| 1 | H & P Exploration Co. | Alice, TX 78333 | Oil & Gas Operator | May 2019 |
| 2 | H & T Oil & Gas Company, Inc. | Alice, TX 78333 | Oil & Gas Operator | Mar 2008 |
| 3 | Halex Oil Corporation | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 4 | Hall Energy Company LLC | Oklahoma City, OK 73120-5020 | Oil & Gas Operator | Jul 2022 |
| 5 | Hanson Minerals Co. | Houston, TX 77042 | Oil & Gas Operator | Oct 1993 |
| 6 | Hanson Production Company | Cuero, TX 77954 | Oil & Gas Operator | Jul 2009 |
| 7 | Hardwick Oil Company | Sugar Land, TX 77478 | Oil & Gas Operator | Nov 2014 |
| 8 | Harper Hefte, Inc. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | Oct 2025 |
| 9 | Harrison Interests, LTD. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 10 | Hart Petroleum Services, Inc | Corpus Chrsti, TX 78410 | Oil & Gas Operator | Jul 2025 |
| 11 | Harvey Brothers Oil & Gas | Corpus Chrsti, TX 78408 | Oil & Gas Operator | Jul 2004 |
| 12 | Harvey, Mike W. Oil & Gas | Corpus Chrsti, TX 78408 | Oil & Gas Operator | Aug 2003 |
| 13 | Harwood Exploration, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Aug 1995 |
| 14 | Hat Creek Energy LLC | Denver, CO 80209 | Oil & Gas Operator | Jun 2019 |
| 15 | Hawn Brothers | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2003 |
| 16 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 17 | Headington Oil Company, L.P. | Dallas, TX 75231 | Oil & Gas Operator | Mar 2008 |
| 18 | Headwaters Energy Partners, LLC | Dripping SPGS, TX 78620 | Oil & Gas Operator | Oct 2025 |
| 19 | Hedrick Production Inc. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2025 |
| 20 | High Plains Gas Systems, Inc. | Houston, TX 77019 | Oil & Gas Operator | Oct 2025 |
| 21 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Oct 2025 |
| 22 | Hollimon Oil Corporation | Castroville, TX 78009 | Oil & Gas Operator | Nov 2016 |
| 23 | Hollub, Lambert Drilling Company | Seguin, TX 78155 | Oil & Gas Operator | Oct 2025 |
| 24 | Hou-Tex, Inc. | Houston, TX 77224 | Oil & Gas Operator | Jun 2001 |
| 25 | Huber J M Corp | Edison, NJ 08837 | Oil & Gas Operator | Oct 2025 |
| 26 | Hughes, Dan A. Company | Beeville, TX 78104 | Oil & Gas Operator | May 2006 |
| 27 | Hughes, Dan A. Company, L.P. | Beeville, TX 78104 | Oil & Gas Operator | Oct 2025 |
| 28 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 29 | Hunter & Hedrick Production, Inc | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Dec 1995 |
| 30 | Hunter Petroleum Inc. | Alice, TX 78333 | Oil & Gas Operator | May 2014 |
| 31 | Hurd Ent.LTD/U.S.Enercorp,LLC | San Antonio, TX 78209 | Oil & Gas Operator | Aug 2002 |
| 32 | Hurd Enterprises, LTD. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 33 | Hydrocarbon Operating, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2025 |
| 34 | Hyquest Energy, Inc. | Midland, TX 79710 | Oil & Gas Operator | Mar 2015 |