| 1 | H & S Production, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Mar 2004 |
| 2 | H.K.E. | Stafford, TX 77497 | Oil & Gas Operator | Oct 2025 |
| 3 | Halcon Resources Operating, Inc. | Tulsa, OK 74135 | Oil & Gas Operator | Dec 2013 |
| 4 | Halex Oil Corporation | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 5 | Hall Energy Company LLC | Oklahoma City, OK 73120-5020 | Oil & Gas Operator | Jul 2022 |
| 6 | Hamman Oil & Refining Company | Houston, TX 77098 | Oil & Gas Operator | Oct 2025 |
| 7 | Hanson Minerals Co. | Houston, TX 77042 | Oil & Gas Operator | Oct 1993 |
| 8 | Hanson Production Company | Cuero, TX 77954 | Oil & Gas Operator | Jul 2009 |
| 9 | Harvard Petroleum Corporation | Roswell, NM 88201 | Oil & Gas Operator | Dec 2004 |
| 10 | Hawthorn Energy Partners, LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Oct 2025 |
| 11 | Hazoco, L.L.C. | Bellville, TX 77418 | Oil Operator | Oct 2025 |
| 12 | Hemus, Inc. | Bellaire, TX 77401 | Oil & Gas Operator | Sep 1994 |
| 13 | Heritage Expl. & Prod. Co., Inc. | Stafford, TX 77497 | Oil & Gas Operator | Dec 2000 |
| 14 | Heritage Operating Co., Inc. The | Stafford, TX 77497 | Oil & Gas Operator | May 1997 |
| 15 | Hgi Corporation | Nada, TX 77460 | Oil & Gas Operator | Apr 2016 |
| 16 | High Plains Gas Systems, Inc. | Houston, TX 77019 | Oil & Gas Operator | Oct 2025 |
| 17 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Oct 2025 |
| 18 | Hinds Petroleum, LP | Houston, TX 77263 | Oil Operator | Feb 2017 |
| 19 | Hoc Operating Co., Inc. | Houston, TX 77056 | Oil & Gas Operator | Nov 1999 |
| 20 | Hollimon Oil Corporation | Castroville, TX 78009 | Oil & Gas Operator | Nov 2016 |
| 21 | Houston Operating, Inc. | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 22 | Howard Exploration, Inc. | Houston, TX 77069 | Oil & Gas Operator | Oct 2025 |
| 23 | Howell Drilling, Inc. | San Antonio, TX 78230 | Oil & Gas Operator | Aug 2003 |
| 24 | HRB Operating Company, Inc. | Bridgeport, TX 76426 | Oil & Gas Operator | Oct 2025 |
| 25 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 26 | Hurd Enterprises, LTD. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 27 | Hyquest Energy, Inc. | Midland, TX 79710 | Oil & Gas Operator | Mar 2015 |