Magnetotelluric Imaging of the Sub-Andean Resources - Integrating Resistivity Structure in the Geology: Framework of the Foothills

Abstract

In thrust-belt areas, seismic imaging techniques are negatively affected by the generally poor signal-to-noise ratio of the reflections due to the steep topography and to the almost vertical layering of the formations. These challenges yield increasingly expensive deployment of seismic campaigns for oil and gas exploration in foothill areas. The magnetotelluric (MT) method has been successfully used as a complementary tool in the exploration of foothill plays as it provides a low cost alternative to improve the understanding of the subsurface geology. A case history of a Magnetotelluric (MT) survey carried out in the Sub-Andean Foothills of Bolivia is used to discuss the challenges and tools available to model, interpret and integrate MT data in the geological context of the thrust belts system encountered in Southern Bolivia. Examples of numerical feasibility studies are used to identify the expected interpretation challenges of MT data in a single domain as well as incorporationg a-priori geological knowledge. Modeling results of the 2D/3D inverted geoloelectric structure are further integrated with 3D geological models such as to test the sensitivity of the MT response of the recorded data to the geoelectric structure of the target formations. To this end a geosteering approach is used to optimize the 3D resitivity structure of the model in close relation to the subsurface geological structure expected in the survey area.

AAPG Datapages/Search and Discovery Article #90326 © 2018 AAPG Latin America & Caribbean Region, Optimizing Exploration and Development in Thrust Belts and Foreland Basins. Santa Cruz de la Sierra, Bolivia, June 6-8, 2018