Chemical Characteristics of Buried Karst Hot Water Storage in Southwest Suburb of Zhengzhou
In order to investigate the rich geothermal resources stored in buried Lower Paleozoic carbonate rocks in the southwestern outskirts of Zhengzhou,a study on the hydrochemical profile of the main thermal reservoir layers in this area was conducted,through the analysis of hydrochemical and isotopic characteristics.The results show that:the hydrochemical types of geothermal fluids are mainly SO4-Ca and SO4·HCO3-Ca,which are weak alkaline water and fresh-brackish water.According to the comprehensive judgment of heat balance analysis and ion analysis,the geothermal fluid is in the initial period of water-rock interaction.The thermal storage temperature is estimated to be 52.9~92.4 ℃ by quartz temperature scale,and the circulating depth of the thermal storage is 1 388~3 069 m.The main supply source is the atmospheric precipitation in the low mountain area of the west and southwest,which is 606~920 m above sea level.During the long migration process to the eastern plain(the migration rate is about 1.571~0.129 m/a),strong water-rock inter-action is caused by carbonate rock minerals and gypsum,and a large amount of hydrothermal energy is accumulated in the deep karst caves,dissolution gaps and bedrock fractures.Geothermal fluids above 70 ℃ are expected to be obtained at 3 000 m depth.The re-search results not only deepen the understanding of the hydrochemical characteristics of the Lower Paleozoic carbonate reservoirs in the region,but also provide valuable guidance for the exploration and development of hydrothermal geothermal resources in this area.