High-Resolution Spatiotemporal Monitoring Data During Groundwater Heat Pump System Operation

Sustainability is one of the points in the design stage of the groundwater heat pump (GWHP) system. Thermal impacts on the surrounding environments should be accurately configured to ensure system sustainability. To achieve that goal, a sophisticated characterization of the target aquifer is required. So far, considering heterogeneity of subsurface environment in system design is challenging because there is lack of case studies provided high-resolution monitoring data enough to catch the heterogeneity. In this study, to detect the hydraulic and thermal responses to the GWHP operation, 12 monitoring wells were densely constructed between two geothermal wells at Eum-Seong, Republic of Korea. During the system operation, the high-resolution spatiotemporal changes in hydraulic pressure and temperature were detected by pressure sensors and fiber optic-distributed temperature sensing (FO-DTS). Monitored results were interpreted by time-series analysis to derive the thermal front velocity between monitoring wells. During the GWHP system operation, groundwater level monitoring results showed that a dynamic flow condition was generated especially near the geothermal wells up to 20 times of background flow. The estimated effective thermal velocities were comparable with the theoretically calculated velocities, but the higher velocity randomly appeared at the specific depths. From this case study, we confirmed FO-DTS was applicable to monitor the GWHP system. Those three-dimensional high-resolution monitoring data enabled to prove the existence of horizontal and vertical heterogeneity, indicating the need for accurate characterization of aquifer properties.

 

Acknowledgements

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2022R1A2C1006696). This work was also supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government(MSIT) (No. 2022R1A5A1085103).