| 1 | H & P Exploration Co. | Alice, TX 78333 | Oil & Gas Operator | May 2019 |
| 2 | H Oil Company, Inc. | Edna, TX 77957 | Oil & Gas Operator | Mar 2005 |
| 3 | Halbouty, Michel T. | Houston, TX 77056 | Oil & Gas Operator | Aug 1997 |
| 4 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 5 | Hankamer, Curtis Corporation,The | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 6 | Hanson Minerals Co. | Houston, TX 77042 | Oil & Gas Operator | Oct 1993 |
| 7 | Hanson Production Company | Cuero, TX 77954 | Oil & Gas Operator | Jul 2009 |
| 8 | Harken Exploration Company | Houston, TX 77079 | Oil & Gas Operator | Mar 2008 |
| 9 | Harrigan Energy Partners, Inc. | Houston, TX 77058 | Oil & Gas Operator | Sep 2010 |
| 10 | Harvest Petroleum Inc. | Frisco, TX 75033 | Oil & Gas Operator | Oct 2025 |
| 11 | Harwood Exploration, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Aug 1995 |
| 12 | Hazelett Oil Company, Inc. | Dale, TX 78616 | Oil & Gas Operator | Sep 2005 |
| 13 | Hec Petroleum, Inc | Midland, TX 79705 | Oil & Gas Operator | Mar 2006 |
| 14 | Hibernia Resources, LLC | Houston, TX 77027 | Oil & Gas Operator | Jun 2014 |
| 15 | Hicks Exploration, LLC | Dover, OK 73734 | Gas Operator | Feb 2025 |
| 16 | High Bluff Operating, LLC | Littleton, CO 80161 | Oil & Gas Operator | May 2018 |
| 17 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Oct 2025 |
| 18 | Hodge T F | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2007 |
| 19 | Hollimon Oil Corporation | Castroville, TX 78009 | Oil & Gas Operator | Nov 2016 |
| 20 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Oct 2025 |
| 21 | Horizon Exploration Company | Houston, TX 77019 | Oil & Gas Operator | Aug 2002 |
| 22 | Horizon Prod. And Operating, LLC | Houston, TX 77019 | Oil & Gas Operator | Oct 2025 |
| 23 | Hou-Tex, Inc. | Houston, TX 77224 | Oil & Gas Operator | Jun 2001 |
| 24 | Houston Gulf Energy Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Oct 2025 |
| 25 | Houston Operating, Inc. | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 26 | Howard Exploration, Inc. | Houston, TX 77069 | Oil & Gas Operator | Oct 2025 |
| 27 | Howard, Douglas J. | Houston, TX 77070 | Oil & Gas Operator | Mar 2008 |
| 28 | Howell Drilling, Inc. | San Antonio, TX 78230 | Oil & Gas Operator | Aug 2003 |
| 29 | Hughes, Dan A. Company | Beeville, TX 78104 | Oil & Gas Operator | May 2006 |
| 30 | Hugoton Operating Company, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 31 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 32 | Hunt Petroleum (Aec), Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 33 | Hunt, WM. Herbert, Trust Est. | Dallas, TX 75201 | Oil & Gas Operator | Sep 1998 |
| 34 | Hurd Enterprises, LTD. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 35 | Hydrocarbon Horizons, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Jun 2023 |
| 36 | Hydrocarbon Operating, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 37 | Hyquest Energy, Inc. | Midland, TX 79710 | Oil & Gas Operator | Mar 2015 |