A Numerical Model of the Kizildere Geothermal Field, Turkey

Commercial power generation at Kizildere began in 1984 with the installation of 17.4MWe (gross) Kizildere I power plant. Fluid production (and hence electric generation) gradually fell due to reservoir pressure decline related to little or no injection. More rapid production declines due to calcite scaling in production wells were periodically reversed after mechanical cleaning and acidization creating cyclical production behavior. Zorlu Energy Group acquired the geothermal field in 2008 and initiated wellfield and power plant modification to restore Kizildere I to capacity, and drilling deep wells (up to 2700 m) to supply fluid requirements for Kizildere II, a 80 MW geothermal power plant commissioned in late 2013. This paper presents a numerical reservoir model which was developed as a tool to support the management of the Kizildere reservoir which includes the intermediate depth reservoir in Igdecik marbles which supplies Kizildere I and a deeper reservoir in Menderes Metamophics which supplies the Kizildere II plant. The natural state numerical model developed herein correctly reproduces the presently available data for pre-production feedzone temperatures and pressures. The numerical model was used to history-match the available production and injection data for the period January 1984 – March 2013; the agreement between the computed and measured pressures in the six (6) observation wells is satisfactory. After history-matching, the numerical model was employed to investigate the feasibility of producing sufficient fluid to supply the fluid requirements for both the Kizildere I and II power plants. The model results for the investigated scenario indicate that a system of 20 production and 8 injection wells should be adequate for producing the required fluid supply. The latter conclusion is of course predicated on the assumed behavior of the deeper reservoir. Acquisition of data in the future on the response of the deeper Paleozoic reservoir to large-scale production and injection will significantly enhance our understanding of this reservoir. After approximately one year of operating Kizildere II, the quantitative results of production, injection and reservoir monitoring will provide a record of the initial reservoir response. The numerical model will then be refined and revised as needed to reflect the enhanced knowledge about the deeper reservoir.