PROCESSING AND INTERPRETATION OF TRANSIENT ELECTROMAGNETICS (TEM) DATA FOR ESTIMATING THE SHALLOW CONDUCTIVE ZONE IN PATUHA GEOTHERMAL AREA

• Main Author: Safa Kamila, Fadila
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/80448
• Institution: Institut Teknologi Bandung

Geothermal areas tend to have lower resistivity values so that low resistivity anomalies can be the main target of geothermal exploration. One of the geophysical methods to detect this type of anomaly in the form of resistivity variations is the Transient Electromagnetics (TEM) method. This research was conducted in the Patuha Geothermal area, using the TEM-FAST 48 tool at 3 locations, namely TTN-01, TTN-05, and TTN-07. This research was conducted to determine the distribution of resistivity to depth, determine the shallow conductive zone in the research area, review the TEM-FAST system to determine and interpret the shallow conductive zone based on variations in resistivity contrast and depth, and correlate TEM data with drilling data and geoelectric data. TEM data processing was carried out using TEM-RESEARCHER (TEM-RES). The results that have been obtained are based on the TEM data resistivity cross-section, the resistivity value in the study area is in the range of 0.1-200 ?m with the lithology type dominated by volcanic breccia and andesite, and there is a shallow conductive zone at a depth of about 20-35 m which is thought to be related to andesite (TTN-01 and TTN-05) and dacite (TTN-07) which are altered with weak to moderate intensity. On the other hand, it is suspected that these conductive zones are also associated with permeable zones in the subsurface. Based on the variation of resistivity contrast value and depth, the smaller the resistivity contrast of the third layer, the shallower the third layer is detected. In addition, the deeper the third layer, the more difficult the third layer will be to detect. The correlation of TEM and geoelectric data at TTN-01 shows patterns and resistivity values that generally correspond to each other. Meanwhile, at TTN-05 in general, the resistivity value in the TEM cross section is relatively lower than geoelectric, but there is a corresponding pattern.