2D sharp boundary inversion to determine tectonic and geological features of geothermal fields through the magnetotelluric method: case study of the Mahallat reservoir in Iran

Multiple processing approaches were applied to magnetotelluric data from the Mahallat geothermal field in central Iran to evaluate the dimensionality and geoelectric strike of the subterranean structures, as well as to comprehend the overall geometry of the targeted reservoir. While conventional smooth inversion methods can generate reliable models, their application, in the absence of initial information, may lead to unrealistic outcomes, especially in media with sharp resistivity contrasts. Consequently, a conventional smooth inversion, alongside the sharp boundary inversion techniques, is applied on real data through two profiles in order to investigate and compare the subsurface structural features. Ultimately, by adopting a target-oriented modelling approach, this study utilises the sharp boundary method to deduce a more suitable configuration for the characteristics of the geothermal reservoir. Thus, to a large extent, this approach can facilitate the interpretational complications of underground geothermal structures. Correspondingly, this research led to recognising a hydrothermal reservoir with a proper layout at a depth of 1,800 and 1,200 m underneath profiles A and B, respectively. Moreover, deeper reservoirs were identified and depicted as conceptual geological models obtained through the incorporation of sharp boundary inversion results and geological information.