2,5D MODELING OF GEOTHERMAL SYSTEM USING GRAVITY METHOD IN SAMPURAGA GEOTHERMAL FIELD, MANDAILING –NATAL, NORTH SUMATERA

• Main Author: Talitha Nadia, Alfa
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69069
• Institution: Institut Teknologi Bandung

Tectonism and volcanism dynamics of Indonesia have caused the presence of huge geothermal potentials of up to 23,765.5 MWe with the largest accumulation located in Sumatra. This has led to a lot of research on Sumatera, one of them is conducted in Sampuraga Geothermal Field, Mandailing - Natal, North Sumatra. The purpose of the research is to create a conceptual model of Sampuraga Geothermal System. The data used for modeling consist of gravity, geoelectric, geomagnetic, and geochemical data based on PSDMBP research on 2007. The processing of gravity data resulting Complete Bouger Anomaly (CBA) map ranging from -37 to -18 mGal which after that is being separated as regional and residual anomaly map using moving average of 15 windows width and second-order polynomial. The 2,5D gravity model is created by crossing a southwest-northeast segment on second-order polynomial residual anomaly map, since the map shows a fit between the anomaly contour pattern and the litology linearization. The intrusion of diorite with a density contrast +0,13 gr/cm3 might still keeping the residual heat, hence predicted as the geothermal heat source. Based on integrated analysis of gravity, geoelectric, geomagnetic model, and geochemical data, the estimated 600 m thick pyroclastic flow unit is predicted as the caprock, while the porphyry andecite lava unit below it is predicted as the reservoir.