Estimation of Pore Size Distribution and Permeability of Shaly Sands from Induced Polarization Time Spectra

The induced polarization decay curve contains much information, which can be decomposed to a multi-exponential decay component. The singular value decomposition 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 the total porosity from core measurements.