Seismoelectric conversion at poroelastic/elastic interfaces and the role of dielectric permittivity: experimental and numerical analysis

Seismoelectric phenomena, caused by electrokinetic coupling between seismic and electromagnetic fields, have attracted significant interest in geological reservoir characterization for their sensitivity to pore-fluid contrasts. Consequently, most studies have focused on seismic-to-electromagnetic conversions at fluid/poroelastic and poroelastic/poroelastic interfaces. However, when investigating permeable zones in unfractured media, often associated with geothermal reservoirs, poroelastic/elastic interfaces must be considered. To address this, we conducted laboratory and numerical experiments using a container filled with quartz sand saturated with a NaCl solution, with one of five thin layers made of different materials (four elastic and one poroelastic) embedded within the sand. Our numerical simulations assume an elastic medium as poroelastic using limiting values for certain physical parameters. The results confirm that seismoelectric conversion occurs at poroelastic/elastic transitions, showing a strong agreement between experiments and simulations. Furthermore, we inferred that the amplitudes of electromagnetic waves generated at poroelastic/elastic interfaces are mainly controlled by contrasts of dielectric permittivity.