Low Temperature Geothermal Reservoirs in the Portuguese Hercynian Massif

Abstract

A number of mineral springs clearly related with deep geological process and neotectonic activity are reported at the Portuguese Hercynian Massif. Twenty seven springs have discharge temperatures between and Thermal baths are installed over these natural occurrences. In the last fifteen years, almost all classical dug wells or spring arrangements were replaced by drilled wells with depths up to Drilling provided considerable new information on the nature of the mineral spring systems. Following these investigations two small low-enthalpy geothermal projects for direct use became operational. Surface consumers in some other sites are adequate for economical direct utilisation of geothermal heat. Chemical geothermometers suggest reservoir temperatures up to However, the possibility of electricity production with binary power plants may deplete the resources for traditional thermal (spas) use in some sites.