Occurrence and modeling of geothermal water in the basement aquifer system near Tianjin, China

A large-scale low-to-moderate temperature geothermal resource has been found to occur in deep-seated basement aquifers in northeastern North China Plain near Tianjin. Carbonate rocks of Middle and Upper Proterozaic and Ordovician age on Cangxian uplift are capable of yielding 960 similar to4,200m(3)/d of 60 degreesC to 96 degreesC water to wells at depth of more than 1,000m. Conductive heat flow from the crust at depth is responsible for this anomalous geothermal field. The geothermal water is of meteoric origin and is recharged from precipitation in the northern mountain area and circulated from north to south to Tianjin. A 3-D density-dependent numerical model was used to simultaneously simulate and predict the spatial and temporal evolution of pressure and temperature in the geothermal water system. The results indicate that a pumping period of 5 months followed by a shut-in period of 7 months is helpful in maintaining the geothermal resource potential in the area.