| 1 | H & D Operating Company | Refugio, TX 78377 | Oil & Gas Operator | May 2015 |
| 2 | H & P Exploration Co. | Alice, TX 78333 | Oil & Gas Operator | May 2019 |
| 3 | H & T Oil & Gas Company, Inc. | Alice, TX 78333 | Oil & Gas Operator | Mar 2008 |
| 4 | Halex Oil Corporation | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 5 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 6 | Hamilton Brothers Oil Co. | Houston, TX 77057 | Oil & Gas Operator | Mar 2015 |
| 7 | Hamilton, John M. | Wichita Falls, TX 76301 | Oil & Gas Operator | May 2001 |
| 8 | Hamilton-Tedford Oper. Co., LLC | Wichita Falls, TX 76301 | Oil Operator | May 2007 |
| 9 | Hamman Oil & Refining Company | Houston, TX 77098 | Oil & Gas Operator | Oct 2025 |
| 10 | Hanson Minerals Co. | Houston, TX 77042 | Oil & Gas Operator | Oct 1993 |
| 11 | Hanson Production Company | Cuero, TX 77954 | Oil & Gas Operator | Jul 2009 |
| 12 | Hardin Energy Co., Inc. | Bigfoot, TX 78005 | Oil Operator | Oct 2025 |
| 13 | Hardin, W.V. Estate | San Antonio, TX 78258 | Oil & Gas Operator | Apr 2002 |
| 14 | Hardwick Oil Company | Sugar Land, TX 77478 | Oil & Gas Operator | Nov 2014 |
| 15 | Haring Energy Company | Tuleta, TX 78162 | Oil & Gas Operator | Mar 2003 |
| 16 | Harper Hefte, Inc. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | Oct 2025 |
| 17 | Hart Petroleum Services, Inc | Corpus Chrsti, TX 78410 | Oil & Gas Operator | Jul 2025 |
| 18 | Harvey Brothers Oil & Gas | Corpus Chrsti, TX 78408 | Oil & Gas Operator | Jul 2004 |
| 19 | Harvey, Mike W. Oil & Gas | Corpus Chrsti, TX 78408 | Oil & Gas Operator | Aug 2003 |
| 20 | Harwood Exploration, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Aug 1995 |
| 21 | Hazelett Oil Company, Inc. | Dale, TX 78616 | Oil & Gas Operator | Sep 2005 |
| 22 | Headwaters Energy Partners, LLC | Dripping SPGS, TX 78620 | Oil & Gas Operator | Oct 2025 |
| 23 | Hec Petroleum, Inc | Midland, TX 79705 | Oil & Gas Operator | Mar 2006 |
| 24 | Henderson, Peter Oil Co. | San Angelo, TX 76906 | Oil & Gas Operator | Feb 2020 |
| 25 | Hewitt, Robert J. | Victoria, TX 77901 | Oil & Gas Operator | Jun 2004 |
| 26 | Hoc Operating Co., Inc. | Houston, TX 77056 | Oil & Gas Operator | Nov 1999 |
| 27 | Holden Energy Corporation | Ardmore, OK 73401 | Oil & Gas Operator | Mar 2015 |
| 28 | Hollimon Oil Corporation | Castroville, TX 78009 | Oil & Gas Operator | Nov 2016 |
| 29 | Horizon Ridge Oil Company | Austin, TX 78738 | Oil Operator | Oct 2025 |
| 30 | Houston Gulf Energy Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Oct 2025 |
| 31 | Howard Exploration, Inc. | Houston, TX 77069 | Oil & Gas Operator | Oct 2025 |
| 32 | Howell Drilling, Inc. | San Antonio, TX 78230 | Oil & Gas Operator | Aug 2003 |
| 33 | Hughes, Dan A. Company | Beeville, TX 78104 | Oil & Gas Operator | May 2006 |
| 34 | Hughes, Dan A. Company, L.P. | Beeville, TX 78104 | Oil & Gas Operator | Oct 2025 |
| 35 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 36 | Hunter Petroleum Inc. | Alice, TX 78333 | Oil & Gas Operator | May 2014 |
| 37 | Huntington Energy LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Oct 2025 |
| 38 | Hydrocarbon Horizons, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Jun 2023 |
| 39 | Hydrocarbon Operating, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 40 | Hyquest Energy, Inc. | Midland, TX 79710 | Oil & Gas Operator | Mar 2015 |