RESERVOIR MODELLING FOR THE BERLIN GEOTHERMAL FIELD EL SALVADOR

Abstract

The Berlin Geothermal field is located 100 km to the eastern part of the country. The field began to commercial operation in February 1992 when 2x5 Mwe Back Pressure units went on line. Later on in October 1999, 2 x 27.5 Mwe Condensing type units also went on line. At the beginning of the exploitation the reservoir yields up to 80 kg/s of total mass at 1300 kJ/kg using wells TR-2 as producer and TR-9 as injector. In 1994 the former Geothermal Division of CEL starts to drill 18 producer and injection wells in order to achieve the steam requirements for the power station and to complete the injection capacity for the brine. At the moment the Berlin field has 26 wells: 8 producer, 14 injector, 1 monitoring and 3 abandoned, the gross power production is close to 58 Mwe and there are no evidence of thermal breakthrough, and some boiling are observed in the surrounding of some producer wells.

In order to predict the reservoir behavior Lumped and 3-D numerical model have been prepared by GESAL. Three scenarios of exploitation have been used, 50 Mwe for the actual condition, 60 Mwe increasing with the back pressure operation that are already installed, 85 Mwe increasing with one additional 27 Mwe condensing type unit.

The results of the modeling for 85 Mwe scenario shows it is possible to achieve that production, the pressure drawdown of the reservoir will range 30-35 bar for 20 years forecasting. The saturation for the whole reservoir will less than 20%, and the cooling effect to the system will range 20?C. According with the results one additional 27 MWe is possible to be installed at the Berlin Geothermal Field in a sustainable way for at least 20 year.