Estimation of permeability of shaly sand reservoir from induced polarization relaxation time spectra

The induced polarization (IP) decay curve contains more information than the polarizability which was used in the conventional induced polarization logging tool. The Singular Value Decomposition (SVD) method makes it possible to transform induced polarization decay data into relaxation time spectra. The appropriate number of relaxation arrangement points in relaxation data inversion ranges from 32 to 64. The induced polarization relaxation time spectrum can be used to quantitatively estimate the pore size distribution of the shaly sands saturated with the NaCl brine. Combining the average IP relaxation time constant with the porosity can markedly improve the accuracy of determining the permeability over using total porosity from core measurements.