Geothermal potential evaluation and development prioritization based on geochemistry of geothermal waters from Kangding area, western Sichuan, China

摘要

Kangding geothermal area is located in the western Sichuan, belonging to southeastern margin of Tibetan Plateau. Similar to world-renowned south Tibetan and western Yunnan geothermal belt, western Sichuan has intensive surface thermal manifestations including boiling and hot springs. The emerging temperature of thermal waters ranges from 47 to 79 degrees C with total dissolved solids lying between 899 and 2550 mg/L. delta H-2-delta O-18 isotopes indicate a meteoric source for the thermal waters and a significant positive oxygen-18 shift in the southern region. It is suggested that southern thermal waters experienced stronger water-rock interaction and are closer to thermodynamic equilibrium, which is also proved by the water type classification. The reservoir temperature calculated by empirical and theoretical chemical thermometry is 180-225 degrees C for the north and 225-310 degrees C for the south. Evidences of hydrogeochemistry, stable isotopes, geothermometry and radiocarbon dating indicate that southern region of Kangding area shows greater geothermal potential than the northern region. In addition, based on the hydrogeochemical modeling of mineral saturation, underlying problem of scaling is likely to occur in the study area. According to the results of reservoir temperature, south Kangding sub-district has greater potential in geothermal power generation and development than northern Kangding. Therefore, further exploration and drilling work should give priority to the south Kangding area.