Changes in Thermodynamic Conditions of the Ahuachapan Reservoir Due to Production and Injection

Abstract

Since large-scale exploitation of the Ahuachaph reservoir began in 1975 with the commencement of the first 30 ' MW, unit, large changes in the reservoir thermodynamic condition have occurred. Drawdowns up to 15 bars have developed in the production field and significant temperam changes have been observed. In most cases temperatures have declined due to boiling in the reservoir stimulated by the pressure diawdown; cooling due to reinjection of spent geothermal fluids has also been observed. There art indications of a cold fluid recharge to the reservoir from the west and north. Inmasing temperatures in the southeast comer of the wellfield show that significant recharge of hot fluids to the wellfield comes from the southeast; they also indicate that the recharge rate has increased with time as the pressure declines in the reservoir.