Numerical Reservoir Simulation of Alaşehir Geothermal Field

Abstract

Use of a comprehensive reservoir simulation is essential for an effective geothermal reservoir management. TOUGH2 has become a widely used simulator for this purpose. In this study, one of the most exploited geothermal fields in Turkey, Alaşehir geothermal field has been modeled by using TOUGH2 reservoir simulator. The study includes more than 100 wells, which are operated by 7 different developers. The total installed capacity of geothermal power plants in the field is 212 MWe, but additional capacity (98 MWe) is planned to be commissioned by the end of 2020. The proximity of licensed areas and strong well interferences have made the simulation necessary for a successful reservoir management. Different data sources including pressure transient tests, reservoir monitoring and tracer test data were coupled to construct a large numerical model, which has dimensions of 18 kmx12kmx5.5km. During model calibration, good matches were obtained between model results and actual decline in the reservoir temperature, pressure and non-condensable gases (NCG) production. The effect of planned power plants on the field performance is studied by performing scenario runs using maximum possible flow rates. Model results indicated that commissioning of new power plants and additional make up wells that will compensate missing production accelerates pressure decline to more than 3 bars/year.