul 2015 |
| 326 | Hinkle Engineering, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Nov 2016 |
| 327 | Hinkle Oil And Gas Inc | Oklahoma City, OK 73112-4275 | Oil & Gas Operator | Feb 2026 |
| 328 | Hodgden Operating Co., Inc. | Enid, OK 73702 | Oil & Gas Operator | Feb 2026 |
| 329 | Hondo Oil & Gas Company | Roswell, NM 88202 | Oil & Gas Operator | Aug 2006 |
| 330 | Horizon Natural Gas Company | Tulsa, OK 74170 | Oil & Gas Operator | Oct 2024 |
| 331 | Horizon Natural Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2019 |
| 332 | Huber J M Corp | Edison, NJ 08837 | Oil & Gas Operator | Apr 2026 |
| 333 | Hull Oil Co. | Wichita Falls, TX 76308 | Oil & Gas Operator | Sep 2021 |
| 334 | Hunt Engineering Inc | Norman, OK 73069-4093 | Oil & Gas Operator | Feb 2019 |
| 335 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Apr 2026 |
| 336 | Hurley Charles B | Santa Ana, CA 92706 | Oil & Gas Operator | Apr 2015 |
| 337 | Inca Oil Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | May 2009 |
| 338 | Indian Oil Company | Gainesville, TX 76241 | Oil & Gas Operator | Apr 2026 |
| 339 | Indrex Inc | Tulsa, OK 74133 | Oil & Gas Operator | Dec 2000 |
| 340 | Internorth Inc | Tulsa, OK 74136 | Oil & Gas Operator | Apr 2014 |
| 341 | Investment Equipment LLC | FT Morgan, CO 80701 | Oil & Gas Operator | Jan 2026 |
| 342 | Iochem Corporation | Oklahoma City, OK 73118-7483 | Oil & Gas Operator | Feb 2026 |
| 343 | J B Drilling Company Inc | Muldrow, OK 74948-6601 | Oil & Gas Operator | Feb 2026 |
| 344 | J D Operating Company | Tulsa, OK 74105 | Oil & Gas Operator | Jun 2005 |
| 345 | J L Hajek Enterprises LLC | Ames, OK 73718 | Oil & Gas Operator | Nov 2025 |
| 346 | J-Brex Company | Amarillo, TX 79101 | Oil & Gas Operator | Apr 2026 |
| 347 | J-O Oil Co | | Oil & Gas Operator | Dec 2000 |
| 348 | Jakmen Inc | Edmond, OK 73034-5313 | Oil & Gas Operator | Jun 2015 |
| 349 | January Investments LLC | Norman, OK 73069-8224 | Oil & Gas Operator | Feb 2026 |
| 350 | Jec Operating LLC | Oklahoma City, OK 73114-2717 | Oil & Gas Operator | Jan 2026 |
| 351 | Jico Exploration Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 2004 |
| 352 | Jma Energy Company LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Feb 2026 |
| 353 | Jma Resources Inc | Oklahoma City, OK 73112 | Oil & Gas Operator | Feb 2026 |
| 354 | Jobe Oil & Gas | Comanche, OK 73529-0244 | Oil & Gas Operator | Feb 2026 |
| 355 | Johnson E Lyle | Oklahoma City, OK 73142 | Oil & Gas Operator | Jan 2026 |
| 356 | Johnson Exploration Company | Oklahoma City, OK 73102-7008 | Oil & Gas Operator | Jun 2015 |
| 357 | Jolen Operating Company | Oklahoma City, OK 73102 | Oil & Gas Operator | Jan 2026 |
| 358 | Jones & Pellow Oil Co | Oklahoma City, OK 73118-1115 | Oil & Gas Operator | Feb 2015 |
| 359 | Jones Babe Inc | Floydada, TX 79235-0180 | Oil & Gas Operator | May 2019 |
| 360 | Jones Brent | Duncan, OK 73533-6608 | Oil & Gas Operator | Nov 2015 |
| 361 | Jones Energy, LLC | Oklahoma City, OK 73134 | Oil & Gas Operator | Jan 2026 |
| 362 | K & M Oil Company LLC | Hennessey, OK 73742 | Oil & Gas Operator | Feb 2026 |
| 363 | K S Oil Company Inc | Norman, OK 73072-7480 | Oil & Gas Operator | Jan 2026 |
| 364 | K-Tel Petroleum | Englewood, CO 80111-4628 | Oil & Gas Operator | Sep 2007 |
| 365 | Kahn George Operating Co | Seminole, OK 74818 | Oil & Gas Operator | Nov 2000 |
| 366 | Kaiser-Francis Oil Company | Tulsa, OK 74121 | Oil & Gas Operator | Apr 2026 |
| 367 | Kennedy & Mitchell, Inc. | Houston, TX 77084 | Oil & Gas Operator | Aug 2013 |
| 368 | Kenneth W Cory LTD | Bellaire, TX 77401 | Oil & Gas Operator | Jan 2026 |
| 369 | Kerr McGee Rocky MTN Corp | Denver, CO 80202-5736 | Oil & Gas Operator | Mar 2015 |
| 370 | Kerr-McGee Corporation | Dallas, TX 75380 | Oil & Gas Operator | Feb 2026 |
| 371 | Kerr-McGee Oil & Gas Onshore LP | Houston, TX 77046 | Oil & Gas Operator | Apr 2026 |
| 372 | Key Production Company, Inc. | Longview, TX 75606 | Oil & Gas Operator | Feb 2026 |
| 373 | Kibtec Oil & Gas Inc | Cashion, OK 73016 | Oil & Gas Operator | Aug 2024 |
| 374 | Kingery Drilling Co., Inc. | Ardmore, OK 73402 | Oil & Gas Operator | Feb 2026 |
| 375 | Kingfisher CSG Pullr & Const Inc | Hennessey, OK 73742-0024 | Oil & Gas Operator | Apr 2014 |
| 376 | Kingfisher Resources Inc | Clinton, OK 73601 | Oil & Gas Operator | Feb 2026 |
| 377 | Kirkpatrick Oil Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Apr 2026 |
| 378 | Klabzuba Royalty Company | Prague, OK 74864-0567 | Oil & Gas Operator | Dec 2019 |
| 379 | Klo LLC | Tulsa, OK 74120-2428 | Oil & Gas Operator | Feb 2026 |
| 380 | KNG Producers | Dumas, TX 79029 | Oil & Gas Operator | Oct 2009 |
| 381 | Koch Hydrocarbon Company | Wichita, KS 67220-3203 | Oil & Gas Operator | Nov 2014 |
| 382 | Koch Oil Company | | Oil & Gas Operator | May 2017 |
| 383 | KRS Oil Company | Frisco, TX 75034 | Oil & Gas Operator | Apr 2020 |
| 384 | KTP Energy, Inc. | Lakewood, CO 80226 | Oil & Gas Operator | Aug 2019 |
| 385 | Ladd Petroleum Corp. | Denver, CO 80202 | Oil & Gas Operator | Oct 2004 |
| 386 | Lagoon Water Logistics LLC | Oklahoma City, OK 73103 | Oil Operator | Jul 2024 |
| 387 | Laguna Petroleum Corporation | Houston, TX 77046 | Oil & Gas Operator | Apr 2026 |
| 388 | Lancer Petroleum Corporation | Irving, TX 75014 | Oil & Gas Operator | Feb 2014 |
| 389 | Landmark Exploration Co | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2013 |
| 390 | Langham Petroleum Expl. Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 2009 |
| 391 | Laran Operating LLC | Dover, OK 73734-0057 | Oil & Gas Operator | Mar 2015 |
| 392 | Lariat Petroleum Inc | Tulsa, OK 74119 | Oil & Gas Operator | Sep 2024 |
| 393 | Latex Petroleum Corp. | Houston, TX 77090 | Oil & Gas Operator | Aug 2012 |
| 394 | Latigo Oil & Gas, Inc. | Woodward, OK 73801 | Oil & Gas Operator | Feb 2026 |
| 395 | Latigo Petroleum, LLC | Pampa, TX 79066 | Oil & Gas Operator | Apr 2026 |
| 396 | LCB Resources LLC | Kingfisher, OK 73750-2322 | Oil & Gas Operator | Feb 2026 |
| 397 | Le Norman Energy Corporation | Duncan, OK 73534 | Oil & Gas Operator | Nov 2014 |
| 398 | Legacy Reserves Operating LP | Denver, CO 80201 | Oil & Gas Operator | Apr 2026 |
| 399 | Lime Rock Resources A, L.P. | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 400 | Lime Rock Resources II-A, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2026 |