Study on shallow geothermal field in Nanjing: Based on distributed optical fiber temperature measurement system

Shallow geothermal energy has attracted extensive attention at home and abroad as a new type renewable energy. Resistance temperature sensors, as susceptible to electromagnetic interference, are not suitable for long-term use. The distribution-based fiber optic temperature measurement technology with strong anti-interference ability was used in 19 boreholes to a depth of 100 meters in Nanjing City. In the winter of 2018 and spring of 2019, the distribution of shallow uground temperature in Nanjing was obtained from the 19 boreholes. Based on the hydrological and geological conditions in Nanjing, it is concluded that the change of shallow ground temperature is lagged relative to the change of air temperature. For the shallow ground temperature in the same location, the flow of groundwater will lead to different ground temperature in different seasons. Structural conditions significantly affect the distribution of shallow ground temperature. The results can provide a reference for the utilization and further development of shallow geothermal energy in Nanjing.