| 5201 | Horizon Exploration Company | Houston, TX 77019 | Oil & Gas Operator | Aug 2002 |
| 5202 | Horizon Exploration Services | El Paso, TX 79922 | Oil Operator | Apr 2025 |
| 5203 | Horizon Natural Gas Company | Tulsa, OK 74170 | Oil & Gas Operator | Oct 2024 |
| 5204 | Horizon Natural Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2019 |
| 5205 | Horizon Oil & Gas Co. | Dallas, TX 75221 | Oil & Gas Operator | Jan 2005 |
| 5206 | Horizon Prod. And Operating, LLC | Houston, TX 77019 | Oil & Gas Operator | Apr 2025 |
| 5207 | Horizon Ridge Oil Company | Austin, TX 78738 | Oil Operator | Apr 2025 |
| 5208 | Horizon Well Services, Inc. | Abilene, TX 79604 | Oil & Gas Operator | Apr 2025 |
| 5209 | Horn Energy | Eastland, TX 76448 | Oil & Gas Operator | Apr 2025 |
| 5210 | Horn, Tom D. | Pampa, TX 79066 | Gas Operator | Nov 2013 |
| 5211 | Horn, W. J. | Graham, TX 76450 | Oil & Gas Operator | Oct 2004 |
| 5212 | Horne & Moore Oil Co. | Holliday, TX 76366 | Oil & Gas Operator | Feb 2001 |
| 5213 | Horseshoe Production, LLC | Bryson, TX 76427 | Oil Operator | Apr 2025 |
| 5214 | Horst Energy LLC | Fort Worth, TX 76124 | Oil & Gas Operator | Jun 2019 |
| 5215 | Hosford Energy Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 1994 |
| 5216 | Hou-Tex, Inc. | Houston, TX 77224 | Oil & Gas Operator | Jun 2001 |
| 5217 | Houchin, O. E. Inc. | Olney, IL 62450 | Oil & Gas Operator | Feb 1997 |
| 5218 | Houghton Oil & Gas, Inc. | Midland, TX 79701 | Oil & Gas Operator | Mar 2009 |
| 5219 | Houston Energy Operating, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jul 2020 |
| 5220 | Houston Energy, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2014 |
| 5221 | Houston Expl. & Prod. Co., Inc. | Austin, TX 78746 | Oil & Gas Operator | Aug 2003 |
| 5222 | Houston Exploration Co, The | Houston, TX 77002 | Oil & Gas Operator | Apr 2017 |
| 5223 | Houston Gulf Energy Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 2025 |
| 5224 | Houston Hydrocarbons, Inc. (A) | Houston, TX 77042 | Oil & Gas Operator | Sep 2004 |
| 5225 | Houston Oil & Gas Company, Inc. | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 5226 | Houston Oil & Minerals Corp. | Houston, TX 77002 | Oil & Gas Operator | Aug 1996 |
| 5227 | Houston Oil Prod Enterprises,Inc | Houston, TX 77006 | Oil & Gas Operator | Apr 2025 |
| 5228 | Houston Operating, Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2025 |
| 5229 | Houston Petroleum Company | Houston, TX 77027 | Oil & Gas Operator | Apr 2025 |
| 5230 | Houston Resources Corp. | Houston, TX 77002 | Oil & Gas Operator | Apr 2003 |
| 5231 | Houtchens, D. D. | Gainesville, TX 76240 | Oil & Gas Operator | Apr 2025 |
| 5232 | Houtchens, DD & Anna D LVNG TRST | Garland, TX 75043 | Oil Operator | Apr 2025 |
| 5233 | Hovgard & Fitzgerald | Abilene, TX 79608 | Oil & Gas Operator | Mar 1996 |
| 5234 | Howard Exploration, Inc. | Houston, TX 77069 | Oil & Gas Operator | Apr 2025 |
| 5235 | Howard Operating Co. | Saint Jo, TX 76265 | Oil & Gas Operator | Apr 2025 |
| 5236 | Howard, Anthony E. F. | Tyler, TX 75701 | Oil & Gas Operator | Jun 2001 |
| 5237 | Howard, Douglas J. | Houston, TX 77070 | Oil & Gas Operator | Mar 2008 |
| 5238 | Howell & Sandlin, Inc. | Marshall, TX 75671 | Oil & Gas Operator | Jan 2001 |
| 5239 | Howell Crane & Rigging, Inc. | San Antonio, TX 78220 | Oil Operator | Apr 2025 |
| 5240 | Howell Drilling, Inc. | San Antonio, TX 78230 | Oil & Gas Operator | Aug 2003 |
| 5241 | Howell Oil & Gas, Inc. | Marshall, TX 75671 | Oil & Gas Operator | Oct 2019 |
| 5242 | Howell Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 2015 |
| 5243 | Howell, Ray | Breckenridge, TX 76424 | Oil & Gas Operator | May 1998 |
| 5244 | Howitzer Operating, LLC | Dallas, TX 75380 | Oil Operator | Apr 2025 |
| 5245 | Howle Operating Account, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Dec 1999 |
| 5246 | Howle, A.G. | Breckenridge, TX 76424 | Oil & Gas Operator | Dec 2011 |
| 5247 | HPC Energy LLC | Midland, TX 79703 | Oil & Gas Operator | Aug 2013 |
| 5248 | HPC Operating, Inc. | Dallas, TX 75379 | Oil & Gas Operator | Mar 2008 |
| 5249 | HPPC, Inc. | Midland, TX 79701 | Oil & Gas Operator | Feb 2023 |
| 5250 | HR Petroleum | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Apr 1998 |
| 5251 | HRB Oil | Houston, TX 77042 | Oil & Gas Operator | Oct 1998 |
| 5252 | HRB Operating Company Inc | Bridgeport, TX 76426 | Oil & Gas Operator | Apr 2025 |
| 5253 | Hrbacek Oil Corp. | La Grange, TX 78945 | Oil & Gas Operator | Feb 2004 |
| 5254 | HRF Exploration & Production LLC | Gaylord, MI 49734-0160 | Gas Operator | Apr 2025 |
| 5255 | HRF Exploration & Production,Inc | Denver, CO 80237 | Oil & Gas Operator | Mar 2009 |
| 5256 | HRH Energy Group Incorporated | Carrollton, TX 75006 | Oil & Gas Operator | Nov 2009 |
| 5257 | Hronek, Kenneth | Caldwell, TX 77836 | Oil & Gas Operator | Apr 2025 |
| 5258 | Hrubetz Oil Co. | Dallas, TX 75225 | Oil Operator | Sep 1986 |
| 5259 | Hrubetz Operating Company | Dallas, TX 75225 | Oil & Gas Operator | Feb 1999 |
| 5260 | HS Resources, Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2005 |
| 5261 | HTR Operating Co., Inc. | Hurst, TX 76053 | Oil & Gas Operator | Apr 2025 |
| 5262 | Hub-Cap Oil Company | Arlington, TX 76016 | Oil & Gas Operator | Dec 2013 |
| 5263 | Hubbard Operating | Ozona, TX 76943 | Gas Operator | Apr 2025 |
| 5264 | Hubcap Oil, LLC | Boerne, TX 78015 | Oil Operator | Apr 2025 |
| 5265 | Hubco Exploration Inc. | Houston, TX 77073 | Oil & Gas Operator | Sep 2002 |
| 5266 | Huber Energy L.P. | Houston, TX 77079 | Oil & Gas Operator | Feb 2007 |
| 5267 | Huber Energy Panhandle LP | Houston, TX 77079 | Oil & Gas Operator | Oct 2005 |
| 5268 | Huber J M Corp | Edison, NJ 08837 | Oil & Gas Operator | Apr 2025 |
| 5269 | Huddleston Oil And Gas Company | Millsap, TX 76066 | Gas Operator | Dec 2002 |
| 5270 | Hudgens Operating Co., Inc. | Abilene, TX 79603 | Oil & Gas Operator | Jul 1995 |
| 5271 | Hudson Brothers Mining Co., Inc. | Cisco, TX 76437 | Oil & Gas Operator | Jun 1994 |
| 5272 | Hudson, Comer Oil & Gas | Cisco, TX 76437 | Oil & Gas Operator | Jan 2003 |
| 5273 | Huff Minerals, LTD. | Amarillo, TX 79101 | Gas Operator | Apr 2025 |
| 5274 | Huff, Jack | Midland, TX 79710 | Oil & Gas Operator | Dec 2004 |
| 5275 | Huffman, H. L., LTD. | Fort Worth, TX 76113 | Oil & Gas Operator | Sep 1994 |
| 5276 | Hufo Production Corporation | Midland, TX 79702 | Oil & Gas Operator | Jul 2002 |
| 5277 | Huggs Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Apr 2003 |
| 5278 | Hughes & Patterson Oper. Corp. | Albany, TX 76430 | Oil & Gas Operator | Apr 2025 |
| 5279 | Hughes & Shawver | Olney, TX 76374 | Oil & Gas Operator | Aug 1996 |
| 5280 | Hughes Legacy LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2022 |
| 5281 | Hughes Oil Company Inc | Odessa, TX 79765 | Oil & Gas Operator | Feb 2004 |
| 5282 | Hughes Supplies, Inc. | Greenwood, LA 71033 | Oil & Gas Operator | Jul 2019 |
| 5283 | Hughes, Bill Drilling, Inc. | Graham, TX 76450 | Oil & Gas Operator | Apr 2025 |
| 5284 | Hughes, Bob Oil Company | San Angelo, TX 76901 | Oil & Gas Operator | Jul 2011 |
| 5285 | Hughes, Dan A. Company | Beeville, TX 78104 | Oil & Gas Operator | May 2006 |
| 5286 | Hughes, Dan A. Company, L.P. | Beeville, TX 78104 | Oil & Gas Operator | Apr 2025 |
| 5287 | Hughey, Gaylord T. SR. Oper. Co. | Tyler, TX 75711 | Oil & Gas Operator | Feb 1998 |
| 5288 | Hughey, W. R., Operating Co. | Tyler, TX 75711 | Oil & Gas Operator | Feb 2005 |
| 5289 | Hugoton Energy Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2019 |
| 5290 | Hugoton Operating Company, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Apr 2025 |
| 5291 | Hugus Investment Company, Inc. | Tyler, TX 75711 | Oil & Gas Operator | Apr 2025 |
| 5292 | Hulen Operating Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Apr 2025 |
| 5293 | Hull Oil Co. | Wichita Falls, TX 76308 | Oil & Gas Operator | Sep 2021 |
| 5294 | Hulse, J. T. | Archer City, TX 76351 | Oil & Gas Operator | Apr 2025 |
| 5295 | Hulse, Tommy P. | Archer City, TX 76351 | Oil & Gas Operator | Feb 2009 |
| 5296 | Hulsey Larry O & Co | Graham, TX 76046 | Oil & Gas Operator | Jun 2012 |
| 5297 | Hulsey Oil Company | Dallas, TX 75205 | Oil & Gas Operator | Aug 1999 |
| 5298 | Humak Processors, Inc. | Tyler, TX 75710 | Oil & Gas Operator | Aug 2005 |
| 5299 | Humber Oil Company | Albany, TX 76430 | Oil & Gas Operator | Apr 2025 |
| 5300 | Humble Oil & Refining Co. | Houston, TX 77252 | Oil & Gas Operator | Jan 2000 |