Geophysics Field Camp (GFC): A Student Project Aimed to Investigate the Low to Moderate Temperature Geothermal System in Mt Pancar Area, Bogor (Indonesia)

Supriyanto, Mohammad Syamsu Rosid, Yunus Daud, Wambra Aswo Nuqramadha, Fikri Fahmi, Surya Aji Pratama, Agus Sulistyono, Dzil Mulki Heditama, Yunus Daud

Research output: Contribution to journalArticlepeer-review

Abstract

Geophysics Field Camp (GFC) is a curriculum related project conducted by undergraduate students of the Department of Physics (Geothermal Laboratory), the University of Indonesia. The project is designed to educate the students in understanding a geophysical project from survey design, data acquisition, data processing, through modeling and interpretation. In addition, geological mapping and geochemical survey are also added to support the geophysical data. Mt Pancar geothermal prospect is located in the Bogor district, West Java Province, Indonesia. The geological condition of the area consists of Tertiary volcanic formation of the Mt. Pancar and Quartenary volcanic formation of Mt. Panisan covering Tertiary sedimentary formation. The surface manifestations found in this geothermal area are hot springs, warm grounds and altered rocks. The hot springs are found in
Kawah Merah (T = 70oC) and Kawah Putih (T = 51oC) with neutral pH and minor silica sinter. There is no indication of thermal activity on the summit of Mt Pancar. The subsurface temperature, as indicated by Na/K geothermometry, is in the range of 180-190oC. Based on the preliminary information it can be concluded that the Mt Pancar geothermal area can be classified as a low to moderate geothermal resource. To develop initial conceptual model of the geothermal system, geophysical investigations including Audio-frequency Magnetotelluric (AMT) and gravity surveys were then carried out. Ten soundings of AMT data were
accomplished along two profiles both crossing Mt Pancar summit and the other ends crossing Kawah Merah (Line AB) and Kawah Putih (Line CD) hot springs area, respectively, whereas gravity survey was conducted on 155 stations in a grid survey design.
Three-dimensional inversion of AMT data was then carried out along the profile lines using MT3DInv-X software. The results show a conductive layer (< 15 ohm-m) from near surface down to about 2000 meter depth. The conductive layer is interpreted as the clay cap of the geothermal system distributed between Mt. Pancar and Kawah Merah (Line AB) and Mt. Pancar and Kawah
Putih (Line CD). The slightly resistive layer (20 – 100 ohm-m) was also found underlying the clay cap which is interpreted as the reservoir zone. A more resistive basement (> 100 ohm-m) was encountered forming structure-like graben. The graben structure possibly controls the hydrothermal system in Mt Pancar area. In addition, 2-dimensional gravity modeling using Grav2D-X
software supports the resistivity inversion results. Integrated interpretation was then accomplished by incorporating AMT and
gravity data supported by geological and geochemical data. Based on this study, a conceptual model of the MT Pancar Geothermal Area was developed to explain the geothermal occurrence in this area.
Original languageEnglish
JournalProceedings World Geothermal Congress 2015 Melbourne, Australia, 19-25 April 2015
Publication statusPublished - 2015

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