Geothermal Study by MT Method in Meshkinshahr, North-Western Iran

Geothermal reservoirs are usually located at a depth range of 2 to 5 km, so to efficiently utilize such resources an advanced prospecting method is needed to detect these deep geologic structures. Since temperature and permeability are some of the parameters controlling electrical resistivity, electromagnetic and electrical methods can provide a model of the subsurface relating changes in the resistivity to changes in lithology and temperature. This study aimed to two-dimensionally characterize geothermal reservoirs by a Magnetotelluric (MT) survey. The Moiel valley of Mt. Sabalan, NW Iran, was chosen as the case study area. A MT survey was carried out at 26 sites with elevation from 2400 to 3830 m. Static shifts were corrected prior to the inversion based upon the geology and TDEM results. 2D modeling of the MT data along the selected profiles shows remarkable confirmation of the subsurface geology using apparent resistivity variation. Estimated depth range of the geothermal reservoirs is from 1000 down to -2500 m. The final model showed that resistivity of the conductive zone is less than 20 Ωm.