Oil & Gas Companies in Harper County, OK
| Company Name | Company Location | Company Type | Most Recent Production |
| 1 | E2 Operating LLC | Tulsa, OK 74135 | Oil & Gas Operator | Oct 2025 |
| 2 | Eagle Oil & Gas Co. | Dallas, TX 75225 | Oil & Gas Operator | Oct 2025 |
| 3 | Earlsboro Energies Corporation | Oklahoma City, OK 73116-3605 | Oil & Gas Operator | Jun 2025 |
| 4 | Edinger Engineering, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Jul 2025 |
| 5 | El Paso Production Company | Houston, TX 77002 | Oil & Gas Operator | Mar 2016 |
| 6 | Elder & Vaughn Inc | Oklahoma City, OK 73154-0938 | Oil & Gas Operator | Mar 2008 |
| 7 | Elite Tank Trucks, Inc | | Oil & Gas Operator | Jul 2025 |
| 8 | Encore Operating LP | Plano, TX 75024 | Oil & Gas Operator | May 2025 |
| 9 | Enervest Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 10 | Enserch Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | Apr 2015 |
| 11 | EOG (Oklahoma) Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Oct 2016 |
| 12 | EOG Resources, Inc. | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 13 | EP Energy E&P Company, LP | Houston, TX 77210 | Oil & Gas Operator | Jan 2023 |
| 14 | Esenjay Exploration, Inc | Houston, TX 77042 | Oil & Gas Operator | Jun 2025 |
| 15 | Esis Inc | | Oil & Gas Operator | Feb 2017 |
| 16 | Excelco Energy Inc. | Kingwood, TX 77339 | Oil & Gas Operator | Jul 2018 |
| 17 | Exco Resources Inc | Dallas, TX 75251 | Oil & Gas Operator | Jun 2025 |
| 18 | Exxon Mobil Corporation | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 19 | Exxonmobil Oil Corp | Houston, TX 77210 | Oil & Gas Operator | Jul 2025 |
Production numbers shown above are only for Harper County, OK and for the production period listed.