[Alumnos] Invitacion a la charla de Laurence Jouniaux HOY 11hs Salon Meridiano

[secyt en fcaglp.fcaglp.unlp.edu.ar]

Novedades!


   Invitación a la charla que Laurence Jouniaux ( Institut de Physique  
du Globe, Francia)
   dará en el Salón Meridiano hoy a las 11hs, sobre
   "Electrocinética en medios porosos : acoplamiento entre el flujo de  
fluido y el
   eléctrico".



   Electrokinetics in porous media : coupling between the fluid flow and
   the electrical flow

   Abstract: Electrokinetics are used for a better knowledge and
   understanding of the near-surface earth system in terms of fluids
   (water, ice, oil, gas), as encountered in the management of hydraulic
   and hydrocarbon reservoirs, the remediation of contaminated aquifers,
   the resource prospection in glaciated regions, and the exploitability
   of geothermal or fractured reservoirs. Electrokinetics arise from a
   relative motion between fluids and rock and are linked to the
   existence of the electric double layer at the interface between rock
   and fluid. This effect is at the origin of self-potential and
   seismo-electric observations. An appropriate interpretation of the
   observations needs to know the effect of the water-content on these
   electric signals. We performed laboratory experiments to deduce the
   effect of water content on streaming potential coefficient in
   unconsolidated medium (sand), and deduced that the streaming
   coefficient first increases and then decreases when the water-content
   decreases. We showed that this behaviour is explained by a dependence
   of the time derivative of the pressure during the experiments of
   drainage. And we pointed out that not only the interface area of
   rock/water is important, but also the interface of water/air. We
   performed field measurements of
   seismo-electric conversions, with different water-content deduced from
   Georadar and electrical tomography measurements. We compare the
   measured transfert function between the electrical field and the
   acceleration, as a function of water-content, to the one predicted
   with the previous laboratory observations. The comparison showed that
   the observed behaviour in laboratory can be assumed in the field,
   although the data are scattered and that more field observations are
   needed.



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