Analysis on Geothermal Field Dynamic Characteristics of Low - Medium Temperature Geothermal Reservoir Under Exploitation and Reinjection

There is high geothermal temperature background value in Tianjin, one of the four municipalities of China. In Tianjin geothermal resources have been exploited with large scale for a long time and convert to recycling exploitation mode by reinjection. The continuous steady wellhead temperature monitoring data of geothermal well shows that the temperature of geothermal fluid has no apparent fluctuate for long-term exploitation. The temperature is measured in a reinjection well during and after reinjection. The result shows that while recharge in low temperature original water, the bottom temperature of borehole decreased by 0.1～0.76℃/a; But after reinjection the temperature of extraction reservoir recovers month by month. It also indicates that after reinjection the geothermal temperature of reinjection region gradually recovers to the original temperature of last year before the next reinjection stage.