| 1 | Hadden, Pennell & Rohret | Lakewood, CO 80228 | Oil Operator | Nov 1994 |
| 2 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 3 | Hamon Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Dec 2011 |
| 4 | Hancock, Burton W | Morrison, CO 80465 | Oil & Gas Operator | Dec 2017 |
| 5 | Harken Southwest Corp | Dallas, TX 752612007 | Oil & Gas Operator | Feb 2001 |
| 6 | Harper Oil Co. | Denver, CO 80217 | Oil & Gas Operator | Jun 2025 |
| 7 | Harrison, Thomas D | Park City, UT 84060-7307 | Gas Operator | Dec 1998 |
| 8 | Harvest (Us) Holdings, Inc | Houston, TX 77077 | Oil & Gas Operator | Apr 2011 |
| 9 | Helbing & Podpechan | Clarence, OK 74018 | Oil & Gas Operator | May 1983 |
| 10 | Held By Production, Inc. | Houston, TX 77251 | Oil & Gas Operator | May 1996 |
| 11 | Hershey Oil | Pasadena, CA 91103 | Oil & Gas Operator | Dec 1988 |
| 12 | Hiko Bell Mining & Oil Co | Vernal, UT 84078 | Oil & Gas Operator | Oct 2003 |
| 13 | Hill, A G | Dallas, TX 75201 | Oil & Gas Operator | May 2008 |
| 14 | Hill, Gillman A | Englewood, CO 80112 | Oil & Gas Operator | Jun 1993 |
| 15 | Holcomb Oil & Gas Inc | Farmington, NM 87401 | Oil & Gas Operator | Sep 2025 |
| 16 | Holden Energy Corporation | Ardmore, OK 73401 | Oil & Gas Operator | Mar 2015 |
| 17 | Hollandsworth & Travis Oil | Longview, TX 75606 | Oil Operator | May 2003 |
| 18 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Dec 2025 |
| 19 | Homeland Gas & Oil, Inc | Roosevelt, UT 84066-1574 | Oil & Gas Operator | Sep 2025 |
| 20 | Hondo Oil & Gas Company | Roswell, NM 88202 | Oil & Gas Operator | Aug 2006 |
| 21 | Hot Rod Oil | Vernal, UT 84078 | Oil & Gas Operator | Oct 2025 |
| 22 | Houston Exploration Co, The | Houston, TX 77002 | Oil & Gas Operator | Apr 2017 |
| 23 | Howell Oil Company | Hutchinson, KS 67504 | Oil & Gas Operator | Jun 2025 |
| 24 | HPC Incorporated | Denver, CO 80202 | Oil & Gas Operator | Nov 1998 |
| 25 | Hugoton Energy Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2019 |
| 26 | Humble Oil & Refining Co. | Houston, TX 77252 | Oil & Gas Operator | Jan 2000 |
| 27 | Hunt Petroleum (Aec), Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 28 | Huntford Resources Corp | Englewood, CO 80112 | Oil & Gas Operator | Nov 2001 |
| 29 | Husky Oil Company | Cody, WY 82414 | Oil & Gas Operator | Dec 1984 |
| 30 | Hyland Oil Corporation | | Oil & Gas Operator | Apr 1990 |