Study on the hydrochemistry, genesis and development potential of Huleitang geothermal water in Weihai City, Shandong Province

Abundant medium and low temperature geothermal resources are stored in Shandong Province. Huleitang spring, located in Weihai of Shandong province, is a unique artesian spring in this area. Due to some unidentified genesis of Huleitang spring, the effective utilization of the geothermal resources cannot implement to a certain extent. In order to find out the genetic model of the Huleitang spring, this study comprehensively uses ground investigation, geophysical prospecting and sample analysis to analyze and study. The results show that the formation of the Hulaitang spring is controlled by Rongcheng fault in the region, and by Qinglonghe fault and Tangxi fault in the local area. Its source recharges from atmospheric precipitation, and its heat source is geothermal heating. The estimated recharge elevation is 436～559 m, the calculated geothermal reservoir temperature is 109～118℃, and the calculated circulation depth is 2159～2368 m. In summary, the genetic model of the Hulaitang spring is as follows: recharges from precipitation of Weide mountain area, infiltrates down along the Rongcheng fault and participates in the groundwater circulation system. In the process of runoff, the water type of SO₄•Cl－Na was formed with the temperature of 110°C about 2 km underground by absorbing the heat of surrounding rock, dissolving and filtering, and water-rock interaction. Due to the increase of temperature and pressure, the hot water flows to the surface along the structural fractures. In the upwelling process, it mixes with some cold water, and the temperature decreases. However, it emerges as a free-flow spring at the intersection of Qinglonghe fault and Tangxi fault where is distributed with the minimum hydrostatic pressure. According to the evaluation and analysis of geothermal water development and utilization potential, geothermal water of Hulaitang spring area can be used for physiotherapy, bathing and heating, which can provide 1840 beds for physiotherapy, 460,000 people for bathing and 9.08 million m² for heating each year.