Abstract:

Comprehensive geophysical investigations are fundamental for the exploration and development of geothermal resources, providing high-resolution, non-invasive characterization of the subsurface. Geothermal reservoirs are frequently situated in geologically complex settings, such as volcanic terrains or faulted regions, where heat and fluid distribution exhibit significant spatial variability. Conventional, limited exploration approaches risk overlooking subtle but critical features, potentially leading to unsuccessful drilling and economic loss. Integrating multiple geophysical techniques allows for detailed assessment of reservoir geometry, depth, permeability, and thermal potential, enabling optimized drilling strategies and efficient energy extraction.
Electrical and electromagnetic methods, including magnetotellurics (MT) and electrical resistivity tomography (ERT), are particularly effective in delineating zones of high conductivity associated with hydrothermal fluids, impermeable sealing layers, and shallow geological structures. MT surveys provide deep resistivity profiles, whereas ERT resolves near-surface variations. Seismic approaches, such as reflection profiling and the horizontal-to-vertical (H/V) spectral ratio method, reveal stratigraphy, fault networks, and fracture systems, critical for understanding fluid migration and reservoir compartmentalization. Gravity and magnetic surveys identify density and magnetization contrasts related to magmatic intrusions and hydrothermal alteration. Very Low Frequency (VLF) measurements complement these methods by mapping conductive faults and lithological boundaries. Collectively, these integrated geophysical datasets enhance subsurface models, reduce exploration uncertainty, and support sustainable, targeted development of geothermal energy resources.