Title: Direct coupled reservoir-wellbore modeling approach for the Berlín Geothermal Field, El Salvador

Abstract

The Berlin Geothermal Field in El Salvador is used for power generation purposes
with an installed capacity of 109.2MW and delivering by 2021, 14.75% of the total
energy generation in the country. In this study a numerical model for the geothermal
system was developed based on a current conceptual model using a direct coupled
reservoir-wellbore modeling approach implemented with the simulators TOUGH2
and FLOWELL. The purpose is to predict the reservoir response to different production
scenarios. It is calibrated against formation conditions and 30 years of
production data, including pressure drawdown and flowing enthalpy time series. Parameter
estimation was carried out through inverse modeling using iTOUGH2 and a
sensitivity analysis showed that the horizontal permeability for the main geothermal
reservoir and cap-rock rock produce the most impact on the overall calibration of
the system. The wellbore simulator was essential during the forecasting stage as it
compensates for the mass flow rate yield from each feedzone due to pressure drawdown
in the system, allowing to locate future make-up wells properly over time. The
production scenarios estimate it is possible to maintain the current power generation
for the next 30 years with the proper drilling program of about one make-up well
every 2 years.