Hydrogeochemistry Of Geothermal Field Of Long Mu Bay, Hainan Province

In the paper,a preliminary research was made on the chemical composition,numerical values of ?18O and ? D,value of 14 C isotope of geothermal water of Longmu bay geothermal field after briefly analyzed the background of geothermal geology in Hainan Province,analyzed mineral equilibrium by Phreeqc software,discussed hydrogeochemical characteristics of the geothermal water by Aquachem software.In the paper,on the basis of briefly analysis about the background of geothermal geology in Hainan Province,a preliminary research such as the chemical composition,numerical values of ?18O and ? D,value of 14 C isotope of geothermal water of Longmu bay geothermal field was made,then analyzed mineral equilibrium by Phreeqc software,discussed hydrogeochemical characteristics of the geothermal water by Aquachem software.According to the cool groundwater sampled near the research area,whose atmospheric precipitation equation(? D = 8.02 ?18O+ 7.64(R2=0.9562))was obtained through using least square method fitting experimental results.The research on isotopes composition of geothermal water shows that the geothermal water in study area is recharged from the precipitations,which has high replenishment elevation and the range of altitude in recharge area is 510 ? 730 m;The range of geothermal water age is 3500 ~ 15000 a,which shows that the supply line of geothermal water of Longmu bay is long and the groundwater runoff is slow.The study of Water chemistry show that:The water of study area mainly for the underground hot water type is HCO3-Na·Ca or HCO3-Na·Ca,the degree of mineralization value is between 317 ~ 657 mg/L,PH value is between 6.56 ~ 8.35.the SiO2 in hot water content is between 36.2 ~ 81.7 mg/L.The study of Water chemistry show that:the main type of the underground hot water in study area is HCO3-Na·Ca or HCO3-Na·Ca;,the degree of mineralization value is between 317 ~ 657 mg/L;and the PH value is between 6.56 ~ 8.35;the content of SiO2 in hot water is between 36.2 ~ 81.7 mg/L.By comparing the calculative results of several kinds of geochemical thermometer with the measured temperature data by geophysical,which indicates that the results calculated by chalcedony geothermometer is predicted deep geothermalreservoir temperature of mid-low temperature geothermal water in Longmu bay area reasonably.But the results of geothermal reservoir temperature calculated by Na-K,Na-K-Ca cation etc.temperature scale shows that predicted geothermal reservoir temperature in research area in this way is unreasonable.The range of geothermal reservoir temperature of Longmu bay calculated by chalcedony geochemical is 80~115 ?.The geothermal resources quantity of research area calculated by thermal storage method is 1.55×1015 kJ,and the available geothermal energy of geothermal water yearly output is 2.51×108 MJ that account for 1.61% of thermal energy calculated by geothermal reserve method,so this is a small geothermal fields.The geothermal fluid in the area can be directly used in physical therapy,bathing,heating,etc.,and can be used as the low temperature siliceous freshwater development and utilization,which has great potential on development and social benefits.