Natural-State Reservoir Model of Sorik Marapi Geothermal Field

Abstract

The Sorik Marapi Geothermal Field is located west and northwest of Sorik Marapi, an active andesitic stratovolcano, on the western splay of the Sumatra Fault Zone (SFZ) and within the Panyabungan Graben. A conceptual model of the reservoir has been developed by integrating the geology, geophysics, geochemistry and well testing results obtained to date. The conceptual model is characterized by a primary upflow originating in the fractured basement rocks located near well T-09 in the drilled area with a temperature of greater than 300°C. The conceptual model was used to develop a 3-D numerical natural state model; the model was calibrated by matching feedzone pressures and temperature profiles in wells. The calibrated natural state model will be used to history-match the available production data and to make an assessment of the production capacity of the drilled area. As geothermal development brings additional data from geoscientific studies, drilling and testing, the conceptual and numerical reservoir models will be updated and used to forecast the reservoir response to various development scenarios.