STRUCTURE IDENTIFICATION AND SURFACE MODELING USING GRAVITY DATA OF THE MALINGPING GEOTHERMAL AREA, LEBAK, BANTEN

• Main Author: Aldo Afayed, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69913
• Institution: Institut Teknologi Bandung

One area in Indonesia that has geothermal potential is the Malingping area, located in Lebak Regency, Banten Province. To be able to identify geothermal potential in the area, research on gravity and topography data was obtained from survey results by the PSDG Team in 2014. Gravity data was processed and produced a complete Bouguer anomaly value with a range of 90 mGal to 138 mGal. Furthermore, regional and residual anomalies are separated from the complete Bouguer anomaly using the moving average and Gaussian filtering methods. Then a tilt derivative calculation is also carried out by considering the residual anomaly map and geological map to identify subsurface structures. Then from the residual anomaly map a 2.5D forward model is made to describe the geological model below the surface. The residual anomaly of the moving average filter results shows a value of -3.5 mGal to 4.5 mGal, while the Gaussian filter results show a value of -2.2 mGal to 2.4 mGal. The two residual anomalies show almost the same distribution pattern of the anomalies, so that for future 2.5D modeling one of these residual anomalies is used. Based on tilt derivative calculations, values of -1.4 radians to 1.3 radians are obtained and the dominance of fault structures trending northwestsoutheast. The residual anomaly map resulting from the moving average method is used for the 2.5D forward modeling process, using a background density in the form of a laboratory average of 2.42 gr/cc. Based on the results of 2.5D forward modeling, bedrock in the form of breccia and andesite lava is obtained which is part of the Cimapag formation, with a density of 2.76 gr/cc, alternating sandstone and claystone which is part of the Bojongmanik formation, with a density of 2.6 gr/cc, Cipacar formation with a density of 2.35 gr/cc. Furthermore, the results of the 2.5D forward modeling and analysis of geology, geophysics, geochemistry of the research area are used to create a geothermal conceptual model. Based on this conceptual model, it is possible to identify reservoir areas indicated by the Cimapag formation, caprock areas indicated by the Bojongmanik formation, and the presence of the Citando hot spring which is right on the fault structure trending northwest-southeast.