| 1 | Hall-Houston Oil Company | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 2 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 3 | Hampton Resources Corporation | Houston, TX 77010 | Oil & Gas Operator | Mar 1996 |
| 4 | Harvest Oil & Gas, LLC | | Oil & Gas Operator | Feb 2012 |
| 5 | Hassie Hunt Expl. Company | | Oil & Gas Operator | Aug 2008 |
| 6 | Helis Oil & Gas Company, L.L.C. | New Orleans, LA 70130 | Oil & Gas Operator | Oct 2023 |
| 7 | Henderson Petroleum Corp | San Angelo, TX 76906 | Oil & Gas Operator | Jul 2013 |
| 8 | Hess Corporation, A De Corp. | | Oil & Gas Operator | Oct 2006 |
| 9 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Oct 2025 |
| 10 | Hilliard Oil & Gas Inc | New Orleans, LA 70112 | Oil & Gas Operator | May 2001 |
| 11 | Hillside Oil & Gas, LLC | Midland, TX 79708 | Oil & Gas Operator | Apr 2016 |
| 12 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Oct 2025 |
| 13 | Howell Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 2015 |
| 14 | Hubco Exploration Inc. | Houston, TX 77073 | Oil & Gas Operator | Sep 2002 |
| 15 | Huffco Petroleum Corporation | | Oil & Gas Operator | Jul 1988 |
| 16 | Hughes Denny Offshore Expl Inc | | Oil & Gas Operator | Nov 1988 |
| 17 | Hughes Eastern Petroleum, Inc. | | Oil & Gas Operator | Apr 1993 |
| 18 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 19 | Hunt Petroleum (Aec), Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 20 | Hunt Petroleum Corporation | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |