Numerical modelling of an advective geothermal system in the Central Andes: Sustainable utilization through borehole heat exchangers

Abstract

The utilization of low-enthalpy geothermal resources emerges as a promising solution for district heating in the Central Andes region. Focused on the Pismanta field, a representative example of the prevalent advective geothermal systems in the area, this study investigates into the intricate dynamics of the geothermal reservoir. Situated within a fault-controlled basin, the Pismanta field undergoes deep infiltration of meteoric water, leading to peak temperatures of up to 90 °C. Numerical simulations conducted at varying scales yield critical insights into the characteristics, efficient exploitation, and potential repercussions of energy extraction from the reservoir. A comprehensive approach is adopted to facilitate the optimal management of this geothermal resource and a strategic closed-loop system comprising 10 shallow interconnected borehole heat exchangers (BHE) is proposed. This recommendation takes into account the specific basin geometry and the intricate interplay of pressures within the confined geothermal reservoir. Extensive simulations over a 10-year period show the sensitivity of the system to operating flow rates. By employing the suggested configuration, it is anticipated that a maximum thermal power extraction of 1 MW can be achieved. The circulating water within the system is projected to maintain a temperature of approximately 26 °C.