Initial Geochemical Monitoring Ulubelu Geothermal Field

Abstract

Ulubelu geothermal field started operating in 2012. Since then conducted geochemical monitoring to see the changes that occurred in the first year of operation. Three clusters contributed to generate 2 x 55 MW: cluster B, C, and D. During the geochemical monitoring activity, we found decrease in chloride and silica concentration occurred in Clusters C and D from baseline until August 2012 associated with the cold water influx from one of the well of each cluster. In cluster B, had seen indication of steam entry from shallow depth, although not quite significant. Since August 2012 until December 2013 had seen increasing chloride and decreasing silica trend indicating return injection from cluster A and F as reinjection cluster. Meanwhile NCG trends in production well decreased support the conclusion about injection return. Further studies are needed like tracer injection and MEQ to obtain a more comprehensive assessment.