The electrokinetic effect in a fluid-saturated porous rock is defined as the couplingand conversion between seismic and electric energies. When seismic waves propagatethrough a fluid-saturated formation and cause a pore fluid-flow relative to the solidmatrix, the motion of the cations in the fluid- flow forms a streaming electrical currentand induces an electromagnetic wave at any discontinuous interface of the formationor stationary electric potential inside the homogeneous formation. Another conversionof energies opposite to the seismoelectric conversion is when an alternating electricfield induces a relative fluid-flow in a fluid-saturated porous rock where fluid-flow cangenerate an electroseismic wave in the rock. In this paper we study the electrokineticsin porous sandstone and man-made porous models at high frequencies. A P-wave orS-wave transducer excites different acoustic wave modes in a cylinder, layer, or boreholemodel. Our experiments observe and record the radial or stationary seismoelectricsignals induced at the interface or inside the formation. Some relative experiments haveconfirmed the reliability of the electrokinetic phenomenon observed in our experimentsand the mechanism that is different from the piezoelectric effect. The results show thatthe seismoelectric signal induced by the extensional or flexural wave in the sandstonecylinder is a stationary local electric potential. The seismoelectric signal induced at the interface of the layer model is an electromagnetic wave which can be received withinthe fluid-filled porous medium. Experimental measurements performed in a boreholemodel by means of vertical seismic profiling (VSP) and single borehole logging showit is possible to conduct seismoelectric measurements in a deep borehole of petroleumformation. Measurements of electrokinetics can thus provide an effective means forestimating parameters in a fluid-saturated porous formation.
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