LMA - Laboratoire de Mécanique et d’Acoustique

M. Dietrich - Seing the light of sound, hearing the sound of light - a geophysical perspective

Salle J. Perès, Bât. C

Le 30 juin 2015 de 11h00 à 12h00

Michel Dietrich, Directeur de Recherche


Transient electrokinetic coupling phenomena created at the microscopic scale by the passage of seismic waves through fluid-saturated porous media generate conversions between seismic and electromagnetic (EM) energy which can be observed at the macroscopic scale. Far from being a mere scientific curiosity, transient seismoelectric or electroseismic phenomena are especially appealing to oil and gas exploration and hydrogeology as they open up the (fairly unique) possibility to characterize fluid-bearing geological formations with the resolution of seismic methods. Indeed, electrokinetic effects are likely to reconcile the sensitivity of electromagnetic exploration methods to fluids with the high resolving power of seismic prospecting techniques for structural imaging, thus naturally bridging the gap between these two important geophysical investigation means. Accounting for the electromagnetic dimension of the seismic wave propagation, or conversely, accounting for the seismic dimension of electromagnetic wave propagation gives new insights into the microstructure and physico-chemistry of fluid-filled porous or fractured media. In practice, however, the effective recording of the small-amplitude seismic-to-EM converted waves continues to be a key challenge for reasons which are not yet fully understood. These technical difficulties currently limit the development of the seismo-electric and electroseismic methods as geophysical exploration techniques. In an attempt to solve some of these problems, we present analytical and numerical developments to simulate the full-waveform propagation of the coupled seismoelectromagnetic waves in plane-layered fluid-saturated porous media, by also accounting for some aspects of the source and receiver characteristics. Our simulation code uses the macroscopic governing equations derived by Pride [1994], which couple Biot’s theory and Maxwell equations via flux/force transport equations.

Voir en ligne : Page personnelle de Michel Dietrich