Resolving Complex Overthrust Features Using Magnetotellurics - The Bolivian Foothills Case Study

The sub-Andean foothills are an area of increasing interest for oil and gas exploration. Exploration in these areas however is challenged by several factors. Their accessibility due to thick forest coverage and steep terrains is not straightforward, thus making exploration and development plans more complex and far more expensive. Targeting the most promising areas is of paramount importance to reduce the footprint of any exploration and production activity. A reliable understanding of the subsurface is fundamental, so is also choosing the best geophysical tools to achieve these objectives. Satellite and airborne techniques are utilized, since they cover large areas in time and economical effective manners. However they lack the resolution to infer the geology at depth. Seismic imaging is the principal tool to infer the earth geometries from their elastic properties. However in these areas reflection signal to noise ratio is severely reduced by steep topography and almost vertical bedding, thus making its use for imaging limited. The Magnetotelluric (MT) method has been successfully used as a complementary tool in the sub-Andean environment. In this paper we show how MT can be used to enhance depth imaging and help understand the structures and their potential for exploration.