Temperature distribution and controlling factors of the Tangquan geothermal field in Hebei Province

Abstract: Located in the northwest of Zunhua City of Hebei Province, Tangquan is characterized by hilly landscape and rich geothermal resources. In this paper, the authors studied the borehole data of many bedrock thermal wells (water wells) in the study area, and investigated the distribution characteristics and controlling factors of the geothermal field. The results show that borehole temperature is significantly affected by groundwater flow, and the vast majority of temperature wells are characterized by convective heat transfer, with a few temperature wells characterized dominantly by heat transfer conduction. The geothermal anomaly center of the study area is located in the area from Tangquan Fuquan Palace to the sanatorium, and the anomaly center exhibits bipolar distribution; the temperature of water at the depth of 50m in the geothermal anomaly center is about 51~54°C, and that at the depth of 100m is up to 60~67°C. The geothermal water of the geothermal system is caused by gradual heating action of surrounding rocks under the normal heat flow background in the process of deep circulation of groundwater. The water storage structure from Fuquan Palace to the sanitarium is formed by a buried basin with granite confining floor. Because faults cut through monolithic granite body, and cause the upward migration of the heat flux of the deep rock along the fault, whereas the heat flux is mixed with fissure water of the gneisses and is concentrated in the area from Fuquan Palace to the sanatorium. Because the gneiss fractures the aquifer in Fuquan Palace area and sanitarium area, the deep heat can quickly reach the shallow strata and give rise to local abnormal high temperature in the shallow part. The geothermal fluid belongs to continental sedimentary water that is formed in the strata with dissolved salt brine, and is mainly derived from meteoric water.