| Title | Study of EGS Heat Recovery by Multi-Parallel Fracture Model at Desert Peak Field, USA |
|---|---|
| Authors | Haizhen ZHAI, Zheng SU, Nengyou WU |
| Year | 2017 |
| Conference | Stanford Geothermal Workshop |
| Keywords | enhanced geothermal systems (EGS), heat recovery, multi-parallel fracture model, Desert Peak |
| Abstract | Heat recovery is an effective way to ensure the long-term stable operation of EGS. Based on the geological background of American Desert Peak field, we studied the heat extraction and heat recovery process with multi-parallel fracture model. The results suggest that, in the initial period of heat recovery process, temperature rises rapidly in a large gradient, while slows down in the latter period. Two main affecting factors of the recovery process are the initial temperature field and the recovery time period. For affecting the initial temperature of the recovery process together, the property of the reservoir (i.e. the stimulation degree of the reservoir and the heat conductivity of the rock) and the fluid flow has the same impact on the heat recovery process as on the heat extraction process. The thickness of heat transfer unit (HTU), fluid flow, and the heat extraction and recovery period are negatively correlated with outlet temperature and lifetime. The heat conductivity of the rock is positively associated with outlet temperature and lifetime. The system with a circulation fluid flow of 100 kg/s, thickness of HTU of 100 m, heat extraction and recovery period of 5 years, has a lifetime of 34.0 years, which is prolonged for 11.9 years compared to continuous heat extraction. |