A time domain induced polarization relaxation time spectrum inversion method based on a damping factor and residual correction

Abstract

Relaxation time spectra (RTS) derived from time domain induced polarization data (TDIP) are helpful to assess oil reservoir pore structures. However, due to the sensitivity to the signal-to-noise ratio (SNR), the inversion accuracy of the traditional singular value decomposition (SVD) inversion method reduces with a decrease of SNR. In order to enhance the inversion accuracy and improve robustness of the inversion method to the SNR, an improved inversion method, based on damping factor and spectrum component residual correction, is proposed in this study. The numerical inversion results show that the oscillation of the RTS derived from the SVD method increased with a decrease of SNR, which makes components of the improved method, and the RTS has high inversion accuracy and robustness. Moreover, RTS derived from core sample data is basically in accord with the pore-size distribution curve, and the RTS derived from the actual induced polarization logging data is smooth and continuous, which indicates that the improved method is practicable.

Numerical Simulation Study on the Relationships between Mineralized Structures and Induced Polarization Properties of Seafloor Polymetallic Sulfide Rocks

“…A relaxation time distribution (RTD) can characterize polarization magnitude as a function of its characteristic relaxation time. These characteristic relaxation times relate to the physical properties of rocks, such as pore-size distribution in sandstone, and the polarizable sources [33][34][35]. In this study, based on the time-dependent chargeability decays obtained from the numerical simulation, the RTD was inverted using a regularization method.…”