The Ahuacapan Geothermal Field after 20 Years of Exploitation

Abstract

A study of the physical and chemical data of Ahuachapan field, during 20 years of production allows a formulation of the conceptual model of the field. Chloride content, SO2and Na-K-Ca temperatures, Cl/SO4 ratio, enthalpy-chloride relations and gas geothermometry have been used to understand the main phenomena affecting the observed fluid compositions. The main phenomena can be' summarized as due to:
1) an upflow zone located in the South part of the field with a fluid moving laterally mostly North at different depths from 5430 tci 1000 m
2) a shallow rescharge, at depth of the 0rde.r of 500 m, a of diluted water from E-NE of ametheoric water due to lowering of the pressure in the original reservoir
3) a deep rescharge made of an andesitic acidic and gassy fluid from depth ;4) local boiling.