Multiscale induced polarization tomography in hydrogeophysics: A new approach

Induced polarization is a geophysical method that has gained ground in the last decade in hydrogeophysics. Yet the acquisition of high quality induced polarization data may be challenging using the current technologies mostly because of capacitive coupling effects especially for short durations in the injected current. In addition, making a true 3D induced polarization survey is very tedious and time consuming in field conditions. We discuss the advantages of a new generation of induced polarization equipment composed of individual stations able to measure the two components of the electric field along the ground surface. We show how this approach allows for integrating the whole data avoiding negative apparent resistivity/chargeability data. The use of decentralized recording stations solves the issue of capacitive coupling effects. We present a completely novel induced polarization data inversion methodology based on the measurement of the electric field components. In addition, a robust geostatistical inversion approach is discussed for recovering the conductivity and chargeability fields using the electric field components measured on the ground surface. We also treat the case of time lapse monitoring by using a low-rank Kalman filter approximation, which is computationally very appealing in terms of computational time and storage savings. The effectiveness of the new methodology is demonstrated on several realistic synthetic case studies. These numerical tests show that this electric field-based approach is robust and very promising for applications in hydrogeophysics