Analysis Of The Scaling Mechanism And Trend Of Thermal Groundwater In Kangding County Of Sichuan Province

There are abundant Medium and high-temperature geothermal resources inKangding County of Sichuan Province, and the resources has gained extensiveapplications. The geothermal system consists basically of three reservoirs, there is twolayers of Permianent(P) and the Yulin River fault containing hot water.The geochemical methods adopted in this paper are used to interpret thechemical and isotopic characteristics of thermal waters in the Kangding geothermalfield, that is AquaChem software, index method and WATCH program. According tothe geochemical characters of thermalwater, we can ascertain the cause of formationin the Kangding geothermal field and the scaling.To determine the scale trend of thermal water, we have adopted index methodand WATCH program. By the log(Q/K), Most of the thermal water in the Kangdingfield have the potential of scaling. The main precipitated scaling matter is CaCO3.And Calcite are responsible for the scaling. An allowable supersaturation is found bycomparing the degree of calcite supersatureation and actual scaling status in theselected samples. The saturation index0.175～0.238is the boundary between calcitescaling and no scaling.The thermal fluid does not seem to be in equilibrium with anyhydrothermal minerals in the reservoir, except for chalcedony and quartz. By runningAquaChem software, it gains triangular diagram of a variety of water. the mainchemical type of geothermal water is Na-HCO3·Cl. The relationship between stableisotopes of δD and δ18O indicates the meteoric origin of thermal water in theKangding field. Several kinds of geothermometers are used to predict the subsurfacetemperatures in the Kangding geothermal field. The subsurface temperature is in therange of51.4～103.8℃on the base of calculation on the chalcedony geothermometer.The geothermometer calculations indicate that one can expect the highest temperaturein the arear of F5and F2fault, and the drilling of geothermal wells are mainlydistributed there, Therefore, the main potential for further development of thegeothermal resources is in that region.