Gas chemistry of the Ahuachapán Berlín geothermal fields, El Salvador

Abstract

Gas compositions of reactive gases in geothermal fluids of the Ahuachapán and Berlín fields have been used to estimate sub-surface conditions such as temperature and initial aquifer steam fraction. Inert or conservative gas compositions provide information on the source of the gases in the reservoir liquid. Of the fourteen gas geothermometers used in this study, the H2S and CO2 geothermometers yield the best temperature values. The initial steam fractions in the aquifers of both Ahuachapán and Berlín geothermal reservoirs are low and generally negative, i.e. the aquifer water flowing into these wells has lost some steam. The computed concentrations of N2 and Ar also indicate the presence of a secondary steam component in the well discharges.