Reinjection experiments in the basement geothermal reservoir, Tianjin, China

Abstract

IThe end of 2001, about 196 production wells, (including 12 reinjection wells) had been drilled in Tianjin. The annual production rate was 22 Mm 3 in 2001 and the reinjection rate was about 1.66 Mm 3 . The depth to the water level ranges from 22 to 70 m and the draw-down rate is 6-9 m/year. The effect of reinjection in the WR45 doublet is analysed, but no temperature changes have been observed in surrounding geothermal production wells, up to the present. The main side effect anticipated from reinjection is a cooling of the reservoir. Tracer tests are very important for understanding the mode of transport and flow-channel/fracture-space characteristics in doublet production/reinjection systems, and to estimate the possible cooling resulting from injection.