Deep-seated Geothermal Resources of the Parana Basin

Abstract

Updated data sets on terrestrial heat flow and thermal springs have been employed in outlining the nature of deep-seated geothermal resources of the Parana basin. A 1^o x1^o grid system was adopted for data processing and in determinations of vertical distributions of excess temperatures. The results obtained have led to an improved understanding of the occurrence of high temperature geothermal resources and allowed estimates of associated resource base. It has been possible to identify more than 20 crustal blocks where the resource base per unit area, referred to the accessible depth limit of 6 km, are in the range of 2x10¹¹ to 9x10¹¹ Joules. There are indications pointing to occurrence of medium temperature geothermal resources at depths of 4 to 6 km in several sectors of the central and western parts of the basin. The area extent of such blocks has dimensions of several tens of kilometers. Most high temperature resources occur within the well-known sectors of fault-controlled magmatic activity associated with the eruption of Serra Geral flood basalts. In addition, isolated pockets of high enthalpy geothermal resources are found to be present along the northwestern border. The results have also allowed better assessments of low temperature resources of the Guarani aquifer system, which span over large areas of southern Brazil, western Uruguay and northern Argentina.