Seismoelectric Measurements in an Artificial Porous Sample with Anisotropic Permeability

Abstract

Summary An artificial porous sample with cracks is built using quartz-sand. The sample is a small cubic, with 39% in porosity. Its anisotropic permeabilities are about 14.7 D, 13.8 D, and 8.3 D in X, Y, and Z directions, respectively. Seismoelectric measurements are performed in a water tank. The amplitude of the seismoelectric signal induced by an acoustic wave propagating in the direction with higher permeability is higher than that in the direction with lower permeability. Seismoelectric measurements are also performed with natural rock samples of Berea sandstone 500 and 100. Because the rock sample is isotropic in permeability, the amplitudes of the seismoelectric signals induced in the different directions are identical. Because the permeability of Berea sandstone 500 is higher than that of Berea sandstone 100, the amplitude of the seismoelectric signals induced in Berea 500 is higher than that in Berea 100. Experimental results show that the seismoelectric conversion is related not only to the porosity, but also to the permeability. The seismoelectric signals induced in the high permeability direction is stronger than that in the lower permeability direction. Seismoelectric measurements might help to measure the permeability of a formation directly.