GEOTHERMAL SYSTEM MODELING BASED ON THE GRAVITY DATA OF PAMANCALAN GEOTHERMAL FIELD, LEBAK REGENCY, BANTEN

• Main Author: Tsaqifurrahman, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67744
• Institution: Institut Teknologi Bandung

Indonesia is located at the confluence of two continental plates and two oceanic plates. Subduction of the Indian Plate under the Eurasian Plate produces a volcanic arc in western Indonesia. This has resulted in Indonesia becoming an area with intense volcanic activity, resulting in a large geothermal potential. Indonesia has a geothermal potential of 28.617 MW. One of the geothermal areas in Indonesia is the Pamancalan Geothermal Area, Lebak Regency, Banten Province. This study aims to create a conceptual model of the geothermal system in the Pamancalan Geothermal area. This is done to be able to map the potential in the Pamancalan Geothermal Area. This study uses Complete Bouguer Anomaly (CBA) data, elevation data, and geological data obtained from the results of the PSDMBP research in 2011 the Pamancalan Geothermal Area. The density value used is obtained from the results of the average density of rock samples which are considered to represent the research area. The complete Bouguer anomaly value ranges from 128-168 mGal. The separation of complete Bouguer anomaly to regional and residual anomaly is carried out using two methods, namely the trend surface interpolation method and the moving average method. Residual anomaly shows anomaly results with a value range of -13 – 11 mGal for trend surface interpolation method and -9 – 8 mGal for moving average method. The residual map chosen is the residual map using the moving average method because it better represents the geological condition. The 2,5-dimensional forward modelling uses residual anomaly data from the moving average method, elevation data, and geological information in the research area. The background density value used for modelling is 2,63 gr/cc. Modeling results show the existence of heat source in the form of intrusion with density contrast of 0,23 gr/cc, a recharge zone in the lava Gunung Batu unit, and a discharge zone in the Cipamancalan Fault. The presence of intrusion indicates the presence of a heat source. The rock interpreted as reservoir is Citarete Sandstone unit and the rock interpreted as caprock is andesite lava Pasir Reungit unit.