Numerical Simulation of the Sumikawa Geothermal Reservoir, Japan, Using iTOUGH2

Abstract

The Sumikawa geothermal power plant has been operating with installed capacity of 50 MWe since 1995. A numerical model of reservoir was developed by inversion analysis using the iTOUGH2 simulator. Sensitivity analysis for reservoir parameters of rock types, mainly permeabilities, was first performed and a priority of parameters to be estimated was determined through natural state simulation. After sensitivity analysis, inversion analysis was performed for a natural state and for a period of 20 years after beginning production activity. Rock permeabilities were estimated on the basis of measured temperature and pressure data in the natural state, and specific enthalpy and flow rate during production. After inversion analysis, simulated temperature and feed zone depth pressure in wellbores were compared with measurement to confirm goodness of the model. Simulated specific enthalpy during production period was also compared with measurement as a production and reinjection history matching.