Geochemical Modeling of Thermal Springs from Colombia

Abstract

A preliminary geochemical modeling of Azufral and Paipa geothermal systems, and the N-NE area of Cundinamarca District (Republic of Colombia), was carried out; based on chemical analyses from the most remarkable thermal springs by using GWB software. Activity coefficients were obtained by the Debye-Huckel approach and virial methods according to sample salinity. The estimated temperatures were as follows. (1) The fluid equilibrium temperature for El Batan, the hottest spring water in Paipa (75.5?C), although equilibrium with chalcedony phase was about 100?C, while the calculated saturation indices suggested an equilibrium temperature of 107?C. For most of Paipa's samples, anhydrite was found supersaturated above 90?C. (2) Most Azufral samples have an equilibrium temperature between about 57?C and slightly above 200?C. The fluid's equilibrium temperature with quartz, for seven thermal springs in Azufral geothermal system, varies between 166 and about 200?C. (3) Cundinamarca District, whose highest sampling temperature was 50.8?C, showed lower equilibrium temperature, which was not higher than 93?C. As modelling was performed using spring data, it is possible that higher temperatures occurred at depth since hot waters are affected by cooling processes such as mixing with cooler waters when ascending to the surface. However, the results obtained indicated the presence of medium temperature geothermal resources in Colombia and allowed a preliminary identification of the most interesting zones.