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Abstract

Propagation of ultrasound through a porous body saturated with liquid generates electric response. This electro-acoustic effect is called “seismoelectric current”, whereas reverse version, when electric field is driving force, is “electroseismic current”. It is possible to measure seismoelectric current with existing electro-acoustic devices, which had been designed for characterizing liquid dispersions. Such versatility allows calibration of said devise using dispersion and then applying it for characterizing porous body. In general, magnitude of seismoelectric current depends on porosity, pore size, zeta potential of pore surfaces and elastic properties of matrix. It is possible to adjust conductivity of liquid for simplifying these dependences. For instance, liquid with high ionic strength causes double layers become thin comparing to the pore size, which eliminates dependence of said currents on pore size. We suggest using such case for characterizing porosity. Magnitude of the said currents is proportional to zeta potential. This parameter can be calculated when porosity is known. In contrary, saturation of porous body with low conducting liquid leads to complete overlap of double layers, which can be used for characterizing pore size. Phase of the said currents can be used for determining iso-electric point because it rotates 180 degrees when liquid composition varies through this point.

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