A COMPARISON OF SINGLE-POROSITY AND DUAL-POROSITY MODELS IN PROBABILISTIC RESOURCE ASSESSMENT USING EXPERIMENTAL DESIGN AND RESPONSE SURFACE METHODLOGY: A CASE STUDY OF THE BEDUGUL GEOTHERMAL FIELD

• Main Author: Jackli Keintjem, Renaldio
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62341
• Institution: Institut Teknologi Bandung

Resource assessment of the geothermal field is a critical step in field development. The prevailing method for resource assessment of geothermal fields is the single porosity model. Whereas the dual porosity model is widely used in geothermal brownfields. Experimental Design & Response Surface Methodology (ED & RSM) combined with the probabilistic approach is employed in this research to determine the proper approach for resource assessment of geothermal greenfield. The uncertainty parameters with significant effect to the result of resource assessment could be identified using ED & RSM combined with probabilistic approach. Bedugul geothermal field is chosen as the object of this research. The single porosity model of Bedugul geothermal field was build and validated with well data for natural state and production test matching coupled with RMSE (Root Mean Square Error) and MAPE (Mean Average Percentage Error) analysis. The conceptual model of the Bedugul geothermal field is updated based on the calibrated single porosity model. The results of the model production run are integrated into Minitab 20 and generate regression equations and uncertainty parameters analysis. The regression equation then integrated into Monte Carlo simulation to obtain the probabilistic potential of the reservoir. The results of the single porosity model are 80 MW (P10), 101 MW (P50), and 122 MW (P90). And the results of the dual porosity model are 64 MW (P10), 85 MW (P50), dan 107 MW (P90), lower than the results of the single porosity model. The significant parameter that affects the output of single porosity is PI as the production parameter. In the dual porosity model, the most significant parameter is feed zone as the parameter of the reservoir. Based on the comparison of output and uncertainty parameter, numerical model with single porosity is the most reliable method for probabilistic resource assessment of geothermal greenfield confirmed by fewer uncertainty parameters and higher MWe output.