Electrokinetics Of A Fluid-Saturated Rock Sample: Laboratory Experiments

Abstract

The conversion between seismic and electromagnetic energies was discovered in a fluidfilled porous formation. When seismic waves propagate through a fluid-saturated porous formation, relative motion between the pore fluid and the solid matrix is generated and cation motion in the fluid is formed. The streaming electric current induces electromagnetic waves in the formation. There is an opposite phenomenon, i.e., the conversion of electric energy into acoustic energy in the porous formation. The electroseismics in porous sandstone samples are investigated by ultrasonic experiments in our laboratory. A compressional or a shear transducer excites an acoustic wave in the water-saturated sample and the electric signals generated on the surface are measured by an electrode. The relationship between the electric potential and acoustic wave or the conductivity of water-saturated rocks is studied. The electro-seismic conversion in rock samples is also investigated. Electroseismics could provide an effective means for estimating the fluid-saturated porous formation.