Integrating Geothermometer and High Resolution Thermometer to Characterize the Geothermal Characteristics of Ilan Plain, Taiwan

Abstract

In Taiwan, a new geothermal exploration phase has been carrying out in the Ilan Plain for the development of a new geothermal power plant since 2012. Silica geothermometry and high resolution thermometer are expected to provide much better constraints for the entire operation of this power plant exploration. Two higher geothermal gradient areas, Sanxing and Loudong, are recognized based on long-term shallow bore-holes in situ temperature data. The geothermal gradient is estimated to be about 4-8 Ž/100m for these two areas. However, the major elements of the geothermal fluids of Sanxing and Luodong areas are characterized as Ca-Mg-HCO3 and Na-HCO3 types, respectively. The geothermal reservoir temperature of these two areas was estimate by applying silica geothermometry and they are about 84-113Ž. The area with higher temperature estimated by silica geothermometry coincides with the area holds higher geothermal gradients. The oxygen and hydrogen isotopic values of geothermal fluid are close the meteoric water line of the northeastern Taiwan indicating a possible mixing may have occurred during the equilibrium process.