| 1 | H & H Oil Productions | Tulsa, OK 74145 | Oil Operator | Jul 1999 |
| 2 | H.L.S. Energy Co., Inc. | Uvalde, TX 78801 | Oil & Gas Operator | Aug 2003 |
| 3 | Hadson Petro USA Inc | | Oil & Gas Operator | Nov 2016 |
| 4 | Hadson Petroleum Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2015 |
| 5 | Halcon Holdings Inc | Ada, OK 74820 | Oil & Gas Operator | Nov 2018 |
| 6 | Halliburton Oil Producing Co. | Duncan, OK 73534 | Oil & Gas Operator | Apr 2016 |
| 7 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jan 2025 |
| 8 | Hamil Oil & Gas LLC | Kingfisher, OK 73750-6500 | Oil & Gas Operator | Apr 2025 |
| 9 | Hamon Jake L | Dallas, TX 75201-3902 | Oil & Gas Operator | Nov 1997 |
| 10 | Happy Hill Operating LLC | Guthrie, OK 73044-7361 | Oil & Gas Operator | Oct 2017 |
| 11 | Harbert Energy Corp | Irving, TX 75015-2510 | Oil & Gas Operator | Feb 1993 |
| 12 | Hargraves Elston | Ponca City, OK 74604 | Oil & Gas Operator | Jul 2003 |
| 13 | Harris Minerals Corp (The) | Oklahoma City, OK 73162-1045 | Oil & Gas Operator | Apr 2025 |
| 14 | Hazelwood Prod & Exp Co LLC | Oklahoma City, OK 73116-9037 | Oil & Gas Operator | Apr 2025 |
| 15 | Heartland Exploration | Oklahoma City, OK 73102 | Oil & Gas Operator | Jan 2000 |
| 16 | Heartland Exploration Inc | Edmond, OK 73013 | Oil & Gas Operator | Dec 2015 |
| 17 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Mar 2025 |
| 18 | Heritage Petroleum, Inc. | Stillwater, OK 74076 | Oil & Gas Operator | Jul 2025 |
| 19 | Hewitt Energy Group, Inc. | Salt Lake City, UT 84111 | Oil & Gas Operator | Apr 2015 |
| 20 | Hexagon Oil And Gas Inc. | Fort Worth, TX 76132 | Oil & Gas Operator | Jul 2025 |
| 21 | Highmount Operating LLC | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2014 |
| 22 | Hill John H | Dallas, TX 75240-7077 | Oil & Gas Operator | Jul 2015 |
| 23 | Hill Oil Company Inc | Shawnee, OK 74804 | Oil & Gas Operator | Apr 2025 |
| 24 | Hill Resources Inc | | Oil & Gas Operator | Nov 2022 |
| 25 | Hinkle Engineering, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Nov 2016 |
| 26 | Hoke Jr J T | Edmond, OK 73034 | Oil Operator | Nov 1998 |
| 27 | Hondo Oil & Gas Company | Roswell, NM 88202 | Oil & Gas Operator | Aug 2006 |
| 28 | Howco Oil And Gas | Stroud, OK 74079-9604 | Oil & Gas Operator | Mar 2015 |
| 29 | Hoyt Oil & Gas LLC | Cushing, OK 74023-0442 | Oil & Gas Operator | Apr 2025 |
| 30 | Hugoton Energy Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2019 |
| 31 | Hulen Operating Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Jul 2025 |
| 32 | Hux Oil Company LLC | Kingfisher, OK 73750 | Oil & Gas Operator | Apr 2025 |