GEOTHERMAL SYSTEM MODELING BASED ON THE GRAVITY DATA OF AMOHOLA’S GEOTHERMAL AREA, KONAWE, SOUTH-EAST SULAWESI, INDONESIA

• Main Author: Reinard A.G, Julius
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/65781
• Institution: Institut Teknologi Bandung

Indonesia is an archipelagic country with abundant geothermal resources. This cause Indonesia to occupy the 2nd position in the world as a country with abundant geothermal resource potential, with a capacity of 1,948MW in 2018. One of the areas in Indonesia that has geothermal potential is the Amohola Geothermal Area, which is located in Southeast Sulawesi. To maximize the geothermal potential, an exploration needs to be done so geothermal energy in the area can be exploited. Therefore, this study aims to create a conceptual model of the geothermal system of the Amohola Geothermal Area. The data that is used in this study are gravity and topographic data from the results of research by PSDMBP in 2014 in the Amohola Geothermal Area. Then from the data, the latitude correction, free air correction, and Bouguer correction will be made, followed by the separation of regional and residual anomalies using the moving average method and the trend surface analysis second-order polynomial method. The results of the two methods will be compared, then the most optimal result will be chosen to portray the geothermal system of the Amohola Geothermal Area. After separating regional and residual anomalies, the selected residual map is the trend surface analysis second-order polynomial map because the contrast between the anomaly values is more explicit. The trend surface analysis second-order residual polynomial anomaly map is then used for the 2.5D forward modelling process, using a background density of 2.63 gr/cc from the laboratory average density. From the results of 2.5D forward modelling, it was found that there was an intrusion in the form of igneous rock formed by tectonic plate activity with initial speculation that the intrusion was a heat source. In this modelling, it can be seen that basement rock is in the form of limestone, in accordance with the stratigraphy contained in the geological map. Based on the modelling results, there is also an initial assumption that the reservoir is under conglomerate rock, with conglomerate rock as the cap rock. For the outflow area, there is also an initial assumption that the area is in the Amohola Hot Spring which is located right on the fault.