| 1 | H-M Resource Management, Inc. | Houston, TX 77055 | Oil & Gas Operator | Feb 2023 |
| 2 | Hall-Houston Oil Company | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 3 | Hardwick Oil Company | Sugar Land, TX 77478 | Oil & Gas Operator | Nov 2014 |
| 4 | Haring Energy Company | Tuleta, TX 78162 | Oil & Gas Operator | Mar 2003 |
| 5 | Harken Exploration Company | Houston, TX 77079 | Oil & Gas Operator | Mar 2008 |
| 6 | Hart Petroleum Services, Inc | Corpus Christ, TX 78410 | Oil & Gas Operator | Jul 2025 |
| 7 | Harvest Petroleum Inc. | Frisco, TX 75033 | Oil & Gas Operator | Apr 2026 |
| 8 | Hawn Brothers Company | Corpus Christ, TX 78401 | Oil & Gas Operator | Jan 2003 |
| 9 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 10 | Headline Resources, Inc. | Richardson, TX 75080 | Oil & Gas Operator | Aug 1997 |
| 11 | Heartland Production, Inc. | Cuero, TX 77954 | Oil & Gas Operator | Apr 2026 |
| 12 | Hewitt, Robert J. | Victoria, TX 77901 | Oil & Gas Operator | Jun 2004 |
| 13 | Hibernia Resources, LLC | Houston, TX 77027 | Oil & Gas Operator | Jun 2014 |
| 14 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Apr 2026 |
| 15 | HK Energy Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2023 |
| 16 | Hollimon Oil Corporation | Castroville, TX 78009 | Oil & Gas Operator | Nov 2016 |
| 17 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Apr 2026 |
| 18 | Horadam, Henry L. | Victoria, TX 77905 | Oil & Gas Operator | Oct 2008 |
| 19 | Hou-Tex, Inc. | Houston, TX 77224 | Oil & Gas Operator | Jun 2001 |
| 20 | Houston Gulf Energy Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 2026 |
| 21 | Houston Hydrocarbons, Inc. (A) | Houston, TX 77042 | Oil & Gas Operator | Sep 2004 |
| 22 | Howard Exploration, Inc. | Houston, TX 77069 | Oil & Gas Operator | Dec 2025 |
| 23 | Howell Drilling, Inc. | San Antonio, TX 78230 | Oil & Gas Operator | Aug 2003 |
| 24 | Howell Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 2015 |
| 25 | HR Petroleum | Corpus Christ, TX 78413 | Oil & Gas Operator | Apr 1998 |
| 26 | Hughes Legacy LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2022 |
| 27 | Hughes, Dan A. Company | Beeville, TX 78104 | Oil & Gas Operator | May 2006 |
| 28 | Hunt Petroleum Corp. | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 29 | Hunt, WM. Herbert, Trust Est. | Dallas, TX 75201 | Oil & Gas Operator | Sep 1998 |
| 30 | Hunter Petroleum Inc. | Alice, TX 78333 | Oil & Gas Operator | May 2014 |
| 31 | Hurd Enterprises, LTD. | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2026 |
| 32 | Hydrocarbon Horizons, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Jun 2023 |
| 33 | Hyquest Energy, Inc. | Midland, TX 79710 | Oil & Gas Operator | Mar 2015 |