HYDROCHEMICAL CHARACTERISTICS OF GUANTAO GEOTHERMAL RESERVOIR IN EASTERN JIYUAN-KAIFENG SAG: Implication for Its Formation

The analysis of geothermal water of Guantao Formation in eastern Jiyuan-Kaifeng sag shows that the geothermal water is hydrochemically neutral water, salt water and extra-hard water, mainly Cl-Na type, and its chemical characteristics, controlling factors and characteristic coefficients are significantly different from those in upper Minghuazhen Formation, Quaternary groundwater and surface water. The geothermal water in Guantao Formation is sedimentary type of lixiviation water in continental salt rock strata, occurred in sandstone pores, with regional faults and fissures as channels for heat conduction and migration, and terrestrial heat flow for heat conduction and warming, accompanied by constant lixiviation, evaporation and concentration. On the other hand, due to the well sealed geothermal reservoir, the migration of geothermal water is much stagnant, which contribute to the complete reducibility and higher concentration degree of geothermal water. Compared with Kaifeng-Lankao fault depression, the geothermal water in Guantao Formation of Kaifeng fault uplift shows higher degree of reducibility and concentration.