Magnetotellurics Data Application in Medium Enthalpy Geothermal Prospects

Abstract

The research is aimed at delineating the reservoir and defining the geothermal system of Lili-Sepporaki through the interpretation of magnetotellurics data. Lili-Sepporaki is an andesitic-trachytic volcanic rich geothermal prospect located in western Sulawesi Province, Indonesia. In essence, hydrothermal conditions affect the properties of rocks, such as resistivity, and this can be studied using magnetotellurics, a passive electromagnetic technique. Magnetotellurics data were processed and interpreted using Phoenix and WinGLink software programs. A total of five two-dimensional resistivity models and five elevation maps were produced, and these showed a general decrease in rocks’ resistivity with depth. The analysis found out that the reservoir stretches from the center, northwards. The reservoir substantially starts to be seen at a depth of 600 m below sea level and deepens towards the east and northwest. Another magnetotelluric survey should be carried out with more stations, mainly aimed at a three-dimensional inversion, to get a detailed geothermal model and also to study the dense, low resistive structure in the southeast.