Reservoir Engineering of the Ahuachapan Geothermal Field

Abstract

Reservoir engineering in the Ahuachapan geothermal field, where there is an installed capacity of 2x30 MW + 1x35 MW, is at present mainly oriented towards field management, so as to predict production declines and to permit one to make the correct, timely intervention in order to guarantee the full rate of extraction. From the conceptual model on which reservoir engineering is based, a mathematical model was derived, a modified version of the original by Faust and Mercer. The match of observed against simulated evaluation for the first 12 years of exploitation provided the best matching parameter; these were then used to predict the future behavior of the field under different production/reinjection rates and sites. The main result to date has been the realization that two additional wells are needed if one is to sustain the full rate of extraction for the next twenty years.