Application of hydrogeochemical methods in geothermal resource exploration: A case study of Yingcheng City, Hubei Province

Abstract

Hydrogeochemical studies of geothermal fluid are widely used to determine the formation mechanism and occurrence environment and predict favourable exploration areas for geothermal resources. Objective In order to understand the heat source and causative mechanisms of the geothermal system, the areas of geothermal anomalies are delineated in Yingcheng City, Hubei Province. Methods This study examines the geochemical origins of major components in geothermal fluid and evaluates the thermal reservoir temperatures of geothermal fluid based on the hydrochemical and isotopic characteristics of geothermal water and shallow groundwater. By integrating the temperature and hydrochemical data of shallow groundwater in the area, the geothermal anomaly zones are delineated. Results The results show that geothermal water hydrochemistry is mainly SO4-Ca, and the main thermal storage enclosing rock of the geothermal system is marine carbonate rock, with a thermal reservoir temperature of approximately 112.2 ℃. Atmospheric precipitation infiltration and water-rock interactions in carbonate thermal reservoirs are the main sources of chemical components in geothermal water. The hydrochemical and hydrogen-oxygen isotope characteristics of the geothermal water indicate that the recharge source of the geothermal water is the precipitation from the mountainous areas in the western part of the study area.The atmospheric precipitation infiltrates from the recharge area and then continuously moves to the centre of the southeastern basin with a circulation depth of 3 436.7 m to 5 030.2 m. Conclusion Comparisons with the typical magma-heat source type of geothermal system as well as the results of the data of radioactive elements in the rocks, this study showed that the geothermal system of Yingcheng is formed by the heating of geothermal temperature gradient. Combined with the temperature and hydrochemistry data of the shallow underground cold water in the area, the final geothermal anomaly area is located in North of Chenhe Town Southwest of Yingchengcity, but the influence of objective constraints such as well depths and anthropogenic contamination on the results of the circle still needs to be considered.

Keywords

• hydrogeochemistry
• geothermometer
• geothermal anomaly
• geothermal resource exploration
• geothermal system
• yingcheng city