Fifty Years of Operation at the Ahuachapán Geothermal Field

Abstract

The Ahuachapán Geothermal Field has reached 50 years of production. During the first decade, a pressure drawdown of approximately 15 bar led to the expansion of a steam cap and the lateral inflow of cool water from a shallow aquifer. In the 1990s, the borefield expanded to the southeast, stabilizing mass extraction by encountering highly permeable wells at deeper zones with varying water levels. Since reinjection began in Chipilapa in the early 2000s, on the northwest side of the field, pressure drawdown in the central area has decreased. As the conceptual model evolves, new wells drilled in the mid-2000s on the east side of the field have encountered temperatures of 275°C. However, the degree of connection with the existing wellfield is still under investigation. It is believed to represent a separate upflow, potentially serving as a prospect for future expansion. Numerical reservoir models predict that the current strategy will keep a stable power generation, though some cooling is anticipated.