| 301 | H-M Resource Management, Inc. | Houston, TX 77055 | Oil & Gas Operator | Feb 2023 |
| 302 | Ha.P.C. Oil, Inc. | Gonzales, TX 78629 | Oil & Gas Operator | Aug 2006 |
| 303 | Haas, C. F. Oil & Gas Inc. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Jul 2025 |
| 304 | Halbouty, Michel T. | Houston, TX 77056 | Oil & Gas Operator | Aug 1997 |
| 305 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jan 2025 |
| 306 | Hamilton Brothers Oil Co. | Houston, TX 77057 | Oil & Gas Operator | Mar 2015 |
| 307 | Hamman Oil & Refining Company | Houston, TX 77098 | Oil & Gas Operator | Jul 2025 |
| 308 | Hankey Oil Company | Houston, TX 77027 | Oil & Gas Operator | Feb 2010 |
| 309 | Hankey Operating, Inc. | Houston, TX 77027 | Oil & Gas Operator | Mar 2016 |
| 310 | Hanson Minerals Co. | Houston, TX 77042 | Oil & Gas Operator | Oct 1993 |
| 311 | Hanson Production Company | Cuero, TX 77954 | Oil & Gas Operator | Jul 2009 |
| 312 | Hardwick Oil Company | Sugar Land, TX 77478 | Oil & Gas Operator | Nov 2014 |
| 313 | Haring Energy Company | Tuleta, TX 78162 | Oil & Gas Operator | Mar 2003 |
| 314 | Harken Exploration Company | Houston, TX 77079 | Oil & Gas Operator | Mar 2008 |
| 315 | Harper Hefte, Inc. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | Jul 2025 |
| 316 | Hart Petroleum Services, Inc | Robstown, TX 78380 | Oil & Gas Operator | Jul 2025 |
| 317 | Harvey Brothers Oil & Gas | Corpus Chrsti, TX 78408 | Oil & Gas Operator | Jul 2004 |
| 318 | Harwood Exploration, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Aug 1995 |
| 319 | Hawn Brothers | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2003 |
| 320 | Hazoco, L.L.C. | Bellville, TX 77418 | Oil Operator | Jul 2025 |
| 321 | Henry, J.R. Inc | Brenham, TX 77833 | Oil & Gas Operator | Jul 2025 |
| 322 | Hermat Salt Water Disposal, Inc. | Corpus Chrsti, TX 78426 | Oil Operator | Aug 2012 |
| 323 | Hewitt, Robert J. | Victoria, TX 77901 | Oil & Gas Operator | Jun 2004 |
| 324 | Hgi Corporation | Nada, TX 77460 | Oil & Gas Operator | Apr 2016 |
| 325 | Hibbard Energy, LP | Whitehouse, TX 75791 | Oil & Gas Operator | Jul 2025 |
| 326 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Jul 2025 |
| 327 | Hollimon Oil Corporation | Castroville, TX 78009 | Oil & Gas Operator | Nov 2016 |
| 328 | Holloway Oil Company | Austin, TX 78764 | Oil & Gas Operator | Feb 2004 |
| 329 | Horizon Prod. And Operating, LLC | Houston, TX 77019 | Oil & Gas Operator | Jul 2025 |
| 330 | Houston Energy, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2014 |
| 331 | Houston Gulf Energy Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Jul 2025 |
| 332 | Houston Oil & Minerals Corp. | Houston, TX 77002 | Oil & Gas Operator | Aug 1996 |
| 333 | Houston Operating, Inc. | Houston, TX 77027 | Oil & Gas Operator | Jul 2025 |
| 334 | HRB Operating Company, Inc. | Bridgeport, TX 76426 | Oil & Gas Operator | Jul 2025 |
| 335 | Hughes, Dan A. Company | Beeville, TX 78104 | Oil & Gas Operator | May 2006 |
| 336 | Hughes, Dan A. Company, L.P. | Beeville, TX 78104 | Oil & Gas Operator | Jul 2025 |
| 337 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Jul 2025 |
| 338 | Hunt Petroleum Corporation | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 339 | Hunt, WM. Herbert, Trust Est. | Dallas, TX 75201 | Oil & Gas Operator | Sep 1998 |
| 340 | Hunter Petroleum Inc. | Alice, TX 78333 | Oil & Gas Operator | May 2014 |
| 341 | Hurd Ent.LTD/U.S.Enercorp,LLC | San Antonio, TX 78209 | Oil & Gas Operator | Aug 2002 |
| 342 | Hurd Enterprises, LTD. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2025 |
| 343 | Hydrocarbon Horizons, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Jun 2023 |
| 344 | Hydrocarbon Operating, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2025 |
| 345 | Hyquest Energy, Inc. | Midland, TX 79710 | Oil & Gas Operator | Mar 2015 |
| 346 | Imperial Oil Company | Houston, TX 77073 | Oil & Gas Operator | Oct 2004 |
| 347 | Inca Oil Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | May 2009 |
| 348 | Indexgeo & Associates, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 2009 |
| 349 | Inland Ocean, Inc. | San Antonio, TX 78205 | Oil & Gas Operator | Jul 2025 |
| 350 | Intercity Management Corp. | Corpus Chrsti, TX 78412 | Oil & Gas Operator | Jul 2025 |
| 351 | Ip Petroleum Company, Inc. | Houston, TX 77210 | Oil & Gas Operator | Mar 2008 |
| 352 | Ipact | Austin, TX 78734 | Oil & Gas Operator | Jul 2025 |
| 353 | Ipr Energy Partners, L.P. | Bowie, TX 76230 | Oil & Gas Operator | Aug 2014 |
| 354 | Ipr Energy Partners, LLC | Bowie, TX 76230 | Oil & Gas Operator | Jul 2025 |
| 355 | Ipr USA Corp. | Irving, TX 75039 | Oil & Gas Operator | Jun 2009 |
| 356 | Italian-American Oil Co., Inc. | Tomball, TX 77377 | Oil & Gas Operator | Jul 2025 |
| 357 | J G Oil & Gas | Albany, TX 76430 | Oil & Gas Operator | Jul 2025 |
| 358 | Jackson, Jeral W. Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2004 |
| 359 | Janssen, Nelson | Victoria, TX 77904 | Oil & Gas Operator | Jul 2025 |
| 360 | Jasper Operating Company | Dallas, TX 75206 | Oil & Gas Operator | Jun 2002 |
| 361 | Jaybird Resources, LLC | Cuero, TX 77954 | Oil Operator | Jul 2025 |
| 362 | Jetco Exploration | Victoria, TX 77903 | Oil & Gas Operator | May 2007 |
| 363 | JMC Resources Corp. | Houston, TX 77077 | Oil & Gas Operator | Jul 2025 |
| 364 | Joint Resources Company | Fort Worth, TX 76107 | Oil & Gas Operator | Jul 2025 |
| 365 | Jones, L. E. Operating, Inc. | Duncan, OK 73534 | Oil & Gas Operator | Jul 2025 |
| 366 | Jones, L. E. Production Co. | Duncan, OK 73534 | Oil & Gas Operator | Jul 2014 |
| 367 | JTB Oil Company, Inc. | Refugio, TX 78377 | Oil & Gas Operator | Jul 2025 |
| 368 | K.M.A. Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | Aug 2003 |
| 369 | Kaiser-Francis Oil Company | Tulsa, OK 74121 | Oil & Gas Operator | Jul 2025 |
| 370 | Kaler Energy Corp. | Boerne, TX 78006 | Oil & Gas Operator | Jul 2025 |
| 371 | Kamlok Oil & Gas, Inc. | Houston, TX 77240 | Oil & Gas Operator | Jun 1996 |
| 372 | KCS Resources, Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2009 |
| 373 | Keahey Exploration, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Mar 2002 |
| 374 | Kebo Oil & Gas, Inc. | Portland, TX 78374 | Oil & Gas Operator | Jul 2025 |
| 375 | Ken Petroleum Corporation | Dallas, TX 75206 | Oil & Gas Operator | Feb 2019 |
| 376 | Kenne Exploration, Inc. | Missouri City, TX 77489 | Oil & Gas Operator | Jul 2025 |
| 377 | Kerr-McGee Corporation | Dallas, TX 75380 | Oil & Gas Operator | Apr 2025 |
| 378 | Kerr-McGee Oil & Gas Onshore LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2017 |
| 379 | Kerr-McGee Oil & Gas Onshore LP | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 380 | Key Operating & Equipment, Inc. | Midlothian, TX 76065 | Oil & Gas Operator | Nov 2024 |
| 381 | Killam Oil Co., LTD. | Laredo, TX 78042 | Oil & Gas Operator | Jul 2025 |
| 382 | Killam Oil Company | Laredo, TX 78042 | Oil & Gas Operator | Mar 1994 |
| 383 | Kling, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Dec 2000 |
| 384 | Klotzman, M. S. Exploration Co. | Victoria, TX 77903 | Oil & Gas Operator | Jul 2025 |
| 385 | KP Exploration, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 1997 |
| 386 | Kriken Oil & Gas | Corpus Chrsti, TX 78426 | Oil & Gas Operator | Jul 2005 |
| 387 | KTC Oil Enterprises, LLC | Dallas, TX 75247 | Oil & Gas Operator | Jul 2025 |
| 388 | Laguna Oil & Gas Corp. | Weesatche, TX 77993 | Oil & Gas Operator | Jul 2025 |
| 389 | Lance Exploration Company | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 1994 |
| 390 | Lapco Oil & Gas Company | Houston, TX 77069 | Oil & Gas Operator | Oct 2015 |
| 391 | Le Norman Energy Corporation | Duncan, OK 73534 | Oil & Gas Operator | Nov 2014 |
| 392 | Legacy Oil & Gas, Inc. | Portland, TX 78374 | Oil & Gas Operator | Jul 2025 |
| 393 | Legend Natural Gas II, LP | Houston, TX 77094 | Oil & Gas Operator | Feb 2015 |
| 394 | Legend Natural Gas, LP | Houston, TX 77084 | Oil & Gas Operator | Aug 2004 |
| 395 | Lighthouse Exploration, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Jul 2007 |
| 396 | Lightning Oil Company | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2025 |
| 397 | Lime Rock Resources A, L.P. | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 398 | Linc Gulf Coast Petroleum, Inc. | Katy, TX 77494 | Oil & Gas Operator | Jul 2025 |
| 399 | Live Oak Gas Company | Dallas, TX 75251 | Oil & Gas Operator | Jul 2025 |
| 400 | Lomak Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Aug 1998 |