No abstract

Background The Karaha-Talaga Bodas (K-TB) geothermal field was declared commercially operated in April 2018 with a capacity of 30 MW. This geothermal field is located on a ridge trending north-south to the north of Mount Galunggung, West Java, Indonesia (Fig. 1). The first exploration program of the K-TB geothermal field was conducted in December 1994 by Karaha Bodas Company (KBC). Nineteen shallow-slim and twelve full-sized wells had been drilled by 1998, and by 2010, 14 total full-sized wells had been drilled in the K-TB field (GeothermEx 1998). The K-TB field consists of two parts: the northern part (the Kawah Karaha area) and the southern part (the Talaga Bodas area). The K-TB field is estimated to have large geothermal potential with a partially steam-dominated system and temperatures reaching Abstract A numerical simulation study of the Karaha-Talaga Bodas geothermal field was carried out to assess the resource and to analyze and predict reservoir behavior under various development scenarios. The three-dimensional natural state model of the Karaha-Talaga Bodas field has been validated with the pressure and temperature of seven wells and the conceptual model of the field. This study explores the application of an experimental design and response surface method for capturing relevant uncertainties existing in the geothermal reservoir simulation; thus, the results of this approach are the assessment of probabilistic resources. The power potential calculated from reservoir simulation results is used to develop proxy equations and then Monte Carlo simulations were applied on proxy models to produce probabilistic distributions of power potential output. Based on Monte Carlo Simulation, the probabilistic power capacity of Karaha-Talaga Bodas field is 120 MW as P50. This model is also used to estimate potential field responses based on two different field development scenarios. Forecasting two development scenarios shows that the best development is 60 MW with a make-up well strategy drilled in the deep-water zone. This scenario requires the number of production, injection, and make-up wells to be 11, 3, and 4, respectively. The reservoir response shows that the pressure drop is between 0.2 and 0.6 bar/year while the temperature drop is 2-14 °C for 30 years.