A Study Of Hydrochemistry And Tufa In Thermal Groundwater In The Zhouliangzhuang Geothermal Fileld, Tianjin

Geothermal resource is utilized widely in Tianjin. The Zhouliangzhuang geothermal field lies in the north of Tianjin, which belongs to a geothermal system of the sedimentary basin type of middle-low temperature. The Ordovician reservoir, Cambrian reservoir and Meso-to Neo Proterozoic reservoir are the main reservoirs.The hot water of Wang 4 well which lies in the Zhouliangzhuang village of Tianjin, has flowed automatically for nearly 30 years, with the temperature 90.2 ℃. Wang 2 well and the Wang 3 well are not far from the Wang 4 well, with the temperatures 94.5 ℃ and 60 ℃. However, the thick tufa only grows around the Wang 4 well.The geochemical characteristics of Wang 4 well, Wang 2 well and Wang 3 well are similarly. Analyzed the geochemical characteristics of thermal fluid by Aquachem, the geochemical types of the three wells are same. Simulated by WATCH, the Wollastonite and the Quartz had been saturated already, the Fluorite and the Chalcedony are close to saturation, and the other minerals are not saturated. The water quality of this area is well. Judged by LI index method, the geothermal fluid will erode slightly; the trend of scaling of Wang 4 well calculated by RI and Puckorius index methods is only middling, which is not consilient with the fact.The reason of growth of the tufe is described by analyzing the geochemical condition and water dynamic condition. Because of the inaccurate data of CO₂, we can't get the reason from the geochemical condition. But the geochemical condition it is the necessary condition. The growth of the tufa goes with the flowing of the thermal fluid from the top of the tank to the ground, which is the advantaged water dynamic condition. That is, the rapid and thin fluid is the main reason of the growth of the tufa. So, the appropriate geochemical condition and the advantaged water dynamic condition compose the growth of the tufa of Wang 4 well.With WATCH program, the geothermal reservoir temperature is in the range of 104.7 -124.8℃ on the base of calculation of the quartz geothermometer, which proves the Wumishan geothermal reservoir has large potential to develop and utilize.On the base of cascading utilization, this paper put forward to the geothermal resources utilization project. In the project the geothermal reservoir is widely utilized in heating, industry, aquiculture, greenhouse, bath and recuperates.