PROCESSING AND INTERPRETATION GRAVITY DATA OF SUMANI GEOTHERMAL FIELD, SOLOK REGENCY, WEST SUMATERA

• Main Author: Milenia Maretha, Dara
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/63786
• Institution: Institut Teknologi Bandung

Sumatera is one of the islands that has the largest geothermal potential in Indonesia. This is because Sumatera has a geological structure that is controlled by several volcanic activities that cause surface manifestations in the form of hot springs, fumaroe, solfatara, and alteration rocks. One area that has geothermal potential in Sumatra which is the object of this research is the Sumani geothermal area, Solok Regency, West Sumatra. The purpose of this study was to determine the model of the geothermal system that developed in the Sumani geothermal area. Therefore, it is necessaryto conduct geophysical exploration phase can use one of the geophysical methods, namely the gravity method. In this study, data on the Complete Bouguer Anomaly (CBA) value of the Sumani geothermal field were used. The corrected data was gridding using the kriging method to obtain a digital topographic map and a Complete Bouguer Anomaly map. The complete Bouguer Anomaly map has a range of values ranging from -42 mGal to 2 mGal. Then separate regional and residual anomalies using different methods, namely the Trend Surface Analysis Second-Order Polynomial and Moving Average, where the window width is determined by performing spectral analysis 1D. from the results of the separation of anomalies using the two methods, a residual anomalies map was chosen using moving average methods for 2,5 dimensional modeling because it is more optimal. The regional anomaly map using both methods shows the same tendency, namely the low anomaly is in the middle of the study with a nortweast-souteast direction. The selected residual anomaly has a value range of -13 mGal to 15 mGal. The 2,5 D forward modeling was carried out with a background density 2.67 gr/cc and obtained igneous rock intrusion which is thought to be a source of hot for the manifestation of hot water. The reservoir in the Sumani area is estimated to be in tertiary volcanic and the caprock is estimated to be in a layer of altered pyroclastic flows.