Application of Silica Heat Flow on Geothermal Water Circulation Depth Estimation in the Chingshui Geothermal Field, Taiwan

Abstract

Application of Silica Heat Flow on Geothermal Water Circulation Depth Estimation in the Chingshui Geothermal Feld, Taiwan Ching-Huei Kuo1*, Chia-Mei Liu1, Sheng-Rong Song2, Yu-Wei Tsai1 1Department of Geology, Chinese Culture University, Taiwan 2Institute of Geosciences, National Taiwan University, Taiwan Abstract The Chingshui geothermal field is one of the greatest geothermal potential and the most studied areas in Taiwan. It serves as the prototype to the development of geothermal energy in Taiwan for the next eon. Eight hot springs samples, located in the slate formation of the Central Range, were collected in the Chingshui geothermal field and the in situ temperature and pH values are measured ranging from 63.2 °C to 96.0 °C and from 6.14 to 9.2, respectively. Based on the concentrations of major elements, these hot springs are characterized as the Na-HCO3- water. The oxygen and hydrogen isotopic values of these samples are from -6.56 ‰ to -4.66 ‰ and from -54.1 ‰ to -40.3 ‰, respectively. In addition, two silica geothermometers, conductive and adiabatic cooling, were used to calculate the temperature of the geothermal reservoir. The reservoir temperature is estimated to be about 201°C± 19.3°C and the silica heat flow is 268 mW/m2. This infers that the geothermal water circulation depth is about the 1.9 km in the Chingshui geothermal field. This value is consistent with previous results from the borehole measurements and stable isotopic values of carbonate vein of IC 16.