GRAVITY DATA PROCESSING AND INTERPRETATION OF THE MATALOKO GEOTHERMAL FIELD SUBSURFACE MODEL

• Main Author: Farras, Fadhil
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69818
• Institution: Institut Teknologi Bandung

The Mataloko geothermal area, Ngada Regency, East Nusa Tenggara is the object of study in this research. This study aims to determine the geothermal model in the Mataloko area using the gravity method. It is important to conduct this research because the Mataloko area has hot water manifestations with temperatures (35.3 -91°? ) and fumaroles (93.3 -96°? ) which indicate the existence of a geothermal system. In this study, data processing was carried out in the form of observational gravity measurements from the PT Tunggal Buana Utama Team in 2019 and the Complete Bouguer anomaly was obtained, with a background density of 2.11 g/cc obtained using the Parasnis method. The complete Bouguer anomaly in the Mataloko geothermal area has a range of 114.5 mGal to 126.5 mGal. Next, the anomaly is separated using the Moving Average, Gaussian, and Butterworth filters. The filtering results of the Moving Average method, namely the residual anomaly, show the distribution of the anomaly values that are considered by geological information so that they are used as input in carrying out 2D forward modeling. Furthermore, forward modeling and 2D inversion modeling are carried out on two trajectories with a direction of Southeast - West and North East - South. The modeling results show the layering where the high anomaly value comes from intrusion and some locations have low anomaly values due to the irregularity of the layering. Based on the results of the study, it can be identified the existence of a reservoir located at a depth of more than 700 m with a caprock layer at a depth of 900-1000 meters above sea level, for the location of the upflow zone is estimated to be in the east of the study area and the control structure is a normal fault. and faults estimated from the gravity structure.